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POSQL Server: Query fast, but slow from procedure
 

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  1. POSQL Server: Query fast, but slow from procedure
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    <p>A query runs fast:</p> <pre><code>DECLARE @SessionGUID uniqueidentifier SET @SessionGUID = 'BCBA333C-B6A1-4155-9833-C495F22EA908' SELECT * FROM Report_Opener WHERE SessionGUID = @SessionGUID ORDER BY CurrencyTypeOrder, Rank </code></pre> <p><strong>subtree cost: 0.502</strong></p> <p>But putting the same SQL in a stored procedure runs slow, and with a totally different execution plan</p> <pre><code>CREATE PROCEDURE dbo.ViewOpener @SessionGUID uniqueidentifier AS SELECT * FROM Report_Opener WHERE SessionGUID = @SessionGUID ORDER BY CurrencyTypeOrder, Rank EXECUTE ViewOpener @SessionGUID </code></pre> <p><strong>Subtree cost: 19.2</strong></p> <p>I've run</p> <pre><code>sp_recompile ViewOpener </code></pre> <p>And it still runs the same (badly), and I've also changed the stored procedure to</p> <pre><code>CREATE PROCEDURE dbo.ViewOpener @SessionGUID uniqueidentifier AS SELECT *, 'recompile please' FROM Report_Opener WHERE SessionGUID = @SessionGUID ORDER BY CurrencyTypeOrder, Rank </code></pre> <p>And back again, trying to really trick it into recompiling.</p> <p>I've dropped and recreated the stored procedure in order to get it to generate a new plan.</p> <p>I've tried forcing recompiles, <strong>and prevent parameter sniffing</strong>, by using a decoy variable:</p> <pre><code>CREATE PROCEDURE dbo.ViewOpener @SessionGUID uniqueidentifier AS DECLARE @SessionGUIDbitch uniqueidentifier SET @SessionGUIDbitch = @SessionGUID SELECT * FROM Report_Opener WHERE SessionGUID = @SessionGUIDbitch ORDER BY CurrencyTypeOrder, Rank </code></pre> <p>I've also tried defining the stored procedure <strong><code>WITH RECOMPILE</code></strong>:</p> <pre><code>CREATE PROCEDURE dbo.ViewOpener @SessionGUID uniqueidentifier WITH RECOMPILE AS SELECT * FROM Report_Opener WHERE SessionGUID = @SessionGUID ORDER BY CurrencyTypeOrder, Rank </code></pre> <p>So that it's plan is never cached, and I've tried forcing a recompile at execute:</p> <pre><code>EXECUTE ViewOpener @SessionGUID WITH RECOMPILE </code></pre> <p>Which didn't help.</p> <p>I've tried converting the procedure to dynamic SQL:</p> <pre><code>CREATE PROCEDURE dbo.ViewOpener @SessionGUID uniqueidentifier WITH RECOMPILE AS DECLARE @SQLString NVARCHAR(500) SET @SQLString = N'SELECT * FROM Report_OpenerTest WHERE SessionGUID = @SessionGUID ORDER BY CurrencyTypeOrder, Rank' EXECUTE sp_executesql @SQLString, N'@SessionGUID uniqueidentifier', @SessionGUID </code></pre> <p>Which didn't help.</p> <p>The entity "<code>Report_Opener</code>" is a view, which is not indexed. The view only references underlying tables. No table contains computed columns, indexed or otherwise.</p> <p>For the hell of it I tried creating the view with </p> <pre><code>SET ANSI_NULLS ON SET QUOTED_IDENTIFER ON </code></pre> <p>That didn't fix it.</p> <p>How is it that</p> <ul> <li>the query is fast</li> <li>moving the query to a view, and selecting from the view is fast</li> <li>selecting from the view from a stored procedure is 40x slower?</li> </ul> <p>I tried moving the definition of the view directly into the stored procedure (violating 3 business rules, and breaking an important encapsulation), and that makes it only about 6x slower.</p> <p>Why is the stored procedure version so slow? What can possibly account for SQL Server running ad-hoc SQL faster than a different kind of ad-hoc SQL? </p> <p>I'd really rather not</p> <ul> <li>embed the SQL in code</li> <li><p>change the code at all</p> <pre><code>Microsoft SQL Server 2000 - 8.00.2050 (Intel X86) Mar 7 2008 21:29:56 Copyright (c) 1988-2003 Microsoft Corporation Standard Edition on Windows NT 5.2 (Build 3790: Service Pack 2) </code></pre></li> </ul> <p>But what can account for SQL Server being unable to run as fast as SQL Sever running a query, if not parameter sniffing.