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Is this how VFP works?
Message
 
À
12/03/2007 09:21:19
Mike Yearwood
Toronto, Ontario, Canada
Information générale
Forum:
Visual FoxPro
Catégorie:
Autre
Versions des environnements
Visual FoxPro:
VFP 9 SP1
Divers
Thread ID:
01202551
Message ID:
01202696
Vues:
14
This statement came from my memory of a FT or FPA article from awhile back about . . . ??? . . . how VFP achieves its speed or about indexes or something of that sort. I'm doubtful they do all of what you mention for only the purposes of the CONTINUE command. I stand by my statement until irrefutable documentation proves me wrong. <g>

>>The guy is wrong. One "trick" that VFP does use to get its speed is to try to load the entire index for a table into memory, but that's very different that loading the entire table.
>
>I don't think that's quite right either. It loads some of each index tag's data or .idx file and builds a bitmap with one bit per record, which remains in memory for the purposes of the CONTINUE command.
>
>> Perhaps he said that and you were thinking he meant the table? But if he said it loads the entire table, he's not right.
>>
>>>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?
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