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Indicators of potential scaling issues

From: Kevin Lidh <>
Date: Sat, 4 Feb 2006 08:45:03 -0700
Message-ID: <>

One of the systems I help maintain is a very large (5 TB) implementation of a CRM product. My primary charge, though, is to assist our customer with testing of new functionality on a very scaled-down (830 GB) version. We have the typical problems of the CBO not making the same decisions because of differing statistics (which I'm working on) but the point of this e-mail was a meeting we had yesterday afternoon. My concern was that we aren't looking at the right things to identify potentially bad, or worse yet dibilitating, SQL before they get into production. Our customer's Oracle consultant said high buffer gets per execution (+3000). I said there has to be more that would be an indication of an SQL that won't scale when a greater load is applied, meaning frequency and concurrency. He asked, "Isn't buffer gets the leading indication of a scaling issue?" My question was, "Isn't that like saying height is a leading factor for describing a human?" He countered with the obvious question which I don't have the answer to: what else would you look at?. I've read papers about the Tailor atomic modelling method for capacity planning and I'm in the middle of Tom Kyte's and Jonathan Lewis's new books but I think I'm still missing some critical pieces. I apologize for the lack of brevity of this e-mail (and if this isn't the right forum for this question) but I wanted to frame my question so there isn't any ambiguity. My question is, are there combinations of statistics and/or information I can get from the database during the execution of a test on a scaled-down system which would indicate that an SQL (or combination) won't scale up even if it performs fine in the test? I have no problems doing the reading and research on my own if you just have general ideas.

Thank you for your consideration of this question,

Kevin Lidh

Received on Sat Feb 04 2006 - 09:45:03 CST

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