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  • JavaScript replace with callback - performance question

    - by Tomalak
    In JavaScript, you can define a callback handler in regex string replace operations: str.replace(/str[123]|etc/, replaceCallback); Imagine you have a lookup object of strings and replacements. var lookup = {"str1": "repl1", "str2": "repl2", "str3": "repl3", "etc": "etc" }; and this callback function: var replaceCallback = function(match) { if (lookup[match]) return lookup[match]; else return match; } How would you assess the performance of the above callback? Are there solid ways to improve it? Would if (match in lookup) //.... or even return lookup[match] | match; lead to opportunities for the JS compiler to optimize, or is it all the same thing?

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  • jms unresolved message-destination-ref

    - by portoalet
    hi, I am using netbeans 6.8, and glassfish v3, and making a simple jms application to work. I got this: com.sun.enterprise.container.common.spi.util.InjectionException: Exception attempting to inject Unresolved Message-Destination-Ref jms/[email protected]@null into class enterpriseapplication4.Main Code: public class Main { @Resource(name = "jms/myQueue") private static Topic myQueue; @Resource(name = "jms/myFactory") private static ConnectionFactory myFactory; ... // the rest is just boiler plate created by netbeans } In my Glassfish v3 admin console, I have jms/myFactory as my ConnectionFactory and jms/myQueue as my Destination Resources. What am I missing? Full stack: WARNING: enterprise.deployment.backend.invalidDescriptorMappingFailure com.sun.enterprise.container.common.spi.util.InjectionException: Exception attempting to inject Unresolved Message-Destination-Ref jms/[email protected]@null into class enterpriseapplication4.Main at com.sun.enterprise.container.common.impl.util.InjectionManagerImpl._inject(InjectionManagerImpl.java:614) at com.sun.enterprise.container.common.impl.util.InjectionManagerImpl.inject(InjectionManagerImpl.java:384) at com.sun.enterprise.container.common.impl.util.InjectionManagerImpl.injectClass(InjectionManagerImpl.java:210) at com.sun.enterprise.container.common.impl.util.InjectionManagerImpl.injectClass(InjectionManagerImpl.java:202) at org.glassfish.appclient.client.acc.AppClientContainer$ClientMainClassSetting.getClientMainClass(AppClientContainer.java:599) at org.glassfish.appclient.client.acc.AppClientContainer.getMainMethod(AppClientContainer.java:498) at org.glassfish.appclient.client.acc.AppClientContainer.completePreparation(AppClientContainer.java:397) at org.glassfish.appclient.client.acc.AppClientContainer.prepare(AppClientContainer.java:311) at org.glassfish.appclient.client.AppClientFacade.prepareACC(AppClientFacade.java:264) at org.glassfish.appclient.client.acc.agent.AppClientContainerAgent.premain(AppClientContainerAgent.java:75) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:323) at sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:338) Caused by: javax.naming.NamingException: Lookup failed for 'java:comp/env/jms/myQueue' in SerialContext targetHost=localhost,targetPort=3700 [Root exception is javax.naming.NameNotFoundException: No object bound for java:comp/env/jms/myQueue [Root exception is java.lang.NullPointerException]] at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:442) at javax.naming.InitialContext.lookup(InitialContext.java:392) at com.sun.enterprise.container.common.impl.util.InjectionManagerImpl._inject(InjectionManagerImpl.java:513) ... 15 more Caused by: javax.naming.NameNotFoundException: No object bound for java:comp/env/jms/myQueue [Root exception is java.lang.NullPointerException] at com.sun.enterprise.naming.impl.JavaURLContext.lookup(JavaURLContext.java:218) at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:428) ... 17 more Caused by: java.lang.NullPointerException at javax.naming.InitialContext.getURLScheme(InitialContext.java:269) at javax.naming.InitialContext.getURLOrDefaultInitCtx(InitialContext.java:318) at javax.naming.InitialContext.lookup(InitialContext.java:392) at com.sun.enterprise.naming.util.JndiNamingObjectFactory.create(JndiNamingObjectFactory.java:75) at com.sun.enterprise.naming.impl.GlassfishNamingManagerImpl.lookup(GlassfishNamingManagerImpl.java:688) at com.sun.enterprise.naming.impl.GlassfishNamingManagerImpl.lookup(GlassfishNamingManagerImpl.java:657) at com.sun.enterprise.naming.impl.JavaURLContext.lookup(JavaURLContext.java:148) ... 18 more Regards

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  • Seeking on a Heap, and Two Useful DMVs

