Re: Oracle strace output - detail
Date: Thu, 12 Jan 2012 22:12:45 +0000
Why do you say it shouldn't make a difference?
It makes a huge difference CPU-wise.
Remember you're dealing with a general regexp parsing library, and not an optimised Oracle kernel standard sql LIKE % query. regexp_like will never beat a LIKE % query.
Forget looking at a sqlplus strace - the SQL is executed on the server, not the client. Check the CPU % of the 2 queries in the DB. That'll prove my point.
On 12 Jan 2012, at 21:35, Herring Dave - dherri <Dave.Herring_at_acxiom.com> wrote:
> I can't help with strace, but can give a suggestion with "regexp_like". Try adding in the beginning-of-line and end-of-line anchors:
> That *shouldn't* make a difference, but it does, at least under 10.2.0.2. I had great intentions 3 yrs ago to performance test various options with REGEXP functions in Oracle but unfortunately didn't find the time to make it happen. If you figure out why the line anchors make it so much faster than please share, as I've love to know.
> DAVID HERRING
> Acxiom Corporation
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> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Steve Gardiner
> Sent: Thursday, January 12, 2012 8:40 AM
> To: oracle-l_at_freelists.org
> Subject: Oracle strace output - detail
> Oracle-l readers,
> Does anyone have an idea how to decode this strace entry? Or where to
> look for more info?
> 0.000222 read(11,