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Modifying stored procedures
Message
From
06/06/2002 07:34:19
Hilmar Zonneveld
Independent Consultant
Cochabamba, Bolivia
 
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Miscellaneous
Thread ID:
00664934
Message ID:
00665339
Views:
25
>Hi, Hilmar!
>
>>>
>Can you briefly explain what is a "dirty read"?
><<
>
>"Dirty read" is the possibilitiy of all xBase databases to be able to read a record which is locked by another!
>This works due to a technical trick:
>- Locks are setted on a specific area of the DBF file.
>- But not the real location of the locked record in the DBF file is locked, but a virtual region outside of EOF.
>- If anybody other try to make the same virtual lock, it denied.
>- But if anybody want's to read the locked record - it works!
>
>BTW: This is the history, I'm not sure about behind the scenes of the current VFP versions. And I don't know how backend databases like SQL2000 work!
>
>So far!

Thanks for the information. I wasn't aware of how locking worked, nor about the name, "dirty read". I assume the "dirty" part is that another user can change the record in the meantime.

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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