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  • Too much I/O in the morning ?

    - by steveh99999
    Interesting little improvement on a SQL 2005 system I encountered recently….. Some background - this system had a fairly ‘traditional OLTP’ workload ie  heavily used during day – till around 9pm, then had a batch window for several hours, then not much activity in the early hours of the day, until normal workload resumed the following morning. Using perfmon, I noticed that every morning, we would see a big spike in SQL Server I/O when the application started to be used... As it was 2005 I decided to look at what tables were in cache before and after the overnight batch processing ran… ( using DMV equivalent of dbcc memusage that I posted earlier). Here’s what I saw :-     So, contents of data cache split fairly evenly between my 'important/heavily used' tables.   After this:- some application batch processing,backups, DBCC checks and reindexes were run.  A fairly standard batch I'd suggest. Cache contents then looked like this :- Hmmmm – most of cache is now being used by a table I’ve described as ‘unimportant’. Why ? Well, that table was the last to be reindexed…. purely due to luck, as  the reindexing stored procedure performing a loop in alphabetical order through all application tables...  When the application starts to be used again – all this ‘unimportant’ data has to be replaced in cache by data that is heavily used… So, we changed the overnight reindex scripts –  the most heavily accessed tables are now the last to be reindexed. Obvious really, but we did see a significant reduction in early-morning I/O after changing the order of our reindexing.  

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  • Is there a canonical source supporting "all-surrogates"?

    - by user61852
    Background The "all-PK-must-be-surrogates" approach is not present in Codd's Relational Model or any SQL Standard (ANSI, ISO or other). Canonical books seems to elude this restrictions too. Oracle's own data dictionary scheme uses natural keys in some tables and surrogate keys in other tables. I mention this because these people must know a thing or two about RDBMS design. PPDM (Professional Petroleum Data Management Association) recommend the same canonical books do: Use surrogate keys as primary keys when: There are no natural or business keys Natural or business keys are bad ( change often ) The value of natural or business key is not known at the time of inserting record Multicolumn natural keys ( usually several FK ) exceed three columns, which makes joins too verbose. Also I have not found canonical source that says natural keys need to be immutable. All I find is that they need to be very estable, i.e need to be changed only in very rare ocassions, if ever. I mention PPDM because these people must know a thing or two about RDBMS design too. The origins of the "all-surrogates" approach seems to come from recommendations from some ORM frameworks. It's true that the approach allows for rapid database modeling by not having to do much business analysis, but at the expense of maintainability and readability of the SQL code. Much prevision is made for something that may or may not happen in the future ( the natural PK changed so we will have to use the RDBMS cascade update funtionality ) at the expense of day-to-day task like having to join more tables in every query and having to write code for importing data between databases, an otherwise very strightfoward procedure (due to the need to avoid PK colisions and having to create stage/equivalence tables beforehand ). Other argument is that indexes based on integers are faster, but that has to be supported with benchmarks. Obviously, long, varying varchars are not good for PK. But indexes based on short, fix-length varchar are almost as fast as integers. The questions - Is there any canonical source that supports the "all-PK-must-be-surrogates" approach ? - Has Codd's relational model been superceded by a newer relational model ?

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  • SQL RDBMS : one query or multiple calls

    - by None None
    After looking around the internet, I decided to create DAOs that returned objects (POJOs) to the calling business logic function/method. For example: a Customer object with a Address reference would be split in the RDBMS into two tables; Customer and ADDRESS. The CustomerDAO would be in charge of joining the data from the two tables and create both an Address POJO and Customer POJO adding the address to the customer object. Finally return the fulll Customer POJO. Simple, however, now i am at a point where i need to join three or four tables and each representing an attribute or list of attributes for the resulting POJO. The sql will include a group by but i will still result with multiple rows for the same pojo, because some of the tables are joining a one to many relationship. My app code will now have to loop through all the rows trying to figure out if the rows are the same with different attributes or if the record should be a new POJO. Should I continue to create my daos using this technique or break up my Pojo creation into multiple db calls to make the code easier to understand and maintain?

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  • Oracle Support Master Note for Troubleshooting Advanced Queuing and Oracle Streams Propagation Issues (Doc ID 233099.1)

