Comments on: Intelligent (aka adaptive) Cursor Sharing Problem

By: admin

admin — Mon, 08 Jun 2009 11:37:21 +0000

Kerry,

thank you very much for sharing your experience with this feature on 11.1.0.7.

Best regards,
Martin

By: Kerry Osborne

Kerry Osborne — Wed, 03 Jun 2009 23:44:07 +0000

I haven’t really seen a big problem with excessive numbers of child cursors due to Adaptive Cursor Sharing (ACS) in 11.1.0.7. We migrated a 10g system with significant bind variable peeking issues about a month ago. The old systems is still up and being running in parallel with the new system. (well sort of – data is being loaded, but queries on the old system have pretty much ceased) Anyway, both systems have similar numbers of child cursors (no significant difference).We also have another system that has been in production for about a year. It also does not seem to suffer from excessive numbers of child cursors. There are a few that have double digit numbers, but we’ve not had any issues with memory fragmentation issues in the shared pool (i.e. no 4031 errors). It certainly does not look anything like the massive numbers generated by 11.1.0.6 and previous releases with high version count bugs. I must admit though that I haven’t looked very closely at this issue, due to the fact that it just hasn’t been a problem. I did do a post over on my blog earlier this week with observations about ACS after the migration from 10g to 11.1.10.7 if you’re interested. ACS Post

Kerry

By: Martin

Martin — Mon, 27 Apr 2009 20:11:33 +0000

Hi coskan, thank you very much for posting your comment!
Yes, i saw that posting. However, i am still waiting to see how this new feature is behaving on a high-load production system.

Regards,
Martin

By: coskan

coskan — Fri, 24 Apr 2009 18:42:45 +0000

Maybe you already saw but I think the developers of CBO gave the answer to your question.

http://optimizermagic.blogspot.com/2009/04/update-on-adaptive-cursor-sharing.html