</p> <hr> <p>My next attempt will be to have <code>StoredProcedureA</code> call <code>StoredProcedureB</code> call <code>StoredProcedureC</code> call <code>StoredProcedureD</code> to query the view.</p> <p>And failing that, have the stored procedure call a stored procedure, call a UDF, call a UDF, call a stored procedure, call a UDF to query the view.</p> <hr> <p>To sum up, the following run fast from QA, but slow when put into a stored procedure:</p> <p>The original:</p> <pre><code>--Runs fine outside of a stored procedure SELECT * FROM Report_OpenerTest WHERE SessionGUID = @SessionGUID ORDER BY CurrencyTypeOrder, Rank </code></pre> <p><code>sp_executesql</code>:</p> <pre><code>--Runs fine outside of a stored procedure DECLARE @SQLString NVARCHAR(500) SET @SQLString = N'SELECT * FROM Report_OpenerTest WHERE SessionGUID = @SessionGUID ORDER BY CurrencyTypeOrder, Rank' EXECUTE sp_executesql @SQLString, N'@SessionGUID uniqueidentifier', @SessionGUID </code></pre> <p><code>EXEC(@sql)</code>:</p> <pre><code>--Runs fine outside of a stored procedure DECLARE @sql NVARCHAR(500) SET @sql = N'SELECT * FROM Report_OpenerTest WHERE SessionGUID = '''+CAST(@SessionGUID AS varchar(50))+''' ORDER BY CurrencyTypeOrder, Rank' EXEC(@sql) </code></pre> <hr> <p>Execution Plans</p> <p>The <strong>good</strong> plan:</p> <pre><code> |--Sort(ORDER BY:([Expr1020] ASC, [Currencies].[Rank] ASC)) |--Compute Scalar(DEFINE:([Expr1020]=If ([Currencies].[CurrencyType]='ctCanadianCash') then 1 else If ([Currencies].[CurrencyType]='ctMiscellaneous') then 2 else If ([Currencies].[CurrencyType]='ctTokens') then 3 else If ([Currencies].[CurrencyType] |--Nested Loops(Left Outer Join, OUTER REFERENCES:([Openers].[OpenerGUID])) |--Filter(WHERE:((([Currencies].[IsActive]&lt;&gt;0 AND [Currencies].[OnOpener]&lt;&gt;0) AND ((((((([Currencies].[CurrencyType]='ctUSCoin' OR [Currencies].[CurrencyType]='ctMiscellaneousUS') OR [Currencies].[CurrencyType]='ctUSCash') OR [Currencies]. | |--Nested Loops(Left Outer Join, OUTER REFERENCES:([Currencies].[CurrencyGUID], [Openers].[OpenerGUID]) WITH PREFETCH) | |--Nested Loops(Left Outer Join) | | |--Bookmark Lookup(BOOKMARK:([Bmk1016]), OBJECT:([GrobManagementSystemLive].[dbo].[Windows])) | | | |--Nested Loops(Inner Join, OUTER REFERENCES:([Openers].[WindowGUID])) | | | |--Bookmark Lookup(BOOKMARK:([Bmk1014]), OBJECT:([GrobManagementSystemLive].[dbo].[Openers])) | | | | |--Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[Openers].[IX_Openers_SessionGUID]), SEEK:([Openers].[SessionGUID]=[@SessionGUID]) ORDERED FORWARD) | | | |--Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[Windows].[IX_Windows]), SEEK:([Windows].[WindowGUID]=[Openers].[WindowGUID]) ORDERED FORWARD) | | |--Clustered Index Scan(OBJECT:([GrobManagementSystemLive].[dbo].[Currencies].[IX_Currencies_CurrencyType])) | |--Clustered Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[OpenerDetails].[IX_OpenerDetails_OpenerGUIDCurrencyGUID]), SEEK:([OpenerDetails].[OpenerGUID]=[Openers].[OpenerGUID] AND [OpenerDetails].[CurrencyGUID]=[Currenc |--Hash Match(Cache, HASH:([Openers].[OpenerGUID]), RESIDUAL:([Openers].[OpenerGUID]=[Openers].[OpenerGUID])) |--Stream Aggregate(DEFINE:([Expr1006]=SUM(If (((([Currencies].[CurrencyType]='ctMiscellaneous' OR [Currencies].[CurrencyType]='ctTokens') OR [Currencies].[CurrencyType]='ctChips') OR [Currencies].[CurrencyType]='ctCanadianCoin') OR [ |--Nested Loops(Inner Join, OUTER REFERENCES:([OpenerDetails].[CurrencyGUID]) WITH PREFETCH) |--Nested Loops(Inner Join) | |--Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[Openers].[IX_Openers_OneOpenerPerSession]), SEEK:([Openers].[OpenerGUID]=[Openers].[OpenerGUID]) ORDERED FORWARD) | |--Clustered Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[OpenerDetails].