    - by faye.todd(at)oracle.com
    Master Note for Troubleshooting Advanced Queuing and Oracle Streams Propagation Issues (Doc ID 233099.1) Copyright (c) 2010, Oracle Corporation. All Rights Reserved. In this Document  Purpose  Last Review Date  Instructions for the Reader  Troubleshooting Details     1. Scope and Application      2. Definitions and Classifications     3. How to Use This Guide     4. Basic AQ Propagation Troubleshooting     5. Additional Troubleshooting Steps for AQ Propagation of User-Enqueued and Dequeued Messages     6. Additional Troubleshooting Steps for Propagation in an Oracle Streams Environment     7. Performance Issues  References Applies to: Oracle Server - Enterprise Edition - Version: 8.1.7.0 to 11.2.0.2 - Release: 8.1.7 to 11.2Information in this document applies to any platform. Purpose This document presents a step-by-step methodology for troubleshooting and resolving problems with Advanced Queuing Propagation in both Streams and basic Advanced Queuing environments. It also serves as a master reference for other more specific notes on Oracle Streams Propagation and Advanced Queuing Propagation issues. Last Review Date December 20, 2010 Instructions for the Reader A Troubleshooting Guide is provided to assist in debugging a specific issue. When possible, diagnostic tools are included in the document to assist in troubleshooting. Troubleshooting Details 1. Scope and Application This note is intended for Database Administrators of Oracle databases where issues are being encountered with propagating messages between advanced queues, whether the queues are used for user-created messaging systems or for Oracle Streams. It contains troubleshooting steps and links to notes for further problem resolution.It can also be used a template to document a problem when it is necessary to engage Oracle Support Services. Knowing what is NOT happening can frequently speed up the resolution process by focusing solely on the pertinent problem area. This guide is divided into five parts: Section 2: Definitions and Classifications (discusses the different types and features of propagations possible - helpful for understanding the rest of the guide) Section 3: How to Use this Guide (to be used as a start part for determining the scope of the problem and what sections to consult) Section 4. Basic AQ propagation troubleshooting (applies to both AQ propagation of user enqueued and dequeued messages as well as Oracle Streams propagations) Section 5. Additional troubleshooting steps for AQ propagation of user enqueued and dequeued messages Section 6. Additional troubleshooting steps for Oracle Streams propagation Section 7. Performance issues 2. Definitions and Classifications Given the potential scope of issues that can be encountered with AQ propagation, the first recommended step is to do some basic diagnosis to determine the type of problem that is being encountered. 2.1. What Type of Propagation is Being Used? 2.1.1. Buffered Messaging For an advanced queue, messages can be maintained on disk (persistent messaging) or in memory (buffered messaging). To determine if a queue is buffered or not, reference the GV_$BUFFERED_QUEUES view. If the queue does not appear in this view, it is persistent. 2.1.2. Propagation mode - queue-to-dblink vs queue-to-queue As of 10.2, an AQ propagation can also be defined as queue-to-dblink, or queue-to-queue: queue-to-dblink: The propagation delivers messages or events from the source queue to all subscribing queues at the destination database identified by the dblink. A single propagation schedule is used to propagate messages to all subscribing queues. Hence any changes made to this schedule will affect message delivery to all the subscribing queues. This mode does not support multiple propagations from the same source queue to the same target database. queue-to-queue: Added in 10.2, this propagation mode delivers messages or events from the source queue to a specific destination queue identified on the database link. This allows the user to have fine-grained control on the propagation schedule for message delivery. This new propagation mode also supports transparent failover when propagating to a destination Oracle RAC system. With queue-to-queue propagation, you are no longer required to re-point a database link if the owner instance of the queue fails on Oracle RAC. This mode supports multiple propagations to the same target database if the target queues are different. The default is queue-to-dblink. To verify if queue-to-queue propagation is being used, in non-Streams environments query DBA_QUEUE_SCHEDULES.DESTINATION - if a remote queue is listed along with the remote database link, then queue-to-queue propagation is being used. For Streams environments, the DBA_PROPAGATION.QUEUE_TO_QUEUE column can be checked.See the following note for a method to switch between the two modes:Document 827473.1 How to alter propagation from queue-to-queue to queue-to-dblink 2.1.3. Combined Capture and Apply (CCA) for Streams In 11g Oracle Streams environments, an optimization called Combined Capture and Apply (CCA) is implemented by default when possible. Although a propagation is configured in this case, Streams does not use it; instead it passes information directly from capture to an apply receiver. To see if CCA is in use: COLUMN CAPTURE_NAME HEADING 'Capture Name' FORMAT A30COLUMN OPTIMIZATION HEADING 'CCA Mode?' FORMAT A10SELECT CAPTURE_NAME, DECODE(OPTIMIZATION,0, 'No','Yes') OPTIMIZATIONFROM V$STREAMS_CAPTURE; Also, see the following note:Document 463820.1 Streams Combined Capture and Apply in 11g 2.2. Queue Table Compatibility There are three types of queue table compatibility. In more recent databases, queue tables may be present in all three modes of compatibility: 8.0 - earliest version, deprecated in 10.2 onwards 8.1 - support added for RAC, asynchronous notification, secure queues, queue level access control, rule-based subscribers, separate storage of history information 10.0 - if the database is in 10.1-compatible mode, then the default value for queue table compatibility is 10.0 2.3. Single vs Multiple Consumer Queue Tables If more than one recipient can dequeue a message from a queue, then its queue table is multiple consumer. You can propagate messages from a multiple-consumer queue to a single-consumer queue. Propagation from a single-consumer queue to a multiple-consumer queue is not possible. 3. How to Use This Guide 3.1. Are Messages Being Propagated at All, or is the Propagation Just Slow? Run the following query on the source database for the propagation (assuming that it is running): select TOTAL_NUMBER from DBA_QUEUE_SCHEDULES where QNAME='<source_queue_name>'; If TOTAL_NUMBER is increasing, then propagation is most likely functioning, although it may be slow. For performance issues, see Section 7. 3.2. Propagation Between Persistent User-Created Queues See Sections 4 and 5 (and optionally Section 6 if performance is an issue). 3.3. Propagation Between Buffered User-Created Queues See Sections 4, 5, and 6 (and optionally Section 7 if performance is an issue). 3.4. Propagation between Oracle Streams Queues (without Combined Capture and Apply (CCA) Optimization) See Sections 4 and 6 (and optionally Section 7 if performance is an issue). 3.5. Propagation between Oracle Streams Queues (with Combined Capture and Apply (CCA) Optimization) Although an AQ propagation is not used directly in this case, some characteristics of the message transfer are inferred from the propagation parameters used. Some parts of Sections 4 and 6 still apply. 3.6. Messaging Gateway Propagations This note does not apply to Messaging Gateway propagations. 4. Basic AQ Propagation Troubleshooting 4.1. Double-check Your Code Make sure that you are consistent in your usage of the database link(s) names, queue names, etc. It may be useful to plot a diagram of which queues are connected via which database links to make sure that the logical structure is correct. 4.2. Verify that Job Queue Processes are Running 4.2.1. Versions 10.2 and Lower - DBA_JOBS Package For versions 10.2 and lower, a scheduled propagation is managed by DBMS_JOB package. The propagation is performed by job queue process background processes. Therefore we need to verify that there are sufficient processes available for the propagation process. We should have at least 4 job queue processes running and preferably more depending on the number of other jobs running in the database. It should be noted that for AQ specific work, AQ will only ever use half of the job queue processes available.An issue caused by an inadequate job queue processes parameter setting is described in the following note:Document 298015.1 Kwqjswproc:Excep After Loop: Assigning To Self 4.2.1.1. Job Queue Processes in Initalization Parameter File The parameter JOB_QUEUE_PROCESSES in the init.ora/spfile should be > 0. The value can be changed dynamically via connect / as sysdbaalter system set JOB_QUEUE_PROCESSES=10; 4.2.1.2. Job Queue Processes in Memory The following command will show how many job queue processes are currentlyin use by this instance (this may be different than what is in the init.ora/spfile): connect / as sysdbashow parameter job; 4.2.1.3. OS PIDs Corresponding to Job Queue Processes Identify the operating system process ids (spids) of job queue processes involved in propagation via select p.SPID, p.PROGRAM from V$PROCESS p, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j where s.SID=jr.SID and s.PADDR=p.ADDR and jr.JOB=j.JOBand j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%'; and these SPIDs can be used to check at the operating system level that they exist.In 8i a job queue process will have a name similar to: ora_snp1_<instance_name>.In 9i onwards you will see a coordinator process: ora_cjq0_ and multiple slave processes: ora_jnnn_<instance_name>, where nnn is an integer between 1 and 999. 4.2.2. Version 11.1 and Above - Oracle Scheduler In version 11.1 and above, Oracle Scheduler is used to perform AQ and Streams propagations. Oracle Scheduler automatically tunes the number of slave processes for these jobs based on the load on the computer system, and the JOB_QUEUE_PROCESSES initialization parameter is only used to specify the maximum number of slave processes. Therefore, the JOB_QUEUE_PROCESSES initialization parameter does not need to be set (it defaults to a very high number), unless you want to limit the number of slaves that can be created. If JOB_QUEUE_PROCESSES = 0, no propagation jobs will run.See the following note for a discussion of Oracle Streams 11g and Oracle Scheduler:Document 1083608.1 11g Streams and Oracle Scheduler 4.2.2.1. Job Queue Processes in Initalization Parameter File The parameter JOB_QUEUE_PROCESSES in the init.ora/spfile should be > 0, and preferably be left at its default value. The value can be changed dynamically via connect / as sysdbaalter system set JOB_QUEUE_PROCESSES=10; To set the JOB_QUEUE_PROCESSES parameter to its default value, run: connect / as sysdbaalter system reset JOB_QUEUE_PROCESSES; and then bounce the instance. 4.2.2.2. Job Queue Processes in Memory The following command will show how many job queue processes are currently in use by this instance (this may be different than what is in the init.ora/spfile): connect / as sysdbashow parameter job; 4.2.2.3. OS PIDs Corresponding to Job Queue Processes Identify the operating system process ids (SPIDs) of job queue processes involved in propagation via col PROGRAM for a30select p.SPID, p.PROGRAM, j.JOB_namefrom v$PROCESS p, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j where s.SID=jr.SESSION_ID and s.PADDR=p.ADDRand jr.JOB_name=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%'; and these SPIDs can be used to check at the operating system level that they exist.You will see a coordinator process: ora_cjq0_ and multiple slave processes: ora_jnnn_<instance_name>, where nnn is an integer between 1 and 999. 4.3. Check the Alert Log and Any Associated Trace Files The first place to check for propagation failures is the alert logs at all sites (local and if relevant all remote sites). When a job queue process attempts to execute a schedule and fails it will always write an error stack to the alert log. This error stack will also be written in a job queue process trace file, which will be written to the BACKGROUND_DUMP_DEST location for 10.2 and below, and in the DIAGNOSTIC_DEST location for 11g. The fact that errors are written to the alert log demonstrates that the schedule is executing. This means that the problem could be with the set up of the schedule. In this example the ORA-02068 demonstrates that the failure was at the remote site. Further investigation revealed that the remote database was not open, hence the ORA-03114 error. Starting the database resolved the problem. Thu Feb 14 10:40:05 2002 Propagation Schedule for (AQADM.MULTIPLEQ, SHANE816.WORLD) encountered following error:ORA-04052: error occurred when looking up Remote object [email protected]: error occurred at recursive SQL level 4ORA-02068: following severe error from SHANE816ORA-03114: not connected to ORACLEORA-06512: at "SYS.DBMS_AQADM_SYS", line 4770ORA-06512: at "SYS.DBMS_AQADM", line 548ORA-06512: at line 1 Other potential errors that may be written to the alert log can be found in the following notes:Document 827184.1 AQ Propagation with CLOB data types Fails with ORA-22990 (11.1)Document 846297.1 AQ Propagation Fails : ORA-00600[kope2upic2954] or Ora-00600[Kghsstream_copyn] (10.2, 11.1)Document 731292.1 ORA-25215 Reported on Local Propagation When Using Transformation with ANYDATA queue tables (10.2, 11.1, 11.2)Document 365093.1 ORA-07445 [kwqppay2aqe()+7360] Reported on Propagation of a Transformed Message (10.1, 10.2)Document 219416.1 Advanced Queuing Propagation Fails with ORA-22922 (9.0)Document 1203544.1 AQ Propagation Aborted with ORA-600 [ociksin: invalid status] on SYS.DBMS_AQADM_SYS.AQ$_PROPAGATION_PROCEDURE After Upgrade (11.1, 11.2)Document 1087324.1 ORA-01405 ORA-01422 reported by Advanced Queuing Propagation schedules after RAC reconfiguration (10.2)Document 1079577.1 Advanced Queuing Propagation Fails With "ORA-22370 incorrect usage of method" (9.2, 10.2, 11.1, 11.2)Document 332792.1 ORA-04061 error relating to SYS.DBMS_PRVTAQIP reported when setting up Statspack (8.1, 9.0, 9.2, 10.1)Document 353325.1 ORA-24056: Internal inconsistency for QUEUE <queue_name> and destination <dblink> (8.1, 9.0, 9.2, 10.1, 10.2, 11.1, 11.2)Document 787367.1 ORA-22275 reported on Propagating Messages with LOB component when propagating between 10.1 and 10.2 (10.1, 10.2)Document 566622.1 ORA-22275 when propagating >4K AQ$_JMS_TEXT_MESSAGEs from 9.2.0.8 to 10.2.0.1 (9.2, 10.1)Document 731539.1 ORA-29268: HTTP client error 401 Unauthorized Error when the AQ Servlet attempts to Propagate a message via HTTP (9.0, 9.2, 10.1, 10.2, 11.1)Document 253131.1 Concurrent Writes May Corrupt LOB Segment When Using Auto Segment Space Management (ORA-1555) (9.2)Document 118884.1 How to unschedule a propagation schedule stuck in pending stateDocument 222992.1 DBMS_AQADM.DISABLE_PROPAGATION_SCHEDULE Returns ORA-24082Document 282987.1 Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueDocument 1204080.1 AQ Propagation Failing With ORA-25329 After Upgraded From 8i or 9i to 10g or 11g.Document 1233675.1 AQ Propagation stops after upgrade to 11.2.0.1 ORA-30757 4.3.1. Errors Related to Incorrect Network Configuration The most common propagation errors result from an incorrect network configuration. The list below contains common errors caused by tnsnames.ora file or database links being configured incorrectly: - ORA-12154: TNS:could not resolve service name- ORA-12505: TNS:listener does not currently know of SID given in connect descriptor- ORA-12514: TNS:listener could not resolve SERVICE_NAME - ORA-12541: TNS-12541 TNS:no listener 4.4. Check the Database Links Exist and are Functioning Correctly For schedules to remote databases confirm the database link exists via. SQL> col DBLINK for a45SQL> select QNAME, NVL(REGEXP_SUBSTR(DESTINATION, '[^@]+', 1, 2), DESTINATION) dblink2 from DBA_QUEUE_SCHEDULES3 where MESSAGE_DELIVERY_MODE = 'PERSISTENT';QNAME DBLINK------------------------------ ---------------------------------------------MY_QUEUE ORCL102B.WORLD Connect as the owner of the link and select across it to verify it works and connects to the database we expect. i.e. select * from ALL_QUEUES@ ORCL102B.WORLD; You need to ensure that the userid that scheduled the propagation (using DBMS_AQADM.SCHEDULE_PROPAGATION or DBMS_PROPAGATION_ADM.CREATE_PROPAGATION if using Streams) has access to the database link for the destination. 4.5. Has Propagation Been Correctly Scheduled? Check that the propagation schedule has been created and that a job queue process has been assigned. Look for the entry in DBA_QUEUE_SCHEDULES and SYS.AQ$_SCHEDULES for your schedule. For 10g and below, check that it has a JOBNO entry in SYS.AQ$_SCHEDULES, and that there is an entry in DBA_JOBS with that JOBNO. For 11g and above, check that the schedule has a JOB_NAME entry in SYS.AQ$_SCHEDULES, and that there is an entry in DBA_SCHEDULER_JOBS with that JOB_NAME. Check the destination is as intended and spelled correctly. SQL> select SCHEMA, QNAME, DESTINATION, SCHEDULE_DISABLED, PROCESS_NAME from DBA_QUEUE_SCHEDULES;SCHEMA QNAME DESTINATION S PROCESS------- ---------- ------------------ - -----------AQADM MULTIPLEQ AQ$_LOCAL N J000 AQ$_LOCAL in the destination column shows that the queue to which we are propagating to is in the same database as the source queue. If the propagation was to a remote (different) database, a database link will be in the DESTINATION column. The entry in the SCHEDULE_DISABLED column, N, means that the schedule is NOT disabled. If Y (yes) appears in this column, propagation is disabled and the schedule will not be executed. If not using Oracle Streams, propagation should resume once you have enabled the schedule by invoking DBMS_AQADM.ENABLE_PROPAGATION_SCHEDULE (for 10.2 Oracle Streams and above, the DBMS_PROPAGATION_ADM.START_PROPAGATION procedure should be used). The PROCESS_NAME is the name of the job queue process currently allocated to execute the schedule. This process is allocated dynamically at execution time. If the PROCESS_NAME column is null (empty) the schedule is not currently executing. You may need to execute this statement a number of times to verify if a process is being allocated. If a process is at some time allocated to the schedule, it is attempting to execute. SQL> select SCHEMA, QNAME, LAST_RUN_DATE, NEXT_RUN_DATE from DBA_QUEUE_SCHEDULES;SCHEMA QNAME LAST_RUN_DATE NEXT_RUN_DATE------ ----- ----------------------- ----------------------- AQADM MULTIPLEQ 13-FEB-2002 13:18:57 13-FEB-2002 13:20:30 In 11g, these dates are expressed in TIMESTAMP WITH TIME ZONE datatypes. If the NEXT_RUN_DATE and NEXT_RUN_TIME columns are null when this statement is executed, the scheduled propagation is currently in progress. If they never change it would suggest that the schedule itself is never executing. If the next scheduled execution is too far away, change the NEXT_TIME parameter of the schedule so that schedules are executed more frequently (assuming that the window is not set to be infinite). Parameters of a schedule can be changed using the DBMS_AQADM.ALTER_PROPAGATION_SCHEDULE call. In 10g and below, scheduling propagation posts a job in the DBA_JOBS view. The columns are more or less the same as DBA_QUEUE_SCHEDULES so you just need to recognize the job and verify that it exists. SQL> select JOB, WHAT from DBA_JOBS where WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%';JOB WHAT---- ----------------- 720 next_date := sys.dbms_aqadm.aq$_propaq(job); For 11g, scheduling propagation posts a job in DBA_SCHEDULER_JOBS instead: SQL> select JOB_NAME from DBA_SCHEDULER_JOBS where JOB_NAME like 'AQ_JOB$_%';JOB_NAME------------------------------AQ_JOB$_41 If no job exists, check DBA_QUEUE_SCHEDULES to make sure that the schedule has not been disabled. For 10g and below, the job number is dynamic for AQ propagation schedules. The procedure that is executed to expedite a propagation schedule runs, removes itself from DBA_JOBS, and then reposts a new job for the next scheduled propagation. The job number should therefore always increment unless the schedule has been set up to run indefinitely. 4.6. Is the Schedule Executing but Failing to Complete? Run the following query: SQL> select FAILURES, LAST_ERROR_MSG from DBA_QUEUE_SCHEDULES;FAILURES LAST_ERROR_MSG------------ -----------------------1 ORA-25207: enqueue failed, queue AQADM.INQ is disabled from enqueueingORA-02063: preceding line from SHANE816 The failures column shows how many times we have attempted to execute the schedule and failed. Oracle will attempt to execute the schedule 16 times after which it will be removed from the DBA_JOBS or DBA_SCHEDULER_JOBS view and the schedule will become disabled. The column DBA_QUEUE_SCHEDULES.SCHEDULE_DISABLED will show 'Y'. For 11g and above, the DBA_SCHEDULER_JOBS.STATE column will show 'BROKEN' for the job corresponding to DBA_QUEUE_SCHEDULES.JOB_NAME. Prior to 10g the back off algorithm for failures was exponential, whereas from 10g onwards it is linear. The propagation will become disabled on the 17th attempt. Only the last execution failure will be reflected in the LAST_ERROR_MSG column. That is, if the schedule fails 5 times for 5 different reasons, only the last set of errors will be recorded in DBA_QUEUE_SCHEDULES. Any errors need to be resolved to allow propagation to continue. If propagation has also become disabled due to 17 failures, first resolve the reason for the error and then re-enable the schedule using the DBMS_AQADM.ENABLE_PROPAGATION_SCHEDULE procedure, or DBMS_PROPAGATION_ADM.START_PROPAGATION if using 10.2 or above Oracle Streams. As soon as the schedule executes successfully the error message entries will be deleted. Oracle does not keep a history of past failures. However, when using Oracle Streams, the errors will be retained in the DBA_PROPAGATION view even after the schedule resumes successfully. See the following note for instructions on how to clear out the errors from the DBA_PROPAGATION view:Document 808136.1 How to clear the old errors from DBA_PROPAGATION view?If a schedule is active and no errors are being reported then the source queue may not have any messages to be propagated. 4.7. Do the Propagation Notification Queue Table and Queue Exist? Check to see that the propagation notification queue table and queue exist and are enabled for enqueue and dequeue. Propagation makes use of the propagation notification queue for handling propagation run-time events, and the messages in this queue are stored in a SYS-owned queue table. This queue should never be stopped or dropped and the corresponding queue table never be dropped. 10g and belowThe propagation notification queue table is of the format SYS.AQ$_PROP_TABLE_n, where 'n' is the RAC instance number, i.e. '1' for a non-RAC environment. This queue and queue table are created implicitly when propagation is first scheduled. If propagation has been scheduled and these objects do not exist, try unscheduling and rescheduling propagation. If they still do not exist contact Oracle Support. SQL> select QUEUE_TABLE from DBA_QUEUE_TABLES2 where QUEUE_TABLE like '%PROP_TABLE%' and OWNER = 'SYS';QUEUE_TABLE------------------------------AQ$_PROP_TABLE_1SQL> select NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED2 from DBA_QUEUES where owner='SYS'3 and QUEUE_TABLE like '%PROP_TABLE%';NAME ENQUEUE DEQUEUE------------------------------ ------- -------AQ$_PROP_NOTIFY_1 YES YESAQ$_AQ$_PROP_TABLE_1_E NO NO If the AQ$_PROP_NOTIFY_1 queue is not enabled for enqueue or dequeue, it should be so enabled using DBMS_AQADM.START_QUEUE. However, the exception queue AQ$_AQ$_PROP_TABLE_1_E should not be enabled for enqueue or dequeue.11g and aboveThe propagation notification queue table is of the format SYS.AQ_PROP_TABLE, and is created when the database is created. If they do not exist, contact Oracle Support. SQL> select QUEUE_TABLE from DBA_QUEUE_TABLES2 where QUEUE_TABLE like '%PROP_TABLE%' and OWNER = 'SYS';QUEUE_TABLE------------------------------AQ_PROP_TABLESQL> select NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED2 from DBA_QUEUES where owner='SYS'3 and QUEUE_TABLE like '%PROP_TABLE%';NAME ENQUEUE DEQUEUE------------------------------ ------- -------AQ_PROP_NOTIFY YES YESAQ$_AQ_PROP_TABLE_E NO NO If the AQ_PROP_NOTIFY queue is not enabled for enqueue or dequeue, it should be so enabled using DBMS_AQADM.START_QUEUE. However, the exception queue AQ$_AQ$_PROP_TABLE_E should not be enabled for enqueue or dequeue. 4.8. Does the Remote Queue Exist and is it Enabled for Enqueueing? Check that the remote queue the propagation is transferring messages to exists and is enabled for enqueue: SQL> select DESTINATION from USER_QUEUE_SCHEDULES where QNAME = 'OUTQ';DESTINATION-----------------------------------------------------------------------------"AQADM"."INQ"@M2V102.ESSQL> select OWNER, NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED from [email protected];OWNER NAME ENQUEUE DEQUEUE-------- ------ ----------- -----------AQADM INQ YES YES 4.9. Do the Target and Source Database Charactersets Differ? If a message fails to propagate, check the database charactersets of the source and target databases. Investigate whether the same message can propagate between the databases with the same characterset or it is only a particular combination of charactersets which causes a problem. 4.10. Check the Queue Table Type Agreement Propagation is not possible between queue tables which have types that differ in some respect. One way to determine if this is the case is to run the DBMS_AQADM.VERIFY_QUEUE_TYPES procedure for the two queues that the propagation operates on. If the types do not agree, DBMS_AQADM.VERIFY_QUEUE_TYPES will return '0'.For AQ propagation between databases which have different NLS_LENGTH_SEMANTICS settings, propagation will not work, unless the queues are Oracle Streams ANYDATA queues.See the following notes for issues caused by lack of type agreement:Document 1079577.1 Advanced Queuing Propagation Fails With "ORA-22370: incorrect usage of method"Document 282987.1 Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueDocument 353754.1 Streams Messaging Propagation Fails between Single and Multi-byte Charactersets when using Chararacter Length Semantics in the ADT 4.11. Enable Propagation Tracing 4.11.1. System Level This is set it in the init.ora/spfile as follows: event="24040 trace name context forever, level 10" and restart the instanceThis event cannot be set dynamically with an alter system command until version 10.2: SQL> alter system set events '24040 trace name context forever, level 10'; To unset the event: SQL> alter system set events '24040 trace name context off'; Debugging information will be logged to job queue trace file(s) (jnnn) as propagation takes place. You can check the trace file for errors, and for statements indicating that messages have been sent. For the most part the trace information is understandable. This trace should also be uploaded to Oracle Support if a service request is created. 4.11.2. Attaching to a Specific Process We can also attach to an existing job queue processes that is running a propagation schedule and trace it individually using the oradebug utility, as follows:10.2 and below connect / as sysdbaselect p.SPID, p.PROGRAM from v$PROCESS p, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j where s.SID=jr.SID and s.PADDR=p.