    - by Paul White
    So far in this mini-series on seeks and scans, we have seen that a simple ‘seek’ operation can be much more complex than it first appears.  A seek can contain one or more seek predicates – each of which can either identify at most one row in a unique index (a singleton lookup) or a range of values (a range scan).  When looking at a query plan, we will often need to look at the details of the seek operator in the Properties window to see how many operations it is performing, and what type of operation each one is.  As you saw in the first post in this series, the number of hidden seeking operations can have an appreciable impact on performance. Measuring Seeks and Scans I mentioned in my last post that there is no way to tell from a graphical query plan whether you are seeing a singleton lookup or a range scan.  You can work it out – if you happen to know that the index is defined as unique and the seek predicate is an equality comparison, but there’s no separate property that says ‘singleton lookup’ or ‘range scan’.  This is a shame, and if I had my way, the query plan would show different icons for range scans and singleton lookups – perhaps also indicating whether the operation was one or more of those operations underneath the covers. In light of all that, you might be wondering if there is another way to measure how many seeks of either type are occurring in your system, or for a particular query.  As is often the case, the answer is yes – we can use a couple of dynamic management views (DMVs): sys.dm_db_index_usage_stats and sys.dm_db_index_operational_stats. Index Usage Stats The index usage stats DMV contains counts of index operations from the perspective of the Query Executor (QE) – the SQL Server component that is responsible for executing the query plan.  It has three columns that are of particular interest to us: user_seeks – the number of times an Index Seek operator appears in an executed plan user_scans – the number of times a Table Scan or Index Scan operator appears in an executed plan user_lookups – the number of times an RID or Key Lookup operator appears in an executed plan An operator is counted once per execution (generating an estimated plan does not affect the totals), so an Index Seek that executes 10,000 times in a single plan execution adds 1 to the count of user seeks.  Even less intuitively, an operator is also counted once per execution even if it is not executed at all.  I will show you a demonstration of each of these things later in this post. Index Operational Stats The index operational stats DMV contains counts of index and table operations from the perspective of the Storage Engine (SE).  It contains a wealth of interesting information, but the two columns of interest to us right now are: range_scan_count – the number of range scans (including unrestricted full scans) on a heap or index structure singleton_lookup_count – the number of singleton lookups in a heap or index structure This DMV counts each SE operation, so 10,000 singleton lookups will add 10,000 to the singleton lookup count column, and a table scan that is executed 5 times will add 5 to the range scan count. The Test Rig To explore the behaviour of seeks and scans in detail, we will need to create a test environment.  The scripts presented here are best run on SQL Server 2008 Developer Edition, but the majority of the tests will work just fine on SQL Server 2005.  A couple of tests use partitioning, but these will be skipped if you are not running an Enterprise-equivalent SKU.  Ok, first up we need a database: USE master; GO IF DB_ID('ScansAndSeeks') IS NOT NULL DROP DATABASE ScansAndSeeks; GO CREATE DATABASE ScansAndSeeks; GO USE ScansAndSeeks; GO ALTER DATABASE ScansAndSeeks SET ALLOW_SNAPSHOT_ISOLATION OFF ; ALTER DATABASE ScansAndSeeks SET AUTO_CLOSE OFF, AUTO_SHRINK OFF, AUTO_CREATE_STATISTICS OFF, AUTO_UPDATE_STATISTICS OFF, PARAMETERIZATION SIMPLE, READ_COMMITTED_SNAPSHOT OFF, RESTRICTED_USER ; Notice that several database options are set in particular ways to ensure we get meaningful and reproducible results from the DMVs.  In particular, the options to auto-create and update statistics are disabled.  There are also three stored procedures, the first of which creates a test table (which may or may not be partitioned).  The table is pretty much the same one we used yesterday: The table has 100 rows, and both the key_col and data columns contain the same values – the integers from 1 to 100 inclusive.  The table is a heap, with a non-clustered primary key on key_col, and a non-clustered non-unique index on the data column.  The only reason I have used a heap here, rather than a clustered table, is so I can demonstrate a seek on a heap later on.  The table has an extra column (not shown because I am too lazy to update the diagram from yesterday) called padding – a CHAR(100) column that just contains 100 spaces in every row.  It’s just there to discourage SQL Server from choosing table scan over an index + RID lookup in one of the tests. The first stored procedure is called ResetTest: CREATE PROCEDURE dbo.ResetTest @Partitioned BIT = 'false' AS BEGIN SET NOCOUNT ON ; IF OBJECT_ID(N'dbo.Example', N'U') IS NOT NULL BEGIN DROP TABLE dbo.Example; END ; -- Test table is a heap -- Non-clustered primary key on 'key_col' CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, padding CHAR(100) NOT NULL DEFAULT SPACE(100), CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col) ) ; IF @Partitioned = 'true' BEGIN -- Enterprise, Trial, or Developer -- required for partitioning tests IF SERVERPROPERTY('EngineEdition') = 3 BEGIN EXECUTE (' DROP TABLE dbo.Example ; IF EXISTS ( SELECT 1 FROM sys.partition_schemes WHERE name = N''PS'' ) DROP PARTITION SCHEME PS ; IF EXISTS ( SELECT 1 FROM sys.partition_functions WHERE name = N''PF'' ) DROP PARTITION FUNCTION PF ; CREATE PARTITION FUNCTION PF (INTEGER) AS RANGE RIGHT FOR VALUES (20, 40, 60, 80, 100) ; CREATE PARTITION SCHEME PS AS PARTITION PF ALL TO ([PRIMARY]) ; CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, padding CHAR(100) NOT NULL DEFAULT SPACE(100), CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col) ) ON PS (key_col); '); END ELSE BEGIN RAISERROR('Invalid SKU for partition test', 16, 1); RETURN; END; END ; -- Non-unique non-clustered index on the 'data' column CREATE NONCLUSTERED INDEX [IX dbo.Example data] ON dbo.Example (data) ; -- Add 100 rows INSERT dbo.Example WITH (TABLOCKX) ( key_col, data ) SELECT key_col = V.number, data = V.number FROM master.dbo.spt_values AS V WHERE V.