From cspence@FuelSpot.com Mon, 30 Jul 2001 09:38:12 -0700 From: Christopher Spence Date: Mon, 30 Jul 2001 09:38:12 -0700 Subject: RE: bitmap indexes going wild Message-ID: MIME-Version: 1.0 Content-Type: text/plain Title: Message They way Oracle uses bitmap indexes, they are very poor performance when doing large writes, or data loads. Oracle actually shys away from their use for OLTP environments.   Although bitmap indexes are very cool and can have very significant performance gains, you must be very careful with them, they do not perform as consistent as b-tree indexes and can sometimes pose performance problems due to their increased complexity on writes. "Walking on water and developing software from a specification are easy if both are frozen." Christopher R. Spence Oracle DBA Fuelspot -----Original Message-----From: Koivu, Lisa [mailto:lisa.koivu@efairfield.com] Sent: Monday, July 30, 2001 10:31 AMTo: Multiple recipients of list ORACLE-LSubject: RE: bitmap indexes going wild Hi Stephane, your data loads will also be much much quicker if you drop your bitmap indexes prior to the load.  But then you have to weigh the speed increase of your load against the time it will take to rebuild the bitmaps.  I believe the doco discusses why bitmaps can slow down inserts.  Lisa Koivu Oracle Database Administrator Fairfield Resorts, Inc. 954-935-4117 -----Original Message----- From:   Deshpande, Kirti [SMTP:kirti.deshpande@verizon.com] Sent:   Monday, July 30, 2001 10:00 AM To:     Multiple recipients of list ORACLE-L Subject:        RE: bitmap indexes going wild Stéphane, I have seen such behaviour with bit mapped index since 7.3.4.x. The index did not grow as much in 8.x versions. But it was still unacceptable. We drop all bit mapped indexes prior to data loads and rebuild them afterwards. Regards, - Kirti Deshpande   Verizon Information Services    http://www.superpages.com > -----Original Message----- > From: paquette stephane [SMTP:stephane_paquette@yahoo.com] > Sent: Monday, July 30, 2001 8:30 AM > To:   Multiple recipients of list ORACLE-L > Subject:      bitmap indexes going wild > > Hi, > > 3 bitmap indexes have gone pretty big during data > insert. Once rebuild they returned to their normal > size. > They were previous loads whitout any problem. > > This is on Oracle 816 64bit/Solaris 5.7 > I checked on metalink but found nothing. > Is there any known problems with bitmap indexes on 816 > 64bit. > > I know I can disable the index and use > skip_unusable_indexes but since . > > ===== > Stéphane Paquette > DBA Oracle, consultant entrepôt de données > Oracle DBA, datawarehouse consultant > stephane_paquette@yahoo.com > > ___________________________________________________________ > Do You Yahoo!? -- Vos albums photos en ligne, > Yahoo! Photos : http://fr.photos.yahoo.com > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: =?iso-8859-1?q?paquette=20stephane?= >   INET: stephane_paquette@yahoo.com > > 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: ListGuru@fatcity.com (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: Deshpande, Kirti   INET: kirti.deshpande@verizon.com 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: ListGuru@fatcity.com (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).