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How does VFP fetch data in buffering mode?
Message
 
 
À
29/12/2000 20:15:05
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00457209
Message ID:
00458062
Vues:
16
Hello, John.

No. VFP doesn't perform any additional reading work when you use table buffering. It is a pure workstation work. As you move trough the records and only if you change something (edit,add, or delete a record), that is written just to the buffer, where information is kept about that new value and the old one.

That's what you see using Table.field (the actual value in the buffer), OLDVAL( Table.field ) (the original value in the buffer, before the changes you applied). You can also get to the most current value written on disk using CURVAL( Table.field ). This last function is indeed looking outside the buffer.

So, you shouldn't notice any performance penalty because of the table buffering usage.

Hope this helps.
Happy new year, century, millenium, and more!


> Thank you for your information. I did it!!! :-)
> Again, I would like to know the way of VFP fecthing data. If i am using table buffering - 5, will VFP fecth all of the records of my native table to local memory once I issue USE mytable ??? Pls provide more information if possible.
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