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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Re: Snapshot too old during stress test... how to avoid
Snapshot Too Old Maybe caused bcos of Delayed Block Cleanout Problems.
Now this Bock was updated an Hour ago and u are now selecting it.. It
finds that there are ITL Entries in there and oracle wants to see if the
Transaction has been commited.
He Goes back to the Transaction Table of the RBS Pointed by this ITL and he finds that there is No Rollback entry available.. Why is this ??? The Optimal Parameter Shrunk the RBS Down and with it all the Undo Information needed to do a Block Clean out.
HTH
Best Regards,
Ganesh R
DID : +65-6215-8413
HP : +65-9067-8474
-----Original Message-----
rgaffuri_at_cox.net
Sent: Thursday, June 05, 2003 8:32 PM
To: Multiple recipients of list ORACLE-L
why would removing optimal setting help with snapshot too old?
what I dont understand is that each of my DML transactions are
independent of each other. They query and perform DML on different
tables. None of them overlap. The only time they overlap is when they
hit the data dictionary for some brief queries.
>
> From: Tim Gorman <tim_at_sagelogix.com>
> Date: 2003/06/05 Thu AM 03:25:36 EDT
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Subject: Re: Snapshot too old during stress test... how to avoid
>
> Speaking of this trick with a txn in each RBS, I've got a shell script
> on my website (http://www.evdbt.com/tools.htm) that does just that.
> It is named "prevent1555.sh" which uses a stored procedure created by
> a SQL script named "prevent1555_ddl.sql"...
>
> As Jared mentioned, it is kind of a last resort, but it works...
>
>
>
>
> on 6/4/03 4:05 PM, Jared.Still_at_radisys.com at Jared.Still_at_radisys.com
> wrote:
>
> > .. and if it still doesn't work, use the trick of putting a
> > transaction in each of the rollback segments while the system is
> > otherwise quiesced, and *do not* commit or rollback the
> > transactions.
> >
> > This forces the rollbacks to extend if necessary, they will never
> > wrap back to the first extent ( actually the second) as long as
> > those transactions are not committed.
> >
> > It just uses a lot of disk space. Disk is cheap, right? :)
> >
> > Consider offlining all your production RBS and creating temporary
> > ones that you can easily drop later.
> >
> > I've used it with SAP client copies, which will not run to
> > completion without doing this, at least on our system.
> >
> > Jared
> >
> >
> >
> >
> >
> > Kirtikumar Deshpande <kirtikumar_deshpande_at_yahoo.com>
> > Sent by: root_at_fatcity.com
> > 06/04/2003 09:45 AM
> > Please respond to ORACLE-L
> >
> >
> > To: Multiple recipients of list ORACLE-L
<ORACLE-L_at_fatcity.com>
> > cc:
> > Subject: Re: Snapshot too old during stress test... how
to avoid
> >
> >
> > Try removing optimal setting, and shrinking RBS to the min extents
> > (or even below) before running your tests.
> >
> > - Kirti
> >
> >
> > --- Garry Gillies <g.gillies_at_weir.co.uk> wrote:
> >> From memory (of a course attended looong ago),
> >> Oracle recommends one rollback segment for every
> >> three to four users.
> >> Four rollback segments between thirty six processes
> >> does seem a little mean.
> >>
> >> Garry
> >>
> >>
> >>
> >>
> >>
> >> <rgaffuri_at_cox.net>
> >> Sent by: root_at_fatcity.com
> >> 04/06/03 13:59
> >> Please respond to ORACLE-L
> >>
> >>
> >> To: Multiple recipients of list ORACLE-L
> > <ORACLE-L_at_fatcity.com>
> >> cc:
> >> Subject: Snapshot too old during stress test... how
to
> > avoid
> >>
> >>
> >> Im testing worst case scenarios right now. So Im doing batch
> >> updates,inserts,deletes and 'create table as' from a staging
> >> tablespace
> > of
> >> approximately 5GBs to a master tablespace of approximately 11GBs.
> >>
> >> Ive got my job queue processes set to 36 and Im running 36 at a
> >> time in the background in order to gather statistics and timing
> >> under worst case
> >
> >> scenarios.
> >>
> >> Im in 8.1.7.3 and I have increased the size of my RBS tablespace to
> >> 11GB
> >
> >> for this test. I have 4 standard RBS with optimal size set to 1GB.
> >> Why would I get a snapshot too old? I would think that 11GBs of
> >> rollback
> > would
> >> be big enough. Would increasing the number of Rollback segments
> >> avoid
> > this
> >> even though I have the same amount of space in the tablespace?
> >>
> >> In reality Im going to seriallize the process to avoid this and to
> > improve
> >> performance, however, I want to stress the system.
> >>
> >> any advice?
> >>
> >> --
> >> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> >> --
> >> Author: <rgaffuri_at_cox.net
> >> INET: rgaffuri_at_cox.net
> >>
> >
> >
> >
> > __________________________________
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> > Yahoo! Calendar - Free online calendar with sync to Outlook(TM).
> > http://calendar.yahoo.com
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Tim Gorman
> INET: tim_at_sagelogix.com
>
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: <rgaffuri_at_cox.net INET: rgaffuri_at_cox.net Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Ganesh Raja INET: gans_r_at_rediffmail.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Thu Jun 05 2003 - 09:09:51 CDT
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