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  • Where should you put constants and why?

    - by Tim Meyer
    In our mostly large applications, we usually have a only few locations for constants: One class for GUI and internal contstants (Tab Page titles, Group Box titles, calculation factors, enumerations) One class for database tables and columns (this part is generated code) plus readable names for them (manually assigned) One class for application messages (logging, message boxes etc) The constants are usually separated into different structs in those classes. In our C++ applications, the constants are only defined in the .h file and the values are assigned in the .cpp file. One of the advantages is that all strings etc are in one central place and everybody knows where to find them when something must be changed. This is especially something project managers seem to like as people come and go and this way everybody can change such trivial things without having to dig into the application's structure. Also, you can easily change the title of similar Group Boxes / Tab Pages etc at once. Another aspect is that you can just print that class and give it to a non-programmer who can check if the captions are intuitive, and if messages to the user are too detailed or too confusing etc. However, I see certain disadvantages: Every single class is tightly coupled to the constants classes Adding/Removing/Renaming/Moving a constant requires recompilation of at least 90% of the application (Note: Changing the value doesn't, at least for C++). In one of our C++ projects with 1500 classes, this means around 7 minutes of compilation time (using precompiled headers; without them it's around 50 minutes) plus around 10 minutes of linking against certain static libraries. Building a speed optimized release through the Visual Studio Compiler takes up to 3 hours. I don't know if the huge amount of class relations is the source but it might as well be. You get driven into temporarily hard-coding strings straight into code because you want to test something very quickly and don't want to wait 15 minutes just for that test (and probably every subsequent one). Everybody knows what happens to the "I will fix that later"-thoughts. Reusing a class in another project isn't always that easy (mainly due to other tight couplings, but the constants handling doesn't make it easier.) Where would you store constants like that? Also what arguments would you bring in order to convince your project manager that there are better concepts which also comply with the advantages listed above? Feel free to give a C++-specific or independent answer. PS: I know this question is kind of subjective but I honestly don't know of any better place than this site for this kind of question. Update on this project I have news on the compile time thing: Following Caleb's and gbjbaanb's posts, I split my constants file into several other files when I had time. I also eventually split my project into several libraries which was now possible much easier. Compiling this in release mode showed that the auto-generated file which contains the database definitions (table, column names and more - more than 8000 symbols) and builds up certain hashes caused the huge compile times in release mode. Deactivating MSVC's optimizer for the library which contains the DB constants now allowed us to reduce the total compile time of your Project (several applications) in release mode from up to 8 hours to less than one hour! We have yet to find out why MSVC has such a hard time optimizing these files, but for now this change relieves a lot of pressure as we no longer have to rely on nightly builds only. That fact - and other benefits, such as less tight coupling, better reuseability etc - also showed that spending time splitting up the "constants" wasn't such a bad idea after all ;-)

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  • Slow query with unexpected index scan

    - by zerkms
    Hello I have this query: SELECT * FROM sample INNER JOIN test ON sample.sample_number = test.sample_number INNER JOIN result ON test.test_number = result.test_number WHERE sampled_date BETWEEN '2010-03-17 09:00' AND '2010-03-17 12:00' the biggest table here is RESULT, contains 11.1M records. The left 2 tables about 1M. this query works slowly (more than 10 minutes) and returns about 800 records. executing plan shows clustered index scan (over it's PRIMARY KEY (result.result_number, which actually doesn't take part in query)) over all 11M records. RESULT.TEST_NUMBER is a clustered primary key. if I change 2010-03-17 09:00 to 2010-03-17 10:00 - i get about 40 records. it executes for 300ms. and plan shows index seek (over result.test_number index) if i replace * in SELECT clause to result.test_number (covered with index) - then all become fast in first case too. this points to hdd IO issues, but doesn't clarifies changing plan. so, any ideas? UPDATE: sampled_date is in table sample and covered by index. other fields from this query: test.sample_number is covered by index and result.test_number too. UPDATE 2: obviously than sql server in any reasons don't want to use index. i did a small experiment: i remove INNER JOIN with result, select all test.test_number and after that do SELECT * FROM RESULT WHERE TEST_NUMBER IN (...) this, of course, works fast. but i cannot get what is the difference and why query optimizer choose such inappropriate way to select data in 1st case.

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  • Deleting JPA entity containing @CollectionOfElements throws ConstraintViolationException

    - by Lyle
    I'm trying to delete entities which contain lists of Integer, and I'm getting ConstraintViolationExceptions because of the foreign key on the table generated to hold the integers. It appears that the delete isn't cascading to the mapped collection. I've done quite a bit of searching, but all of the examples I've seen on how to accomplish this are in reference to a mapped collection of other entities which can be annotated; here I'm just storing a list of Integer. Here is the relevant excerpt from the class I'm storing: @Entity @Table(name="CHANGE_IDS") @GenericGenerator( name = "CHANGE_ID_GEN", strategy = "org.hibernate.id.enhanced.SequenceStyleGenerator", parameters = { @Parameter(name="sequence_name", value="course_changes_seq"), @Parameter(name="increment_size", value="5000"), @Parameter(name=" optimizer", value="pooled") } ) @NamedQueries ({ @NamedQuery( name="Changes.getByStatus", query= "SELECT c " + "FROM DChanges c " + "WHERE c.status = :status "), @NamedQuery( name="Changes.deleteByStatus", query= "DELETE " + "FROM Changes c " + "WHERE c.status = :status ") }) public class Changes { @Id @GeneratedValue(generator="CHANGE_ID_GEN") @Column(name = "ID") private final long id; @Enumerated(EnumType.STRING) @Column(name = "STATUS", length = 20, nullable = false) private final Status status; @Column(name="DOC_ID") @org.hibernate.annotations.CollectionOfElements @org.hibernate.annotations.IndexColumn(name="DOC_ID_ORDER") private List<Integer> docIds; } I'm deleting the Changes objects using a @NamedQuery: final Query deleteQuery = this.entityManager.createNamedQuery("Changes.deleteByStatus"); deleteQuery.setParameter("status", Status.POST_FLIP); final int deleted = deleteQuery.executeUpdate(); this.logger.info("Deleted " + deleted + " POST_FLIP Changes");

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  • Prevent full table scan for query with multiple where clauses

    - by Dave Jarvis
    A while ago I posted a message about optimizing a query in MySQL. I have since ported the data and query to PostgreSQL, but now PostgreSQL has the same problem. The solution in MySQL was to force the optimizer to not optimize using STRAIGHT_JOIN. PostgreSQL offers no such option. Here is the explain: Here is the query: SELECT avg(d.amount) AS amount, y.year FROM station s, station_district sd, year_ref y, month_ref m, daily d LEFT JOIN city c ON c.id = 10663 WHERE -- Find all the stations within a specific unit radius ... -- 6371.009 * SQRT( POW(RADIANS(c.latitude_decimal - s.latitude_decimal), 2) + (COS(RADIANS(c.latitude_decimal + s.latitude_decimal) / 2) * POW(RADIANS(c.longitude_decimal - s.longitude_decimal), 2)) ) <= 50 AND -- Ignore stations outside the given elevations -- s.elevation BETWEEN 0 AND 2000 AND sd.id = s.station_district_id AND -- Gather all known years for that station ... -- y.station_district_id = sd.id AND -- The data before 1900 is shaky; insufficient after 2009. -- y.year BETWEEN 1980 AND 2000 AND -- Filtered by all known months ... -- m.year_ref_id = y.id AND m.month = 12 AND -- Whittled down by category ... -- m.category_id = '001' AND -- Into the valid daily climate data. -- m.id = d.month_ref_id AND d.daily_flag_id <> 'M' GROUP BY y.year It appears as though PostgreSQL is looking at the DAILY table first, which is simply not the right way to go about this query as there are nearly 300 million rows. How do I force PostgreSQL to start at the CITY table? Thank you!

