I have to add this a bit to this.... Every index that is requested should be "justified". What this translates to: -Proof that the index is actually used must be produced, (or will be used...) I don't know how many times I've been given DDL for an index someone thought their query would use and you pull a simple explain plan and find out otherwise. -The cost to support the index should be calculated- "What will it cost to updates, inserts and deletes that are performed against this object in relation to the savings to have this index in place to the business?" -If it's a partitioned object, what kind of index are you requesting and if it's a global index, you had better be sacrificing a small animal to prove to me the overhead in management to my team is worthy of it... :) Reviewing and auditing index usage in a mature production environment is rarely a waste of time. The task once allowed me to drop 30% of the indexes in an environment and re-allocate over 1TB in space back to the system. Kellyn Pot'Vin Sr. Database Administrator and Developer dbakevlar.com ________________________________ From: "Lange, Kevin G" <kevin.lange@xxxxxxxxxx> To: ORACLE-L <oracle-l@xxxxxxxxxxxxx> Sent: Thursday, August 11, 2011 3:22 PM Subject: RE: How many is too many That is a perfectly stated response. Too many is when adding them starts to hurt performance. I will not tell you how many one of our tables has because you would call me nuts. ________________________________ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Morten Egan Sent: Thursday, August 11, 2011 4:18 PM To: veeeraman@xxxxxxxxx Cc: ORACLE-L Subject: Re: How many is too many The number that is considered a no-no, is the number where things start to go unacceptably slow :) Joking aside, if your program does what it is supposed to do, in an acceptable time, then it really doesn't matter. 2011/8/11 Ram Raman <veeeraman@xxxxxxxxx> 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. -- Regards, Morten Egan http://www.dbping.com This e-mail, including attachments, may include confidential and/or proprietary information, and may be used only by the person or entity to which it is addressed. If the reader of this e-mail is not the intended recipient or his or her authorized agent, the reader is hereby notified that any dissemination, distribution or copying of this e-mail is prohibited. If you have received this e-mail in error, please notify the sender by replying to this message and delete this e-mail immediately.