Re: why did query behavior change ?

  • From: "ed lewis" <eglewis71@xxxxxxxxx>
  • To: <daniel.fink@xxxxxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 10 Dec 2010 08:46:16 -0500

Daniel thanks for the response.

see below.

----- Original Message ----- From: "Daniel Fink" <daniel.fink@xxxxxxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Wednesday, December 08, 2010 5:48 PM
Subject: RE: why did query behavior change ?

Did this impact *every* query accessing this table?  Yes
What were the differences in the execution plans?    None
What were the differences in the execution profiles (changes in physical i/o, consistent gets, cpu time, wait time)?
                           Don't have that info.
When were statistics last gathered on the table?  within the last week
Were there any systemic changes?      None that I am aware of.

------- Original Message -------
On 12/8/2010 10:22 PM ed lewis wrote:
   You just recently experienced a performance issue with queries
accessing a particular table. Response time went from 15-20 seconds,
to 2-3 minutes.The table has around 500,000 rows, and is a "core" table
in the app.

I did run 1 problem query interactively to get the explain plan. The query did a table lookup via an index, and it returned 165 rows. The "consistent gets" though were around 1 million. This is a 3rd party app, so what we can do with the query itself is limited.

   The temporary workaround was to cache the table. This brought
the response time back to normal. By caching the table, I assume the table will be
handled differently in cache.The better results show that.

But why did the query behavior worsen ? I am trying to track down the root cause.

   Any ideas are welcome.

   thanks        ed

 solaris 10
oracle  - 2 node cluster-
clusterware    --


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