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  • Question about SQL Server HierarchyID depth-first performance

    - by AndalusianCat
    I am trying to implement hierarchyID in a table (dbo.[Message]) containing roughly 50,000 rows (will grow substantially in the future). However it takes 30-40 seconds to retrieve about 25 results. The root node is a filler in order to provide uniqueness, therefor every subsequent row is a child of that dummy row. I need to be able to traverse the table depth-first and have made the hierarchyID column (dbo.[Message].MessageID) the clustering primary key, have also added a computed smallint (dbo.[Message].Hierarchy) which stores the level of the node. Usage: A .Net application passes through a hierarchyID value into the database and I want to be able to retrieve all (if any) children AND parents of that node (besides the root, as it is filler). A simplified version of the query I am using: @MessageID hierarchyID /* passed in from application */ SELECT m.MessageID, m.MessageComment FROM dbo.[Message] as m WHERE m.Messageid.IsDescendantOf(@MessageID.GetAncestor((@MessageID.GetLevel()-1))) = 1 ORDER BY m.MessageID From what I understand, the index should be detected automatically without a hint. From searching forums I have seen people utilizing index hints, at least in the case of breadth-first indexes, as apparently CLR calls may be opaque to the query optimizer. I have spent the past few days trying to find a solution for this issue, but to no avail. I would greatly appreciate any assistance, and as this is my first post, I apologize in advance if this would be considered a 'noobish' question, I have read the MS documentation and searched countless forums, but have not came across a succinct description of the specific issue.

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  • GCC emits extra code for boost::shared_ptr dereference

    - by Checkers
    I have the following code: #include <boost/shared_ptr.hpp> struct Foo { int a; }; static int A; void func_shared(const boost::shared_ptr<Foo> &foo) { A = foo->a; } void func_raw(Foo * const foo) { A = foo->a; } I thought the compiler would create identical code, but for shared_ptr version an extra seemingly redundant instruction is emitted. Disassembly of section .text: 00000000 <func_raw(Foo*)>: 0: 55 push ebp 1: 89 e5 mov ebp,esp 3: 8b 45 08 mov eax,DWORD PTR [ebp+8] 6: 5d pop ebp 7: 8b 00 mov eax,DWORD PTR [eax] 9: a3 00 00 00 00 mov ds:0x0,eax e: c3 ret f: 90 nop 00000010 <func_shared(boost::shared_ptr<Foo> const&)>: 10: 55 push ebp 11: 89 e5 mov ebp,esp 13: 8b 45 08 mov eax,DWORD PTR [ebp+8] 16: 5d pop ebp 17: 8b 00 mov eax,DWORD PTR [eax] 19: 8b 00 mov eax,DWORD PTR [eax] 1b: a3 00 00 00 00 mov ds:0x0,eax 20: c3 ret I'm just curious, is this necessary, or it is just an optimizer's shortcoming? Compiling with g++ 4.1.2, -O3 -NDEBUG.

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  • Why is MySQL with InnoDB doing a table scan when key exists and choosing to examine 70 times more ro

    - by andysk
    Hello, I'm troubleshooting a query performance problem. Here's an expected query plan from explain: mysql> explain select * from table1 where tdcol between '2010-04-13:00:00' and '2010-04-14 03:16'; +----+-------------+--------------------+-------+---------------+--------------+---------+------+---------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------------+-------+---------------+--------------+---------+------+---------+-------------+ | 1 | SIMPLE | table1 | range | tdcol | tdcol | 8 | NULL | 5437848 | Using where | +----+-------------+--------------------+-------+---------------+--------------+---------+------+---------+-------------+ 1 row in set (0.00 sec) That makes sense, since the index named tdcol (KEY tdcol (tdcol)) is used, and about 5M rows should be selected from this query. However, if I query for just one more minute of data, we get this query plan: mysql> explain select * from table1 where tdcol between '2010-04-13 00:00' and '2010-04-14 03:17'; +----+-------------+--------------------+------+---------------+------+---------+------+-----------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------------+------+---------------+------+---------+------+-----------+-------------+ | 1 | SIMPLE | table1 | ALL | tdcol | NULL | NULL | NULL | 381601300 | Using where | +----+-------------+--------------------+------+---------------+------+---------+------+-----------+-------------+ 1 row in set (0.00 sec) The optimizer believes that the scan will be better, but it's over 70x more rows to examine, so I have a hard time believing that the table scan is better. Also, the 'USE KEY tdcol' syntax does not change the query plan. Thanks in advance for any help, and I'm more than happy to provide more info/answer questions.

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  • ADO.NET zombie transaction bug? How to ensure that commands will not be executed on implicit transac

    - by TN
    e.g. When deadlock occurs, following SQL commands are successfully executed, even if they have assigned SQL transaction that is after rollback. It seems, it is caused by a new implicit transaction that is created on SQL Server. Someone could expect that ADO.NET would throw an exception that the commands are being executed on a zombie transaction. However, such exception is not thrown. (I think this is a bug in ASP.NET.) Moreover, because of zombie transaction the final Dispose() silently ignores the rollback. Any ideas, how can I ensure that nobody can execute commands on implicit transaction? Or, how to check that transaction is zombie? I found that Commit() and Rollback() check for zombie transaction, however I can call them for a test:) I also found that also reading IsolationLevel will do the check, but I am not sure whether simple calling transaction.IsolationLevel.ToString(); will not be removed by a future optimizer. Or do you know any other safe way invoke a getter (without using reflection or IL emitting)?

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  • Need help in tuning a sql-query

    - by Viper
    Hello, i need some help to boost this SQL-Statement. The execution time is around 125ms. During the runtime of my program this sql (better: equally structured sqls for different tables) will be called 300.000 times. The average row count in the tables lies around 10.000.000 rows and new rows (updates/inserts) will be added with a timestamp each day. Data which are interesting for this particular export-program lies in the last 1-3 days. Maybe this is helpful for an index to create. The data i need is the current valid row for a given id and the forerunner datarow to get the updates (if exists). We use a Oracle 11g database and Dot.Net Framework 3.5 SQL-Statement to boost: select ID_SOMETHING, -- Number(12) ID_CONTRIBUTOR, -- Char(4 Byte) DATE_VALID_FROM, -- DATE DATE_VALID_TO -- DATE from TBL_SOMETHING XID where ID_SOMETHING = :ID_INSTRUMENT and ID_CONTRIBUTOR = :ID_CONTRIBUTOR and DATE_VALID_FROM <= :EXPORT_DATE and DATE_VALID_TO >= :EXPORT_DATE order by DATE_VALID_FROM asc; Here i uploaded the current Explain-Plan for this query. I'm not a database expert so i don't know which index-type would fit best for this requirement. I have seen that there are many different possible index-types which could be applied. Maybe Oracle Optimizer Hints are helpful, too. Does anyone has a good idea for tuning this sql or can point me in a right direction?

