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Fragmentation - why it is usually good for VFP native da
Message
From
19/01/2003 06:48:57
 
 
To
17/01/2003 09:16:05
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Miscellaneous
Thread ID:
00742043
Message ID:
00743241
Views:
15
>>I think this should be just better docummented in the help files. So, when working on level of single record, leave it as is. When doing time-consuming data processing, make PACK first, and then proceed.
>
>I agree that we need more/clearer information in the Help. But be surprised (as I was) that a PACK or PACK MEMO does NOT result in a defragmented .FPT file! It does get de-bloated, I assume, but the Disk Defragmenter "Analyze" shows that it remains fragmented (but with fewer fragments) after the operation.
>

This is because PACK just does a copy of file on disk. If free space on disk used to store copy of file is defragmented, resulting file will be defragmented too. VFP does not do any specific control of this. It is just on the system level.

>>
>>In addition, in many our production applications we have automated administrative/maintenance tools running and making PACK and full REINDEX of every table, check for data integrity and corruption issues etc. I think, if MS would make such utility in tools for next version of VFP, it would be VERY valuable.
>
>Yes, I agree. But this is a separate issue, and be aware that a PACK and/or a full REINDEX will result in a defragmented DBF and CDX (just not the FPT). The PACK will do so, as I learned recently, only if there was at least 1 record deleted during the copy operation it does internally. If no records are dropped then the copy of the table is simply deleted and the internal REINDEX is skipped. However, the FPT processing is still performed.
>

I did not knew this.
As about reindex, I meant complete drop of CDX file and re-creating indexes, as usually many such tools do to avoid index corruption issues.

I think it would be extremely good if MS would place (on the system level) DBF and other files after PACK/REINDEX into the defragmented area.

In addition, you can schedule defragmentation of hard drive each night, for example, just after running of tools for VFP database maintenance. This should take care of this issue. Anyway, it would be extremely good to have all such tols in a single box, or at least better docummented this issue.
Vlad Grynchyshyn, Project Manager, MCP
vgryn@yahoo.com
ICQ #10709245
The professional level of programmer could be determined by level of stupidity of his/her bugs

It is not appropriate to say that question is "foolish". There could be only foolish answers. Everybody passed period of time when knows nothing about something.
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