[type] = N'P' AND V.number BETWEEN 1 AND 100 ; END; GO The second stored procedure, ShowStats, displays information from the Index Usage Stats and Index Operational Stats DMVs: CREATE PROCEDURE dbo.ShowStats @Partitioned BIT = 'false' AS BEGIN -- Index Usage Stats DMV (QE) SELECT index_name = ISNULL(I.name, I.type_desc), scans = IUS.user_scans, seeks = IUS.user_seeks, lookups = IUS.user_lookups FROM sys.dm_db_index_usage_stats AS IUS JOIN sys.indexes AS I ON I.object_id = IUS.object_id AND I.index_id = IUS.index_id WHERE IUS.database_id = DB_ID(N'ScansAndSeeks') AND IUS.object_id = OBJECT_ID(N'dbo.Example', N'U') ORDER BY I.index_id ; -- Index Operational Stats DMV (SE) IF @Partitioned = 'true' SELECT index_name = ISNULL(I.name, I.type_desc), partitions = COUNT(IOS.partition_number), range_scans = SUM(IOS.range_scan_count), single_lookups = SUM(IOS.singleton_lookup_count) FROM sys.dm_db_index_operational_stats ( DB_ID(N'ScansAndSeeks'), OBJECT_ID(N'dbo.Example', N'U'), NULL, NULL ) AS IOS JOIN sys.indexes AS I ON I.object_id = IOS.object_id AND I.index_id = IOS.index_id GROUP BY I.index_id, -- Key I.name, I.type_desc ORDER BY I.index_id; ELSE SELECT index_name = ISNULL(I.name, I.type_desc), range_scans = SUM(IOS.range_scan_count), single_lookups = SUM(IOS.singleton_lookup_count) FROM sys.dm_db_index_operational_stats ( DB_ID(N'ScansAndSeeks'), OBJECT_ID(N'dbo.Example', N'U'), NULL, NULL ) AS IOS JOIN sys.indexes AS I ON I.object_id = IOS.object_id AND I.index_id = IOS.index_id GROUP BY I.index_id, -- Key I.name, I.type_desc ORDER BY I.index_id; END; The final stored procedure, RunTest, executes a query written against the example table: CREATE PROCEDURE dbo.RunTest @SQL VARCHAR(8000), @Partitioned BIT = 'false' AS BEGIN -- No execution plan yet SET STATISTICS XML OFF ; -- Reset the test environment EXECUTE dbo.ResetTest @Partitioned ; -- Previous call will throw an error if a partitioned -- test was requested, but SKU does not support it IF @@ERROR = 0 BEGIN -- IO statistics and plan on SET STATISTICS XML, IO ON ; -- Test statement EXECUTE (@SQL) ; -- Plan and IO statistics off SET STATISTICS XML, IO OFF ; EXECUTE dbo.ShowStats @Partitioned; END; END; The Tests The first test is a simple scan of the heap table: EXECUTE dbo.RunTest @SQL = 'SELECT * FROM Example'; The top result set comes from the Index Usage Stats DMV, so it is the Query Executor’s (QE) view.  The lower result is from Index Operational Stats, which shows statistics derived from the actions taken by the Storage Engine (SE).  We see that QE performed 1 scan operation on the heap, and SE performed a single range scan.  Let’s try a single-value equality seek on a unique index next: EXECUTE dbo.RunTest @SQL = 'SELECT key_col FROM Example WHERE key_col = 32'; This time we see a single seek on the non-clustered primary key from QE, and one singleton lookup on the same index by the SE.  Now for a single-value seek on the non-unique non-clustered index: EXECUTE dbo.RunTest @SQL = 'SELECT data FROM Example WHERE data = 32'; QE shows a single seek on the non-clustered non-unique index, but SE shows a single range scan on that index – not the singleton lookup we saw in the previous test.  That makes sense because we know that only a single-value seek into a unique index is a singleton seek.  A single-value seek into a non-unique index might retrieve any number of rows, if you think about it.  The next query is equivalent to the IN list example seen in the first post in this series, but it is written using OR (just for variety, you understand): EXECUTE dbo.RunTest @SQL = 'SELECT data FROM Example WHERE data = 32 OR data = 33'; The plan looks the same, and there’s no difference in the stats recorded by QE, but the SE shows two range scans.  Again, these are range scans because we are looking for two values in the data column, which is covered by a non-unique index.  I’ve added a snippet from the Properties window to show that the query plan does show two seek predicates, not just one.  Now let’s rewrite the query using BETWEEN: EXECUTE dbo.RunTest @SQL = 'SELECT data FROM Example WHERE data BETWEEN 32 AND 33'; Notice the seek operator only has one predicate now – it’s just a single range scan from 32 to 33 in the index – as the SE output shows.  For the next test, we will look up four values in the key_col column: EXECUTE dbo.RunTest @SQL = 'SELECT key_col FROM Example WHERE key_col IN (2,4,6,8)'; Just a single seek on the PK from the Query Executor, but four singleton lookups reported by the Storage Engine – and four seek predicates in the Properties window.  On to a more complex example: EXECUTE dbo.RunTest @SQL = 'SELECT * FROM Example WITH (INDEX([PK dbo.Example key_col])) WHERE key_col BETWEEN 1 AND 8'; This time we are forcing use of the non-clustered primary key to return eight rows.  The index is not covering for this query, so the query plan includes an RID lookup into the heap to fetch the data and padding columns.  The QE reports a seek on the PK and a lookup on the heap.  The SE reports a single range scan on the PK (to find key_col values between 1 and 8), and eight singleton lookups on the heap.  Remember that a bookmark lookup (RID or Key) is a seek to a single value in a ‘unique index’ – it finds a row in the heap or cluster from a unique RID or clustering key – so that’s why lookups are always singleton lookups, not range scans. Our next example shows what happens when a query plan operator is not executed at all: EXECUTE dbo.RunTest @SQL = 'SELECT key_col FROM Example WHERE key_col = 8 AND @@TRANCOUNT < 0'; The Filter has a start-up predicate which is always false (if your @@TRANCOUNT is less than zero, call CSS immediately).  The index seek is never executed, but QE still records a single seek against the PK because the operator appears once in an executed plan.  The SE output shows no activity at all.  This next example is 2008 and above only, I’m afraid: EXECUTE dbo.RunTest @SQL = 'SELECT * FROM Example WHERE key_col BETWEEN 1 AND 30', @Partitioned = 'true'; This is the first example to use a partitioned table.  QE reports a single seek on the heap (yes – a seek on a heap), and the SE reports two range scans on the heap.  SQL Server knows (from the partitioning definition) that it only needs to look at partitions 1 and 2 to find all the rows where key_col is between 1 and 30 – the engine seeks to find the two partitions, and performs a range scan seek on each partition. The final example for today is another seek on a heap – try to work out the output of the query before running it! EXECUTE dbo.RunTest @SQL = 'SELECT TOP (2) WITH TIES * FROM Example WHERE key_col BETWEEN 1 AND 50 ORDER BY $PARTITION.PF(key_col) DESC', @Partitioned = 'true'; Notice the lack of an explicit Sort operator in the query plan to enforce the ORDER BY clause, and the backward range scan. © 2011 Paul White email: [email protected] twitter: @SQL_Kiwi