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  • C# vs C - Big performance difference

    - by John
    I'm finding massive performance differences between similar code in C anc C#. The C code is: #include <stdio.h> #include <time.h> #include <math.h> main() { int i; double root; clock_t start = clock(); for (i = 0 ; i <= 100000000; i++){ root = sqrt(i); } printf("Time elapsed: %f\n", ((double)clock() - start) / CLOCKS_PER_SEC); } And the C# (console app) is: using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { DateTime startTime = DateTime.Now; double root; for (int i = 0; i <= 100000000; i++) { root = Math.Sqrt(i); } TimeSpan runTime = DateTime.Now - startTime; Console.WriteLine("Time elapsed: " + Convert.ToString(runTime.TotalMilliseconds/1000)); } } } With the above code, the C# completes in 0.328125 seconds (release version) and the C takes 11.14 seconds to run. The c is being compiled to a windows executable using mingw. I've always been under the assumption that C/C++ were faster or at least comparable to C#.net. What exactly is causing the C to run over 30 times slower? EDIT: It does appear that the C# optimizer was removing the root as it wasn't being used. I changed the root assignment to root += and printed out the total at the end. I've also compiled the C using cl.exe with the /O2 flag set for max speed. The results are now: 3.75 seconds for the C 2.61 seconds for the C# The C is still taking longer, but this is acceptable

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  • Upload using python script takes very long on one laptop as compared to another

    - by Engr Am
    I have a python 2.7 code which uses STORBINARY function for uploading files to an ftp server and RETRBINARY for downloading from this server. However, the issue is the upload is taking a very long time on three laptops from different brands as compared to a Dell laptop. The strange part is when I manually upload any file, it takes the same time on all the systems. The manual upload rate and upload rate with the python script is the same on the Dell Laptop. However, on every other brand of laptop (I have tried with IBM, Toshiba, Fujitsu-Siemens) the python script has a very low upload rate than the manual attempt. Also, on all these other laptops, the upload rate using the python script is the same (1Mbit/s) while the manual upload rate is approx. 8 Mbit/s. I have tried to vary the filesize for the upload to no avail. TCP Optimizer improved the download rate on all the systems but had no effect on the upload rate. Download rate using this script on all the systems is fine and same as the manual download rate. I have checked the server and it has more than 90% free space. The network connection is the same for all the laptops, and I try uploading only with one laptop at a time. All the laptops have almost the same system configurations, same operating system and approximately the same free drive space. If anything the Dell laptop is a little less in terms of processing power and RAM than 2 of the others, but I suppose this has no effect as I have checked many times to see how much was the CPU usage and network usage during these uploads and downloads, and I am sure that no other virus or program has been eating up my bandwidth. Here is the code ('ftp' and 'file_path' are inputs to the function): path,filename=os.path.split(file_path) filesize=os.path.getsize(file_path) deffilesize=(filesize/1024)/1024 f = open(file_path, "rb") upstart = time.clock() print ftp.storbinary("STOR "+filename, f) upende = time.clock()-upstart outname="Upload " f.close() return upende, deffilesize, outname

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  • How can I update a record using a correlated subquery?

    - by froadie
    I have a function that accepts one parameter and returns a table/resultset. I want to set a field in a table to the first result of that recordset, passing in one of the table's other fields as the parameter. If that's too complicated in words, the query looks something like this: UPDATE myTable SET myField = (SELECT TOP 1 myFunctionField FROM fn_doSomething(myOtherField) WHERE someCondition = 'something') WHERE someOtherCondition = 'somethingElse' In this example, myField and myOtherField are fields in myTable, and myFunctionField is a field return by fn_doSomething. This seems logical to me, but I'm getting the following strange error: 'myOtherField' is not a recognized OPTIMIZER LOCK HINTS option. Any idea what I'm doing wrong, and how I can accomplish this? *UPDATE: * Based on Anil Soman's answer, I realized that the function is expecting a string parameter and the field being passed is an integer. I'm not sure if this should be a problem as an explicit call to the function using an integer value works - e.g. fn_doSomething(12345) seems to automatically cast the number to an string. However, I tried to do an explicit cast: UPDATE myTable SET myField = (SELECT TOP 1 myFunctionField FROM fn_doSomething(CAST(myOtherField AS varchar(1000))) WHERE someCondition = 'something') WHERE someOtherCondition = 'somethingElse' Now I'm getting the following error: Line 5: Incorrect syntax near '('.

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  • PHP -- automatic SQL injection protection?

    - by ashgromnies
    I took over maintenance of a PHP app recently and I'm not super familiar with PHP but some of the things I've been seeing on the site are making me nervous that it could be vulnerable to a SQL injection attack. For example, see how this code for logging into the administrative section works: $password = md5(HASH_SALT . $_POST['loginPass']); $query = "SELECT * FROM `administrators` WHERE `active`='1' AND `email`='{$_POST['loginEmail']}' AND `password`='{$password}'"; $userInfo = db_fetch_array(db_query($query)); if($userInfo['id']) { $_SESSION['adminLoggedIn'] = true; // user is logged in, other junk happens here, not important The creators of the site made a special db_query method and db_fetch_array method, shown here: function db_query($qstring,$print=0) { return @mysql(DB_NAME,$qstring); } function db_fetch_array($qhandle) { return @mysql_fetch_array($qhandle); } Now, this makes me think I should be able to do some sort of SQL injection attack with an email address like: ' OR 'x'='x' LIMIT 1; and some random password. When I use that on the command line, I get an administrative user back, but when I try it in the application, I get an invalid username/password error, like I should. Could there be some sort of global PHP configuration they have enabled to block these attacks? Where would that be configured? Here is the PHP --version information: # php --version PHP 5.2.12 (cli) (built: Feb 28 2010 15:59:21) Copyright (c) 1997-2009 The PHP Group Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies with the ionCube PHP Loader v3.3.14, Copyright (c) 2002-2010, by ionCube Ltd., and with Zend Optimizer v3.3.9, Copyright (c) 1998-2009, by Zend Technologies

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  • Algorithm for generating an array of non-equal costs for a transport problem optimization

    - by Carlos
    I have an optimizer that solves a transportation problem, using a cost matrix of all the possible paths. The optimiser works fine, but if two of the costs are equal, the solution contains one more path that the minimum number of paths. (Think of it as load balancing routers; if two routes are same cost, you'll use them both.) I would like the minimum number of routes, and to do that I need a cost matrix that doesn't have two costs that are equal within a certain tolerance. At the moment, I'm passing the cost matrix through a baking function which tests every entry for equality to each of the other entries, and moves it a fixed percentage if it matches. However, this approach seems to require N^2 comparisons, and if the starting values are all the same, the last cost will be r^N bigger. (r is the arbitrary fixed percentage). Also there is the problem that by multiplying by the percentage, you end up on top of another value. So the problem seems to have an element of recursion, or at least repeated checking, which bloats the code. The current implementation is basically not very good (I won't paste my GOTO-using code here for you all to mock), and I'd like to improve it. Is there a name for what I'm after, and is there a standard implementation? Example: {1,1,2,3,4,5} (tol = 0.05) becomes {1,1.05,2,3,4,5}

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  • In mysql, is "explain ..." always safe?