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%';-- For the process id (SPID) attach to it via oradebug and generate the following traceoradebug setospid <SPID>oradebug unlimitoradebug Event 10046 trace name context forever, level 12oradebug Event 24040 trace name context forever, level 10-- Trace the process for 5 minutesoradebug Event 10046 trace name context offoradebug Event 24040 trace name context off-- The following command returns the pathname/filename to the file being written tooradebug tracefile_name 11g connect / as sysdbacol PROGRAM for a30select p.SPID, p.PROGRAM, j.JOB_NAMEfrom v$PROCESS p, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j where s.SID=jr.SESSION_ID and s.PADDR=p.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%';-- For the process id (SPID) attach to it via oradebug and generate the following traceoradebug setospid <SPID>oradebug unlimitoradebug Event 10046 trace name context forever, level 12oradebug Event 24040 trace name context forever, level 10-- Trace the process for 5 minutesoradebug Event 10046 trace name context offoradebug Event 24040 trace name context off-- The following command returns the pathname/filename to the file being written tooradebug tracefile_name 4.11.3. Further Tracing The previous tracing steps only trace the job queue process executing the propagation on the source. At times it is useful to trace the propagation receiver process (the session which is enqueueing the messages into the target queue) on the target database which is associated with the job queue process on the source database.These following queries provide ways of identifying the processes involved in propagation so that you can attach to them via oradebug to generate trace information.In order to identify the propagation receiver process you need to execute the query as a user with privileges to access the v$ views in both the local and remote databases so the database link must connect as a user with those privileges in the remote database. The <DBLINK> in the queries should be replaced by the appropriate database link.The queries have two forms due to the differences between operating systems. The value returned by 'Rem Process' is the operating system identifier of the propagation receiver on the remote database. Once identified, this process can be attached to and traced on the remote database using the commands given in Section 4.11.2.10.2 and below - Windows select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from v$PROCESS pl, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SID and s.PADDR=pl.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%' and pl.SPID=substr(sr.PROCESS, instr(sr.PROCESS,':')+1); 10.2 and below - Unix select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SID and s.PADDR=pl.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%' and pl.SPID=sr.PROCESS; 11g - Windows select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SESSION_ID and s.PADDR=pl.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%%' and pl.SPID=substr(sr.PROCESS, instr(sr.PROCESS,':')+1); 11g - Unix select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SESSION_ID and s.PADDR=pl.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%%' and pl.SPID=sr.PROCESS;   5. Additional Troubleshooting Steps for AQ Propagation of User-Enqueued and Dequeued Messages 5.1. Check the Privileges of All Users Involved Ensure that the owner of the database link has the necessary privileges on the aq packages. SQL> select TABLE_NAME, PRIVILEGE from USER_TAB_PRIVS;TABLE_NAME PRIVILEGE------------------------------ ----------------------------------------DBMS_LOCK EXECUTEDBMS_AQ EXECUTEDBMS_AQADM EXECUTEDBMS_AQ_BQVIEW EXECUTEQT52814_BUFFER SELECT Note that when queue table is created, a view called QT<nnn>_BUFFER is created in the SYS schema, and the queue table owner is given SELECT privileges on it. The <nnn> corresponds to the object_id of the associated queue table. SQL> select * from USER_ROLE_PRIVS;USERNAME GRANTED_ROLE ADM DEF OS_------------------------------ ------------------------------ ---- ---- ---AQ_USER1 AQ_ADMINISTRATOR_ROLE NO YES NOAQ_USER1 CONNECT NO YES NOAQ_USER1 RESOURCE NO YES NO It is good practice to configure central AQ administrative user. All admin and processing jobs are created, executed and administered as this user. This configuration is not mandatory however, and the database link can be owned by any existing queue user. If this latter configuration is used, ensure that the connecting user has the necessary privileges on the AQ packages and objects involved. Privileges for an AQ Administrative user Execute on DBMS_AQADM Execute on DBMS_AQ Granted the AQ_ADMINISTRATOR_ROLE Privileges for an AQ user Execute on DBMS_AQ Execute on the message payload Enqueue privileges on the remote queue Dequeue privileges on the originating queue Privileges need to be confirmed on both sites when propagation is scheduled to remote destinations. Verify that the user ID used to login to the destination through the database link has been granted privileges to use AQ. 5.2. Verify Queue Payload Types AQ will not propagate messages from one queue to another if the payload types of the two queues are not verified to be equivalent. An AQ administrator can verify if the source and destination's payload types match by executing the DBMS_AQADM.VERIFY_QUEUE_TYPES procedure. The results of the type checking will be stored in the SYS.AQ$_MESSAGE_TYPES table. This table can be accessed using the object identifier OID of the source queue and the address database link of the destination queue, i.e. [schema.]queue_name[@destination]. Prior to Oracle 9i the payload (message type) had to be the same for all the queue tables involved in propagation. From Oracle9i onwards a transformation can be used so that payloads can be converted from one type to another. The following procedural call made on the source database can verify whether we can propagate between the source and the destination queue tables. connect aq_user1/[email protected] serverout onDECLARErc_value number;BEGINDBMS_AQADM.VERIFY_QUEUE_TYPES(src_queue_name => 'AQ_USER1.Q_1', dest_queue_name => 'AQ_USER2.Q_2',destination => 'dbl_aq_user2.es',rc => rc_value);dbms_output.put_line('rc_value code is '||rc_value);END;/ If propagation is possible then the return code value will be 1. If it is 0 then propagation is not possible and further investigation of the types and transformations used by and in conjunction with the queue tables is required. With regard to comparison of the types the following sql can be used to extract the DDL for a specific type with' %' changed appropriately on the source and target. This can then be compared for the source and target. SET LONG 20000 set pagesize 50 EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM, 'STORAGE',false); SELECT DBMS_METADATA.GET_DDL('TYPE',t.type_name) from user_types t WHERE t.type_name like '%'; EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM, 'DEFAULT'); 5.3. Check Message State and Destination The first step in this process is to identify the queue table associated with the problem source queue. Although you schedule propagation for a specific queue, most of the meta-data associated with that queue is stored in the underlying queue table. The following statement finds the queue table for a given queue (note that this is a multiple-consumer queue table). SQL> select QUEUE_TABLE from DBA_QUEUES where NAME = 'MULTIPLEQ';QUEUE_TABLE --------------------MULTIPLEQTABLE For a small amount of messages in a multiple-consumer queue table, the following query can be run: SQL> select MSG_STATE, CONSUMER_NAME, ADDRESS from AQ$MULTIPLEQTABLE where QUEUE = 'MULTIPLEQ';MSG_STATE CONSUMER_NAME ADDRESS-------------- ----------------------- -------------READY AQUSER2 [email protected] AQUSER1READY AQUSER3 AQADM.INQ In this example we see 2 messages ready to be propagated to remote queues and 1 that is not. If the address column is blank, the message is not scheduled for propagation and can only be dequeued from the queue upon which it was enqueued. The MSG_STATE column values are discussed in Document 102330.1 Advanced Queueing MSG_STATE Values and their Interpretation. If the address column has a value, the message has been enqueued for propagation to another queue. The first row in the example includes a database link (@M2V102.ES). This demonstrates that the message should be propagated to a queue at a remote database. The third row does not include a database link so will be propagated to a queue that resides on the same database as the source queue. The consumer name is the intended recipient at the target queue. Note that we are not querying the base queue table directly; rather, we are querying a view that is available on top of every queue table, AQ$<queue_table_name>.A more realistic query in an environment where the queue table contains thousands of messages is8.0.3-compatible multiple-consumer queue table and all compatibility single-consumer queue tables select count(*), MSG_STATE, QUEUE from AQ$<queue_table_name>  group by MSG_STATE, QUEUE; 8.1.3 and 10.0-compatible queue tables select count(*), MSG_STATE, QUEUE, CONSUMER_NAME from AQ$<queue_table_name>group by MSG_STATE, QUEUE, CONSUMER_NAME; For multiple-consumer queue tables, if you did not see the expected CONSUMER_NAME , check the syntax of the enqueue code and verify the recipients are declared correctly. If a recipients list is not used on enqueue, check the subscriber list in the AQ$_<queue_table_name>_S view (note that a single-consumer queue table does not have a subscriber view. This view records all members of the default subscription list which were added using the DBMS_AQADM.ADD_SUBSCRIBER procedure and also those enqueued using a recipient list. SQL> select QUEUE, NAME, ADDRESS from AQ$MULTIPLEQTABLE_S;QUEUE NAME ADDRESS---------- ----------- -------------MULTIPLEQ AQUSER2 [email protected] AQUSER1 In this example we have 2 subscribers registered with the queue. We have a local subscriber AQUSER1, and a remote subscriber AQUSER2, on the queue INQ, owned by AQADM, at M2V102.ES. Unless overridden with a recipient list during enqueue every message enqueued to this queue will be propagated to INQ at M2V102.ES.For 8.1 style and above multiple consumer queue tables, you can also check the following information at the target: select CONSUMER_NAME, DEQ_TXN_ID, DEQ_TIME, DEQ_USER_ID, PROPAGATED_MSGID from AQ$<queue_table_name> where QUEUE = '<QUEUE_NAME>'; For 8.0 style queues, if the queue table supports multiple consumers you can obtain the same information from the history column of the queue table: select h.CONSUMER, h.TRANSACTION_ID, h.DEQ_TIME, h.DEQ_USER, h.PROPAGATED_MSGIDfrom AQ$<queue_table_name> t, table(t.history) h where t.Q_NAME = '<QUEUE_NAME>'; A non-NULL TRANSACTION_ID indicates that the message was successfully propagated. Further, the DEQ_TIME indicates the time of propagation, the DEQ_USER indicates the userid used for propagation, and the PROPAGATED_MSGID indicates the message ID of the message that was enqueued at the destination. 6. Additional Troubleshooting Steps for Propagation in an Oracle Streams Environment 6.1. Is the Propagation Enabled? For a propagation job to propagate messages, the propagation must be enabled. For Streams, a special view called DBA_PROPAGATION exists to convey information about Streams propagations. If messages are not being propagated by a propagation as expected, then the propagation might not be enabled. To query for this: SELECT p.PROPAGATION_NAME, DECODE(s.SCHEDULE_DISABLED, 'Y', 'Disabled','N', 'Enabled') SCHEDULE_DISABLED, s.PROCESS_NAME, s.FAILURES, s.LAST_ERROR_MSGFROM DBA_QUEUE_SCHEDULES s, DBA_PROPAGATION pWHERE p.DESTINATION_DBLINK = NVL(REGEXP_SUBSTR(s.DESTINATION, '[^@]+', 1, 2), s.DESTINATION) AND s.SCHEMA = p.SOURCE_QUEUE_OWNER AND s.QNAME = p.SOURCE_QUEUE_NAME AND MESSAGE_DELIVERY_MODE = 'PERSISTENT' order by PROPAGATION_NAME; At times, the propagation job may become "broken" or fail to start after an error has been encountered or after a database restart. If an error is indicated by the above query, an attempt to disable the propagation and then re-enable it can be made. In the examples below, for the propagation named STRMADMIN_PROPAGATE where the queue name is STREAMS_QUEUE owned by STRMADMIN and the destination database link is ORCL2.WORLD, the commands would be:10.2 and above exec dbms_propagation_adm.stop_propagation('STRMADMIN_PROPAGATE'); exec dbms_propagation_adm.start_propagation('STRMADMIN_PROPAGATE'); If the above does not fix the problem, stop the propagation specifying the force parameter (2nd parameter on stop_propagation) as TRUE: exec dbms_propagation_adm.stop_propagation('STRMADMIN_PROPAGATE',true); exec dbms_propagation_adm.start_propagation('STRMADMIN_PROPAGATE'); The statistics for the propagation as well as any old error messages are cleared when the force parameter is set to TRUE. Therefore if the propagation schedule is stopped with FORCE set to TRUE, and upon restart there is still an error message in DBA_PROPAGATION, then the error message is current.9.2 or 10.1 exec dbms_aqadm.disable_propagation_schedule('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); exec dbms.aqadm.enable_propagation_schedule('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); If the above does not fix the problem, perform an unschedule of propagation and then schedule_propagation: exec dbms_aqadm.unschedule_propagation('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); exec dbms_aqadm.schedule_propagation('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); Typically if the error from the first query in Section 6.1 recurs after restarting the propagation as shown above, further troubleshooting of the error is needed. 6.2. Check Propagation Rule Sets and Transformations Inspect the configuration of the rules in the rule set that is associated with the propagation process to make sure that they evaluate to TRUE as expected. If not, then the object or schema will not be propagated. Remember that when a negative rule evaluates to TRUE, the specified object or schema will not be propagated. Finally inspect any rule-based transformations that are implemented with propagation to make sure they are changing the data in the intended way.The following query shows what rule sets are assigned to a propagation: select PROPAGATION_NAME, RULE_SET_OWNER||'.'||RULE_SET_NAME "Positive Rule Set",NEGATIVE_RULE_SET_OWNER||'.'||NEGATIVE_RULE_SET_NAME "Negative Rule Set"from DBA_PROPAGATION; The next two queries list the propagation rules and their conditions. The first is for the positive rule set, the second is for the negative rule set: set long 4000select rsr.RULE_SET_OWNER||'.'||rsr.RULE_SET_NAME RULE_SET ,rsr.RULE_OWNER||'.'||rsr.RULE_NAME RULE_NAME,r.RULE_CONDITION CONDITION fromDBA_RULE_SET_RULES rsr, DBA_RULES rwhere rsr.RULE_NAME = r.RULE_NAME and rsr.RULE_OWNER = r.RULE_OWNER and RULE_SET_NAME in(select RULE_SET_NAME from DBA_PROPAGATION) order by rsr.RULE_SET_OWNER, rsr.RULE_SET_NAME;   set long 4000select c.PROPAGATION_NAME, rsr.RULE_SET_OWNER||'.'||rsr.RULE_SET_NAME RULE_SET ,rsr.RULE_OWNER||'.'||rsr.RULE_NAME RULE_NAME,r.RULE_CONDITION CONDITION fromDBA_RULE_SET_RULES rsr, DBA_RULES r ,DBA_PROPAGATION cwhere rsr.RULE_NAME = r.RULE_NAME and rsr.RULE_OWNER = r.RULE_OWNER andrsr.RULE_SET_OWNER=c.NEGATIVE_RULE_SET_OWNER and rsr.RULE_SET_NAME=c.NEGATIVE_RULE_SET_NAMEand rsr.RULE_SET_NAME in(select NEGATIVE_RULE_SET_NAME from DBA_PROPAGATION) order by rsr.RULE_SET_OWNER, rsr.RULE_SET_NAME; 6.3. Determining the Total Number of Messages and Bytes Propagated As in Section 3.1, determining if messages are flowing can be instructive to see whether the propagation is entirely hung or just slow. If the propagation is not in flow control (see Section 6.5.2), but the statistics are incrementing slowly, there may be a performance issue. For Streams implementations two views are available that can assist with this that can show the number of messages sent by a propagation, as well as the number of acknowledgements being returned from the target site: the V$PROPAGATION_SENDER view at the Source site and the V$PROPAGATION_RECEIVER view at the destination site. It is helpful to query both to determine if messages are being delivered to the target. Look for the statistics to increase.Source: select QUEUE_SCHEMA, QUEUE_NAME, DBLINK,HIGH_WATER_MARK, ACKNOWLEDGEMENT, TOTAL_MSGS, TOTAL_BYTESfrom V$PROPAGATION_SENDER; Target: select SRC_QUEUE_SCHEMA, SRC_QUEUE_NAME, SRC_DBNAME, DST_QUEUE_SCHEMA, DST_QUEUE_NAME, HIGH_WATER_MARK, ACKNOWLEDGEMENT, TOTAL_MSGS from V$PROPAGATION_RECEIVER; 6.4. Check Buffered Subscribers The V$BUFFERED_SUBSCRIBERS view displays information about subscribers for all buffered queues in the instance. This view can be queried to make sure that the site that the propagation is propagating to is listed as a subscriber address for the site being propagated from: select QUEUE_SCHEMA, QUEUE_NAME, SUBSCRIBER_ADDRESS from V$BUFFERED_SUBSCRIBERS; The SUBSCRIBER_ADDRESS column will not be populated when the propagation is local (between queues on the same database). 6.5. Common Streams Propagation Errors 6.5.1. ORA-02082: A loopback database link must have a connection qualifier. This error can occur if you use the Streams Setup Wizard in Oracle Enterprise Manager without first configuring the GLOBAL_NAME for your database. 6.5.2. ORA-25307: Enqueue rate too high. Enable flow control DBA_QUEUE_SCHEDULES will display this informational message for propagation when the automatic flow control (10g feature of Streams) has been invoked.Similar to Streams capture processes, a Streams propagation process can also go into a state of 'flow control. This is an informative message that indicates flow control has been automatically enabled to reduce the rate at which messages are being enqueued into at target queue.This typically occurs when the target site is unable to keep up with the rate of messages flowing from the source site. Other than checking that the apply process is running normally on the target site, usually no action is required by the DBA. Propagation and the capture process will be resumed automatically when the target site is able to accept more messages.The following document contains more information:Document 302109.1 Streams Propagation Error: ORA-25307 Enqueue rate too high. Enable flow controlSee the following document for one potential cause of this situation:Document 1097115.1 Oracle Streams Apply Reader is in 'Paused' State 6.5.3. ORA-25315 unsupported configuration for propagation of buffered messages This error typically occurs when the target database is RAC and usually indicates that an attempt was made to propagate buffered messages with the database link pointing to an instance in the destination database which is not the owner instance of the destination queue. To resolve the problem, use queue-to-queue propagation for buffered messages. 6.5.4. ORA-600 [KWQBMCRCPTS101] after dropping / recreating propagation For cause/fixes refer to:Document 421237.1 ORA-600 [KWQBMCRCPTS101] reported by a Qmon slave process after dropping a Streams Propagation 6.5.5. Stopping or Dropping a Streams Propagation Hangs See the following note:Document 1159787.1 Troubleshooting Streams Propagation When It is Not Functioning and Attempts to Stop It Hang 6.6. Streams Propagation-Related Notes for Common Issues Document 437838.1 Streams Specific PatchesDocument 749181.1 How to Recover Streams After Dropping PropagationDocument 368912.1 Queue to Queue Propagation Schedule encountered ORA-12514 in a RAC environmentDocument 564649.1 ORA-02068/ORA-03114/ORA-03113 Errors From Streams Propagation Process - Remote Database is Available and Unschedule/Reschedule Does Not ResolveDocument 553017.1 Stream Propagation Process Errors Ora-4052 Ora-6554 From 11g To 10201Document 944846.1 Streams Propagation Fails Ora-7445 [kohrsmc]Document 745601.1 ORA-23603 'STREAMS enqueue aborted due to low SGA' Error from Streams Propagation, and V$STREAMS_CAPTURE.STATE Hanging on 'Enqueuing Message'Document 333068.1 ORA-23603: Streams Enqueue Aborted Eue To Low SGADocument 363496.1 Ora-25315 Propagating on RAC StreamsDocument 368237.1 Unable to Unschedule Propagation. Streams Queue is InvalidDocument 436332.1 dbms_propagation_adm.stop_propagation hangsDocument 727389.1 Propagation Fails With ORA-12528Document 730911.1 ORA-4063 Is Reported After Dropping Negative Prop.RulesetDocument 460471.1 Propagation Blocked by Qmon Process - Streams_queue_table / 'library cache lock' waitsDocument 1165583.1 ORA-600 [kwqpuspse0-ack] In Streams EnvironmentDocument 1059029.1 Combined Capture and Apply (CCA) : Capture aborts : ORA-1422 after schedule_propagationDocument 556309.1 Changing Propagation/ queue_to_queue : false -> true does does not work; no LCRs propagatedDocument 839568.1 Propagation failing with error: ORA-01536: space quota exceeded for tablespace ''Document 311021.1 Streams Propagation Process : Ora 12154 After Reboot with Transparent Application Failover TAF configuredDocument 359971.1 STREAMS propagation to Primary of physical Standby configuation errors with Ora-01033, Ora-02068Document 1101616.1 DBMS_PROPAGATION_ADM.DROP_PROPAGATION FAILS WITH ORA-1747 7. Performance Issues A propagation may seem to be slow if the queries from Sections 3.1 and 6.3 show that the message statistics are not changing quickly. In Oracle Streams, this more usually is due to a slow apply process at the target rather than a slow propagation. Propagation could be inferred to be slow if the message statistics are changing, and the state of a capture process according to V$STREAMS_CAPTURE.STATE is PAUSED FOR FLOW CONTROL, but an ORA-25307 'Enqueue rate too high. Enable flow control' warning is NOT observed in DBA_QUEUE_SCHEDULES per Section 6.5.2. If this is the case, see the following notes / white papers for suggestions to increase performance:Document 335516.1 Master Note for Streams Performance RecommendationsDocument 730036.1 Overview for Troubleshooting Streams Performance IssuesDocument 780733.1 Streams Propagation Tuning with Network ParametersWhite Paper: http://www.oracle.com/technetwork/database/features/availability/maa-wp-10gr2-streams-performance-130059.pdfWhite Paper: Oracle Streams Configuration Best Practices: Oracle Database 10g Release 10.2, http://www.oracle.com/technetwork/database/features/availability/maa-10gr2-streams-configuration-132039.pdf, See APPENDIX A: USING STREAMS CONFIGURATIONS OVER A NETWORKFor basic AQ propagation, the network tuning in the aforementioned Appendix A of the white paper 'Oracle Streams Configuration Best Practices: Oracle Database 10g Release 10.2' is applicable. References NOTE:102330.1 - Advanced Queueing MSG_STATE Values and their InterpretationNOTE:102771.1 - Advanced Queueing Propagation using PL/SQLNOTE:1059029.1 - Combined Capture and Apply (CCA) : Capture aborts : ORA-1422 after schedule_propagationNOTE:1079577.1 - Advanced Queuing Propagation Fails With "ORA-22370: incorrect usage of method"NOTE:1083608.1 - 11g Streams and Oracle SchedulerNOTE:1087324.1 - ORA-01405 ORA-01422 reported by Adavanced Queueing Propagation schedules after RAC reconfigurationNOTE:1097115.1 - Oracle Streams Apply Reader is in 'Paused' StateNOTE:1101616.1 - DBMS_PROPAGATION_ADM.DROP_PROPAGATION FAILS WITH ORA-1747NOTE:1159787.1 - Troubleshooting Streams Propagation When It is Not Functioning and Attempts to Stop It HangNOTE:1165583.1 - ORA-600 [kwqpuspse0-ack] In Streams EnvironmentNOTE:118884.1 - How to unschedule a propagation schedule stuck in pending stateNOTE:1203544.1 - AQ PROPAGATION ABORTED WITH ORA-600[OCIKSIN: INVALID STATUS] ON SYS.DBMS_AQADM_SYS.AQ$_PROPAGATION_PROCEDURE AFTER UPGRADENOTE:1204080.1 - AQ Propagation Failing With ORA-25329 After Upgraded From 8i or 9i to 10g or 11g.NOTE:219416.1 - Advanced Queuing Propagation fails with ORA-22922NOTE:222992.1 - DBMS_AQADM.DISABLE_PROPAGATION_SCHEDULE Returns ORA-24082NOTE:253131.1 - Concurrent Writes May Corrupt LOB Segment When Using Auto Segment Space Management (ORA-1555)NOTE:282987.1 - Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueNOTE:298015.1 - Kwqjswproc:Excep After Loop: Assigning To SelfNOTE:302109.1 - Streams Propagation Error: ORA-25307 Enqueue rate too high. Enable flow controlNOTE:311021.1 - Streams Propagation Process : Ora 12154 After Reboot with Transparent Application Failover TAF configuredNOTE:332792.1 - ORA-04061 error relating to SYS.DBMS_PRVTAQIP reported when setting up StatspackNOTE:333068.1 - ORA-23603: Streams Enqueue Aborted Eue To Low SGANOTE:335516.1 - Master Note for Streams Performance RecommendationsNOTE:353325.1 - ORA-24056: Internal inconsistency for QUEUE and destination NOTE:353754.1 - Streams Messaging Propagation Fails between Single and Multi-byte Charactersets when using Chararacter Length Semantics in the ADT.NOTE:359971.1 - STREAMS propagation to Primary of physical Standby configuation errors with Ora-01033, Ora-02068NOTE:363496.1 - Ora-25315 Propagating on RAC StreamsNOTE:365093.1 - ORA-07445 [kwqppay2aqe()+7360] reported on Propagation of a Transformed MessageNOTE:368237.1 - Unable to Unschedule Propagation. Streams Queue is InvalidNOTE:368912.1 - Queue to Queue Propagation Schedule encountered ORA-12514 in a RAC environmentNOTE:421237.1 - ORA-600 [KWQBMCRCPTS101] reported by a Qmon slave process after dropping a Streams PropagationNOTE:436332.1 - dbms_propagation_adm.stop_propagation hangsNOTE:437838.1 - Streams Specific PatchesNOTE:460471.1 - Propagation Blocked by Qmon Process - Streams_queue_table / 'library cache lock' waitsNOTE:463820.1 - Streams Combined Capture and Apply in 11gNOTE:553017.1 - Stream Propagation Process Errors Ora-4052 Ora-6554 From 11g To 10201NOTE:556309.1 - Changing Propagation/ queue_to_queue : false -> true does does not work; no LCRs propagatedNOTE:564649.1 - ORA-02068/ORA-03114/ORA-03113 Errors From Streams Propagation Process - Remote Database is Available and Unschedule/Reschedule Does Not ResolveNOTE:566622.1 - ORA-22275 when propagating >4K AQ$_JMS_TEXT_MESSAGEs from 9.2.0.8 to 10.2.0.1NOTE:727389.1 - Propagation Fails With ORA-12528NOTE:730036.1 - Overview for Troubleshooting Streams Performance IssuesNOTE:730911.1 - ORA-4063 Is Reported After Dropping Negative Prop.RulesetNOTE:731292.1 - ORA-25215 Reported On Local Propagation When Using Transformation with ANYDATA queue tablesNOTE:731539.1 - ORA-29268: HTTP client error 401 Unauthorized Error when the AQ Servlet attempts to Propagate a message via HTTPNOTE:745601.1 - ORA-23603 'STREAMS enqueue aborted due to low SGA' Error from Streams Propagation, and V$STREAMS_CAPTURE.STATE Hanging on 'Enqueuing Message'NOTE:749181.1 - How to Recover Streams After Dropping PropagationNOTE:780733.1 - Streams Propagation Tuning with Network ParametersNOTE:787367.1 - ORA-22275 reported on Propagating Messages with LOB component when propagating between 10.1 and 10.2NOTE:808136.1 - How to clear the old errors from DBA_PROPAGATION view ?NOTE:827184.1 - AQ Propagation with CLOB data types Fails with ORA-22990NOTE:827473.1 - How to alter propagation from queue_to_queue to queue_to_dblinkNOTE:839568.1 - Propagation failing with error: ORA-01536: space quota exceeded for tablespace ''NOTE:846297.1 - AQ Propagation Fails : ORA-00600[kope2upic2954] or Ora-00600[Kghsstream_copyn]NOTE:944846.1 - Streams Propagation Fails Ora-7445 [kohrsmc]