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  • /etc/postfix/transport missing; what should it look like?

    - by Thufir
    I'm following the mailman guide but couldn't locate /etc/postfix/ so created it as follows: root@dur:~# root@dur:~# cat /etc/postfix/transport dur.bounceme.net mailman: root@dur:~# root@dur:~# telnet localhost 25 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. 220 dur.bounceme.net ESMTP Postfix (Ubuntu) ehlo fqdn_test 250-dur.bounceme.net 250-PIPELINING 250-SIZE 10240000 250-VRFY 250-ETRN 250-STARTTLS 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN mail from:[email protected] 250 2.1.0 Ok rcpt to:thufir@localhost 451 4.3.0 <thufir@localhost>: Temporary lookup failure rcpt to:[email protected] 451 4.3.0 <[email protected]>: Temporary lookup failure quit 221 2.0.0 Bye Connection closed by foreign host. root@dur:~# root@dur:~# postconf -n alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases append_dot_mydomain = no biff = no broken_sasl_auth_clients = yes config_directory = /etc/postfix default_transport = smtp home_mailbox = Maildir/ inet_interfaces = loopback-only mailbox_command = /usr/lib/dovecot/deliver -c /etc/dovecot/conf.d/01-mail-stack-delivery.conf -m "${EXTENSION}" mailbox_size_limit = 0 mailman_destination_recipient_limit = 1 mydestination = dur, dur.bounceme.net, localhost.bounceme.net, localhost myhostname = dur.bounceme.net mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 readme_directory = no recipient_delimiter = + relay_domains = lists.dur.bounceme.net relay_transport = relay relayhost = smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache smtp_use_tls = yes smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) smtpd_recipient_restrictions = reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination smtpd_sasl_auth_enable = yes smtpd_sasl_authenticated_header = yes smtpd_sasl_local_domain = $myhostname smtpd_sasl_path = private/dovecot-auth smtpd_sasl_security_options = noanonymous smtpd_sasl_type = dovecot smtpd_tls_auth_only = yes smtpd_tls_cert_file = /etc/ssl/certs/ssl-mail.pem smtpd_tls_key_file = /etc/ssl/private/ssl-mail.key smtpd_tls_mandatory_ciphers = medium smtpd_tls_mandatory_protocols = SSLv3, TLSv1 smtpd_tls_received_header = yes smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtpd_use_tls = yes tls_random_source = dev:/dev/urandom transport_maps = hash:/etc/postfix/transport root@dur:~# root@dur:~# tail /var/log/mail.log Aug 28 02:05:15 dur postfix/smtpd[20326]: connect from localhost[127.0.0.1] Aug 28 02:06:10 dur postfix/smtpd[20326]: warning: hash:/var/lib/mailman/data/aliases is unavailable. open database /var/lib/mailman/data/aliases.db: No such file or directory Aug 28 02:06:10 dur postfix/smtpd[20326]: warning: hash:/var/lib/mailman/data/aliases lookup error for "thufir@localhost" Aug 28 02:06:10 dur postfix/smtpd[20326]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 451 4.3.0 <thufir@localhost>: Temporary lookup failure; from=<[email protected]> to=<thufir@localhost> proto=ESMTP helo=<fqdn_test> Aug 28 02:06:23 dur postfix/smtpd[20326]: warning: hash:/var/lib/mailman/data/aliases is unavailable. open database /var/lib/mailman/data/aliases.db: No such file or directory Aug 28 02:06:23 dur postfix/smtpd[20326]: warning: hash:/var/lib/mailman/data/aliases lookup error for "[email protected]" Aug 28 02:06:23 dur postfix/smtpd[20326]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 451 4.3.0 <[email protected]>: Temporary lookup failure; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<fqdn_test> Aug 28 02:06:28 dur postfix/smtpd[20326]: disconnect from localhost[127.0.0.1] Aug 28 02:06:49 dur dovecot: pop3-login: Login: user=<thufir>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=20338, TLS Aug 28 02:06:49 dur dovecot: pop3(thufir): Disconnected: Logged out top=0/0, retr=0/0, del=0/0, size=0 root@dur:~# The manual page is here.

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  • Look-up Tables in SQL

    Lookup tables can be a force for good in a relational database. Whereas the 'One True Lookup Table' remains a classic of bad database design, an auxiliary table that holds static data, and is used to lookup values, still has powerful magic. Joe Celko explains.... NEW! SQL Monitor 2.0Monitor SQL Server Central's servers withRed Gate's new SQL Monitor.No installation required. Find out more.

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  • infer half vector length in BRDF

    - by cician
    it's my first question on stack. Is it possible to infer length of the half angle vector for specular lighting from N·L and N·V without the whole view and light vectors? I may be completely off-track, but I have this gut feeling it's possible... Why? I'm working on a skin shader and I'm already doing one texture lookup with N·L+N·E and one texture lookup for specular with N·H+N·V. The latter one can be transformed into N·L+N·E lookup if only I had the half vector length. Doing so could simplify the shader a bit and move some operations into the pre-computed lookup texture. It would make a huge difference since I'm trying to squeeze as much functionality as possible to a single pass mobile version so instruction count matters. Thanks.

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  • How to inject a Session Bean into a Message Driven Bean?

    - by Hank
    Hi guys, I'm reasonably new to JEE, so this might be stupid.. bear with me pls :D I would like to inject a stateless session bean into a message-driven bean. Basically, the MDB gets a JMS message, then uses a session bean to perform the work. The session bean holds the business logic. Here's my Session Bean: @Stateless public class TestBean implements TestBeanRemote { public void doSomething() { // business logic goes here } } The matching interface: @Remote public interface TestBeanRemote { public void doSomething(); } Here's my MDB: @MessageDriven(mappedName = "jms/mvs.TestController", activationConfig = { @ActivationConfigProperty(propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge"), @ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue") }) public class TestController implements MessageListener { @EJB private TestBean testBean; public TestController() { } public void onMessage(Message message) { testBean.doSomething(); } } So far, not rocket science, right? Unfortunately, when deploying this to glassfish v3, and sending a message to the appropriate JMS Queue, I get errors that glassfish is unable to locate the TestBean EJB: java.lang.IllegalStateException: Exception attempting to inject Remote ejb-ref name=mvs.test.TestController/testBean,Remote 3.x interface =mvs.test.TestBean,ejb-link=null,lookup=null,mappedName=,jndi-name=mvs.test.TestBean,refType=Session into class mvs.test.TestController Caused by: com.sun.enterprise.container.common.spi.util.InjectionException: Exception attempting to inject Remote ejb-ref name=mvs.test.TestController/testBean,Remote 3.x interface =mvs.test.TestBean,ejb-link=null,lookup=null,mappedName=,jndi-name=mvs.test.TestBean,refType=Session into class mvs.test.TestController Caused by: javax.naming.NamingException: Lookup failed for 'java:comp/env/mvs.test.TestController/testBean' in SerialContext [Root exception is javax.naming.NamingException: Exception resolving Ejb for 'Remote ejb-ref name=mvs.test.TestController/testBean,Remote 3.x interface =mvs.test.TestBean,ejb-link=null,lookup=null,mappedName=,jndi-name=mvs.test.TestBean,refType=Session' . Actual (possibly internal) Remote JNDI name used for lookup is 'mvs.test.TestBean#mvs.test.TestBean' [Root exception is javax.naming.NamingException: Lookup failed for 'mvs.test.TestBean#mvs.test.TestBean' in SerialContext [Root exception is javax.naming.NameNotFoundException: mvs.test.TestBean#mvs.test.TestBean not found]]] So my questions are: - is this the correct way of injecting a session bean into another bean (particularly a message driven bean)? - why is the naming lookup failing? Thanks for all your help! Cheers, Hank

