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SELECT faster with SET EXCLUSIVE
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Information générale
Forum:
Visual FoxPro
Catégorie:
Codage, syntaxe et commandes
Divers
Thread ID:
00004967
Message ID:
00005005
Vues:
37
>>this is btw, one of the reasons that sometimes it is faster to
>>"take apart" an SQL statement to several queries
>>
>>Arnon
>
>Arnon is very right on this. I have proved, to my surprise, that 2 SQLs run faster then 1 complex SQL. I do not know wether SQL in VFP is inefficient or what the cause is. But the result is undisputable -- 2 SQLs are faster then 1!!!!

Do you mean a nested select: SELECT * from dba WHERE field IN (SELECT ...
I originally had it as a nested select when I made this post. Wehn I unnseted it and just joined the tables (and made the index fields Integer rather than characcter - quite a job) performance increased about 5 times.

As an asside, I'm convinced that the Integer helped things out. I am using Codebook which indexes using character fields. When I changed this to Integer, all of my querries ran faster. However, you cant set a view parameter blank on an integer field and expect to match all records. You have to set the view to select on LTRIM(STR(id)) and have an index on this. So, I traded execution speed on id searches for select join speed.

-John Gore
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