Re: Problem browsing large file

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From: Dan Freeman (spam_at_microsoft.com)
Date: 03/18/04 

Date: Thu, 18 Mar 2004 10:07:23 -0800

It *may* be trying to update the header. What's SET TABLEVALIDATE set to?

Dan

Ook wrote:
> The plot thickens. I have another app that keeps this file open 24/7.
> If I open the file NOUPDATE with VFP7/8, it pauses for a minute, and
> then the 24/7 app throws an error (table in use). What is extremely
> weird is that this error bypasses the error trap!
>
> It appears that by opening the file, VFP is trying to write to is,
> even though I've opened it NOUPDATE. I'm wondering if VFP is
> detecting something wrong with file or the index, and is trying to
> automatically correct it?
>
> Also, how can table in use error bypass the error trap like that?
>
>
> "Cindy Winegarden" <cindy.winegarden@mvps.org> wrote in message
> news:uZSmdcDDEHA.3608@TK2MSFTNGP10.phx.gbl...
>> In news: %236b8oODDEHA.1588@tk2msftngp13.phx.gbl,
>> Ook <outlookexpress@nospam@embertsdotcom> wrote:
>>> Update - If I set DELETED OFF, the problem goes away. I'm thinking
>>> that the tag on DELETED() is somehow causing this - should you not
>>> create an index on DELETED() with large tables?
>>
>> Hi Ook,
>>
>> FoxPro's Rushmore technology can be a help or a hindrance, and only
>> testing in your environment can decide for you, as you've
>> discovered. I assume that when you open the table FoxPro will read
>> the DELETED() index and then go back to fetch records that qualify -
>> i.e. records that are not deleted. Since your table is large Fox has
>> to read a rather large index before opening the table. Without the
>> index Fox probably fetches all the records and then filters out the
>> deleted records locally.
>>
>> In general, indexes on fields with only a few discrete values (Sex is
>> another one) should be tested to see whether they help or hinder in
>> your environment.
>>
>> There was an excellent article about this by Chris Probst in the
>> May, 1999 issue of FoxPro Advisor magazine.
>>
>> --
>> Cindy Winegarden MCSD, Microsoft Visual FoxPro MVP
>> cindy.winegarden@mvps.org www.cindywinegarden.com