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  • help with delete where not in query

    - by kralco626
    I have a lookup table (##lookup). I know it's bad design because I'm duplicating data, but it speeds up my queries tremendously. I have a query that populates this table insert into ##lookup select distinct col1,col2,... from table1...join...etc... I would like to simulate this behavior: delete from ##lookup insert into ##lookup select distinct col1,col2,... from table1...join...etc... This would clearly update the table correctly. But this is a lot of inserting and deleting. It messes with my indexes and locks up the table for selecting from. This table could also be updated by something like: delete from ##lookup where not in (select distinct col1,col2,... from table1...join...etc...) insert into ##lookup (select distinct col1,col2,... from table1...join...etc...) except if it is already in the table The second way may take longer, but I can say "with no lock" and I will be able to select from the table. Any ideas on how to write the query the second way?

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  • Is there a website to lookup common, already written functions?

    - by pinnacler
    I'm sitting here writing a function that I'm positive has been written before, somewhere on earth. It's just too common to have not been attempted, and I'm wondering why I can't just go to a website and search for a function that I can then copy and paste into my project in 2 seconds, instead of wasting my day reinventing the wheel. Sure there are certain libraries you can use, but where do you find these libraries and when they are absent, is there a site like I'm describing? Possibly a wiki of some type that contains free code that anybody can edit and improve?

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  • Perform case-insensitive lookup on an Array in MongoDB?

    - by Hal
    So, I've decided to get my feet wet with MongoDB and love it so far. It seems very fast and flexible which is great. But, I'm still going through the initial learning curve and as such, I'm spending hours digging for info on the most basic things. I've search throughout the MongoDB online documentation and have spent hours Googling through pages without any mention of this. I know Mongo is still quite new (v1.x) so it explains why there isn't much information yet. I've even trying looking for books on Mongo without much luck. So yes, I've tried to RTFM with no luck, so, now I turn to you. I have an Array of various Hashtags nested in each document (ie: #apples, #oranges, #Apples, #APPLES) and I would like to perform a case-insensitive find() to access all the documents containing apples in any case. It seems that find does support some regex with /i, but I can't seem to get this working either. Anyway, I hope this is a quick answer for someone. Here's my existing call in PHP which is case sensitive: $cursor = $collection->find(array( "hashtags" => array("#".$keyword)))->sort(array('$natural' => -1))->limit(10); Help?

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  • Using PHP to extract data from an ATOM feed and using it reverse lookup coordinates to an actual add

    - by gbhall
    Basically I have a public feed: http://www.google.com/latitude/apps/badge/api?user=-1671995934285587708&type=atom If you go to my Google Profile you can see it says: "Gareth is in 6 Seaside Gardens, Mullaloo WA 6027, Australia (1 minute ago)" google.com/profiles/Gareth.B.Hall How can I, using PHP, display my location on a website the same way it's displayed on my Google Profile? Thanks

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  • what data structure should I use for hash lookup as well as binary search?

    - by zebraman
    I am working on a school homework. I have a list of names. I want to be able to perform binary search on these names (find all names between a lower and upper bound) for first name as well as last name, and perform keyword searches as well (this will be accomplished using hashing. For example, if I have the names Garfield Cat Snoopy Dog Captain Crunch Fat Cat then a binary search of first names (C,H) will return Captain Crunch, Fat Cat, and Garfield Cat. A binary search of last names (Cr,D) will return Captain Crunch. A keyword search of 'cat' will return Fat Cat and Garfield Cat. I understand binary search will only work on a sorted list, but since I am planning on searching two different criteria, I will have to sort the list by last name or first name depending on what I'm searching for. I feel like it will be too inefficient to have to resort the list each time I want to perform a new binary search. Would it just be better for me to set up and maintain two sorted lists (one for sorted by first name, one for sorted by last name)? Also, for hashing, will I have to set up a different table of names for that as well? I understand each keyword will hash to some value determined by a hash function, and this value (or key) is a table address where the corresponding names are stored. So I just want to know what would be the best way to solve this problem? Maintaining separate structures, or is there a way to efficiently do everything I want with just one data structure?

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  • how can I Replace a normalize job title in a contact entity based on a lookup enity

    - by Jarkley
    Folks, Im using MSCRM 4 and I have a contact entity with an actual job title and a normalized job title field. I would like to populate the normalized job title field based on the actual job title. I created a seperate entity which is a table that corelates the nomalized job title with the actual job title eg Administrative CFO equals CFO. I guess this needs to be done via an on-load or on-save script But I cant figure out how to do it. Any help would be much appreciated Regards Joe ( Scotland)

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  • How can I lookup data about a book from its barcode number?

    - by Joel Spolsky
    I'm building the world's simplest library application. All I want to be able to do is scan in a book's UPC (barcode) using a typical scanner (which just types the numbers of the barcode into a field) and then use it to look up data about the book... at a minimum, title, author, year published, and either the Dewey Decimal or Library of Congress catalog number. The goal is to print out a tiny sticker ("spine label") with the card catalog number that I can stick on the spine of the book, and then I can sort the books by card catalog number on the shelves in our company library. That way books on similar subjects will tend to be near each other, for example, if you know you're looking for a book about accounting, all you have to do is find SOME book about accounting and you'll see the other half dozen that we have right next to it which makes it convenient to browse the library. There seem to be lots of web APIs to do this, including Amazon and the Library of Congress. But those are all extremely confusing to me. What I really just want is a single higher level function that takes a UPC barcode number and returns some basic data about the book.

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  • Is there a website to lookup already common code functions?

    - by pinnacler
    I'm sitting here writing a function that I'm positive has been written before, somewhere on earth. It's just too common to have not been attempted, and I'm wondering why I can't just go to a website and search for a function that I can then copy and paste into my project in 2 seconds, instead of wasting my day reinventing the wheel. Sure there are certain libraries you can use, but where do you find these libraries and when they are absent, is there a site like I'm describing?

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  • How can I make hash key lookup case-insensitive?