    - by tye
    If I allow a group of users to submit "explain $whatever" to mysql (via Perl's DBI using DBD::mysql), is there anything that a user could put into $whatever that would make any database changes, leak non-trivial information, or even cause significant database load? If so, how? I know that via "explain $whatever" one can figure out what tables / columns exist (you have to guess names, though) and roughly how many records are in a table or how many records have a particular value for an indexed field. I don't expect one to be able to get any information about the contents of unindexed fields. DBD::mysql should not allow multiple statements so I don't expect it to be possible to run any query (just explain one query). Even subqueries should not be executed, just explained. But I'm not a mysql expert and there are surely features of mysql that I'm not even aware of. In trying to come up with a query plan, might the optimizer actual execute an expression in order to come up with the value that an indexed field is going to be compared against? explain select * from atable where class = somefunction(...) where atable.class is indexed and not unique and class='unused' would find no records but class='common' would find a million records. Might 'explain' evaluate somefunction(...)? And then could somefunction(...) be written such that it modifies data?

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  • Efficiently select top row for each category in the set

    - by VladV
    I need to select a top row for each category from a known set (somewhat similar to this question). The problem is, how to make this query efficient on the large number of rows. For example, let's create a table that stores temperature recording in several places. CREATE TABLE #t ( placeId int, ts datetime, temp int, PRIMARY KEY (ts, placeId) ) -- insert some sample data SET NOCOUNT ON DECLARE @n int, @ts datetime SELECT @n = 1000, @ts = '2000-01-01' WHILE (@n>0) BEGIN INSERT INTO #t VALUES (@n % 10, @ts, @n % 37) IF (@n % 10 = 0) SET @ts = DATEADD(hour, 1, @ts) SET @n = @n - 1 END Now I need to get the latest recording for each of the places 1, 2, 3. This way is efficient, but doesn't scale well (and looks dirty). SELECT * FROM ( SELECT TOP 1 placeId, temp FROM #t WHERE placeId = 1 ORDER BY ts DESC ) t1 UNION ALL SELECT * FROM ( SELECT TOP 1 placeId, temp FROM #t WHERE placeId = 2 ORDER BY ts DESC ) t2 UNION ALL SELECT * FROM ( SELECT TOP 1 placeId, temp FROM #t WHERE placeId = 3 ORDER BY ts DESC ) t3 The following looks better but works much less efficiently (30% vs 70% according to the optimizer). SELECT placeId, ts, temp FROM ( SELECT placeId, ts, temp, ROW_NUMBER() OVER (PARTITION BY placeId ORDER BY ts DESC) rownum FROM #t WHERE placeId IN (1, 2, 3) ) t WHERE rownum = 1 The problem is, during the latter query execution plan a clustered index scan is performed on #t and 300 rows are retrieved, sorted, numbered, and then filtered, leaving only 3 rows. For the former query three times one row is fetched. Is there a way to perform the query efficiently without lots of unions?

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  • MSSQL 2008 - Bit Param Evaluation alters Execution Plan

    - by Nathanial Woolls
    I have been working on migrating some of our data from Microsoft SQL Server 2000 to 2008. Among the usual hiccups and whatnot, I’ve run across something strange. Linked below is a SQL query that returns very quickly under 2000, but takes 20 minutes under 2008. I have read quite a bit on upgrading SQL server and went down the usual paths of checking indexes, statistics, etc. before coming to the conclusion that the following statement, found in the WHERE clause, causes the execution plan for the steps that follow this statement to change dramatically: And ( @bOnlyUnmatched = 0 -- offending line Or Not Exists( The SQL statements and execution plans are linked below. A coworker was able to rewrite a portion of the WHERE clause using a CASE statement, which seems to “trick” the optimizer into using a better execution plan. The version with the CASE statement is also contained in the linked archive. I’d like to see if someone has an explanation as to why this is happening and if there may be a more elegant solution than using a CASE statement. While we can work around this specific issue, I’d like to have a broader understanding of what is happening to ensure the rest of the migration is as painless as possible. Zip file with SQL statements and XML execution plans Thanks in advance!

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  • Linq-to-sql join/where?

    - by Curtis White
    I've the following table structures Users id Types id isBool UsersTypes userid types I want to select all the UserTypes based on id and isBool. I tried this query var q = from usertype in usertypes from type in types where type.isBool == false where userstypes.user == id select usertype; But this did not work as expected. My questions are: Why? Is there any difference in using the join on syntax vs where, where vs where cond1 && cond2? My understanding is query optimizer will optimize. Is there any difference in using where cond1 == var1 && cond2 == var2 with and without the parenthesis? This seems peculiar that it is possible to build this without parenthesis What type of query do I need in this case? I can see that I could do a subquery or use a group but not 100% sure if it is required. An example might be helpful. I'm thinking a subquery may be required in this case.

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  • Oracle Query Optimization: Why is My Second Query Faster?

    - by Patrick Cuff
    I was having some performance issues with an Oracle query, so I downloaded a trial of the Quest SQL Optimizer for Oracle, which made some changes that dramatically improved the query's performance. I'm not exactly sure why the recommended query had such an improvement; can anyone provide an explanation? Before: SELECT t1.version_id, t1.id, t2.field1, t3.person_id, t2.id FROM table1 t1, table2 t2, table3 t3 WHERE t1.id = t2.id AND t1.version_id = t2.version_id AND t2.id = 123 AND t1.version_id = t3.version_id AND t1.VERSION_NAME <> 'AA' order by t1.id Plan Cost: 831 Elapsed Time: 00:00:21.40 Number of Records: 40,717 After: SELECT /*+ USE_NL_WITH_INDEX(t1) */ t1.version_id, t1.id, t2.field1, t3.person_id, t2.id FROM table2 t2, table3 t3, table1 t1 WHERE t1.id = t2.id + 0 AND t1.version_id = t2.version_id + 0 AND t2.id = 123 AND t1.version_id = t3.version_id + 0 AND t1.VERSION_NAME || '' <> 'AA' AND t3.version_id = t2.version_id + 0 order by t1.id Plan Cost: 686 Elapsed Time: 00:00:00.95 Number of Records: 40,717 Questions: Why does re-arranging the order of the tables in the FROM clause help? Why does adding + 0 to the WHERE clause comparisons help? Why does || '' <> 'AA' in the WHERE clause VERSION_NAME comparison help? Is this a more efficient way of handling possible nulls on this column?

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  • The Sitemap Paradox

    - by Jeff Atwood
    We use a sitemap on Stack Overflow, but I have mixed feelings about it. Web crawlers usually discover pages from links within the site and from other sites. Sitemaps supplement this data to allow crawlers that support Sitemaps to pick up all URLs in the Sitemap and learn about those URLs using the associated metadata. Using the Sitemap protocol does not guarantee that web pages are included in search engines, but provides hints for web crawlers to do a better job of crawling your site. Based on our two years' experience with sitemaps, there's something fundamentally paradoxical about the sitemap: Sitemaps are intended for sites that are hard to crawl properly. If Google can't successfully crawl your site to find a link, but is able to find it in the sitemap it gives the sitemap link no weight and will not index it! That's the sitemap paradox -- if your site isn't being properly crawled (for whatever reason), using a sitemap will not help you! Google goes out of their way to make no sitemap guarantees: "We cannot make any predictions or guarantees about when or if your URLs will be crawled or added to our index" citation "We don't guarantee that we'll crawl or index all of your URLs. For example, we won't crawl or index image URLs contained in your Sitemap." citation "submitting a Sitemap doesn't guarantee that all pages of your site will be crawled or included in our search results" citation Given that links found in sitemaps are merely recommendations, whereas links found on your own website proper are considered canonical ... it seems the only logical thing to do is avoid having a sitemap and make damn sure that Google and any other search engine can properly spider your site using the plain old standard web pages everyone else sees. By the time you have done that, and are getting spidered nice and thoroughly so Google can see that your own site links to these pages, and would be willing to crawl the links -- uh, why do we need a sitemap, again? The sitemap can be actively harmful, because it distracts you from ensuring that search engine spiders are able to successfully crawl your whole site. "Oh, it doesn't matter if the crawler can see it, we'll just slap those links in the sitemap!" Reality is quite the opposite in our experience. That seems more than a little ironic considering sitemaps were intended for sites that have a very deep collection of links or complex UI that may be hard to spider. In our experience, the sitemap does not help, because if Google can't find the link on your site proper, it won't index it from the sitemap anyway. We've seen this proven time and time again with Stack Overflow questions. Am I wrong? Do sitemaps make sense, and we're somehow just using them incorrectly?

