I'd recommend you to take a dump. A 10053 dump. And see from there. :)
Tanel. ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Wednesday, October 29, 2003 10:09 PM > Hi, > > I have a puzzle. > > A bitmap index on a varchar2(25) column. table has 7131413 rows, of which > 7125290 are null for the column in question, the rest of the rows are unique > values. There is a histogram on this column, it has 2 buckets. > > A select statement using this column in the where clause generates two > plans, one which uses the index and one which doesn't. The deciding factor > is the length of the string in the filter. > > select * from table where microchip_number = 'avid1' > this produces a plan which uses the bitmap > > select * from table where microchip_number = 'avid12' (and any additional > characters in the string ) > this produces a plan which uses a full table scan. > > I am stumped about how to figure out why the optimizer makes a choice based > upon the length of the string in the predicate. > > Much obliged, > > Josh > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Josh Collier > 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: Tanel Poder 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).
