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 From: Jun Tangunan
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 Jun Tangunan
 To: David Kurniawan
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 David Kurniawan
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Subject: RE: ask deferent between use FLUSH or not
Thread ID: 373419 Message ID: 373452 # Views: 46 # Ratings: 0
Version: Visual FoxPro 9 SP2 Category: General VFP Topics
Date: Friday, March 22, 2013 8:05:52 AM         
   


> >
> >
> > Not Exactly (Equal, LOL) like that Ilyrad. Exactly Equal (==) means both sides should be exactly the same ignoring the SET EXACT setting. == has an implicit SET EXACT ON so to speak.
> >
> > Simple Equal (=), on the other hand, is affected by SET EXACT setting.
> >
> > FLUSH, simply saying, saves "buffered" changes to the tables.
> >
> >
> > http://sandstorm36.blogspot.com
> > http://weblogs.foxite.com/sandstorm36
> Dear Jun
>
> but a mean saves 'buffered' ??? and if i not use FLUSH what the effect actually to tables
>
>
> BR
>
> DAVID KURNIAWAN
>
>
> mamamia


From what I know, changes made to the fields are not written or finalized outright on the table. That is maybe because it is giving allowance for further keystrokes or such things plus it is faster because it does things on a batch. And maybe to reduce risk of table corruption which happens mostly in WRITE. So that is why sometimes when there is a sudden power loss, you sometimes finds out afterwards that what you thought you have changed or saved is not there.

When you issue FLUSH though, those changes will be "really" saved/written to the tables without any delay. So data loss when power outage happens is reduced. However, if there are pros of using FLUSH, there are also cons. One is that it is slower and the other is you are making the tables more prone to corruption being it will be doing the disk write on every REPLACE/UPDATE/INSERT when it reached that FLUSH command; more often than when flushing is not applied.

Also, it is good to note that there are certain events that does that disk write as well without explicit use of FLUSH. Things like closing a table or when you LOCK a record or file then issue UNLOCK later.

Someone more experienced or who has analyzed this better than I will step in here to clear things out if I am wrong in my analysis. ;-)


http://sandstorm36.blogspot.com
http://weblogs.foxite.com/sandstorm36

ENTIRE THREAD

ask deferent between use FLUSH or not Posted by David Kurniawan @ 3/22/2013 6:02:51 AM
RE: ask deferent between use FLUSH or not Posted by llyrad atsituab @ 3/22/2013 6:16:06 AM
RE: ask deferent between use FLUSH or not Posted by Jun Tangunan @ 3/22/2013 6:43:43 AM
RE: ask deferent between use FLUSH or not Posted by David Kurniawan @ 3/22/2013 6:56:09 AM
RE: ask deferent between use FLUSH or not Posted by Jun Tangunan @ 3/22/2013 8:05:52 AM
RE: ask deferent between use FLUSH or not Posted by Cetin Basoz @ 3/22/2013 1:01:13 PM