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Is it reasonable to have index on DELETED()?
Message
 
À
21/03/1999 03:53:13
Walter Meester
HoogkarspelPays-Bas
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00196021
Message ID:
00200287
Vues:
14
>Bela,
>If there are not too many deleted records within this resultset there would be no benefit to the deleted() tag as the resultset without the deleted tag would be simular in size as the with the deleted tag. So from a Rushmore point of view there is no need for a index on deleted().
>
>The are some circumstances where an index would benefit the performance:
>
>- You have lots of deleted records in your table (or tables), lets say more than 5 - 10%

The traditional view is that the # deleted records makes no difference, the Deleted tag always improves performance independently. Of course, we have discovered that with NOFILTER the tag doesn't necessarily improve performance, and may even hinder it, but this testing is with no deleted records.

The question is now, is the Deleted index of value with some deleted records in the base table? If so, at what rough percentage of deleted recs will it improve performance? My first thought is that the tag may not improve performance even with many deleted records, if the traditional view above is correct. But further testing is needed on this...
The Anonymous Bureaucrat,
and frankly, quite content not to be
a member of either major US political party.
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