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In a SQL Server database sp_recompile can be run on a stored procedure to update the execution plan. I would like to run this on all stored procedures in a database. Also, I would like to run its equivalent on all table-valued functions but I do not know which sys procedure to run.

Is it possible to do this without manually typing out a sp_recompile line for all of the stored procedure names in SQL Server Management Studio? Likewise for the table valued functions?

I believe I need to do this because the VM SQL Server has had its memory significantly increased but I am only seeing a marginal increase in execution time. The execute plans show 80+ percent of the run time is on a clustered index seek so I don't think there is much more I can do to optimise the stored procedures.

  • Regarding clustered index seek performance, you are probably right performance cannot be improved more if it's a trivial query that selects a single row by unique key, However, with a non-unique key, performance also depends how many rows are actually touched during the scan, – Dan Guzman Sep 29 '17 at 14:56
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You can run sp_recompile on everything by using a cursor to produce ad-hoc SQL for each and run it, if you think that will help:

DECLARE C CURSOR FOR (SELECT [name] FROM sys.objects WHERE [type] IN ('P', 'FN', 'IF'));
DECLARE @name SYSNAME;
OPEN C;
FETCH NEXT FROM C INTO @name;
WHILE @@FETCH_STATUS=0 BEGIN
    EXEC sp_recompile @name;
    FETCH NEXT FROM C INTO @name;
END;
CLOSE C;
DEALLOCATE C;

or you could produce ad-hoc SQL and run that via EXEC, takes less code which might be marginally more efficient:

DECLARE @sql NVARCHAR(MAX) = '';
SELECT @sql += 'EXEC sp_recompile '''+[name]+''''+CHAR(10) FROM sys.objects WHERE [type] IN ('P', 'FN', 'IF');
EXEC (@sql);

(though I find this form sometimes throws people due to looking set-based but building the string up iteratively, and not being a standard SQL pattern)

Another set of objects that might be a similar concern here is views. You can similarly mark them as needing to be reassessed to make sure stored plans and other meta-data is not stale with sp_refreshview, by small modifications to either the cursor or ad-hoc SQL methods shown above:

DECLARE @sql NVARCHAR(MAX) = '';
SELECT @sql += 'EXEC sp_refreshview '''+[name]+''''+CHAR(10) FROM sys.objects WHERE [type] IN ('V');
EXEC (@sql);

The execute plans show 80+ percent of the run time is on a clustered index seek so I don't think there is much more I can do to optimise the stored procedures.

There is sometimes more to optimisation than preferring seeks over scans and so forth, sometimes an index scan is more efficient than many executions of seek operations, and the cost estimates upon which the percent figures you are looking at are calculated are that (estimates) at best (a useful guide but sometimes far from at all accurate).

While "throw more memory at it" can help some database performance issues, at least temporarily, if your bottlenecks are very CPU bound rather than memory and/or IO bound then adding more memory will have very little effect.

  • This is what I was looking for. (+1) while we wait to see if anything else turns up. Thanks for the performance comments. – Edmund Sep 29 '17 at 14:24
  • Execution time reduced to 2 minutes from 3 minutes. – Edmund Sep 29 '17 at 14:51
  • That execution time reduction is almost certainly not due to recompiling. Much more likely, you have blocking affecting throughput. – Max Vernon Sep 29 '17 at 17:01
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If you add memory (even if it's a Hot Added to a VM), and increase Max Server Memory to match, your plan cache will clear out.

That is effectively 'recompiling' all of those things you mentioned, because they won't have a stored plan in cache to re-use. SQL Server will have to build a new one.

You may not have ever set Max Server Memory though. If you're not sure about that, you can run DBCC FREEPROCCACHE to clear out the plan cache.

You do this at your own risk in production. I can't guarantee the new plan will be better.

Memory doesn't solve every performance problem in SQL Server, and a Seek isn't necessarily the finish line of performance tuning.

If you need help with a specific query, you should ask a separate question.

  • It looks as if the DB admins did increase the max memory if view the server properties in SSMS. Many thanks for your performance comments. (+1) – Edmund Sep 29 '17 at 14:22

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