[IX_OpenerDetails_OpenerGUIDCurrencyGUID]), SEEK:([OpenerDetails].[OpenerGUID]=[Openers].[OpenerGUID]) ORDERED FORWARD) |--Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[Currencies].[PK_Currencies_CurrencyGUID]), SEEK:([Currencies].[CurrencyGUID]=[OpenerDetails].[CurrencyGUID]) ORDERED FORWARD) </code></pre> <p>The <strong>bad</strong> plan</p> <pre><code> |--Sort(ORDER BY:([Expr1020] ASC, [Currencies].[Rank] ASC)) |--Compute Scalar(DEFINE:([Expr1020]=If ([Currencies].[CurrencyType]='ctCanadianCash') then 1 else If ([Currencies].[CurrencyType]='ctMiscellaneous') then 2 else If ([Currencies].[CurrencyType]='ctTokens') then 3 else If ([Currencies].[Currency |--Nested Loops(Left Outer Join, OUTER REFERENCES:([Openers].[OpenerGUID])) |--Filter(WHERE:((([Currencies].[IsActive]&lt;&gt;0 AND [Currencies].[OnOpener]&lt;&gt;0) AND ((((((([Currencies].[CurrencyType]='ctUSCoin' OR [Currencies].[CurrencyType]='ctMiscellaneousUS') OR [Currencies].[CurrencyType]='ctUSCash') OR [Currenc | |--Nested Loops(Left Outer Join, OUTER REFERENCES:([Currencies].[CurrencyGUID], [Openers].[OpenerGUID]) WITH PREFETCH) | |--Filter(WHERE:([Openers].[SessionGUID]=[@SessionGUID])) | | |--Concatenation | | |--Nested Loops(Left Outer Join) | | | |--Table Spool | | | | |--Hash Match(Inner Join, HASH:([Windows].[WindowGUID])=([Openers].[WindowGUID]), RESIDUAL:([Windows].[WindowGUID]=[Openers].[WindowGUID])) | | | | |--Clustered Index Scan(OBJECT:([GrobManagementSystemLive].[dbo].[Windows].[IX_Windows_CageGUID])) | | | | |--Table Scan(OBJECT:([GrobManagementSystemLive].[dbo].[Openers])) | | | |--Table Spool | | | |--Clustered Index Scan(OBJECT:([GrobManagementSystemLive].[dbo].[Currencies].[IX_Currencies_CurrencyType])) | | |--Compute Scalar(DEFINE:([Openers].[OpenerGUID]=NULL, [Openers].[SessionGUID]=NULL, [Windows].[UseChipDenominations]=NULL)) | | |--Nested Loops(Left Anti Semi Join) | | |--Clustered Index Scan(OBJECT:([GrobManagementSystemLive].[dbo].[Currencies].[IX_Currencies_CurrencyType])) | | |--Row Count Spool | | |--Table Spool | |--Clustered Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[OpenerDetails].[IX_OpenerDetails_OpenerGUIDCurrencyGUID]), SEEK:([OpenerDetails].[OpenerGUID]=[Openers].[OpenerGUID] AND [OpenerDetails].[CurrencyGUID]=[Cu |--Hash Match(Cache, HASH:([Openers].[OpenerGUID]), RESIDUAL:([Openers].[OpenerGUID]=[Openers].[OpenerGUID])) |--Stream Aggregate(DEFINE:([Expr1006]=SUM([partialagg1034]), [Expr1007]=SUM([partialagg1035]), [Expr1008]=SUM([partialagg1036]), [Expr1009]=SUM([partialagg1037]), [Expr1010]=SUM([partialagg1038]), [Expr1011]=SUM([partialagg1039] |--Nested Loops(Inner Join) |--Stream Aggregate(DEFINE:([partialagg1034]=SUM(If (((([Currencies].[CurrencyType]='ctMiscellaneous' OR [Currencies].[CurrencyType]='ctTokens') OR [Currencies].[CurrencyType]='ctChips') OR [Currencies].[CurrencyType]=' | |--Nested Loops(Inner Join, OUTER REFERENCES:([OpenerDetails].[CurrencyGUID]) WITH PREFETCH) | |--Clustered Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[OpenerDetails].[IX_OpenerDetails_OpenerGUIDCurrencyGUID]), SEEK:([OpenerDetails].[OpenerGUID]=[Openers].[OpenerGUID]) ORDERED FORWARD) | |--Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[Currencies].[PK_Currencies_CurrencyGUID]), SEEK:([Currencies].[CurrencyGUID]=[OpenerDetails].[CurrencyGUID]) ORDERED FORWARD) |--Index Seek(OBJECT:([GrobManagementSystemLive].[dbo].[Openers].[IX_Openers_OneOpenerPerSession]), SEEK:([Openers].[OpenerGUID]=[Openers].[OpenerGUID]) ORDERED FORWARD) </code></pre> <p>The bad-one is eager spooling 6 million rows; the other one isn't.</p> <blockquote> <p><strong>Note:</strong> This isn't a question about tuning a query. I have a query that runs lightning fast. I just want SQL Server to run fast from a stored procedure.</p> </blockquote>
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