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  • MAXDOP in SQL Azure

    - by Herve Roggero
    In my search of better understanding the scalability options of SQL Azure I stumbled on an interesting aspect: Query Hints in SQL Azure. More specifically, the MAXDOP hint. A few years ago I did a lot of analysis on this query hint (see article on SQL Server Central:  http://www.sqlservercentral.com/articles/Configuring/managingmaxdegreeofparallelism/1029/).  Here is a quick synopsis of MAXDOP: It is a query hint you use when issuing a SQL statement that provides you control with how many processors SQL Server will use to execute the query. For complex queries with lots of I/O requirements, more CPUs can mean faster parallel searches. However the impact can be drastic on other running threads/processes. If your query takes all available processors at 100% for 5 minutes... guess what... nothing else works. The bottom line is that more is not always better. The use of MAXDOP is more art than science... and a whole lot of testing; it depends on two things: the underlying hardware architecture and the application design. So there isn't a magic number that will work for everyone... except 1... :) Let me explain. The rules of engagements are different. SQL Azure is about sharing. Yep... you are forced to nice with your neighbors.  To achieve this goal SQL Azure sets the MAXDOP to 1 by default, and ignores the use of the MAXDOP hint altogether. That means that all you queries will use one and only one processor.  It really isn't such a bad thing however. Keep in mind that in some of the largest SQL Server implementations MAXDOP is usually also set to 1. It is a well known configuration setting for large scale implementations. The reason is precisely to prevent rogue statements (like a SELECT * FROM HISTORY) from bringing down your systems (like a report that should have been running on a different in the first place) and to avoid the overhead generated by executing too many parallel queries that could cause internal memory management nightmares to the host Operating System. Is summary, forcing the MAXDOP to 1 in SQL Azure makes sense; it ensures that your database will continue to function normally even if one of the other tenants on the same server is running massive queries that would otherwise bring you down. Last but not least, keep in mind as well that when you test your database code for performance on-premise, make sure to set the DOP to 1 on your SQL Server databases to simulate SQL Azure conditions.

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  • MVC's Html.DropDownList and "There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key '...'

    - by pjohnson
    ASP.NET MVC's HtmlHelper extension methods take out a lot of the HTML-by-hand drudgery to which MVC re-introduced us former WebForms programmers. Another thing to which MVC re-introduced us is poor documentation, after the excellent documentation for most of the rest of ASP.NET and the .NET Framework which I now realize I'd taken for granted. I'd come to regard using HtmlHelper methods instead of writing HTML by hand as a best practice. When I upgraded a project from MVC 3 to MVC 4, several hidden fields with boolean values broke, because MVC 3 called ToString() on those values implicitly, and MVC 4 threw an exception until you called ToString() explicitly. Fields that used HtmlHelper weren't affected. I then went through dozens of views and manually replaced hidden inputs that had been coded by hand with Html.Hidden calls. So for a dropdown list I was rendering on the initial page as empty, then populating via JavaScript after an AJAX call, I tried to use a HtmlHelper method: @Html.DropDownList("myDropdown") which threw an exception: System.InvalidOperationException: There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key 'myDropdown'. That's funny--I made no indication I wanted to use ViewData. Why was it looking there? Just render an empty select list for me. When I populated the list with items, it worked, but I didn't want to do that: @Html.DropDownList("myDropdown", new List<SelectListItem>() { new SelectListItem() { Text = "", Value = "" } }) I removed this dummy item in JavaScript after the AJAX call, so this worked fine, but I shouldn't have to give it a list with a dummy item when what I really want is an empty select. A bit of research with JetBrains dotPeek (helpfully recommended by Scott Hanselman) revealed the problem. Html.DropDownList requires some sort of data to render or it throws an error. The documentation hints at this but doesn't make it very clear. Behind the scenes, it checks if you've provided the DropDownList method any data. If you haven't, it looks in ViewData. If it's not there, you get the exception above. In my case, the helper wasn't doing much for me anyway, so I reverted to writing the HTML by hand (I ain't scared), and amended my best practice: When an HTML control has an associated HtmlHelper method and you're populating that control with data on the initial view, use the HtmlHelper method instead of writing by hand.

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  • Virtual host is not working in Ubuntu 14 VPS using XAMPP 1.8.3

