Microsoft KB Archive/267953

= FIX: Interleaving Prepare And Adhoc Execute of Query May Cause Recompile Loop =

Article ID: 267953

Article Last Modified on 10/31/2003

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APPLIES TO


 * Microsoft SQL Server 2000 Standard Edition
 * Microsoft SQL Server 7.0 Standard Edition

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This article was previously published under Q267953



BUG #: 236625 (SHILOH_BUGS)

BUG #: 58063 (SQLBUG_70)



SYMPTOMS
If one connection prepares a query but never runs the query, while a second connection is running the same query ad hoc, SQL Server might begin to recompile the query infinitely. More and more memory is used as the recompile continues, CPU utilization is high, and the server might become very sluggish. You may eventually encounter the following 17803 error messages in the SQL Server errorlog as memory is depleted:

2000-06-14 17:09:21.31 ods Error: 17803, Severity: 17, State: 14

2000-06-14 17:09:21.31 ods Insufficient memory available..

Generally, you must re-start SQL Server to recover from this situation.



SQL Server 2000
To resolve this problem, obtain the latest service pack for Microsoft SQL Server 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

290211 INF: How to Obtain the Latest SQL Server 2000 Service Pack

Hotfix
NOTE: The following hotfix was created prior to Microsoft SQL Server 2000 Service Pack 1.

The English version of this fix should have the following file attributes or later:   Version     File name     Platform ---  8.00.217    s80217i.exe   x86 NOTE: Due to file dependencies, the most recent hotfix or feature that contains the above files may also contain additional files.

SQL Server 7.0
To resolve this problem, obtain the latest service pack for SQL Server 7.0. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

301511 INF: How to Obtain the Latest SQL Server 7.0 Service Pack



WORKAROUND
To work around this problem:
 * Execute the prepared query at least once.

-or-


 * Consistently have all the connections submit the query ad hoc or prepared.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

SQL Server 2000
This problem was first corrected in SQL Server 2000 Service Pack 1.

SQL Server 7.0
This problem was first corrected in SQL Server 7.0 Service Pack 3.



MORE INFORMATION
A prepare of a query can be performed in OLE DB or ODBC by calling ICommandPrepare::Prepare or SQLPrepare, respectively. This is typically done when the same query is to be run many different times. You run the prepared query by calling ICommand::Execute or SQLExecute.

It might be possible to run DBCC FREEPROCCACHE to flush the plans from the cache. If you can do this, then that is sufficient to stop the recompile loop and the server stabilizes.

You can detect this problem by watching the following Performance Monitor counters:

SQL Server:Cache Manager - Cache Use Counts/sec for Adhoc Sql Plans

SQL Server: SQL Statistics - SQL Recompilations/sec

SQL Server: SQL Statistics - Batch Requests/sec

SQL Server: SQL Statistics - Compilations/sec

The first two counters jump to a very high value (generally 50000 or higher on a multi-processor computer), while the last two counters drop to nearly zero, even if there are queries being sent to the server from other connections.

You do not have to have a multi-processor computer to encounter this problem, but the problem does happen more quickly in a multi-processor computer environment.

Additional query words: Error 17803

Keywords: kbbug kbfix kbsqlserv2000sp1fix KB267953

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