Comments for Intermediate SQL

Comment on ORACLE 11g SQL Plan Management: The Dark Side of SPM. Part 4 by Maxym Kharchenko

Maxym Kharchenko — Sun, 13 May 2012 17:09:29 +0000

Thanks Amit. I agree: large OLTP systems should almost never use automatic tuning features. However, SQL plan management is not an automatic tuning feature (unless you want it to be), it is rather the tool that prevents automated management from kicking in by “freezing” SQL plans in place. We use it extensively to make sure plans are managed by humans … but as with any tool – you need to be aware of all the little quirks that it has to prevent weird problems (and yes, some of them are pretty weird)

Comment on ORACLE 11g SQL Plan Management: The Dark Side of SPM. Part 4 by Amit k

Amit k — Sat, 12 May 2012 19:40:44 +0000

Nice article. However I have seen most of the large OLTP database system never goes for all these automatic tuning features provided by latest version including automatic memory management.
Intact we never gather stats on our OLTP system to maintain plan stability & and performance.

Comment on What are SQL Profiles and why do we need them ? by Thushara

Thushara — Mon, 30 Apr 2012 07:12:45 +0000

short and simple. Straight to the point.

Comment on What are SQL Profiles and why do we need them ? by kunal

kunal — Tue, 24 Apr 2012 04:49:13 +0000

This article was very helpful……….thanks for sharing……

Comment on How AIX Paging Space works. Part 1: Why your program memory footprint gets bloated sometimes by Maxym Kharchenko

Maxym Kharchenko — Thu, 05 Apr 2012 20:14:52 +0000

Thanks Marcus.

lsps command on AIX gives an overall overview of paging space being used at the moment and you can always use svmon if you need detailed per process stats. Is that what you were looking for ?

Comment on How AIX Paging Space works. Part 1: Why your program memory footprint gets bloated sometimes by Marcus

Marcus — Wed, 04 Apr 2012 12:57:39 +0000

Nice article ! As an AIX admin I’d like to know how really to monitor the active usage of the swap as “sps -a” is not a real indicator anymore for the health status of the system …

Comment on How AIX Paging Space works. Part 1: Why your program memory footprint gets bloated sometimes by Anthony

Anthony — Mon, 05 Mar 2012 02:25:57 +0000

Thanks Maxym, for a great explanation.
I had a memory leak problem which I only found by logging process VSZ every 10 seconds and relating to spikes in paging space levels. The offending process was not freeing allocated memory and used 4GB each time it ran. The fact that it only took 20 seconds to run made it hard to catch without regular logging.
cheers,
Anthony

Comment on How AIX Paging Space works. Part 1: Why your program memory footprint gets bloated sometimes by Maxym Kharchenko

Maxym Kharchenko — Thu, 01 Mar 2012 18:07:37 +0000

Thanks, Steven. Glad it helped you

Comment on How AIX Paging Space works. Part 1: Why your program memory footprint gets bloated sometimes by Steven Humphries

Steven Humphries — Thu, 01 Mar 2012 17:51:36 +0000

Fantastic article! Thank you so much for explaining this concept!!!

All the best,

Steve

Comment on How ORACLE Uses Memory on AIX. Part 1: Processes by Maxym Kharchenko

Maxym Kharchenko — Wed, 22 Feb 2012 23:28:49 +0000

Hello John,

You got the gist of it: ORACLE allocates regular memory in AIX lazily (large pages are a different story but I do not believe you are using them since lock_sga=FALSE).

So, sga_target (or, more precisely sga_max_size) is a MAX memory allocation that can be achieved, not the actual allocation. This is precisely, why I came up with these tools to see how much memory is actually used

As for why virtual size < RSS - this is likely because my scripts are slightly simplifying things. When calculating process memory usage they do NOT take into account TEXT segment (ORACLE code). For large instances with lots of processes, this deficiency is minuscule, but in your case, since the instance is very small, the deficiency is significant. Just ignore it and use RSS size in your estimations.

Regards,
Maxym Kharchenko