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  • PHP vs Phpmyadmin

    - by user330306
    Hi there, I've got this code which i execute on phpmyadmin which works 100% Create Temporary Table Searches ( id int, dt datetime); Create Temporary Table Searches1 ( id int, dt datetime, count int); insert into Searches(id, dt) select a.id, now() from tblSavedSearches a; insert into Searches1(id, dt, count) select b.savedSearchesId, (select c.dt from tblSavedSearchesDetails c where b.savedSearchesId = c.savedSearchesId order by c.dt desc limit 1) as 'dt', count(b.savedSearchesId) as 'cnt' from tblSavedSearchesDetails b group by b.savedSearchesId; insert into tblSavedSearchResults(savedSearchId,DtSearched,isEnabled) select id,now(),0 from Searches where not id in (select savedSearchId from tblSavedSearchResults); update tblSavedSearchResults inner join Searches1 on tblSavedSearchResults.savedSearchId = Searches1.id Set tblSavedSearchResults.DtSearched = Searches1.dt, tblSavedSearchResults.isEnabled = 1; However when i put the same code in php as below it generates an error $dba = DbConnect::CreateDbaInstance(); $query = ""; $query.="Create Temporary Table Searches ( id int, dt datetime); "; $query.="Create Temporary Table Searches1 ( id int, dt datetime, count int); "; $query.="insert into Searches(id, dt) select a.id, now() from tblSavedSearches a; "; $query.="insert into Searches1(id, dt, count) "; $query.="select "; $query.=" b.savedSearchesId, "; $query.=" (select c.dt from tblSavedSearchesDetails c where b.savedSearchesId = c.savedSearchesId order by c.dt desc limit 1) as 'dt', "; $query.=" count(b.savedSearchesId) as 'cnt' "; $query.="from tblSavedSearchesDetails b "; $query.="group by b.savedSearchesId; "; $query.="insert into tblSavedSearchResults(savedSearchId,DtSearched,isEnabled) "; $query.="select id,now(),0 from Searches where not id in (select savedSearchId from tblSavedSearchResults); "; $query.="update tblSavedSearchResults "; $query.="inner join Searches1 on tblSavedSearchResults.savedSearchId = Searches1.id "; $query.="Set tblSavedSearchResults.DtSearched = Searches1.dt, tblSavedSearchResults.isEnabled = 1; "; $dba->DbQuery($query) or die(mysql_error()); I get the following error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'Create Temporary Table Searches1 ( id int, dt datetime, count int) insert into S' at line 1 Please if someone could assist me with this ... Thanks

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  • LINQ to SQL and missing Many to Many EntityRefs

    - by Rick Strahl
    Ran into an odd behavior today with a many to many mapping of one of my tables in LINQ to SQL. Many to many mappings aren’t transparent in LINQ to SQL and it maps the link table the same way the SQL schema has it when creating one. In other words LINQ to SQL isn’t smart about many to many mappings and just treats it like the 3 underlying tables that make up the many to many relationship. Iain Galloway has a nice blog entry about Many to Many relationships in LINQ to SQL. I can live with that – it’s not really difficult to deal with this arrangement once mapped, especially when reading data back. Writing is a little more difficult as you do have to insert into two entities for new records, but nothing that can’t be handled in a small business object method with a few lines of code. When I created a database I’ve been using to experiment around with various different OR/Ms recently I found that for some reason LINQ to SQL was completely failing to map even to the linking table. As it turns out there’s a good reason why it fails, can you spot it below? (read on :-}) Here is the original database layout: There’s an items table, a category table and a link table that holds only the foreign keys to the Items and Category tables for a typical M->M relationship. When these three tables are imported into the model the *look* correct – I do get the relationships added (after modifying the entity names to strip the prefix): The relationship looks perfectly fine, both in the designer as well as in the XML document: <Table Name="dbo.wws_Item_Categories" Member="ItemCategories"> <Type Name="ItemCategory"> <Column Name="ItemId" Type="System.Guid" DbType="uniqueidentifier NOT NULL" CanBeNull="false" /> <Column Name="CategoryId" Type="System.Guid" DbType="uniqueidentifier NOT NULL" CanBeNull="false" /> <Association Name="ItemCategory_Category" Member="Categories" ThisKey="CategoryId" OtherKey="Id" Type="Category" /> <Association Name="Item_ItemCategory" Member="Item" ThisKey="ItemId" OtherKey="Id" Type="Item" IsForeignKey="true" /> </Type> </Table> <Table Name="dbo.wws_Categories" Member="Categories"> <Type Name="Category"> <Column Name="Id" Type="System.Guid" DbType="UniqueIdentifier NOT NULL" IsPrimaryKey="true" IsDbGenerated="true" CanBeNull="false" /> <Column Name="ParentId" Type="System.Guid" DbType="UniqueIdentifier" CanBeNull="true" /> <Column Name="CategoryName" Type="System.String" DbType="NVarChar(150)" CanBeNull="true" /> <Column Name="CategoryDescription" Type="System.String" DbType="NVarChar(MAX)" CanBeNull="true" /> <Column Name="tstamp" AccessModifier="Internal" Type="System.Data.Linq.Binary" DbType="rowversion" CanBeNull="true" IsVersion="true" /> <Association Name="ItemCategory_Category" Member="ItemCategory" ThisKey="Id" OtherKey="CategoryId" Type="ItemCategory" IsForeignKey="true" /> </Type> </Table> However when looking at the code generated these navigation properties (also on Item) are completely missing: [global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.wws_Item_Categories")] [global::System.Runtime.Serialization.DataContractAttribute()] public partial class ItemCategory : Westwind.BusinessFramework.EntityBase { private System.Guid _ItemId; private System.Guid _CategoryId; public ItemCategory() { } [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_ItemId", DbType="uniqueidentifier NOT NULL")] [global::System.Runtime.Serialization.DataMemberAttribute(Order=1)] public System.Guid ItemId { get { return this._ItemId; } set { if ((this._ItemId != value)) { this._ItemId = value; } } } [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_CategoryId", DbType="uniqueidentifier NOT NULL")] [global::System.Runtime.Serialization.DataMemberAttribute(Order=2)] public System.Guid CategoryId { get { return this._CategoryId; } set { if ((this._CategoryId != value)) { this._CategoryId = value; } } } } Notice that the Item and Category association properties which should be EntityRef properties are completely missing. They’re there in the model, but the generated code – not so much. So what’s the problem here? The problem – it appears – is that LINQ to SQL requires primary keys on all entities it tracks. In order to support tracking – even of the link table entity – the link table requires a primary key. Real obvious ain’t it, especially since the designer happily lets you import the table and even shows the relationship and implicitly the related properties. Adding an Id field as a Pk to the database and then importing results in this model layout: which properly generates the Item and Category properties into the link entity. It’s ironic that LINQ to SQL *requires* the PK in the middle – the Entity Framework requires that a link table have *only* the two foreign key fields in a table in order to recognize a many to many relation. EF actually handles the M->M relation directly without the intermediate link entity unlike LINQ to SQL. [updated from comments – 12/24/2009] Another approach is to set up both ItemId and CategoryId in the database which shows up in LINQ to SQL like this: This also work in creating the Category and Item fields in the ItemCategory entity. Ultimately this is probably the best approach as it also guarantees uniqueness of the keys and so helps in database integrity. It took me a while to figure out WTF was going on here – lulled by the designer to think that the properties should be when they were not. It’s actually a well documented feature of L2S that each entity in the model requires a Pk but of course that’s easy to miss when the model viewer shows it to you and even the underlying XML model shows the Associations properly. This is one of the issue with L2S of course – you have to play by its rules and once you hit one of those rules there’s no way around them – you’re stuck with what it requires which in this case meant changing the database.© Rick Strahl, West Wind Technologies, 2005-2010Posted in ADO.NET  LINQ  

