"Armstead, Michael A" wrote: > > We're moving from RBO to CBO. > > For those of you who use CBO, what mode do you use FIRST_ROWS or ALL_ROWS? > And why? > > My thinking is if it's a database where most of the querying is done on > small sets of records, then we may want to use FIRST_ROWS. On the other > hand, if our database is used to generate sizable reports, we might use > ALL_ROWS. > > I also understand that we can always change it per session (with alter > session) and per query (with hints). > > Michael Armstead > Principal Database Administrator, OCP-Certified > World Wide Corporate IT Database Administration > GlaxoSmithKline >
Michael, FIRST_ROWS is when you have a nervous user waiting for his/her results - OLTP. ALL_ROWS is when you want all the job to be done as fast as possible - Batch. This is the broad picture. Now, if your queries are used to generate HTML pages, this is no longer OLTP - it's batch since you cannot return the page before the query is completed. HTH, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stephane Faroult 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).
