Re: _MAX_TRANSACTION_COUNT
From: joel garry <joel-garry_at_home.com>
Date: Sun, 21 Mar 2010 10:16:01 -0700 (PDT)
Message-ID: <fea6f549-5d65-478c-93a6-f8beb848f228_at_x23g2000prd.googlegroups.com>
On Mar 20, 2:16 pm, Guy Peleg <makleeengineer..._at_gmail.com> wrote:
> Does anybody know the purpose of _MAX_TRANSACTION_COUNT?
>
> Multiple documents recommend setting the parameter to 12 to improve
> the performance of SQL apply, but why?
>
> SQL> exec dbms_logstdby.apply_set
> ('_MAX_TRANSACTION_COUNT',12);
>
> Regards,
>
> Guy Peleg
> Maklee Engineering
Date: Sun, 21 Mar 2010 10:16:01 -0700 (PDT)
Message-ID: <fea6f549-5d65-478c-93a6-f8beb848f228_at_x23g2000prd.googlegroups.com>
On Mar 20, 2:16 pm, Guy Peleg <makleeengineer..._at_gmail.com> wrote:
> Does anybody know the purpose of _MAX_TRANSACTION_COUNT?
>
> Multiple documents recommend setting the parameter to 12 to improve
> the performance of SQL apply, but why?
>
> SQL> exec dbms_logstdby.apply_set
> ('_MAX_TRANSACTION_COUNT',12);
>
> Regards,
>
> Guy Peleg
> Maklee Engineering
Well, from looking at MOS Tuning SQL Apply Operations for Logical
Standby, I'd say it only applies to 9i where you get alert log
messages like
WARNING: the following transaction makes no progress
WARNING: in the last 300 seconds for the given message!
See http://www.oracle.com/technology/deploy/availability/pdf/MAA_WP_9iR2_SQLApplyBestPractices.pdf about _EAGER_SIZE. I think we can reasonably guess that the purpose is to commit less often, by dedicating a slave to group sql statements that would otherwise be separate commits. I would guess _MAX_TRANSACTION_COUNT would be the grouping size.
jg
-- _at_home.com is bogus. http://www.pcpro.co.uk/blogs/2010/03/19/whats-that-eggy-smell-in-the-server-room/Received on Sun Mar 21 2010 - 12:16:01 CDT