    - by viral4ever
    I am using XAMPP as server in ubuntu 14.04 VPS of digitalocean. I tried to setup virtual hosts. But it is not working and I am getting 403 error of access denied. I changed files too. My files with changes are /opt/lampp/etc/httpd.conf # # This is the main Apache HTTP server configuration file. It contains the # configuration directives that give the server its instructions. # See <URL:http://httpd.apache.org/docs/trunk/> for detailed information. # In particular, see # <URL:http://httpd.apache.org/docs/trunk/mod/directives.html> # for a discussion of each configuration directive. # # Do NOT simply read the instructions in here without understanding # what they do. They're here only as hints or reminders. If you are unsure # consult the online docs. You have been warned. # # Configuration and logfile names: If the filenames you specify for many # of the server's control files begin with "/" (or "drive:/" for Win32), the # server will use that explicit path. If the filenames do *not* begin # with "/", the value of ServerRoot is prepended -- so 'log/access_log' # with ServerRoot set to '/www' will be interpreted by the # server as '/www/log/access_log', where as '/log/access_log' will be # interpreted as '/log/access_log'. # # ServerRoot: The top of the directory tree under which the server's # configuration, error, and log files are kept. # # Do not add a slash at the end of the directory path. If you point # ServerRoot at a non-local disk, be sure to specify a local disk on the # Mutex directive, if file-based mutexes are used. If you wish to share the # same ServerRoot for multiple httpd daemons, you will need to change at # least PidFile. # ServerRoot "/opt/lampp" # # Mutex: Allows you to set the mutex mechanism and mutex file directory # for individual mutexes, or change the global defaults # # Uncomment and change the directory if mutexes are file-based and the default # mutex file directory is not on a local disk or is not appropriate for some # other reason. # # Mutex default:logs # # Listen: Allows you to bind Apache to specific IP addresses and/or # ports, instead of the default. See also the <VirtualHost> # directive. # # Change this to Listen on specific IP addresses as shown below to # prevent Apache from glomming onto all bound IP addresses. # #Listen 12.34.56.78:80 Listen 80 # # Dynamic Shared Object (DSO) Support # # To be able to use the functionality of a module which was built as a DSO you # have to place corresponding `LoadModule' lines at this location so the # directives contained in it are actually available _before_ they are used. # Statically compiled modules (those listed by `httpd -l') do not need # to be loaded here. # # Example: # LoadModule foo_module modules/mod_foo.so # LoadModule authn_file_module modules/mod_authn_file.so LoadModule authn_dbm_module modules/mod_authn_dbm.so LoadModule authn_anon_module modules/mod_authn_anon.so LoadModule authn_dbd_module modules/mod_authn_dbd.so LoadModule authn_socache_module modules/mod_authn_socache.so LoadModule authn_core_module modules/mod_authn_core.so LoadModule authz_host_module modules/mod_authz_host.so LoadModule authz_groupfile_module modules/mod_authz_groupfile.so LoadModule authz_user_module modules/mod_authz_user.so LoadModule authz_dbm_module modules/mod_authz_dbm.so LoadModule authz_owner_module modules/mod_authz_owner.so LoadModule authz_dbd_module modules/mod_authz_dbd.so LoadModule authz_core_module modules/mod_authz_core.so LoadModule authnz_ldap_module modules/mod_authnz_ldap.so LoadModule access_compat_module modules/mod_access_compat.so LoadModule auth_basic_module modules/mod_auth_basic.so LoadModule auth_form_module modules/mod_auth_form.so LoadModule auth_digest_module modules/mod_auth_digest.so LoadModule allowmethods_module modules/mod_allowmethods.so LoadModule file_cache_module modules/mod_file_cache.so LoadModule cache_module modules/mod_cache.so LoadModule cache_disk_module modules/mod_cache_disk.so LoadModule socache_shmcb_module modules/mod_socache_shmcb.so LoadModule socache_dbm_module modules/mod_socache_dbm.so LoadModule socache_memcache_module modules/mod_socache_memcache.so LoadModule dbd_module modules/mod_dbd.so LoadModule bucketeer_module modules/mod_bucketeer.so LoadModule dumpio_module modules/mod_dumpio.so LoadModule echo_module modules/mod_echo.so LoadModule case_filter_module modules/mod_case_filter.so LoadModule case_filter_in_module modules/mod_case_filter_in.so LoadModule buffer_module modules/mod_buffer.so LoadModule ratelimit_module modules/mod_ratelimit.so LoadModule reqtimeout_module modules/mod_reqtimeout.so LoadModule ext_filter_module modules/mod_ext_filter.so LoadModule request_module modules/mod_request.so LoadModule include_module modules/mod_include.so LoadModule filter_module modules/mod_filter.so LoadModule substitute_module modules/mod_substitute.so LoadModule sed_module modules/mod_sed.so LoadModule charset_lite_module modules/mod_charset_lite.so LoadModule deflate_module modules/mod_deflate.so LoadModule mime_module modules/mod_mime.so LoadModule ldap_module modules/mod_ldap.so LoadModule log_config_module modules/mod_log_config.so LoadModule log_debug_module modules/mod_log_debug.so LoadModule logio_module modules/mod_logio.so LoadModule env_module modules/mod_env.so LoadModule mime_magic_module modules/mod_mime_magic.so LoadModule cern_meta_module modules/mod_cern_meta.so LoadModule expires_module modules/mod_expires.so LoadModule headers_module modules/mod_headers.so LoadModule usertrack_module modules/mod_usertrack.so LoadModule unique_id_module modules/mod_unique_id.so LoadModule setenvif_module modules/mod_setenvif.so LoadModule version_module modules/mod_version.so LoadModule remoteip_module modules/mod_remoteip.so LoadModule proxy_module modules/mod_proxy.so LoadModule proxy_connect_module modules/mod_proxy_connect.so LoadModule proxy_ftp_module modules/mod_proxy_ftp.so LoadModule proxy_http_module modules/mod_proxy_http.so LoadModule proxy_fcgi_module modules/mod_proxy_fcgi.so LoadModule proxy_scgi_module modules/mod_proxy_scgi.so LoadModule proxy_ajp_module modules/mod_proxy_ajp.so LoadModule proxy_balancer_module modules/mod_proxy_balancer.so LoadModule proxy_express_module modules/mod_proxy_express.so LoadModule session_module modules/mod_session.so LoadModule session_cookie_module modules/mod_session_cookie.so LoadModule session_dbd_module modules/mod_session_dbd.so LoadModule slotmem_shm_module modules/mod_slotmem_shm.so LoadModule ssl_module modules/mod_ssl.so LoadModule lbmethod_byrequests_module modules/mod_lbmethod_byrequests.so LoadModule lbmethod_bytraffic_module modules/mod_lbmethod_bytraffic.so LoadModule lbmethod_bybusyness_module modules/mod_lbmethod_bybusyness.so LoadModule lbmethod_heartbeat_module modules/mod_lbmethod_heartbeat.so LoadModule unixd_module modules/mod_unixd.so LoadModule dav_module modules/mod_dav.so LoadModule status_module modules/mod_status.so LoadModule autoindex_module modules/mod_autoindex.so LoadModule info_module modules/mod_info.so LoadModule suexec_module modules/mod_suexec.so LoadModule cgi_module modules/mod_cgi.so LoadModule cgid_module modules/mod_cgid.so LoadModule dav_fs_module modules/mod_dav_fs.so LoadModule vhost_alias_module modules/mod_vhost_alias.so LoadModule negotiation_module modules/mod_negotiation.so LoadModule dir_module modules/mod_dir.so LoadModule actions_module modules/mod_actions.so LoadModule speling_module modules/mod_speling.so LoadModule userdir_module modules/mod_userdir.so LoadModule alias_module modules/mod_alias.so LoadModule rewrite_module modules/mod_rewrite.so <IfDefine JUSTTOMAKEAPXSHAPPY> LoadModule php4_module modules/libphp4.so LoadModule php5_module modules/libphp5.so </IfDefine> <IfModule unixd_module> # # If you wish httpd to run as a different user or group, you must run # httpd as root initially and it will switch. # # User/Group: The name (or #number) of the user/group to run httpd as. # It is usually good practice to create a dedicated user and group for # running httpd, as with most system services. # User root Group www </IfModule> # 'Main' server configuration # # The directives in this section set up the values used by the 'main' # server, which responds to any requests that aren't handled by a # <VirtualHost> definition. These values also provide defaults for # any <VirtualHost> containers you may define later in the file. # # All of these directives may appear inside <VirtualHost> containers, # in which case these default settings will be overridden for the # virtual host being defined. # # # ServerAdmin: Your address, where problems with the server should be # e-mailed. This address appears on some server-generated pages, such # as error documents. e.g. [email protected] # ServerAdmin [email protected] # # ServerName gives the name and port that the server uses to identify itself. # This can often be determined automatically, but we recommend you specify # it explicitly to prevent problems during startup. # # If your host doesn't have a registered DNS name, enter its IP address here. # #ServerName www.example.com:@@Port@@ # XAMPP ServerName localhost # # Deny access to the entirety of your server's filesystem. You must # explicitly permit access to web content directories in other # <Directory> blocks below. # <Directory /> AllowOverride none Require all denied </Directory> # # Note that from this point forward you must specifically allow # particular features to be enabled - so if something's not working as # you might expect, make sure that you have specifically enabled it # below. # # # DocumentRoot: The directory out of which you will serve your # documents. By default, all requests are taken from this directory, but # symbolic links and aliases may be used to point to other locations. # DocumentRoot "/opt/lampp/htdocs" <Directory "/opt/lampp/htdocs"> # # Possible values for the Options directive are "None", "All", # or any combination of: # Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews # # Note that "MultiViews" must be named *explicitly* --- "Options All" # doesn't give it to you. # # The Options directive is both complicated and important. Please see # http://httpd.apache.org/docs/trunk/mod/core.html#options # for more