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  • Exploring the Excel Services REST API

    - by jamiet
    Over the last few years Analysis Services guru Chris Webb and I have been on something of a crusade to enable better access to data that is locked up in countless Excel workbooks that litter the hard drives of enterprise PCs. The most prominent manifestation of that crusade up to now has been a forum thread that Chris began on Microsoft Answers entitled Excel Web App API? Chris began that thread with: I was wondering whether there was an API for the Excel Web App? Specifically, I was wondering if it was possible (or if it will be possible in the future) to expose data in a spreadsheet in the Excel Web App as an OData feed, in the way that it is possible with Excel Services? Up to recently the last 10 words of that paragraph "in the way that it is possible with Excel Services" had completely washed over me however a comment on my recent blog post Thoughts on ExcelMashup.com (and a rant) by Josh Booker in which Josh said: Excel Services is a service application built for sharepoint 2010 which exposes a REST API for excel documents. We're looking forward to pros like you giving it a try now that Office365 makes sharepoint more easily accessible.  Can't wait for your future blog about using REST API to load data from Excel on Offce 365 in SSIS. made me think that perhaps the Excel Services REST API is something I should be looking into and indeed that is what I have been doing over the past few days. And you know what? I'm rather impressed with some of what Excel Services' REST API has to offer. Unfortunately Excel Services' REST API also has one debilitating aspect that renders this blog post much less useful than it otherwise would be; namely that it is not publicly available from the Excel Web App on SkyDrive. Therefore all I can do in this blog post is show you screenshots of what the REST API provides in Sharepoint rather than linking you directly to those REST resources; that's a great shame because one of the benefits of a REST API is that it is easily and ubiquitously demonstrable from a web browser. Instead I am hosting a workbook on Sharepoint in Office 365 because that does include Excel Services' REST API but, again, all I can do is show you screenshots. N.B. If anyone out there knows how to make Office-365-hosted spreadsheets publicly-accessible (i.e. without requiring a username/password) please do let me know (because knowing which forum on which to ask the question is an exercise in futility). In order to demonstrate Excel Services' REST API I needed some decent data and for that I used the World Tourism Organization Statistics Database and Yearbook - United Nations World Tourism Organization dataset hosted on Azure Datamarket (its free, by the way); this dataset "provides comprehensive information on international tourism worldwide and offers a selection of the latest available statistics on international tourist arrivals, tourism receipts and expenditure" and you can explore the data for yourself here. If you want to play along at home by viewing the data as it exists in Excel then it can be viewed here. Let's dive in.   The root of Excel Services' REST API is the model resource which resides at: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model Note that this is true for every workbook hosted in a Sharepoint document library - each Excel workbook is a RESTful resource. (Update: Mark Stacey on Twitter tells me that "It's turned off by default in onpremise Sharepoint (1 tickbox to turn on though)". Thanks Mark!) The data is provided as an ATOM feed but I have Firefox's feed reading ability turned on so you don't see the underlying XML goo. As you can see there are four top level resources, Ranges, Charts, Tables and PivotTables; exploring one of those resources is where things get interesting. Let's take a look at the Tables Resource: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Tables Our workbook contains only one table, called ‘Table1’ (to reiterate, you can explore this table yourself here). Viewing that table via the REST API is pretty easy, we simply append the name of the table onto our previous URI: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Tables('Table1') As you can see, that quite simply gives us a representation of the data in that table. What you cannot see from this screenshot is that this is pure HTML that is being served up; that is all well and good but actually we can do more interesting things. If we specify that the data should be returned not as HTML but as: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Tables('Table1')?$format=image then that data comes back as a pure image and can be used in any web page where you would ordinarily use images. This is the thing that I really like about Excel Services’ REST API – we can embed an image in any web page but instead of being a copy of the data, that image is actually live – if the underlying data in the workbook were to change then hitting refresh will show a new image. Pretty cool, no? The same is true of any Charts or Pivot Tables in your workbook - those can be embedded as images too and if the underlying data changes, boom, the image in your web page changes too. There is a lot of data in the workbook so the image returned by that previous URI is too large to show here so instead let’s take a look at a different resource, this time a range: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Ranges('Data!A1|C15') That URI returns cells A1 to C15 from a worksheet called “Data”: And if we ask for that as an image again: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Ranges('Data!A1|C15')?$format=image Were this image resource not behind a username/password then this would be a live image of the data in the workbook as opposed to one that I had to copy and upload elsewhere. Nonetheless I hope this little wrinkle doesn't detract from the inate value of what I am trying to articulate here; that an existing image in a web page can be changed on-the-fly simply by inserting some data into an Excel workbook. I for one think that that is very cool indeed! I think that's enough in the way of demo for now as this shows what is possible using Excel Services' REST API. Of course, not all features work quite how I would like and here is a bulleted list of some of my more negative feedback: The URIs are pig-ugly. Are "_vti_bin" & "ExcelRest.aspx" really necessary as part of the URI? Would this not be better: http://server/Documents/TourismExpenditureInMillionsOfUSD.xlsx/Model/Tables(‘Table1’) That URI provides the necessary addressability and is a lot easier to remember. Discoverability of these resources is not easy, we essentially have to handcrank a URI ourselves. Take the example of embedding a chart into a blog post - would it not be better if I could browse first through the document library to an Excel workbook and THEN through the workbook to the chart/range/table that I am interested in? Call it a wizard if you like. That would be really cool and would, I am sure, promote this feature and cut down on the copy-and-paste disease that the REST API is meant to alleviate. The resources that I demonstrated can be returned as feeds as well as images or HTML simply by changing the format parameter to ?$format=atom however for some inexplicable reason they don't return OData and no-one on the Excel Services team can tell me why (believe me, I have asked). $format is an OData parameter however other useful parameters such as $top and $filter are not supported. It would be nice if they were. Although I haven't demonstrated it here Excel Services' REST API does provide a makeshift way of altering the data by changing the value of specific cells however what it does not allow you to do is add new data into the workbook. Google Docs allows this and was one of the motivating factors for Chris Webb's forum post that I linked to above. None of this works for Excel workbooks hosted on SkyDrive This blog post is as long as it needs to be for a short introduction so I'll stop now. If you want to know more than I recommend checking out a few links: Excel Services REST API documentation on MSDNSo what does REST on Excel Services look like??? by Shahar PrishExcel Services in SharePoint 2010 REST API Syntax by Christian Stich. Any thoughts? Let's hear them in the comments section below! @Jamiet 

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  • Incremental Statistics Maintenance – what statistics will be gathered after DML occurs on the table?

    - by Maria Colgan
    Incremental statistics maintenance was introduced in Oracle Database 11g to improve the performance of gathering statistics on large partitioned table. When incremental statistics maintenance is enabled for a partitioned table, oracle accurately generated global level  statistics by aggregating partition level statistics. As more people begin to adopt this functionality we have gotten more questions around how they expected incremental statistics to behave in a given scenario. For example, last week we got a question around what partitions should have statistics gathered on them after DML has occurred on the table? The person who asked the question assumed that statistics would only be gathered on partitions that had stale statistics (10% of the rows in the partition had changed). However, what they actually saw when they did a DBMS_STATS.GATHER_TABLE_STATS was all of the partitions that had been affected by the DML had statistics re-gathered on them. This is the expected behavior, incremental statistics maintenance is suppose to yield the same statistics as gathering table statistics from scratch, just faster. This means incremental statistics maintenance needs to gather statistics on any partition that will change the global or table level statistics. For instance, the min or max value for a column could change after just one row is inserted or updated in the table. It might easier to demonstrate this using an example. Let’s take the ORDERS2 table, which is partitioned by month on order_date.  We will begin by enabling incremental statistics for the table and gathering statistics on the table. After the statistics gather the last_analyzed date for the table and all of the partitions now show 13-Mar-12. And we now have the following column statistics for the ORDERS2 table. We can also confirm that we really did use incremental statistics by querying the dictionary table sys.HIST_HEAD$, which should have an entry for each column in the ORDERS2 table. So, now that we have established a good baseline, let’s move on to the DML. Information is loaded into the latest partition of the ORDERS2 table once a month. Existing orders maybe also be update to reflect changes in their status. Let’s assume the following transactions take place on the ORDERS2 table this month. After these transactions have occurred we need to re-gather statistic since the partition ORDERS_MAR_2012 now has rows in it and the number of distinct values and the maximum value for the STATUS column have also changed. Now if we look at the last_analyzed date for the table and the partitions, we will see that the global statistics and the statistics on the partitions where rows have changed due to the update (ORDERS_FEB_2012) and the data load (ORDERS_MAR_2012) have been updated. The column statistics also reflect the changes with the number of distinct values in the status column increase to reflect the update. So, incremental statistics maintenance will gather statistics on any partition, whose data has changed and that change will impact the global level statistics.

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  • Exploring the Excel Services REST API

    - by jamiet
    Over the last few years Analysis Services guru Chris Webb and I have been on something of a crusade to enable better access to data that is locked up in countless Excel workbooks that litter the hard drives of enterprise PCs. The most prominent manifestation of that crusade up to now has been a forum thread that Chris began on Microsoft Answers entitled Excel Web App API? Chris began that thread with: I was wondering whether there was an API for the Excel Web App? Specifically, I was wondering if it was possible (or if it will be possible in the future) to expose data in a spreadsheet in the Excel Web App as an OData feed, in the way that it is possible with Excel Services? Up to recently the last 10 words of that paragraph "in the way that it is possible with Excel Services" had completely washed over me however a comment on my recent blog post Thoughts on ExcelMashup.com (and a rant) by Josh Booker in which Josh said: Excel Services is a service application built for sharepoint 2010 which exposes a REST API for excel documents. We're looking forward to pros like you giving it a try now that Office365 makes sharepoint more easily accessible.  Can't wait for your future blog about using REST API to load data from Excel on Offce 365 in SSIS. made me think that perhaps the Excel Services REST API is something I should be looking into and indeed that is what I have been doing over the past few days. And you know what? I'm rather impressed with some of what Excel Services' REST API has to offer. Unfortunately Excel Services' REST API also has one debilitating aspect that renders this blog post much less useful than it otherwise would be; namely that it is not publicly available from the Excel Web App on SkyDrive. Therefore all I can do in this blog post is show you screenshots of what the REST API provides in Sharepoint rather than linking you directly to those REST resources; that's a great shame because one of the benefits of a REST API is that it is easily and ubiquitously demonstrable from a web browser. Instead I am hosting a workbook on Sharepoint in Office 365 because that does include Excel Services' REST API but, again, all I can do is show you screenshots. N.B. If anyone out there knows how to make Office-365-hosted spreadsheets publicly-accessible (i.e. without requiring a username/password) please do let me know (because knowing which forum on which to ask the question is an exercise in futility). In order to demonstrate Excel Services' REST API I needed some decent data and for that I used the World Tourism Organization Statistics Database and Yearbook - United Nations World Tourism Organization dataset hosted on Azure Datamarket (its free, by the way); this dataset "provides comprehensive information on international tourism worldwide and offers a selection of the latest available statistics on international tourist arrivals, tourism receipts and expenditure" and you can explore the data for yourself here. If you want to play along at home by viewing the data as it exists in Excel then it can be viewed here. Let's dive in.   The root of Excel Services' REST API is the model resource which resides at: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model Note that this is true for every workbook hosted in a Sharepoint document library - each Excel workbook is a RESTful resource. (Update: Mark Stacey on Twitter tells me that "It's turned off by default in onpremise Sharepoint (1 tickbox to turn on though)". Thanks Mark!) The data is provided as an ATOM feed but I have Firefox's feed reading ability turned on so you don't see the underlying XML goo. As you can see there are four top level resources, Ranges, Charts, Tables and PivotTables; exploring one of those resources is where things get interesting. Let's take a look at the Tables Resource: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Tables Our workbook contains only one table, called ‘Table1’ (to reiterate, you can explore this table yourself here). Viewing that table via the REST API is pretty easy, we simply append the name of the table onto our previous URI: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Tables('Table1') As you can see, that quite simply gives us a representation of the data in that table. What you cannot see from this screenshot is that this is pure HTML that is being served up; that is all well and good but actually we can do more interesting things. If we specify that the data should be returned not as HTML but as: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Tables('Table1')?$format=image then that data comes back as a pure image and can be used in any web page where you would ordinarily use images. This is the thing that I really like about Excel Services’ REST API – we can embed an image in any web page but instead of being a copy of the data, that image is actually live – if the underlying data in the workbook were to change then hitting refresh will show a new image. Pretty cool, no? The same is true of any Charts or Pivot Tables in your workbook - those can be embedded as images too and if the underlying data changes, boom, the image in your web page changes too. There is a lot of data in the workbook so the image returned by that previous URI is too large to show here so instead let’s take a look at a different resource, this time a range: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Ranges('Data!A1|C15') That URI returns cells A1 to C15 from a worksheet called “Data”: And if we ask for that as an image again: http://server/_vti_bin/ExcelRest.aspx/Documents/TourismExpenditureInMillionsOfUSD.xlsx/model/Ranges('Data!A1|C15')?$format=image Were this image resource not behind a username/password then this would be a live image of the data in the workbook as opposed to one that I had to copy and upload elsewhere. Nonetheless I hope this little wrinkle doesn't detract from the inate value of what I am trying to articulate here; that an existing image in a web page can be changed on-the-fly simply by inserting some data into an Excel workbook. I for one think that that is very cool indeed! I think that's enough in the way of demo for now as this shows what is possible using Excel Services' REST API. Of course, not all features work quite how I would like and here is a bulleted list of some of my more negative feedback: The URIs are pig-ugly. Are "_vti_bin" & "ExcelRest.aspx" really necessary as part of the URI? Would this not be better: http://server/Documents/TourismExpenditureInMillionsOfUSD.xlsx/Model/Tables(‘Table1’) That URI provides the necessary addressability and is a lot easier to remember. Discoverability of these resources is not easy, we essentially have to handcrank a URI ourselves. Take the example of embedding a chart into a blog post - would it not be better if I could browse first through the document library to an Excel workbook and THEN through the workbook to the chart/range/table that I am interested in? Call it a wizard if you like. That would be really cool and would, I am sure, promote this feature and cut down on the copy-and-paste disease that the REST API is meant to alleviate. The resources that I demonstrated can be returned as feeds as well as images or HTML simply by changing the format parameter to ?$format=atom however for some inexplicable reason they don't return OData and no-one on the Excel Services team can tell me why (believe me, I have asked). $format is an OData parameter however other useful parameters such as $top and $filter are not supported. It would be nice if they were. Although I haven't demonstrated it here Excel Services' REST API does provide a makeshift way of altering the data by changing the value of specific cells however what it does not allow you to do is add new data into the workbook. Google Docs allows this and was one of the motivating factors for Chris Webb's forum post that I linked to above. None of this works for Excel workbooks hosted on SkyDrive This blog post is as long as it needs to be for a short introduction so I'll stop now. If you want to know more than I recommend checking out a few links: Excel Services REST API documentation on MSDNSo what does REST on Excel Services look like??? by Shahar PrishExcel Services in SharePoint 2010 REST API Syntax by Christian Stich. Any thoughts? Let's hear them in the comments section below! @Jamiet 

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  • MDM 2010 Summit in San Francisco

    - by Tony Ouk
    Since 2006, the MDM Global Summit Series has brought master data expertise to more than 5,000 delegates worldwide. The Series is designed to reinforce the importance of data governance as a key factor to your MDM program's success while providing real-world experience and all-in-one access to solutions providers. Come join us June 2-3, 2010 at the Hyatt Regency in San Francisco.  For more information including registration details, visit the MDM Global Summit Series website.