    - by mseery
    Evidently hash keys are compared in a case-sensitive manner. $ perl -e '%hash = ( FOO => 1 ); printf "%s\n", ( exists $hash{foo} ) ? "Yes" : "No";' No $ perl -e '%hash = ( FOO => 1 ); printf "%s\n", ( exists $hash{FOO} ) ? "Yes" : "No";' Yes Is there a setting to change that for the current script? Thanks.

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  • CouchDB emit with lookup key that is array, such that order of array elements are ignored.

    - by MatternPatching
    When indexing a couchdb view, you can emit an array as the key such as: emit(["one", "two", "three"], doc); I appreciate the fact that when searching the view, the order is important, but sometimes I would like the view to ignore it. I have thought of a couple of options. 1. By convention, just emit the contents in alphabetical order, and ensure that looking up uses the same convention. 2. Somehow hash in a manner that disregards the order, and emit/search based on that hash. (This is fairly easy, if you simply hash each one individually, "sum" the hashes, then mod.) Note: I'm sure this may be covered somewhere in the authoritative guide, but I was unsuccessful in finding it.

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  • lookup datasource in context every time, Is it right?

    - by Srikanth Dyapa
    In my application i configured more than one datasource (for diff databases). Whenever user sends a request depends upon user category i need to look up for the respective datasource in the context and get a connection from that datasource to execute queries which are assigned to that user. Is it right way to achieve my requirement? I am using tomcat 6, struts 1.3. The databases may be oracle or mysql or both. Give me an optimized solution. Thanks in advance.

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  • Need help with local network printing while using VPN on Ubuntu 10.10 desktop

    - by MountainX
    I can print to my HP printer via the LAN when I'm not connected to the VPN. When connected to the VPN, printing fails. OpenVPN 2.1.0 x86_64-pc-linux-gnu [SSL] [LZO2] [EPOLL] [PKCS11] [MH] [PF_INET6] [eurephia] built on Jul 12 2010 I can ping the printer while connected to the VPN: $ ping 192.168.100.12 PING 192.168.100.12 (192.168.100.12) 56(84) bytes of data. 64 bytes from 192.168.100.12: icmp_req=1 ttl=255 time=9.17 ms --- 192.168.100.12 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss... $ ping HpPrinter.local PING HpPrinter.local (192.168.100.12) 56(84) bytes of data. 64 bytes from HpPrinter.local (192.168.100.12): icmp_req=1 ttl=255 time=0.383 ms --- HpPrinter.local ping statistics --- 4 packets transmitted, 4 received, 0% packet loss... But here's the error when I try to print while connected to the VPN: hpijs[9990]: io/hpmud/jd.c 784: mdns lookup HpPrinter.local retry 1... ... hpijs[9990]: io/hpmud/jd.c 784: mdns lookup HpPrinter.local retry 20... hpijs[9990]: io/hpmud/jd.c 780: error timeout mdns lookup HpPrinter.local hpijs[9990]: io/hpmud/jd.c 88: unable to read device-id hp[9982]: io/hpmud/jd.c 784: mdns lookup HpPrinter.local retry 1... ... hp[9982]: io/hpmud/jd.c 784: mdns lookup HpPrinter.local retry 20... hp[9982]: io/hpmud/jd.c 780: error timeout mdns lookup HpPrinter.local hp[9982]: io/hpmud/jd.c 88: unable to read device-id hp[9982]: prnt/backend/hp.c 745: ERROR: open device failed stat=12: hp:/net/Officejet_Pro_L7600?zc=HpPrinter I am running iptables rules, but the problem doesn't appear related to the firewall. I've tested with no rules (i.e., no firewall). The printing problem happens when the VPN is connected. I can guess it is an mdns problem, but searching google about mdns didn't turn up anything that seemed related to this (at my level of knowledge). Any suggestions?

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  • Dovecot Virtual Users Not Authenticating

    - by blankabout
    We have a standard Postfix/Dovecot installation working perfectly with real users but cannot work out how to add virtual users, all virtual user login attempts fail with authentication errors. Following are snippets from the configuration files: /etc/postfix/main.cf: virtual_mailbox_domains = virtualexample.com virtual_mailbox_base = /var/spool/vhosts virtual_mailbox_recipients = hash:/etc/postfix/virtual_mailbox_recipients /etc/dovecot/dovecot.conf: !include conf.d/*.conf /etc/dovecot/conf.d/10-auth.conf auth_mechanisms = cram-md5 digest-md5 plain passdb { driver = passwd-file # Path for passwd-file. Also set the default password scheme. args = scheme=cram-md5 /etc/cram-md5.pwd } /etc/cram-md5.pwd [email protected]{MD5}$1$uIMvzy92$9Xt67B/qw4u6txkkxzne80 This is a snippet from the log when a login attempt is made: auth: Debug: Loading modules from directory: /usr/lib64/dovecot/auth auth: Debug: Module loaded: /usr/lib64/dovecot/auth/libauthdb_ldap.so auth: Debug: Module loaded: /usr/lib64/dovecot/auth/libdriver_sqlite.so auth: Debug: Module loaded: /usr/lib64/dovecot/auth/libmech_gssapi.so auth: Debug: passwd-file /etc/cram-md5.pwd: Read 1 users auth: Debug: auth client connected (pid=21990) auth: Debug: client in: AUTH#0111#011CRAM-MD5#011service=imap#011lip=1.1.1.1#011rip=2.2.2.2#011lport=143#011rport=51774 auth: Debug: client out: CONT#0111#011PDI1Njc0NjQ1NzQ3MTY0NTkuMTM0MTIxNzkwN0BncDM+ auth: Debug: client in: CONT auth: Debug: passwd-file([email protected],2.2.2.2): lookup: [email protected] file=/etc/cram-md5.pwd auth: Debug: client out: OK#0111#[email protected] auth: Debug: master in: REQUEST#0111630404609#01121990#0111#011b66b5f46b520a08e1d19d3d249be7073 auth: Debug: passwd([email protected],2.2.2.2): lookup auth: passwd([email protected],2.2.2.2): unknown user auth: Error: userdb([email protected],2.2.2.2): user not found from userdb passwd auth: Debug: master out: NOTFOUND#0111630404609 imap: Error: Authenticated user not found from userdb, auth lookup id=1630404609 (client-pid=21990 client-id=1) imap-login: Internal login failure (pid=21990 id=1) (auth failed, 1 attempts): user=, method=CRAM-MD5, rip=2.2.2.2, lip=1.1.1.1, mpid=21993 auth: Debug: auth client connected (pid=22010) auth: Debug: client in: AUTH#0111#011CRAM-MD5#011service=imap#011lip=1.1.1.1#011rip=2.2.2.2#011lport=143#011rport=51775 auth: Debug: client out: CONT#0111#011PDcxMDkwNDY1NTQzODUzMDkuMTM0MTIxNzkyOEBncDM+ auth: Debug: client in: CONT auth: Debug: passwd-file([email protected],2.2.2.2): lookup: [email protected] file=/etc/cram-md5.pwd auth: Debug: client out: OK#0111#[email protected] auth: Debug: master in: REQUEST#011343539713#01122010#0111#011e47b1345784e2845d59e794afa9a6bbe auth: Debug: passwd([email protected],2.2.2.2): lookup auth: passwd([email protected],2.2.2.2): unknown user auth: Error: userdb([email protected],2.2.2.2): user not found from userdb passwd auth: Debug: master out: NOTFOUND#011343539713 imap: Error: Authenticated user not found from userdb, auth lookup id=343539713 (client-pid=22010 client-id=1) imap-login: Internal login failure (pid=22010 id=1) (auth failed, 1 attempts): user=, method=CRAM-MD5, rip=2.2.2.2, lip=1.1.1.1, mpid=22011 It would appear that the user lookup is not working, even tho' the log suggests that Dovecot is using the /etc/cram-md5.pwd file and the user is configured in that same file. There are of course dozens of examples of using virtual users with Dovecot, but all the ones we have found either refer to Dovecot 1.x (we are using 2.x), using only virtual users (we must use real AND virtual users) or want to use a MySQL db, we need to use a text file. Some hints about where we are going wrong would be very much appreciated.