information. # #Options Indexes FollowSymLinks # XAMPP Options Indexes FollowSymLinks ExecCGI Includes # # AllowOverride controls what directives may be placed in .htaccess files. # It can be "All", "None", or any combination of the keywords: # Options FileInfo AuthConfig Limit # #AllowOverride None # since XAMPP 1.4: AllowOverride All # # Controls who can get stuff from this server. # Require all granted </Directory> # # DirectoryIndex: sets the file that Apache will serve if a directory # is requested. # <IfModule dir_module> #DirectoryIndex index.html # XAMPP DirectoryIndex index.html index.html.var index.php index.php3 index.php4 </IfModule> # # The following lines prevent .htaccess and .htpasswd files from being # viewed by Web clients. # <Files ".ht*"> Require all denied </Files> # # ErrorLog: The location of the error log file. # If you do not specify an ErrorLog directive within a <VirtualHost> # container, error messages relating to that virtual host will be # logged here. If you *do* define an error logfile for a <VirtualHost> # container, that host's errors will be logged there and not here. # ErrorLog "logs/error_log" # # LogLevel: Control the number of messages logged to the error_log. # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. # LogLevel warn <IfModule log_config_module> # # The following directives define some format nicknames for use with # a CustomLog directive (see below). # LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %b" common <IfModule logio_module> # You need to enable mod_logio.c to use %I and %O LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %I %O" combinedio </IfModule> # # The location and format of the access logfile (Common Logfile Format). # If you do not define any access logfiles within a <VirtualHost> # container, they will be logged here. Contrariwise, if you *do* # define per-<VirtualHost> access logfiles, transactions will be # logged therein and *not* in this file. # CustomLog "logs/access_log" common # # If you prefer a logfile with access, agent, and referer information # (Combined Logfile Format) you can use the following directive. # #CustomLog "logs/access_log" combined </IfModule> <IfModule alias_module> # # Redirect: Allows you to tell clients about documents that used to # exist in your server's namespace, but do not anymore. The client # will make a new request for the document at its new location. # Example: # Redirect permanent /foo http://www.example.com/bar # # Alias: Maps web paths into filesystem paths and is used to # access content that does not live under the DocumentRoot. # Example: # Alias /webpath /full/filesystem/path # # If you include a trailing / on /webpath then the server will # require it to be present in the URL. You will also likely # need to provide a <Directory> section to allow access to # the filesystem path. # # ScriptAlias: This controls which directories contain server scripts. # ScriptAliases are essentially the same as Aliases, except that # documents in the target directory are treated as applications and # run by the server when requested rather than as documents sent to the # client. The same rules about trailing "/" apply to ScriptAlias # directives as to Alias. # ScriptAlias /cgi-bin/ "/opt/lampp/cgi-bin/" </IfModule> <IfModule cgid_module> # # ScriptSock: On threaded servers, designate the path to the UNIX # socket used to communicate with the CGI daemon of mod_cgid. # #Scriptsock logs/cgisock </IfModule> # # "/opt/lampp/cgi-bin" should be changed to whatever your ScriptAliased # CGI directory exists, if you have that configured. # <Directory "/opt/lampp/cgi-bin"> AllowOverride None Options None Require all granted </Directory> <IfModule mime_module> # # TypesConfig points to the file containing the list of mappings from # filename extension to MIME-type. # TypesConfig etc/mime.types # # AddType allows you to add to or override the MIME configuration # file specified in TypesConfig for specific file types. # #AddType application/x-gzip .tgz # # AddEncoding allows you to have certain browsers uncompress # information on the fly. Note: Not all browsers support this. # #AddEncoding x-compress .Z #AddEncoding x-gzip .gz .tgz # # If the AddEncoding directives above are commented-out, then you # probably should define those extensions to indicate media types: # AddType application/x-compress .Z AddType application/x-gzip .gz .tgz # # AddHandler allows you to map certain file extensions to "handlers": # actions unrelated to filetype. These can be either built into the server # or added with the Action directive (see below) # # To use CGI scripts outside of ScriptAliased directories: # (You will also need to add "ExecCGI" to the "Options" directive.) # #AddHandler cgi-script .cgi # XAMPP, since LAMPP 0.9.8: AddHandler cgi-script .cgi .pl # For type maps (negotiated resources): #AddHandler type-map var # # Filters allow you to process content before it is sent to the client. # # To parse .shtml files for server-side includes (SSI): # (You will also need to add "Includes" to the "Options" directive.) # # XAMPP AddType text/html .shtml AddOutputFilter INCLUDES .shtml </IfModule> # # The mod_mime_magic module allows the server to use various hints from the # contents of the file itself to determine its type. The MIMEMagicFile # directive tells the module where the hint definitions are located. # #MIMEMagicFile etc/magic # # Customizable error responses come in three flavors: # 1) plain text 2) local redirects 3) external redirects # # Some examples: #ErrorDocument 500 "The server made a boo boo." #ErrorDocument 404 /missing.html #ErrorDocument 404 "/cgi-bin/missing_handler.pl" #ErrorDocument 402 http://www.example.com/subscription_info.html # # # MaxRanges: Maximum number of Ranges in a request before # returning the entire resource, or one of the special # values 'default', 'none' or 'unlimited'. # Default setting is to accept 200 Ranges. #MaxRanges unlimited # # EnableMMAP and EnableSendfile: On systems that support it, # memory-mapping or the sendfile syscall may be used to deliver # files. This usually improves server performance, but must # be turned off when serving from networked-mounted # filesystems or if support for these functions is otherwise # broken on your system. # Defaults: EnableMMAP On, EnableSendfile Off # EnableMMAP off EnableSendfile off # Supplemental configuration # # The configuration files in the etc/extra/ directory can be # included to add extra features or to modify the default configuration of # the server, or you may simply copy their contents here and change as # necessary. # Server-pool management (MPM specific) #Include etc/extra/httpd-mpm.conf # Multi-language error messages Include etc/extra/httpd-multilang-errordoc.conf # Fancy directory listings Include etc/extra/httpd-autoindex.conf # Language settings #Include etc/extra/httpd-languages.conf # User home directories #Include etc/extra/httpd-userdir.conf # Real-time info on requests and configuration #Include etc/extra/httpd-info.conf # Virtual hosts Include etc/extra/httpd-vhosts.conf # Local access to the Apache HTTP Server Manual #Include etc/extra/httpd-manual.conf # Distributed authoring and versioning (WebDAV) #Include etc/extra/httpd-dav.conf # Various default settings Include etc/extra/httpd-default.conf # Configure mod_proxy_html to understand HTML4/XHTML1 <IfModule proxy_html_module> Include etc/extra/proxy-html.conf </IfModule> # Secure (SSL/TLS) connections <IfModule ssl_module> # XAMPP <IfDefine SSL> Include etc/extra/httpd-ssl.conf </IfDefine> </IfModule> # # Note: The following must must be present to support # starting without SSL on platforms with no /dev/random equivalent # but a statically compiled-in mod_ssl. # <IfModule ssl_module> SSLRandomSeed startup builtin SSLRandomSeed connect builtin </IfModule> # XAMPP Include etc/extra/httpd-xampp.conf Include "/opt/lampp/apache2/conf/httpd.conf" I used command shown in this example. I used below lines to change and add group Add group "groupadd www" Add user to group "usermod -aG www root" Change htdocs group "chgrp -R www /opt/lampp/htdocs" Change sitedir group "chgrp -R www /opt/lampp/htdocs/mysite" Change htdocs chmod "chmod 2775 /opt/lampp/htdocs" Change sitedir chmod "chmod 2775 /opt/lampp/htdocs/mysite" And then I changed my vhosts.conf file # Virtual Hosts # # Required modules: mod_log_config # If you want to maintain multiple domains/hostnames on your # machine you can setup VirtualHost containers for them. Most configurations # use only name-based virtual hosts so the server doesn't need to worry about # IP addresses. This is indicated by the asterisks in the directives below. # # Please see the documentation at # <URL:http://httpd.apache.org/docs/2.4/vhosts/> # for further details before you try to setup virtual hosts. # # You may use the command line option '-S' to verify your virtual host # configuration. # # VirtualHost example: # Almost any Apache directive may go into a VirtualHost container. # The first VirtualHost section is used for all requests that do not # match a ServerName or ServerAlias in any <VirtualHost> block. # <VirtualHost *:80> ServerAdmin [email protected] DocumentRoot "/opt/lampp/docs/dummy-host.example.com" ServerName dummy-host.example.com ServerAlias www.dummy-host.example.com ErrorLog "logs/dummy-host.example.com-error_log" CustomLog "logs/dummy-host.example.com-access_log" common </VirtualHost> <VirtualHost *:80> ServerAdmin [email protected] DocumentRoot "/opt/lampp/docs/dummy-host2.example.com" ServerName dummy-host2.example.com ErrorLog "logs/dummy-host2.example.com-error_log" CustomLog "logs/dummy-host2.example.com-access_log" common </VirtualHost> NameVirtualHost * <VirtualHost *> ServerAdmin [email protected] DocumentRoot "/opt/lampp/htdocs/mysite" ServerName mysite.com ServerAlias mysite.com ErrorLog "/opt/lampp/htdocs/mysite/errorlogs" CustomLog "/opt/lampp/htdocs/mysite/customlog" common <Directory "/opt/lampp/htdocs/mysite"> Options Indexes FollowSymLinks Includes ExecCGI AllowOverride All Order Allow,Deny Allow from all Require all granted </Directory> </VirtualHost> but still its not working and I am getting 403 error on my ip and domain however I can access phpmyadmin. If anyone can help me, please help me.

