RE: inconsistent query performance

Hi Ken,

It's the exact same query and literals each time. And it's based on views - which are based on other views. ;-) So that may be an issue, too.

Anyway, I didn't want to burden everyone with the details of the query. I was just hoping to get some avenues to pursue. Like I said in the original post, I'm rusty with Oracle and needed some starting points. Thanks to you, Carlos, TJ, and Jeffrey. Your suggestions will get me started.

Y'all are a great resource.

Bob Stauffer
DBA/Database Developer

From: Ken Naim [mailto:kennethnaim_at_gmail.com] Sent: Wednesday, January 18, 2017 2:31 PM To: Stauffer, Bob <RStauffer_at_fult.com>; oracle-l_at_freelists.org Subject: RE: inconsistent query performance

How complex is the query? Can you send out the sql and/or the explain plan? Are there just tables in the from(s) or are there also views. Also are there any function calls? Are you seeing different performance on the same exact query or are you changing any of the literals?

Ken

From: oracle-l-bounce_at_freelists.org<mailto:oracle-l-bounce_at_freelists.org> [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Stauffer, Bob Sent: Wednesday, January 18, 2017 1:28 PM To: 'oracle-l_at_freelists.org' <oracle-l_at_freelists.org<mailto:oracle-l_at_freelists.org>> Subject: inconsistent query performance

Hi all,

Oracle RDBMS EE 11.2.0.4.0 - 64bit
Red Hat Enterprise Linux 5.11

Any suggestions on how I can troubleshoot a query that performs inconsistently? Sometimes it takes a minute to run and sometimes it takes over an hour. It generally uses one of two explain plans - one fast and one slow. Although it sometimes uses a different plan. I've checked the stats and they are up to date. I generally run it in TOAD, but the same problem occurs in SQLPlus, SQL Developer, and other interfaces. It doesn't matter whether the system is busy or quiet. And it happens within the same session - I can run it one right after another and it will change the plan for each execution.

Any help would be appreciated. I'm a little rusty with Oracle.

Thanks much.

Bob Stauffer
DBA/Database Developer

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