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Char and varchar - performance problem
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To
20/07/2009 13:41:56
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Environment versions
Visual FoxPro:
VFP 9 SP2
OS:
Windows Server 2003
Network:
Windows 2003 Server
Database:
MS SQL Server
Miscellaneous
Thread ID:
01413408
Message ID:
01413410
Views:
48
Hi Oscar,

Perhaps you can create this as a stored procedure and specify the parameter as CHAR with the correct length? That's the first idea that comes to mind, I'm not sure if there is a way with direct query.

Also, did you try to list every field you need explicitly?

>Hello
>
>I submit a query via SQLexec. The query looks basically like this (it is actually much more complex)
>
>SELECT * FROM TABLEX WHERE FIELD1 = ?AMES
>
>Where AMES = "200905" (VFP variable)
>
>It takes very long to complete (say 20 minutes). Using SQL profiler, I detect that SQL server does this:
>
>
>exec sp_executesql N'SELECT * FROM TABLEX WHERE FIELD1 = @P1',N'@P1 varchar(6)','200905'
>
>Running this from Query Analyzer runs slowly too.
>
>However, FIELD1 is actually char(6) not varchar(6). There is an index on FIELD1.
>
>From query analyzer, changing just varchar(6) to char(6), slashes execution time down from 20 minutes to 6 seconds.!
>
>How can I force VFP (or the ODBC driver) to correctly use char instead of varchar?
>
>Using SQL 2005 with SQL Client.
>
>TIA
If it's not broken, fix it until it is.


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