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Is this how VFP works?
Message
De
10/03/2007 16:50:33
Hilmar Zonneveld
Independent Consultant
Cochabamba, Bolivie
 
 
Information générale
Forum:
Visual FoxPro
Catégorie:
Autre
Versions des environnements
Visual FoxPro:
VFP 9 SP1
Divers
Thread ID:
01202551
Message ID:
01202553
Vues:
10
>I was at the user group meeting last week and one of the guys there (seemed to be very knowledgeable) said the following:
>
>When you use SQL Select command and even if your WHERE clause is getting just one record (WHERE MYPK = nPk), VFP downloads the entire table (even if it has 1000,000 records) to the local drive and then selects the desired record from the local drive.
>
>Is this true?

Not necessarily. If there is an index - in the example, on MyPk - VFP will use Rushmore Optimization. It will fetch the required keys from the index, analyze which records need to be included, and only get the required records.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
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