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  • ODI 11g – How to Load Using Partition Exchange

    - by David Allan
    Here we will look at how to load large volumes of data efficiently into the Oracle database using a mixture of CTAS and partition exchange loading. The example we will leverage was posted by Mark Rittman a couple of years back on Interval Partitioning, you can find that posting here. The best thing about ODI is that you can encapsulate all those ‘how to’ blog posts and scripts into templates that can be reused – the templates are of course Knowledge Modules. The interface design to mimic Mark's posting is shown below; The IKM I have constructed performs a simple series of steps to perform a CTAS to create the stage table to use in the exchange, then lock the partition (to ensure it exists, it will be created if it doesn’t) then exchange the partition in the target table. You can find the IKM Oracle PEL.xml file here. The IKM performs the follows steps and is meant to illustrate what can be done; So when you use the IKM in an interface you configure the options for hints (for parallelism levels etc), initial extent size, next extent size and the partition variable;   The KM has an option where the name of the partition can be passed in, so if you know the name of the partition then set the variable to the name, if you have interval partitioning you probably don’t know the name, so you can use the FOR clause. In my example I set the variable to use the date value of the source data FOR (TO_DATE(''01-FEB-2010'',''dd-MON-yyyy'')) Using a variable lets me invoke the scenario many times loading different partitions of the same target table. Below you can see where this is defined within ODI, I had to double single-quote the strings since this is placed inside the execute immediate tasks in the KM; Note also this example interface uses the LKM Oracle to Oracle (datapump), so this illustration uses a lot of the high performing Oracle database capabilities – it uses Data Pump to unload, then a CreateTableAsSelect (CTAS) is executed on the external table based on top of the Data Pump export. This table is then exchanged in the target. The IKM and illustrations above are using ODI 11.1.1.6 which was needed to get around some bugs in earlier releases with how the variable is handled...as far as I remember.

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  • Oracle Open World starts on Sunday, Sept 30

    - by Mike Dietrich
    Oracle Open World 2012 starts on Sunday this week - and we are really looking forward to see you in one of our presentations, especially theDatabase Upgrade on SteriodsReal Speed, Real Customers, Real Secretson Monday, Oct 1, 12:15pm in Moscone South 307(just skip the lunch - the boxed food is not healthy at all): Monday, Oct 1, 12:15 PM - 1:15 PM - Moscone South - 307 Database Upgrade on Steroids:Real Speed, Real Customers, Real Secrets Mike Dietrich - Consulting Member Technical Staff, Oracle Georg Winkens - Technical Manager, Amadeus Data Processing Carol Tagliaferri - Senior Development Manager, Oracle  Looking to improve the performance of your database upgrade and learn about other ways to reduce upgrade time? Isn’t everyone? In this session, you will learn directly from Oracle’s Upgrade Development team about what you can do to speed things up. Find out about ways to reduce upgrade downtime such as using a transient logical standby database and/or Oracle GoldenGate, and get other hints and tips. Learn about new features that improve upgrade performance and reduce downtime. Hear Georg Winkens, DB Services technical manager from Amadeus, speak about his upgrade experience, and get real-life performance measurements and advice for a successful upgrade. . And don't forget: we already start on Sunday so if you'd like to learn about the SAP database upgrades at Deutsche Messe: Sunday, Sep 30, 11:15 AM - 12:00 PM - Moscone West - 2001Oracle Database Upgrade to 11g Release 2 with SAP Applications Andreas Ellerhoff - DBA, Deutsche Messe AG Mike Dietrich - Consulting Member Technical Staff, Oracle Jan Klokkers - Sr.Director SAP Development, Oracle Deutsche Messe began to use Oracle6 Database at the end of the 1980s and has been using Oracle Database technology together with SAP applications successfully since 2002. At the end of 2010, it took the first steps of an upgrade to Oracle Database 11g Release 2 (11.2), and since mid-2011, all SAP production systems there run successfully with Oracle Database 11g. This presentation explains why Deutsche Messe uses Oracle Database together with SAP applications, discusses the many reasons for the upgrade to Release 11g, and focuses on the operational top aspects from a DBA perspective. . And unfortunately the Hands-On-Lab is sold out already ... We would like to apologize but we have absolutely ZERO influence on either the number of runs or the number of available seats.  Tuesday, Oct 2, 10:15 AM - 12:45 PM - Marriott Marquis - Salon 12/13 Hands On Lab:Upgrading an Oracle Database Instance, Using Best Practices Roy Swonger - Senior Director, Software Development, Oracle Carol Tagliaferri - Senior Development Manager, Oracle Mike Dietrich - Consulting Member Technical Staff, Oracle Cindy Lim - PMTS, Oracle Carol Palmer - Principal Product Manager, Oracle This hands-on lab gives participants the opportunity to work through a database upgrade from an older release of Oracle Database to the very latest Oracle Database release available. Participants will learn how the improved automation of the upgrade process and the generation of fix-up scripts can quickly help fix database issues prior to upgrading. The lab also uses the new parallel upgrade feature to improve performance of the upgrade, resulting in less downtime. Come get inside information about database upgrades from the Database Upgrade development team. . See you soon

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