RE: How many is too many

From: Walker, Jed S <Jed_Walker_at_cable.comcast.com>
Date: Fri, 12 Aug 2011 19:54:22 +0000
Message-ID: <BAA6E28B6241F046AED1E62D8697516C4E393DE6_at_COPDCEXMB08.cable.comcast.com>



Yes, but a simple loop I’ve found usually results in the lock being acquired after a bit (but not always).

I just monitored one of our oltp systems for several months and found 150+ indexes of 500 never used. Developers often create “what they think” is needed rather than what is needed – getting back to your earlier point about “sacrificing a small animal”

From: Kellyn Pot'vin [mailto:kellyn.potvin_at_ymail.com] Sent: Friday, August 12, 2011 1:48 PM
To: Walker, Jed S; veeeraman_at_gmail.com; ORACLE-L Subject: Re: How many is too many

When stating an index audit, monitoring was what I was referring to, but in 10g, you have to get a lock on the object to turn on the monitoring...This can be the biggest hurdle, more so than the overhead of the index or monitoring for usage. Kellyn



From: "Walker, Jed S" <Jed_Walker_at_cable.comcast.com> To: "veeeraman_at_gmail.com" <veeeraman_at_gmail.com>; ORACLE-L <oracle-l_at_freelists.org> Sent: Friday, August 12, 2011 1:42 PM
Subject: RE: How many is too many
I don’t think it is so much a number as “is the index used”. You can use the “alter index [no]monitoring” command to turn on monitoring and then watch v$object_usage to see which are used. Make sure you observe over a good time period to ensure you don’t miss any reports that are not run too often.

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Ram Raman Sent: Thursday, August 11, 2011 2:45 PM To: ORACLE-L
Subject: How many is too many

Listers,

  I am looking at a table in our system and it has 12 indexes, we are planning on adding another one. I am aware of the effects of having too many indexes, but in this case adding an extra index helps a certain query that runs slow. Other queries and most other operations against the table are acceptable too. I see a few tables like this; is there a number above which is considered a no-no when it comes to adding more indexes.

PS. The tables and queries are structured in a way that seem to require several indexes - it is a third party product.

TIA,
Ram.

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Received on Fri Aug 12 2011 - 14:54:22 CDT

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