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  • Mozilla Thunderbird

    - by sadik khan
    I am a frequent user of Ubuntu and recently upgraded from Lucid to Ubuntu 11.10. I was not able to properly configure Thunderbird, so I switched to Evolution. First of all what I want is smooth way to configure Thunderbird with all features enabled, like global address list and calendar setting. I also want to know how to remove Thunderbird from global appmenu email icon, and how to insert Evolution email icon in its place. Thanks Sadik khan

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  • Why a graduate program in South Africa?

    - by anca.rosu
    South Africa, like many other countries, is desperate for skills. Good, solid, technical skills – together with a get-up-and-go attitude – and the desire to work for a world-class organization that is leading the way! In addition, we have made a commitment in South Africa that we need to transform our organization and develop and empower Black individuals who historically have not had the opportunity to participate in the global economy. It is through this investment in our country's people that we contribute to the development of a nation capable of competing on the global stage. This makes for an exciting recipe! We have: Plenty of young and talented individuals who are eager to get stuck in and learn. Formal, recognized qualifications that form the basis for further development. A huge big global organization – Oracle – that is committed to developing these graduates and giving them an opportunity that is out of this world! Mix the above ‘ingredients’ together Tackle and remove potential “lumps & bumps” along the way as we learn and grow together Nurture and care for each other in a warm but tough environment What have we achieved? In most cases, the outcome is an awesome bunch of new talent that is well equipped to face the IT world. Where we have the opportunity and suitable headcount available to employ these graduates at Oracle we snap them up – alternatively our business partners and customers are always eager to recruit Oracle graduates into their organizations! These individuals go through real-life work place experience whilst at Oracle. In some cases they get to travel internationally. The excitement and buzz gets into their system and their blood becomes truly RED! Oracle RED! This is valuable talent and expertise to have in our eco-system and it’s an exciting program to be a part of not only as a graduate but as an Oracle employee too!   If you have any questions related to this article feel free to contact  [email protected].  You can find our job opportunities via http://campus.oracle.com. Technorati Tags: South Africa,technical skills,graduate program,opportunity,global organization,new talent

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  • Giving a Zone "More Power"

    - by Brian Leonard
    In addition to the traditional virtualization benefits that Solaris zones offer, applications running in zones are also running in a more secure environment. One way to quantify this is compare the privileges available to the global zone with those of a local zone. For example, there a 82 distinct privileges available to the global zone: bleonard@solaris:~$ ppriv -l | wc -l 82 You can view the descriptions for each of those privileges as follows: bleonard@solaris:~$ ppriv -lv contract_event Allows a process to request critical events without limitation. Allows a process to request reliable delivery of all events on any event queue. contract_identity Allows a process to set the service FMRI value of a process contract template. ... Or for just one or more privileges: bleonard@solaris:~$ ppriv -lv file_dac_read file_dac_write file_dac_read Allows a process to read a file or directory whose permission bits or ACL do not allow the process read permission. file_dac_write Allows a process to write a file or directory whose permission bits or ACL do not allow the process write permission. In order to write files owned by uid 0 in the absence of an effective uid of 0 ALL privileges are required. However, in a non-global zone, only 43 of the 83 privileges are available by default: root@myzone:~# ppriv -l zone | wc -l 43 The missing privileges are: cpc_cpu dtrace_kernel dtrace_proc dtrace_user file_downgrade_sl file_flag_set file_upgrade_sl graphics_access graphics_map net_mac_implicit proc_clock_highres proc_priocntl proc_zone sys_config sys_devices sys_ipc_config sys_linkdir sys_dl_config sys_net_config sys_res_bind sys_res_config sys_smb sys_suser_compat sys_time sys_trans_label virt_manage win_colormap win_config win_dac_read win_dac_write win_devices win_dga win_downgrade_sl win_fontpath win_mac_read win_mac_write win_selection win_upgrade_sl xvm_control However, just like Tim Taylor, it is possible to give your zones more power. For example, a zone by default doesn't have the privileges to support DTrace: root@myzone:~# dtrace -l ID PROVIDER MODULE FUNCTION NAME The DTrace privileges can be added, however, as follows: bleonard@solaris:~$ sudo zonecfg -z myzone Password: zonecfg:myzone> set limitpriv="default,dtrace_proc,dtrace_user" zonecfg:myzone> verify zonecfg:myzone> exit bleonard@solaris:~$ sudo zoneadm -z myzone reboot Now I can run DTrace from within the zone: root@myzone:~# dtrace -l | more ID PROVIDER MODULE FUNCTION NAME 1 dtrace BEGIN 2 dtrace END 3 dtrace ERROR 7115 syscall nosys entry 7116 syscall nosys return ... Note, certain privileges are never allowed to be assigned to a zone. You'll be notified on boot if you attempt to assign a prohibited privilege to a zone: bleonard@solaris:~$ sudo zoneadm -z myzone reboot privilege "dtrace_kernel" is not permitted within the zone's privilege set zoneadm: zone myzone failed to verify Here's a nice listing of all the privileges and their zone status (default, optional, prohibited): Privileges in a Non-Global Zone.

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  • Probation is Over: PASS Board Year 1, Q2

    - by Denise McInerney
    Though it's not always official every job begins with a probation period. You start out with lots of questions and every day you find out how much more you have to learn. Usually after a few months you discover that you can actually answer some questions and have at least an idea of what you are supposed to be doing. Now at the end of my second quarter on the "job" of serving on the PASS Board I have reached that point. My probation period is over. The last three months were busy for the entire Board with the budget process, an in-person meeting and moving forward with PASS Global Growth plans. I had also set a specific goal for myself for my 2nd quarter: to see the Board to adopt a Code of Conduct for the PASS Summit. Code of Conduct When I ran for the Board I included my desire to see PASS establish a code of conduct in my campaign platform.  I was motivated to do this for a few reasons. Other technical conferences have had incidents of harassment. Most of these did not have a policy in place prior to having a problem, though several conference organizers have since adopted anti-harassment policies or codes of conduct. I felt it would be in PASS' interest to establish a policy so we would be prepared should there be an incident.   "This is Community" Adopting a code of conduct would reinforce our community orientation and send a message about the positive character of the Summit. PASS is a leader among technical organizations for its promotion and support of women. Adopting a code of conduct would further demonstrate our leadership in this area. After researching similar polices from other organizations I published a first draft in April. I solicited feedback from the Board, HQ staff and some PASS members. Incorporating that feedback I presented version 4 at the May Board meeting, where we had a good discussion. You can read the meeting minutes for details. I incorporated points from  the Board discussion as well as feedback from a legal review to produce a final version which has been submitted to the Board. It will be discussed at the Board meeting July 12. You can read the full text at the end of this post. Virtual Chapters In the first quarter we started ramping up marketing support for the Virtual Chapters. Since then each edition of the Connector has highlighted a different VC to help get out the message about the variety of eductional opporutnities that are offered. These VC profiles will continue in the coming months. I was very pleased to welcome the new DBA Fundamentals VC which is geared toward new DBAs, people who are considering entering the field and those transitioning from a different IT role. Thanks to the contributions of Erin Stellato, Michelle Nalliah and Karla Landrum we published a "Virtual Chapter Guidebook". This document includes great advice on how to build and promote a VC. It's also a reference for how things work, from budgets to webinar hosting. I think this document will be extremely valuable to all our VC leaders and am grateful to those who put it together. Board Meeting/SQL Rally The Board met in May in Dallas. Among the items discussed were Global Growth, the budget, future events and the upcoming elections. We covered a lot of ground in two days and I will again refer you to the meeting minutes for details. The meeting schedule allowed us to participate in the SQL Rally networking events and one full day of the conference. I enjoyed having the opportunity to meet and talk with many PASS members. And my hat is off to the SQL Rally organizers who put on an outstanding event. Global Growth PASS has undertaken a major intitiative to reach and engage SQL Server professionals around the world. This Global Growth plan is ambitious and will have a significant impact on the strategic direction of the organization. We have been reaching out to the community for feedback, including hosting Twitter chats and live Town Hall meetings. I co-hosted two of these events and appreciated hearing the different perspectives of the people who participated If you have not done so I encourage you to read about the Global Growth vision and proposed governance changes  and submit your feedback. FY13 Budget July 1 is the beginning of PASS' fiscal year, which makes the end of June the deadline for approving a budget. Each director submits a budget for his or her portfolio. For the Virtual Chapter portfolio I focused on how we can allocate resources to grow the VCs. Budgeting is a give-and-take process, and while I didn't get everything I asked for I'm pleased the FY13 budget includes a significant increase in financial support for the Virtual Chapters. Many people put a lot of work into the budget, but no two people deserve credit more than VP of Finance Douglas McDowell and Accounting Manager Sandy Cherry. Thanks to both of them for getting us across the goal line on time. SQL Saturday I attended SQL Saturdays in Orange Co. CA and Phoenix. It's always inspiring to see the enthusiasm in the community for learning and networking. These events are successful due to the hard work of many volunteers. Thanks to the organizers in both cities for all your efforts. Next Up This quarter we'll be gearing up plans for the VCs at the Summit and exploring ways the VCs can best support PASS' Global Growth work. I'll also be wrapping up work on the Code of Conduct and attending a Board meeting in September. And I will be at SQL Saturday #144 in Sacramento later this month. Here is the language of the Code of Conduct I have submitted to the Board for consideration: PASS Code of Conduct The PASS Summit provides database professionals from a variety of backgrounds with an opportunity to connect, share and learn.  We value the strong sense of community that characterizes this event and we seek to foster an inclusive, professional atmosphere. We are dedicated to providing a harassment-free conference experience for everyone, regardless of gender, race, sexual orientation, disability, physical appearance, religion or any other protected classification.  Everyone at the Summit is expected to follow the Code of Conduct. This includes but is not limited to: PASS Staff, Exhibitors, Speakers, Attendees and anyone affiliated with the event. Participants are expected to follow the Code of Conduct at all Summit events, including PASS-sponsored social events. Participant behavior Harassment includes, but is not limited to, offensive verbal comments related to gender, race, sexual orientation, disability, physical appearance, religion, or any other protected classification.  Intimidation, threats, stalking, harassing photography or recording, sustained disruption of talks or other events, inappropriate physical contact and unwelcome attention will also be considered harassment. Similarly, sexual, racist, derogatory, threatening or other inappropriate language and imagery are not appropriate for any conference venue, including sessions.  Recourse If a participant engages in any conduct that is prohibited under this Code of Conduct, the conference organizers may take any action they deem appropriate, including warning the offender or expelling the offender from the conference. No refunds will be granted to attendees expelled from the Summit due to violations of the Code of Conduct. If you are being harassed, witness harassment, or have any other concerns, please contact a member of conference staff immediately. Conference staff can be identified by their “Headquarters/Staff” shirts and are trained to handle the situation appropriately. A Code of Conduct Committee (CCC) made up of the Executive Manager and three members of the Board of Directors designated by the President will be authorized to take action in response to an incident or behavior that violates the Code of Conduct.

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  • Information Driven Value Chains: Achieving Supply Chain Excellence in the 21st Century With Oracle -

    World-class supply chains can help companies achieve top line and bottom line results in today’s complex,global world.Tune into this conversation with Rick Jewell,SVP,Oracle Supply Chain Development,to hear about Oracle’s vision for world class SCM,and the latest and greatest on Oracle Supply Chain Management solutions.You will learn about Oracle’s complete,best-in-class,open and integrated solutions,which are helping companies drive profitability,achieve operational excellence,streamline innovation,and manage risk and compliance in today’s complex,global world.

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  • Firefox Slow down and 100% CPU after gnome-settings-deamon update

    - by digitaljail
    I'm on Ubuntu 12.04 (Unity) with Firefox 17.0.1 instaled. after the latest update of the gnome-settings-deamon (3.4.2-0ubuntu0.5,3.4.2-0ubuntu0.6) FireFox starts taking 100% of my CPU, periodically. I have tried various things: 1) Disabled All the non standard extensions = No change to the CPU Usage 2) Disabled Flash PlugIns (also updated same time) = No change to CPU Usage 3) Disabled "Global Menu integration 3.6.4) Extension = HOOOA CPU OK !!! Any suggestion to get back global menu integration with no more CPU problems?

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  • Information Driven Value Chains: Achieving Supply Chain Excellence in the 21st Century With Oracle -

    World-class supply chains can help companies achieve top line and bottom line results in today’s complex,global world.Tune into this conversation with Rick Jewell,SVP,Oracle Supply Chain Development,to hear about Oracle’s vision for world class SCM,and the latest and greatest on Oracle Supply Chain Management solutions.You will learn about Oracle’s complete,best-in-class,open and integrated solutions,which are helping companies drive profitability,achieve operational excellence,streamline innovation,and manage risk and compliance in today’s complex,global world.

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  • Register Now to the New Oracle Argus Safety 7 Implementation Boot Camp in Miami, Florida - Nov 12-15, 2013!

    - by Roxana Babiciu
    Oracle's Argus Safety 7 boot camp is an instructor-led training course which provides a good understanding of how Oracle Argus Safety Standard Edition and Oracle Argus Safety Japan products addresses complex pharmacovigilance requirements and helps ensure global regulatory compliance by enabling sound safety decisions. Oracle Argus Safety's advanced database helps ensure global regulatory compliance thus in turn enabling sound safety decisions. Register now to this boot camp, a 4-day (in class) instructor led event taught using a combination of lectures and hands-on exercises.

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  • Register Now to the New Oracle Argus Safety 7 Implementation Boot Camp - Tokyo, Japan - Dec 10-13, 2013!

    - by Roxana Babiciu
    Oracle's Argus Safety 7 boot camp is an instructor-led training course which provides a good understanding of how Oracle Argus Safety Standard Edition and Oracle Argus Safety Japan products addresses complex pharmacovigilance requirements and helps ensure global regulatory compliance by enabling sound safety decisions. Oracle Argus Safety's advanced database helps ensure global regulatory compliance thus in turn enabling sound safety decisions. Read more here. 

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  • Shakespeare and storing Unicode characters

    - by John Paul Cook
    This post is about the political issues involved with using multiple languages in a global organization and how to troubleshoot the technical details. The CHAR and VARCHAR data types are NOT suitable for global data. Some people still cling to CHAR and VARCHAR justifying their use by truthfully saying that they only take up half the space of NCHAR and NVARCHAR data types. But you’ll never be able to store Chinese, Korean, Greek, Japanese, Arabic, or many other languages unless you use NCHAR and NVARCHAR...(read more)

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  • Google Optimization is the Key to Online Success For Any Business

    Google is by far the most used and preferred search engine in the world. It is miles ahead of its biggest rival when it comes to the global audience and for the same reason it provides one of the most attractive platforms for business owners to promote their business to a large global audience. Since most people use Google to search for anything they want as a business owner your primary requirement is to get good ranking on this search engine more than anywhere else.

