RE: Index degree changed on all indexes to cpu_count on

From: <>
Date: Thu, 24 Jan 2013 06:34:08 -0600
Message-ID: <>

When was the last_ddl from dba_objects for the affected indexes? (May be too late to check that now)

Also - when was the last time they were rebuilt? If rebuilt with PARALLEL "x" then that becomes the new parallel (just throwing that out there in case it was an oversight - double check me on that, but I believe that's right as I got bit by it in a past life)

Based on the "when you hear hoofbeats think horses, not zebras", some script [whether manual or automated] was executed that did that (and it was probably an oversight) on the part of someone - hence an education/learning experience.



-----Original Message-----

From: [] On Behalf Of Fred Tilly Sent: Thursday, January 24, 2013 4:27 AM To:
Subject: Index degree changed on all indexes to cpu_count on

Hi All,
We have a customer who recently started complaining about performance of our application which had been running smoothly for several years. On looking at some AWR reports the top wait was 'PX Deq Credit: send blkd'

We looked at the explain plans and could see that parallel query was now being used where it had not been before.

On examining the database all indexes on all schemas including sys had there degree set to 8, which also just happens to be the cpu_count for the server.

On looking at other customer environments also on the index degree was set to 1.

The DBA who manages the server has no idea how the indexes all got changed to a degree of 8 and it is not something we had seen before.

The database was originally and had been upgraded to sometime ago.

Anyone got any ideas.




-- Received on Thu Jan 24 2013 - 13:34:08 CET

Original text of this message