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  • Conflicting ip routes with local table on attaching a virtual network interface

    - by user1071840
    I have an EC2 instance with these ip rules: $ sudo ip rule show 0: from all lookup local 32766: from all lookup main 32767: from all lookup default I can attach an elastic network interface to it with a private IP. Say the IP of my machine is 10.1.3.12 and the IP of the interface is 10.1.1.190. As soon as I attach the interface to my machine a new entry is added to the routing policy and local routing table: sudo ip rule show 0: from all lookup local 32765: from 10.1.1.190 lookup 10003 32766: from all lookup main 32767: from all lookup default $ sudo ip route show table local broadcast 10.1.1.0 dev eth3 proto kernel scope link src 10.1.1.190 local 10.1.1.190 dev eth3 proto kernel scope host src 10.1.1.190 broadcast 10.1.1.255 dev eth3 proto kernel scope link src 10.1.1.190 broadcast 10.1.3.0 dev eth0 proto kernel scope link src 10.1.3.12 local 10.1.3.12 dev eth0 proto kernel scope host src 10.1.3.12 broadcast 10.1.3.255 dev eth0 proto kernel scope link src 10.1.3.12 broadcast 127.0.0.0 dev lo proto kernel scope link src 127.0.0.1 local 127.0.0.0/8 dev lo proto kernel scope host src 127.0.0.1 local 127.0.0.1 dev lo proto kernel scope host src 127.0.0.1 broadcast 127.255.255.255 dev lo proto kernel scope link src 127.0.0.1 I can send traffic to this ENI directly from a host that can have the same IP as the host the ENI is attached to. This is where the problem starts. I ran tcpdump on the port in question and saw multiple SYNs going to the ENI with src '10.1.3.12' and destination '10.1.1.190' but didn't see even a single ACK. In my understanding if ACKs were being sent from the ENI they'd have destination as 10.1.3.12 i.e. the same as the local machine's IP and such packets will now be routed as local packets matching local routing policy: local 10.1.3.12 dev eth0 proto kernel scope host src 10.1.3.12 I'd like to send all the packets originating from 10.1.1.190 (my ENI) to go back on the same interface i.e. eth3 in this case. Contents of the nee table 10003 are: $ sudo ip route show table 10003 default via 10.1.1.1 dev eth3 I think I can do the following: I don't know if its possible but probably decrease the priority of local table so the packets match the table 10003. Use iptables to mangle these packets and update the local table route to include the mark information But I'm not sure if these are the right approaches.

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  • So…is it a Seek or a Scan?

