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PACK on Memo issue
Message
De
09/02/1999 21:08:48
 
 
À
09/02/1999 20:24:18
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00185770
Message ID:
00185787
Vues:
16
>Alvin,
>
>Memo files can get corrupted...
>
>As for the reason why? I do not have an anser to that.
>
>There are a few utilities you can use to repair damaged memo files.
>
>The one that comes first to mind is FoxFix.
>
>Good Luck
>
>:)
>
>Pascal

The reason is simple..it's called memo bloat and exists in other xBase-type files. When you add a memo, a block of dispace is reserved for that memo (SET MEMOBLOCK). When that area is filled, the entire memo is copied to the end of the FPT and another block is allocated to it. The original location is marked as no longer being used. The memo pointer in the DBF is then updated to indicate the new position of the text in the FPT. I may have the order of these steps mixed up, but this is basically what happens. With all that moving around of the data and updating of the pointer, things can...and do go wrong.
Craig Berntson
MCSD, Microsoft .Net MVP, Grape City Community Influencer
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