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Any studies on when PACKing really helps?
Message
De
27/12/2006 10:35:40
 
 
À
27/12/2006 10:26:15
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
01180412
Message ID:
01180491
Vues:
13
>>>>for tables without any memo fields:
>>>>Was wondering if anyone knew at what precentage point deleted records casue a significant performance hit when doing SQL statements.
>>>>Is it a basic standard or does it depend on the number of fields and/or type of fields.
>>>
>>>Imho, they don't cause performance hit, because if SET DELETED ON, VFP will have to check for deleted records regardless if they are in a table or not.
>>
>>It's more complicated than that. With SET DELETED ON if there is an index tag, this tag will be brought from the server to the PC for examination. That can be a substantial wait time as Chris Probst pointed out in FPA.
>>
>>Without the tag, other aspects of the query will filter out the records and SET DELETED will have far fewer records to examine.
>
>Sure, having tag on two-state fields (e.g. logical) is counter-productive.

Unless you use the new binary index type, which was introduced in VFP9.
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