RAC, SELECT FOR UPDATE, connection pools

From: Herring Dave - dherri <Dave.Herring_at_acxiom.com>
Date: Fri, 12 Feb 2010 07:46:18 -0600
Message-ID: <7ED53A68952D3B4C9540B4EFA5C76E360757C476_at_CWYMSX04.Corp.Acxiom.net>

I'm wondering if I could get a little more detail about what Martin listed below:

'"select for update" as soon as a user modified data. This was in a connection pool... That obviously wasn't too great.'

I'm supporting a env on Linux, involving a 4-node RAC with matching DG. It's an OLTP db with app servers using connection pools, where I'll see unbalanced batches of connections coming in (2000 on 1 node, 80 on another), which eventually even out across the servers. I also see frequent "SELECT ... FOR UPDATE" statements.

I'm relatively new to this env and really struggle in getting details on how the apps are working, so when I saw the quote above from Martin I figured I'd jump at getting more details on other's experiences with this type of situation.

I think to start I'm just looking for issues you've run into, as again, I get very little detail out of the app team in terms of what they're doing and how things are configured.

I realize this is really directed towards Martin Bach, but I figured I'd post to the group in case anyone has a similar setup. I'm pretty much having to reverse engineer the whole app to know what's going on, which is such a treat. :-(


Dave Herring  | DBA, Global Technology Services A c x i o m C o r p o r a t i o n
630-944-4762 office | 630-430-5988 cell | 630-944-4989 fax 1501 Opus Pl | Downers Grove, IL, 60515 | U.S.A. | www.acxiom.com Service Desk: 888-243-4566, https://servicedesk.acxiom.com, GSCA_at_DNB.com

-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Martin Bach Sent: Thursday, February 04, 2010 6:00 AM To: mwf_at_rsiz.com
Cc: veeeraman_at_gmail.com; 'Guillermo Alan Bort'; 'Thomas Roach'; 'ORACLE-L' Subject: Re: RAC for dev env

I can only second that email from Mark!

Developing against single instance when prod is RAC - I can't count the number of times I have seen developers code against single instance Oracle (and maybe even a subset of production data only), release the new code which then promptly fails to scale/work in RAC?

I dealt with an application development "framework" once that dynamically changed to "select for update" as soon as a user modified data. This was in a connection pool... That obviously wasn't too great.

Also don't forget that you might actually _have_ to invoke DR and then you could be hit big time for not running in a RAC configuration. I only hope that has been figured into the equation or somebody from high up acknowledges that.



Martin Bach
OCM 10g

On 02/03/2010 08:44 PM, Mark W. Farnham wrote:

> So I believe your management dictated constraints are: RAC for prod,
> single instance databases for everything else.
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Received on Fri Feb 12 2010 - 07:46:18 CST

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