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Bizzare error when indexing a cursor (with 2nd tag or mo
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À
02/12/2005 18:12:36
Information générale
Forum:
Visual FoxPro
Catégorie:
Problèmes
Divers
Thread ID:
01074433
Message ID:
01074469
Vues:
11
Thanks for the clarificaion. My comment about ReadWrite and efficiency was just an assumption based on this asked-to-myself question: "Why not then make all cursors read-write automatically?"

>Others have given you the answer, but I want to elaborate on your "lose a lot of efficiency..." statement.
>
>There is virtually NO efficiency lost.
>A cursor is by definition EXCLUSIVE.
>When *any* file is EXCLUSIVE the OS will simply store the records in cache (RAM) until something - typically a drain on RAM - causes it to write it out. An exception to this is an FPT, which VFP seems to force to write to HD as a record is created.
>
>cheers
>
>
>>If I create a cursor:
>>select Field1, field2, field3... from MyTable into cursor MyCursor
>>and then I do (to MyCursor):
>>index on field1 tag T1
>>... this works, but if I then do
>>index on field2 tag T2
>>It fails, with a message that a temp file is read-only (I suppose it's referring to the CDX file that is temporarily created).
>>I've tried deleting the tag, doing a "close indexes", etc. But I cannot figure out how to work around this, and it seems you lose a lot of efficiency if you have make the cursor itself ReadWrite just so you can index the cursor with more than 1 tag.
>>What's the solution? Thank very much.
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