Increase the "snapshot too old" query mortality rate?
> -----Original Message-----
> From: Babette Turner-Underwood [mailto:[EMAIL PROTECTED]]
> Sent: Monday, August 20, 2001 9:22 AM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: Performance analysis (enqueue and buffer busy waits)
>
>
> I am curious.
> What are you trying to accomplish by
> decreasing rollback segment size??
>
> - Babette
>
> -----Original Message-----
> Lewis
> Sent: Tuesday, August 14, 2001 6:52 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Looking at your trace file, most of your lost time appears
> to be in an update of F4211.
>
> UPDATE CRPDTA.F4211
> SET SDRSDJ=:BND1,SDPPDJ=:BND2,
> SDCARS=:BND3,SDMOT=:BND4,
> SDFRTH=:BND5,SDUSER=:BND6,SDPID=:BND7,
> SDJOBN=:BND8,SDUPMJ=:BND9,SDTDAY= :BND10
> WHERE ( SDCDCD = :KEY1 )
>
> 9 seconds CPU, 283 seconds elapsed.
>
> I doubt if freelists are your problem, but possibly the
> lost time is initrans. NB from 8.1.6 you can change
> initrans without rebuilding the table - which is good
> if you don't have to go back to the old data and keep
> doing the same concurrent updates.
>
> There is no point in going above initrans = 20, but
> you might push it up to 10. This may improve the
> enqueue (TX mode 4?) problem, but if it does it
> will probably make the log sync problem worse.
>
> Try and swing more resources into DBWn -
> increase LRU latches to start with, and
> check whether async I/O, I/O slaves, or
> multiple db_writers works best for you.
>
> You may also want to review the size of
> your log files (upwards), and your rollback
> segments (downwards).
>
>
> Jonathan Lewis
>
> Seminars on getting the best out of Oracle
> Last few places available for Sept 10th/11th
> See http://www.jlcomp.demon.co.uk/seminar.html
>
>
> [snipped]
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> --
> Author: Babette Turner-Underwood
> INET: [EMAIL PROTECTED]
>
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