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  • How John Got 15x Improvement Without Really Trying

    - by rchrd
    The following article was published on a Sun Microsystems website a number of years ago by John Feo. It is still useful and worth preserving. So I'm republishing it here.  How I Got 15x Improvement Without Really Trying John Feo, Sun Microsystems Taking ten "personal" program codes used in scientific and engineering research, the author was able to get from 2 to 15 times performance improvement easily by applying some simple general optimization techniques. Introduction Scientific research based on computer simulation depends on the simulation for advancement. The research can advance only as fast as the computational codes can execute. The codes' efficiency determines both the rate and quality of results. In the same amount of time, a faster program can generate more results and can carry out a more detailed simulation of physical phenomena than a slower program. Highly optimized programs help science advance quickly and insure that monies supporting scientific research are used as effectively as possible. Scientific computer codes divide into three broad categories: ISV, community, and personal. ISV codes are large, mature production codes developed and sold commercially. The codes improve slowly over time both in methods and capabilities, and they are well tuned for most vendor platforms. Since the codes are mature and complex, there are few opportunities to improve their performance solely through code optimization. Improvements of 10% to 15% are typical. Examples of ISV codes are DYNA3D, Gaussian, and Nastran. Community codes are non-commercial production codes used by a particular research field. Generally, they are developed and distributed by a single academic or research institution with assistance from the community. Most users just run the codes, but some develop new methods and extensions that feed back into the general release. The codes are available on most vendor platforms. Since these codes are younger than ISV codes, there are more opportunities to optimize the source code. Improvements of 50% are not unusual. Examples of community codes are AMBER, CHARM, BLAST, and FASTA. Personal codes are those written by single users or small research groups for their own use. These codes are not distributed, but may be passed from professor-to-student or student-to-student over several years. They form the primordial ocean of applications from which community and ISV codes emerge. Government research grants pay for the development of most personal codes. This paper reports on the nature and performance of this class of codes. Over the last year, I have looked at over two dozen personal codes from more than a dozen research institutions. The codes cover a variety of scientific fields, including astronomy, atmospheric sciences, bioinformatics, biology, chemistry, geology, and physics. The sources range from a few hundred lines to more than ten thousand lines, and are written in Fortran, Fortran 90, C, and C++. For the most part, the codes are modular, documented, and written in a clear, straightforward manner. They do not use complex language features, advanced data structures, programming tricks, or libraries. I had little trouble understanding what the codes did or how data structures were used. Most came with a makefile. Surprisingly, only one of the applications is parallel. All developers have access to parallel machines, so availability is not an issue. Several tried to parallelize their applications, but stopped after encountering difficulties. Lack of education and a perception that parallelism is difficult prevented most from trying. I parallelized several of the codes using OpenMP, and did not judge any of the codes as difficult to parallelize. Even more surprising than the lack of parallelism is the inefficiency of the codes. I was able to get large improvements in performance in a matter of a few days applying simple optimization techniques. Table 1 lists ten representative codes [names and affiliation are omitted to preserve anonymity]. Improvements on one processor range from 2x to 15.5x with a simple average of 4.75x. I did not use sophisticated performance tools or drill deep into the program's execution character as one would do when tuning ISV or community codes. Using only a profiler and source line timers, I identified inefficient sections of code and improved their performance by inspection. The changes were at a high level. I am sure there is another factor of 2 or 3 in each code, and more if the codes are parallelized. The study’s results show that personal scientific codes are running many times slower than they should and that the problem is pervasive. Computational scientists are not sloppy programmers; however, few are trained in the art of computer programming or code optimization. I found that most have a working knowledge of some programming language and standard software engineering practices; but they do not know, or think about, how to make their programs run faster. They simply do not know the standard techniques used to make codes run faster. In fact, they do not even perceive that such techniques exist. The case studies described in this paper show that applying simple, well known techniques can significantly increase the performance of personal codes. It is important that the scientific community and the Government agencies that support scientific research find ways to better educate academic scientific programmers. The inefficiency of their codes is so bad that it is retarding both the quality and progress of scientific research. # cacheperformance redundantoperations loopstructures performanceimprovement 1 x x 15.5 2 x 2.8 3 x x 2.5 4 x 2.1 5 x x 2.0 6 x 5.0 7 x 5.8 8 x 6.3 9 2.2 10 x x 3.3 Table 1 — Area of improvement and performance gains of 10 codes The remainder of the paper is organized as follows: sections 2, 3, and 4 discuss the three most common sources of inefficiencies in the codes studied. These are cache performance, redundant operations, and loop structures. Each section includes several examples. The last section summaries the work and suggests a possible solution to the issues raised. Optimizing cache performance Commodity microprocessor systems use caches to increase memory bandwidth and reduce memory latencies. Typical latencies from processor to L1, L2, local, and remote memory are 3, 10, 50, and 200 cycles, respectively. Moreover, bandwidth falls off dramatically as memory distances increase. Programs that do not use cache effectively run many times slower than programs that do. When optimizing for cache, the biggest performance gains are achieved by accessing data in cache order and reusing data to amortize the overhead of cache misses. Secondary considerations are prefetching, associativity, and replacement; however, the understanding and analysis required to optimize for the latter are probably beyond the capabilities of the non-expert. Much can be gained simply by accessing data in the correct order and maximizing data reuse. 6 out of the 10 codes studied here benefited from such high level optimizations. Array Accesses The most important cache optimization is the most basic: accessing Fortran array elements in column order and C array elements in row order. Four of the ten codes—1, 2, 4, and 10—got it wrong. Compilers will restructure nested loops to optimize cache performance, but may not do so if the loop structure is too complex, or the loop body includes conditionals, complex addressing, or function calls. In code 1, the compiler failed to invert a key loop because of complex addressing do I = 0, 1010, delta_x IM = I - delta_x IP = I + delta_x do J = 5, 995, delta_x JM = J - delta_x JP = J + delta_x T1 = CA1(IP, J) + CA1(I, JP) T2 = CA1(IM, J) + CA1(I, JM) S1 = T1 + T2 - 4 * CA1(I, J) CA(I, J) = CA1(I, J) + D * S1 end do end do In code 2, the culprit is conditionals do I = 1, N do J = 1, N If (IFLAG(I,J) .EQ. 0) then T1 = Value(I, J-1) T2 = Value(I-1, J) T3 = Value(I, J) T4 = Value(I+1, J) T5 = Value(I, J+1) Value(I,J) = 0.25 * (T1 + T2 + T5 + T4) Delta = ABS(T3 - Value(I,J)) If (Delta .GT. MaxDelta) MaxDelta = Delta endif enddo enddo I fixed both programs by inverting the loops by hand. Code 10 has three-dimensional arrays and triply nested loops. The structure of the most computationally intensive loops is too complex to invert automatically or by hand. The only practical solution is to transpose the arrays so that the dimension accessed by the innermost loop is in cache order. The arrays can be transposed at construction or prior to entering a computationally intensive section of code. The former requires all array references to be modified, while the latter is cost effective only if the cost of the transpose is amortized over many accesses. I used the second approach to optimize code 10. Code 5 has four-dimensional arrays and loops are nested four deep. For all of the reasons cited above the compiler is not able to restructure three key loops. Assume C arrays and let the four dimensions of the arrays be i, j, k, and l. In the original code, the index structure of the three loops is L1: for i L2: for i L3: for i for l for l for j for k for j for k for j for k for l So only L3 accesses array elements in cache order. L1 is a very complex loop—much too complex to invert. I brought the loop into cache alignment by transposing the second and fourth dimensions of the arrays. Since the code uses a macro to compute all array indexes, I effected the transpose at construction and changed the macro appropriately. The dimensions of the new arrays are now: i, l, k, and j. L3 is a simple loop and easily inverted. L2 has a loop-carried scalar dependence in k. By promoting the scalar name that carries the dependence to an array, I was able to invert the third and fourth subloops aligning the loop with cache. Code 5 is by far the most difficult of the four codes to optimize for array accesses; but the knowledge required to fix the problems is no more than that required for the other codes. I would judge this code at the limits of, but not beyond, the capabilities of appropriately trained computational scientists. Array Strides When a cache miss occurs, a line (64 bytes) rather than just one word is loaded into the cache. If data is accessed stride 1, than the cost of the miss is amortized over 8 words. Any stride other than one reduces the cost savings. Two of the ten codes studied suffered from non-unit strides. The codes represent two important classes of "strided" codes. Code 1 employs a multi-grid algorithm to reduce time to convergence. The grids are every tenth, fifth, second, and unit element. Since time to convergence is inversely proportional to the distance between elements, coarse grids converge quickly providing good starting values for finer grids. The better starting values further reduce the time to convergence. The downside is that grids of every nth element, n > 1, introduce non-unit strides into the computation. In the original code, much of the savings of the multi-grid algorithm were lost due to this problem. I eliminated the problem by compressing (copying) coarse grids into continuous memory, and rewriting the computation as a function of the compressed grid. On convergence, I copied the final values of the compressed grid back to the original grid. The savings gained from unit stride access of the compressed grid more than paid for the cost of copying. Using compressed grids, the loop from code 1 included in the previous section becomes do j = 1, GZ do i = 1, GZ T1 = CA(i+0, j-1) + CA(i-1, j+0) T4 = CA1(i+1, j+0) + CA1(i+0, j+1) S1 = T1 + T4 - 4 * CA1(i+0, j+0) CA(i+0, j+0) = CA1(i+0, j+0) + DD * S1 enddo enddo where CA and CA1 are compressed arrays of size GZ. Code 7 traverses a list of objects selecting objects for later processing. The labels of the selected objects are stored in an array. The selection step has unit stride, but the processing steps have irregular stride. A fix is to save the parameters of the selected objects in temporary arrays as they are selected, and pass the temporary arrays to the processing functions. The fix is practical if the same parameters are used in selection as in processing, or if processing comprises a series of distinct steps which use overlapping subsets of the parameters. Both conditions are true for code 7, so I achieved significant improvement by copying parameters to temporary arrays during selection. Data reuse In the previous sections, we optimized for spatial locality. It is also important to optimize for temporal locality. Once read, a datum should be used as much as possible before it is forced from cache. Loop fusion and loop unrolling are two techniques that increase temporal locality. Unfortunately, both techniques increase register pressure—as loop bodies become larger, the number of registers required to hold temporary values grows. Once register spilling occurs, any gains evaporate quickly. For multiprocessors with small register sets or small caches, the sweet spot can be very small. In the ten codes presented here, I found no opportunities for loop fusion and only two opportunities for loop unrolling (codes 1 and 3). In code 1, unrolling the outer and inner loop one iteration increases the number of result values computed by the loop body from 1 to 4, do J = 1, GZ-2, 2 do I = 1, GZ-2, 2 T1 = CA1(i+0, j-1) + CA1(i-1, j+0) T2 = CA1(i+1, j-1) + CA1(i+0, j+0) T3 = CA1(i+0, j+0) + CA1(i-1, j+1) T4 = CA1(i+1, j+0) + CA1(i+0, j+1) T5 = CA1(i+2, j+0) + CA1(i+1, j+1) T6 = CA1(i+1, j+1) + CA1(i+0, j+2) T7 = CA1(i+2, j+1) + CA1(i+1, j+2) S1 = T1 + T4 - 4 * CA1(i+0, j+0) S2 = T2 + T5 - 4 * CA1(i+1, j+0) S3 = T3 + T6 - 4 * CA1(i+0, j+1) S4 = T4 + T7 - 4 * CA1(i+1, j+1) CA(i+0, j+0) = CA1(i+0, j+0) + DD * S1 CA(i+1, j+0) = CA1(i+1, j+0) + DD * S2 CA(i+0, j+1) = CA1(i+0, j+1) + DD * S3 CA(i+1, j+1) = CA1(i+1, j+1) + DD * S4 enddo enddo The loop body executes 12 reads, whereas as the rolled loop shown in the previous section executes 20 reads to compute the same four values. In code 3, two loops are unrolled 8 times and one loop is unrolled 4 times. Here is the before for (k = 0; k < NK[u]; k++) { sum = 0.0; for (y = 0; y < NY; y++) { sum += W[y][u][k] * delta[y]; } backprop[i++]=sum; } and after code for (k = 0; k < KK - 8; k+=8) { sum0 = 0.0; sum1 = 0.0; sum2 = 0.0; sum3 = 0.0; sum4 = 0.0; sum5 = 0.0; sum6 = 0.0; sum7 = 0.0; for (y = 0; y < NY; y++) { sum0 += W[y][0][k+0] * delta[y]; sum1 += W[y][0][k+1] * delta[y]; sum2 += W[y][0][k+2] * delta[y]; sum3 += W[y][0][k+3] * delta[y]; sum4 += W[y][0][k+4] * delta[y]; sum5 += W[y][0][k+5] * delta[y]; sum6 += W[y][0][k+6] * delta[y]; sum7 += W[y][0][k+7] * delta[y]; } backprop[k+0] = sum0; backprop[k+1] = sum1; backprop[k+2] = sum2; backprop[k+3] = sum3; backprop[k+4] = sum4; backprop[k+5] = sum5; backprop[k+6] = sum6; backprop[k+7] = sum7; } for one of the loops unrolled 8 times. Optimizing for temporal locality is the most difficult optimization considered in this paper. The concepts are not difficult, but the sweet spot is small. Identifying where the program can benefit from loop unrolling or loop fusion is not trivial. Moreover, it takes some effort to get it right. Still, educating scientific programmers about temporal locality and teaching them how to optimize for it will pay dividends. Reducing instruction count Execution time is a function of instruction count. Reduce the count and you usually reduce the time. The best solution is to use a more efficient algorithm; that is, an algorithm whose order of complexity is smaller, that converges quicker, or is more accurate. Optimizing source code without changing the algorithm yields smaller, but still significant, gains. This paper considers only the latter because the intent is to study how much better codes can run if written by programmers schooled in basic code optimization techniques. The ten codes studied benefited from three types of "instruction reducing" optimizations. The two most prevalent were hoisting invariant memory and data operations out of inner loops. The third was eliminating unnecessary data copying. The nature of these inefficiencies is language dependent. Memory operations The semantics of C make it difficult for the compiler to determine all the invariant memory operations in a loop. The problem is particularly acute for loops in functions since the compiler may not know the values of the function's parameters at every call site when compiling the function. Most compilers support pragmas to help resolve ambiguities; however, these pragmas are not comprehensive and there is no standard syntax. To guarantee that invariant memory operations are not executed repetitively, the user has little choice but to hoist the operations by hand. The problem is not as severe in Fortran programs because in the absence of equivalence statements, it is a violation of the language's semantics for two names to share memory. Codes 3 and 5 are C programs. In both cases, the compiler did not hoist all invariant memory operations from inner loops. Consider the following loop from code 3 for (y = 0; y < NY; y++) { i = 0; for (u = 0; u < NU; u++) { for (k = 0; k < NK[u]; k++) { dW[y][u][k] += delta[y] * I1[i++]; } } } Since dW[y][u] can point to the same memory space as delta for one or more values of y and u, assignment to dW[y][u][k] may change the value of delta[y]. In reality, dW and delta do not overlap in memory, so I rewrote the loop as for (y = 0; y < NY; y++) { i = 0; Dy = delta[y]; for (u = 0; u < NU; u++) { for (k = 0; k < NK[u]; k++) { dW[y][u][k] += Dy * I1[i++]; } } } Failure to hoist invariant memory operations may be due to complex address calculations. If the compiler can not determine that the address calculation is invariant, then it can hoist neither the calculation nor the associated memory operations. As noted above, code 5 uses a macro to address four-dimensional arrays #define MAT4D(a,q,i,j,k) (double *)((a)->data + (q)*(a)->strides[0] + (i)*(a)->strides[3] + (j)*(a)->strides[2] + (k)*(a)->strides[1]) The macro is too complex for the compiler to understand and so, it does not identify any subexpressions as loop invariant. The simplest way to eliminate the address calculation from the innermost loop (over i) is to define a0 = MAT4D(a,q,0,j,k) before the loop and then replace all instances of *MAT4D(a,q,i,j,k) in the loop with a0[i] A similar problem appears in code 6, a Fortran program. The key loop in this program is do n1 = 1, nh nx1 = (n1 - 1) / nz + 1 nz1 = n1 - nz * (nx1 - 1) do n2 = 1, nh nx2 = (n2 - 1) / nz + 1 nz2 = n2 - nz * (nx2 - 1) ndx = nx2 - nx1 ndy = nz2 - nz1 gxx = grn(1,ndx,ndy) gyy = grn(2,ndx,ndy) gxy = grn(3,ndx,ndy) balance(n1,1) = balance(n1,1) + (force(n2,1) * gxx + force(n2,2) * gxy) * h1 balance(n1,2) = balance(n1,2) + (force(n2,1) * gxy + force(n2,2) * gyy)*h1 end do end do The programmer has written this loop well—there are no loop invariant operations with respect to n1 and n2. However, the loop resides within an iterative loop over time and the index calculations are independent with respect to time. Trading space for time, I precomputed the index values prior to the entering the time loop and stored the values in two arrays. I then replaced the index calculations with reads of the arrays. Data operations Ways to reduce data operations can appear in many forms. Implementing a more efficient algorithm produces the biggest gains. The closest I came to an algorithm change was in code 4. This code computes the inner product of K-vectors A(i) and B(j), 0 = i < N, 0 = j < M, for most values of i and j. Since the program computes most of the NM possible inner products, it is more efficient to compute all the inner products in one triply-nested loop rather than one at a time when needed. The savings accrue from reading A(i) once for all B(j) vectors and from loop unrolling. for (i = 0; i < N; i+=8) { for (j = 0; j < M; j++) { sum0 = 0.0; sum1 = 0.0; sum2 = 0.0; sum3 = 0.0; sum4 = 0.0; sum5 = 0.0; sum6 = 0.0; sum7 = 0.0; for (k = 0; k < K; k++) { sum0 += A[i+0][k] * B[j][k]; sum1 += A[i+1][k] * B[j][k]; sum2 += A[i+2][k] * B[j][k]; sum3 += A[i+3][k] * B[j][k]; sum4 += A[i+4][k] * B[j][k]; sum5 += A[i+5][k] * B[j][k]; sum6 += A[i+6][k] * B[j][k]; sum7 += A[i+7][k] * B[j][k]; } C[i+0][j] = sum0; C[i+1][j] = sum1; C[i+2][j] = sum2; C[i+3][j] = sum3; C[i+4][j] = sum4; C[i+5][j] = sum5; C[i+6][j] = sum6; C[i+7][j] = sum7; }} This change requires knowledge of a typical run; i.e., that most inner products are computed. The reasons for the change, however, derive from basic optimization concepts. It is the type of change easily made at development time by a knowledgeable programmer. In code 5, we have the data version of the index optimization in code 6. Here a very expensive computation is a function of the loop indices and so cannot be hoisted out of the loop; however, the computation is invariant with respect to an outer iterative loop over time. We can compute its value for each iteration of the computation loop prior to entering the time loop and save the values in an array. The increase in memory required to store the values is small in comparison to the large savings in time. The main loop in Code 8 is doubly nested. The inner loop includes a series of guarded computations; some are a function of the inner loop index but not the outer loop index while others are a function of the outer loop index but not the inner loop index for (j = 0; j < N; j++) { for (i = 0; i < M; i++) { r = i * hrmax; R = A[j]; temp = (PRM[3] == 0.0) ? 1.0 : pow(r, PRM[3]); high = temp * kcoeff * B[j] * PRM[2] * PRM[4]; low = high * PRM[6] * PRM[6] / (1.0 + pow(PRM[4] * PRM[6], 2.0)); kap = (R > PRM[6]) ? high * R * R / (1.0 + pow(PRM[4]*r, 2.0) : low * pow(R/PRM[6], PRM[5]); < rest of loop omitted > }} Note that the value of temp is invariant to j. Thus, we can hoist the computation for temp out of the loop and save its values in an array. for (i = 0; i < M; i++) { r = i * hrmax; TEMP[i] = pow(r, PRM[3]); } [N.B. – the case for PRM[3] = 0 is omitted and will be reintroduced later.] We now hoist out of the inner loop the computations invariant to i. Since the conditional guarding the value of kap is invariant to i, it behooves us to hoist the computation out of the inner loop, thereby executing the guard once rather than M times. The final version of the code is for (j = 0; j < N; j++) { R = rig[j] / 1000.; tmp1 = kcoeff * par[2] * beta[j] * par[4]; tmp2 = 1.0 + (par[4] * par[4] * par[6] * par[6]); tmp3 = 1.0 + (par[4] * par[4] * R * R); tmp4 = par[6] * par[6] / tmp2; tmp5 = R * R / tmp3; tmp6 = pow(R / par[6], par[5]); if ((par[3] == 0.0) && (R > par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * tmp5; } else if ((par[3] == 0.0) && (R <= par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * tmp4 * tmp6; } else if ((par[3] != 0.0) && (R > par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * TEMP[i] * tmp5; } else if ((par[3] != 0.0) && (R <= par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * TEMP[i] * tmp4 * tmp6; } for (i = 0; i < M; i++) { kap = KAP[i]; r = i * hrmax; < rest of loop omitted > } } Maybe not the prettiest piece of code, but certainly much more efficient than the original loop, Copy operations Several programs unnecessarily copy data from one data structure to another. This problem occurs in both Fortran and C programs, although it manifests itself differently in the two languages. Code 1 declares two arrays—one for old values and one for new values. At the end of each iteration, the array of new values is copied to the array of old values to reset the data structures for the next iteration. This problem occurs in Fortran programs not included in this study and in both Fortran 77 and Fortran 90 code. Introducing pointers to the arrays and swapping pointer values is an obvious way to eliminate the copying; but pointers is not a feature that many Fortran programmers know well or are comfortable using. An easy solution not involving pointers is to extend the dimension of the value array by 1 and use the last dimension to differentiate between arrays at different times. For example, if the data space is N x N, declare the array (N, N, 2). Then store the problem’s initial values in (_, _, 2) and define the scalar names new = 2 and old = 1. At the start of each iteration, swap old and new to reset the arrays. The old–new copy problem did not appear in any C program. In programs that had new and old values, the code swapped pointers to reset data structures. Where unnecessary coping did occur is in structure assignment and parameter passing. Structures in C are handled much like scalars. Assignment causes the data space of the right-hand name to be copied to the data space of the left-hand name. Similarly, when a structure is passed to a function, the data space of the actual parameter is copied to the data space of the formal parameter. If the structure is large and the assignment or function call is in an inner loop, then copying costs can grow quite large. While none of the ten programs considered here manifested this problem, it did occur in programs not included in the study. A simple fix is always to refer to structures via pointers. Optimizing loop structures Since scientific programs spend almost all their time in loops, efficient loops are the key to good performance. Conditionals, function calls, little instruction level parallelism, and large numbers of temporary values make it difficult for the compiler to generate tightly packed, highly efficient code. Conditionals and function calls introduce jumps that disrupt code flow. Users should eliminate or isolate conditionls to their own loops as much as possible. Often logical expressions can be substituted for if-then-else statements. For example, code 2 includes the following snippet MaxDelta = 0.0 do J = 1, N do I = 1, M < code omitted > Delta = abs(OldValue ? NewValue) if (Delta > MaxDelta) MaxDelta = Delta enddo enddo if (MaxDelta .gt. 0.001) goto 200 Since the only use of MaxDelta is to control the jump to 200 and all that matters is whether or not it is greater than 0.001, I made MaxDelta a boolean and rewrote the snippet as MaxDelta = .false. do J = 1, N do I = 1, M < code omitted > Delta = abs(OldValue ? NewValue) MaxDelta = MaxDelta .or. (Delta .gt. 0.001) enddo enddo if (MaxDelta) goto 200 thereby, eliminating the conditional expression from the inner loop. A microprocessor can execute many instructions per instruction cycle. Typically, it can execute one or more memory, floating point, integer, and jump operations. To be executed simultaneously, the operations must be independent. Thick loops tend to have more instruction level parallelism than thin loops. Moreover, they reduce memory traffice by maximizing data reuse. Loop unrolling and loop fusion are two techniques to increase the size of loop bodies. Several of the codes studied benefitted from loop unrolling, but none benefitted from loop fusion. This observation is not too surpising since it is the general tendency of programmers to write thick loops. As loops become thicker, the number of temporary values grows, increasing register pressure. If registers spill, then memory traffic increases and code flow is disrupted. A thick loop with many temporary values may execute slower than an equivalent series of thin loops. The biggest gain will be achieved if the thick loop can be split into a series of independent loops eliminating the need to write and read temporary arrays. I found such an occasion in code 10 where I split the loop do i = 1, n do j = 1, m A24(j,i)= S24(j,i) * T24(j,i) + S25(j,i) * U25(j,i) B24(j,i)= S24(j,i) * T25(j,i) + S25(j,i) * U24(j,i) A25(j,i)= S24(j,i) * C24(j,i) + S25(j,i) * V24(j,i) B25(j,i)= S24(j,i) * U25(j,i) + S25(j,i) * V25(j,i) C24(j,i)= S26(j,i) * T26(j,i) + S27(j,i) * U26(j,i) D24(j,i)= S26(j,i) * T27(j,i) + S27(j,i) * V26(j,i) C25(j,i)= S27(j,i) * S28(j,i) + S26(j,i) * U28(j,i) D25(j,i)= S27(j,i) * T28(j,i) + S26(j,i) * V28(j,i) end do end do into two disjoint loops do i = 1, n do j = 1, m A24(j,i)= S24(j,i) * T24(j,i) + S25(j,i) * U25(j,i) B24(j,i)= S24(j,i) * T25(j,i) + S25(j,i) * U24(j,i) A25(j,i)= S24(j,i) * C24(j,i) + S25(j,i) * V24(j,i) B25(j,i)= S24(j,i) * U25(j,i) + S25(j,i) * V25(j,i) end do end do do i = 1, n do j = 1, m C24(j,i)= S26(j,i) * T26(j,i) + S27(j,i) * U26(j,i) D24(j,i)= S26(j,i) * T27(j,i) + S27(j,i) * V26(j,i) C25(j,i)= S27(j,i) * S28(j,i) + S26(j,i) * U28(j,i) D25(j,i)= S27(j,i) * T28(j,i) + S26(j,i) * V28(j,i) end do end do Conclusions Over the course of the last year, I have had the opportunity to work with over two dozen academic scientific programmers at leading research universities. Their research interests span a broad range of scientific fields. Except for two programs that relied almost exclusively on library routines (matrix multiply and fast Fourier transform), I was able to improve significantly the single processor performance of all codes. Improvements range from 2x to 15.5x with a simple average of 4.75x. Changes to the source code were at a very high level. I did not use sophisticated techniques or programming tools to discover inefficiencies or effect the changes. Only one code was parallel despite the availability of parallel systems to all developers. Clearly, we have a problem—personal scientific research codes are highly inefficient and not running parallel. The developers are unaware of simple optimization techniques to make programs run faster. They lack education in the art of code optimization and parallel programming. I do not believe we can fix the problem by publishing additional books or training manuals. To date, the developers in questions have not studied the books or manual available, and are unlikely to do so in the future. Short courses are a possible solution, but I believe they are too concentrated to be much use. The general concepts can be taught in a three or four day course, but that is not enough time for students to practice what they learn and acquire the experience to apply and extend the concepts to their codes. Practice is the key to becoming proficient at optimization. I recommend that graduate students be required to take a semester length course in optimization and parallel programming. We would never give someone access to state-of-the-art scientific equipment costing hundreds of thousands of dollars without first requiring them to demonstrate that they know how to use the equipment. Yet the criterion for time on state-of-the-art supercomputers is at most an interesting project. Requestors are never asked to demonstrate that they know how to use the system, or can use the system effectively. A semester course would teach them the required skills. Government agencies that fund academic scientific research pay for most of the computer systems supporting scientific research as well as the development of most personal scientific codes. These agencies should require graduate schools to offer a course in optimization and parallel programming as a requirement for funding. About the Author John Feo received his Ph.D. in Computer Science from The University of Texas at Austin in 1986. After graduate school, Dr. Feo worked at Lawrence Livermore National Laboratory where he was the Group Leader of the Computer Research Group and principal investigator of the Sisal Language Project. In 1997, Dr. Feo joined Tera Computer Company where he was project manager for the MTA, and oversaw the programming and evaluation of the MTA at the San Diego Supercomputer Center. In 2000, Dr. Feo joined Sun Microsystems as an HPC application specialist. He works with university research groups to optimize and parallelize scientific codes. Dr. Feo has published over two dozen research articles in the areas of parallel parallel programming, parallel programming languages, and application performance.

