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Pessimistic buffering
Message
De
17/11/2002 16:43:30
Hilmar Zonneveld
Independent Consultant
Cochabamba, Bolivie
 
 
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00723655
Message ID:
00723673
Vues:
20
>I have always used optimistic table buffering in my applications but I came across a situation where I might need to change it to pessimistic buffering.
>
>Under Pessimistic Buffering:
>What happens, on the network, when user A is making changes to a record and user B attempts to make changes to the same record. What kind of message does user B gets?

Well, the difference with pessimistic buffering is that the record will be blocked immediately, as soon as user A starts editing. User B will probably get something similar to "cursor is in use by another".

Optimistic buffering only attempts the (implicit) record lock when changes are being saved (TableUpdate()).

>
>Also, if you have pessimistic table buffering, user A can make changes to one record while user B can make changes to another record? Right?

Yes.

I would recommend optimistic buffering in most cases. The fact that two users can edit the same record is usually no problem: a) they usually won't, in practice, b) nothing bad happens if two users really do edit the same record: the last one to try saving will simply have to undo and start over again.

Hilmar.
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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