Jared Nope, been burned on that one. I just couldn't think of an easy way to test this, but thought if I pointed it out and somebody knew it wasn't true it might irritate them into responding. Has anybody experienced success with reverse key indexes?
Dennis Williams DBA, 80%OCP, 100% DBA Lifetouch, Inc. [EMAIL PROTECTED] -----Original Message----- Sent: Sunday, June 01, 2003 1:30 PM To: Multiple recipients of list ORACLE-L Dennis, are you implicitly asserting that you trust the documentation 100%? ;) On Sunday 01 June 2003 06:44, DENNIS WILLIAMS wrote: > Jared > Like you, I have always understood that b+ tree indexes maintain their > balance automatically. The statement I was referring to is in the Oracle9i > Database Performance Planning manual, Chapter 1: > > "Use of sequences, or timestamps, to generate key values that are indexed > themselves can lead to database hotspot problems, which affect response > time and throughput. This is usually the result of a monotonically growing > key that results in a right-growing index. To avoid this problem, try to > generate keys that insert over the full range of the index. This results in > a well-balanced index that is more scalable and space efficient. You can > achieve this by using a reverse key index or using a cycling sequence to > prefix and sequence values." > > I hate to admit it, but I ran across this tidbit while I was studying for > the OCP. I have no idea what a well-balanced index means. Had good > supportive parents? > > But just when you think the reverse key index must be great, the Concepts > manual points out: > "Using the reverse key arrangement eliminates the ability to run an index > range scanning query on the index. Because lexically adjacent keys are not > stored next to each other in a reverse-key index, only fetch-by-key or > full-index (table) scans can be performed." > > Dennis Williams > DBA, 80%OCP, 100% DBA > Lifetouch, Inc. > > manjunath -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Jared Still INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: DENNIS WILLIAMS INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