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  • Database Table Prefixes

    - by DoctorMick
    We're having a few discussions at work around the naming of our database tables. We're working on a large application with approx 100 database tables (ok, so it isn't that large), most of which can be categorized in to different functional area, and we're trying to work out the best way of naming/organizing these within an Oracle database. The three current options are: Create the different functional areas in separate schemas. Create everything in the same schema but prefix the tables with the functional area Create everything in the same schema with no prefixes We have various pro's and con's around each one but I'd be interested to hear everyone's opinions on what the best solution is.

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  • SQL SERVER – SSMS: Memory Usage By Memory Optimized Objects Report

    - by Pinal Dave
    At conferences and at speaking engagements at the local UG, there is one question that keeps on coming which I wish were never asked. The question around, “Why is SQL Server using up all the memory and not releasing even when idle?” Well, the answer can be long and with the release of SQL Server 2014, this got even more complicated. This release of SQL Server 2014 has the option of introducing In-Memory OLTP which is completely new concept and our dependency on memory has increased multifold. In reality, nothing much changes but we have memory optimized objects (Tables and Stored Procedures) additional which are residing completely in memory and improving performance. As a DBA, it is humanly impossible to get a hang of all the innovations and the new features introduced in the next version. So today’s blog is around the report added to SSMS which gives a high level view of this new feature addition. This reports is available only from SQL Server 2014 onwards because the feature was introduced in SQL Server 2014. Earlier versions of SQL Server Management Studio would not show the report in the list. If we try to launch the report on the database which is not having In-Memory File group defined, then we would see the message in report. To demonstrate, I have created new fresh database called MemoryOptimizedDB with no special file group. Here is the query used to identify whether a database has memory-optimized file group or not. SELECT TOP(1) 1 FROM sys.filegroups FG WHERE FG.[type] = 'FX' Once we add filegroup using below command, we would see different version of report. USE [master] GO ALTER DATABASE [MemoryOptimizedDB] ADD FILEGROUP [IMO_FG] CONTAINS MEMORY_OPTIMIZED_DATA GO The report is still empty because we have not defined any Memory Optimized table in the database.  Total allocated size is shown as 0 MB. Now, let’s add the folder location into the filegroup and also created few in-memory tables. We have used the nomenclature of IMO to denote “InMemory Optimized” objects. USE [master] GO ALTER DATABASE [MemoryOptimizedDB] ADD FILE ( NAME = N'MemoryOptimizedDB_IMO', FILENAME = N'E:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\MemoryOptimizedDB_IMO') TO FILEGROUP [IMO_FG] GO You may have to change the path based on your SQL Server configuration. Below is the script to create the table. USE MemoryOptimizedDB GO --Drop table if it already exists. IF OBJECT_ID('dbo.SQLAuthority','U') IS NOT NULL DROP TABLE dbo.SQLAuthority GO CREATE TABLE dbo.SQLAuthority ( ID INT IDENTITY NOT NULL, Name CHAR(500)  COLLATE Latin1_General_100_BIN2 NOT NULL DEFAULT 'Pinal', CONSTRAINT PK_SQLAuthority_ID PRIMARY KEY NONCLUSTERED (ID), INDEX hash_index_sample_memoryoptimizedtable_c2 HASH (Name) WITH (BUCKET_COUNT = 131072) ) WITH (MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_AND_DATA) GO As soon as above script is executed, table and index both are created. If we run the report again, we would see something like below. Notice that table memory is zero but index is using memory. This is due to the fact that hash index needs memory to manage the buckets created. So even if table is empty, index would consume memory. More about the internals of how In-Memory indexes and tables work will be reserved for future posts. Now, use below script to populate the table with 10000 rows INSERT INTO SQLAuthority VALUES (DEFAULT) GO 10000 Here is the same report after inserting 1000 rows into our InMemory table.    There are total three sections in the whole report. Total Memory consumed by In-Memory Objects Pie chart showing memory distribution based on type of consumer – table, index and system. Details of memory usage by each table. The information about all three is taken from one single DMV, sys.dm_db_xtp_table_memory_stats This DMV contains memory usage statistics for both user and system In-Memory tables. If we query the DMV and look at data, we can easily notice that the system tables have negative object IDs.  So, to look at user table memory usage, below is the over-simplified version of query. USE MemoryOptimizedDB GO SELECT OBJECT_NAME(OBJECT_ID), * FROM sys.dm_db_xtp_table_memory_stats WHERE OBJECT_ID > 0 GO This report would help DBA to identify which in-memory object taking lot of memory which can be used as a pointer for designing solution. I am sure in future we will discuss at lengths the whole concept of In-Memory tables in detail over this blog. To read more about In-Memory OLTP, have a look at In-Memory OLTP Series at Balmukund’s Blog. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL Tagged: SQL Memory, SQL Reports

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