    - by Paul White
    You’re probably most familiar with the terms ‘Seek’ and ‘Scan’ from the graphical plans produced by SQL Server Management Studio (SSMS).  The image to the left shows the most common ones, with the three types of scan at the top, followed by four types of seek.  You might look to the SSMS tool-tip descriptions to explain the differences between them: Not hugely helpful are they?  Both mention scans and ranges (nothing about seeks) and the Index Seek description implies that it will not scan the index entirely (which isn’t necessarily true). Recall also yesterday’s post where we saw two Clustered Index Seek operations doing very different things.  The first Seek performed 63 single-row seeking operations; and the second performed a ‘Range Scan’ (more on those later in this post).  I hope you agree that those were two very different operations, and perhaps you are wondering why there aren’t different graphical plan icons for Range Scans and Seeks?  I have often wondered about that, and the first person to mention it after yesterday’s post was Erin Stellato (twitter | blog): Before we go on to make sense of all this, let’s look at another example of how SQL Server confusingly mixes the terms ‘Scan’ and ‘Seek’ in different contexts.  The diagram below shows a very simple heap table with two columns, one of which is the non-clustered Primary Key, and the other has a non-unique non-clustered index defined on it.  The right hand side of the diagram shows a simple query, it’s associated query plan, and a couple of extracts from the SSMS tool-tip and Properties windows. Notice the ‘scan direction’ entry in the Properties window snippet.  Is this a seek or a scan?  The different references to Scans and Seeks are even more pronounced in the XML plan output that the graphical plan is based on.  This fragment is what lies behind the single Index Seek icon shown above: You’ll find the same confusing references to Seeks and Scans throughout the product and its documentation. Making Sense of Seeks Let’s forget all about scans for a moment, and think purely about seeks.  Loosely speaking, a seek is the process of navigating an index B-tree to find a particular index record, most often at the leaf level.  A seek starts at the root and navigates down through the levels of the index to find the point of interest: Singleton Lookups The simplest sort of seek predicate performs this traversal to find (at most) a single record.  This is the case when we search for a single value using a unique index and an equality predicate.  It should be readily apparent that this type of search will either find one record, or none at all.  This operation is known as a singleton lookup.  Given the example table from before, the following query is an example of a singleton lookup seek: Sadly, there’s nothing in the graphical plan or XML output to show that this is a singleton lookup – you have to infer it from the fact that this is a single-value equality seek on a unique index.  The other common examples of a singleton lookup are bookmark lookups – both the RID and Key Lookup forms are singleton lookups (an RID lookup finds a single record in a heap from the unique row locator, and a Key Lookup does much the same thing on a clustered table).  If you happen to run your query with STATISTICS IO ON, you will notice that ‘Scan Count’ is always zero for a singleton lookup. Range Scans The other type of seek predicate is a ‘seek plus range scan’, which I will refer to simply as a range scan.  The seek operation makes an initial descent into the index structure to find the first leaf row that qualifies, and then performs a range scan (either backwards or forwards in the index) until it reaches the end of the scan range. The ability of a range scan to proceed in either direction comes about because index pages at the same level are connected by a doubly-linked list – each page has a pointer to the previous page (in logical key order) as well as a pointer to the following page.  The doubly-linked list is represented by the green and red dotted arrows in the index diagram presented earlier.  One subtle (but important) point is that the notion of a ‘forward’ or ‘backward’ scan applies to the logical key order defined when the index was built.  In the present case, the non-clustered primary key index was created as follows: CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col ASC) ) ; Notice that the primary key index specifies an ascending sort order for the single key column.  This means that a forward scan of the index will retrieve keys in ascending order, while a backward scan would retrieve keys in descending key order.  If the index had been created instead on key_col DESC, a forward scan would retrieve keys in descending order, and a backward scan would return keys in ascending order. A range scan seek predicate may have a Start condition, an End condition, or both.  Where one is missing, the scan starts (or ends) at one extreme end of the index, depending on the scan direction.  Some examples might help clarify that: the following diagram shows four queries, each of which performs a single seek against a column holding every integer from 1 to 100 inclusive.  The results from each query are shown in the blue columns, and relevant attributes from the Properties window appear on the right: Query 1 specifies that all key_col values less than 5 should be returned in ascending order.  The query plan achieves this by seeking to the start of the index leaf (there is no explicit starting value) and scanning forward until the End condition (key_col < 5) is no longer satisfied (SQL Server knows it can stop looking as soon as it finds a key_col value that isn’t less than 5 because all later index entries are guaranteed to sort higher). Query 2 asks for key_col values greater than 95, in descending order.  SQL Server returns these results by seeking to the end of the index, and scanning backwards (in descending key order) until it comes across a row that isn’t greater than 95.  Sharp-eyed readers may notice that the end-of-scan condition is shown as a Start range value.  This is a bug in the XML show plan which bubbles up to the Properties window – when a backward scan is performed, the roles of the Start and End values are reversed, but the plan does not reflect that.  Oh well. Query 3 looks for key_col values that are greater than or equal to 10, and less than 15, in ascending order.  This time, SQL Server seeks to the first index record that matches the Start condition (key_col >= 10) and then scans forward through the leaf pages until the End condition (key_col < 15) is no longer met. Query 4 performs much the same sort of operation as Query 3, but requests the output in descending order.  Again, we have to mentally reverse the Start and End conditions because of the bug, but otherwise the process is the same as always: SQL Server finds the highest-sorting record that meets the condition ‘key_col < 25’ and scans backward until ‘key_col >= 20’ is no longer true. One final point to note: seek operations always have the Ordered: True attribute.  This means that the operator always produces rows in a sorted order, either ascending or descending depending on how the index was defined, and whether the scan part of the operation is forward or backward.  You cannot rely on this sort order in your queries of course (you must always specify an ORDER BY clause if order is important) but SQL Server can make use of the sort order internally.  In the four queries above, the query optimizer was able to avoid an explicit Sort operator to honour the ORDER BY clause, for example. Multiple Seek Predicates As we saw yesterday, a single index seek plan operator can contain one or more seek predicates.  These seek predicates can either be all singleton seeks or all range scans – SQL Server does not mix them.  For example, you might expect the following query to contain two seek predicates, a singleton seek to find the single record in the unique index where key_col = 10, and a range scan to find the key_col values between 15 and 20: SELECT key_col FROM dbo.Example WHERE key_col = 10 OR key_col BETWEEN 15 AND 20 ORDER BY key_col ASC ; In fact, SQL Server transforms the singleton seek (key_col = 10) to the equivalent range scan, Start:[key_col >= 10], End:[key_col <= 10].  This allows both range scans to be evaluated by a single seek operator.  To be clear, this query results in two range scans: one from 10 to 10, and one from 15 to 20. Final Thoughts That’s it for today – tomorrow we’ll look at monitoring singleton lookups and range scans, and I’ll show you a seek on a heap table. Yes, a seek.  On a heap.  Not an index! If you would like to run the queries in this post for yourself, there’s a script below.  Thanks for reading! IF OBJECT_ID(N'dbo.Example', N'U') IS NOT NULL BEGIN DROP TABLE dbo.Example; END ; -- Test table is a heap -- Non-clustered primary key on 'key_col' CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col) ) ; -- Non-unique non-clustered index on the 'data' column CREATE NONCLUSTERED INDEX [IX dbo.Example data] ON dbo.Example (data) ; -- Add 100 rows INSERT dbo.Example WITH (TABLOCKX) ( key_col, data ) SELECT key_col = V.number, data = V.number FROM master.dbo.spt_values AS V WHERE V.[type] = N'P' AND V.number BETWEEN 1 AND 100 ; -- ================ -- Singleton lookup -- ================ ; -- Single value equality seek in a unique index -- Scan count = 0 when STATISTIS IO is ON -- Check the XML SHOWPLAN SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col = 32 ; -- =========== -- Range Scans -- =========== ; -- Query 1 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col <= 5 ORDER BY E.key_col ASC ; -- Query 2 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col > 95 ORDER BY E.key_col DESC ; -- Query 3 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col >= 10 AND E.key_col < 15 ORDER BY E.key_col ASC ; -- Query 4 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col >= 20 AND E.key_col < 25 ORDER BY E.key_col DESC ; -- Final query (singleton + range = 2 range scans) SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col = 10 OR E.key_col BETWEEN 15 AND 20 ORDER BY E.key_col ASC ; -- === TIDY UP === DROP TABLE dbo.Example; © 2011 Paul White email: [email protected] twitter: @SQL_Kiwi

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