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Is index used
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À
18/09/2002 03:29:24
Information générale
Forum:
Visual FoxPro
Catégorie:
Autre
Titre:
Divers
Thread ID:
00701640
Message ID:
00701829
Vues:
16
>If I have an index on field rfrom C(10)
>index on rfrom tag rfrom
>
>In case of select statement
>
>set exact off
>lvalue='0104'
>
>select * from ranges where alltrim(rfrom)=lvalue
>
>is index used or it is a full scan.
>
>My goal is to learn whether there is anything in a table with the field value for rfrom for which the statement
>atc( alltrim(rfrom) , lvalue ) = 1
>is true
>
>If it is a full scan any suggestions how to organize an index which could be used in the case like this.
>
>Thank you
>Michael

FoxPro will not use your rfrom tag because the index expression, "rfrom", does not EXACTLY match the expression in your query, "alltrim(rfrom)". The SQL SELECT processor will probably create an index on "alltrim(rfrom)" on the fly, but that will take some time to create.

As Tamar points out, the SYS(3054) function can be useful in determining whether Rushmore has kicked in fully, partially, or not at all.

Mike
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