bitmap indices
hi! to speed up queries i have created a bitmap index on a column that contains 2 chars as a maximum. to my surprise the bitmap index does not make the query quicker than the 'usual' B-tree index, though there are only bout 100 different values in half a million rows. has n.e.one got experience with bitmap indices? are there any further poosibilities to adapt them when creating??? tia bye daniel -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Daniel Wisser INET: [EMAIL PROTECTED] Fat City Network Services-- (858) 538-5051 FAX: (858) 538-5051 San Diego, California-- Public Internet access / Mailing Lists 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).
RE: bitmap indices
Hope you are using the CBO and not the RBO. If yu use a Bitmap Index then the Optimizer will use a CBO and if the stats are not proper then u may not get a Proper Result. HTH Best Regards, Ganesh R Tel : +971 (4) 397 3337 Ext 420 Fax : +971 (4) 397 6262 HP : +971 (50) 745 6019 Live to learn... forget... and learn again. -Original Message- Sent: Monday, April 29, 2002 4:43 PM To: Multiple recipients of list ORACLE-L hi! to speed up queries i have created a bitmap index on a column that contains 2 chars as a maximum. to my surprise the bitmap index does not make the query quicker than the 'usual' B-tree index, though there are only bout 100 different values in half a million rows. has n.e.one got experience with bitmap indices? are there any further poosibilities to adapt them when creating??? tia bye daniel -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Daniel Wisser INET: [EMAIL PROTECTED] Fat City Network Services-- (858) 538-5051 FAX: (858) 538-5051 San Diego, California-- Public Internet access / Mailing Lists 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.com -- Author: Ganesh Raja INET: [EMAIL PROTECTED] Fat City Network Services-- (858) 538-5051 FAX: (858) 538-5051 San Diego, California-- Public Internet access / Mailing Lists 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).
Re: bitmap indices
Generate an access path plan for each as well as checking some tkprof output and you'll see why this is the case. hth connor --- Daniel Wisser [EMAIL PROTECTED] wrote: hi! to speed up queries i have created a bitmap index on a column that contains 2 chars as a maximum. to my surprise the bitmap index does not make the query quicker than the 'usual' B-tree index, though there are only bout 100 different values in half a million rows. has n.e.one got experience with bitmap indices? are there any further poosibilities to adapt them when creating??? tia bye daniel -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Daniel Wisser INET: [EMAIL PROTECTED] Fat City Network Services-- (858) 538-5051 FAX: (858) 538-5051 San Diego, California-- Public Internet access / Mailing Lists 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). = Connor McDonald http://www.oracledba.co.uk http://www.oaktable.net Some days you're the pigeon, some days you're the statue __ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: =?iso-8859-1?q?Connor=20McDonald?= INET: [EMAIL PROTECTED] Fat City Network Services-- (858) 538-5051 FAX: (858) 538-5051 San Diego, California-- Public Internet access / Mailing Lists 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).
