Try 'select /*+ ORDERED */' hth connor
--- "Kirsch, Walter J (Northrop Grumman)" <[EMAIL PROTECTED]> wrote: > > 2-cpu, 220mhz, 32-bit HPUX 11.0. Oracle 8.1.7.0.0 > > Could someone explain what's going on here? > > This SQL takes no time at all : > > select > substr(username , 1, 12) "User" > , substr(lock_type, 1, 18) "Lock Type" > , substr(mode_held, 1, 18) "Mode Held" > from sys.dba_lock a > , v$session b > where /*lock_type not in ('Media Recovery','Redo > Thread') > and*/ a.session_id = b.sid; > > with explain plan: > > SELECT STATEMENT Optimizer=CHOOSE (Cost=70 Card=1 > Bytes=148) > NESTED LOOPS (Cost=70 Card=1 Bytes=148) > NESTED LOOPS (Cost=60 Card=1 Bytes=141) > NESTED LOOPS (Cost=20 Card=1 Bytes=107) > FIXED TABLE (FULL) OF X$KSUSE (Cost=10 > Card=1 Bytes=30) > FIXED TABLE (FIXED INDEX #1) OF X$KSUSE > (Cost=10 Card=1 > Bytes=77) > VIEW OF GV$_LOCK > UNION-ALL > VIEW OF GV$_LOCK1 (Cost=20 Card=2 > Bytes=162) > UNION-ALL > FIXED TABLE (FULL) OF X$KDNSSF > (Cost=10 Card=1 > Bytes=94) > FIXED TABLE (FULL) OF X$KSQEQ > (Cost=10 Card=1 > Bytes=94) > FIXED TABLE (FULL) OF X$KTADM (Cost=10 > Card=1 Bytes=94) > FIXED TABLE (FULL) OF X$KTCXB (Cost=10 > Card=1 Bytes=94) > FIXED TABLE (FIXED INDEX #1) OF X$KSQRS > (Cost=10 Card=100 > Bytes=700) > > whereas an uncommented predicate consumes 40 minutes > of CPU (sez TOP) with > this explain plan: > > SELECT STATEMENT Optimizer=CHOOSE (Cost=70 Card=1 > Bytes=148) > NESTED LOOPS (Cost=70 Card=1 Bytes=148) > NESTED LOOPS (Cost=30 Card=1 Bytes=114) > MERGE JOIN (CARTESIAN) (Cost=20 Card=1 > Bytes=37) > FIXED TABLE (FULL) OF X$KSUSE (Cost=10 > Card=1 Bytes=30) > SORT (JOIN) (Cost=10 Card=1 Bytes=7) > FIXED TABLE (FULL) OF X$KSQRS (Cost=10 > Card=1 Bytes=7) > FIXED TABLE (FIXED INDEX #1) OF X$KSUSE > (Cost=10 Card=1 > Bytes=77) > VIEW OF GV$_LOCK > UNION-ALL > VIEW OF GV$_LOCK1 (Cost=20 Card=2 > Bytes=162) > UNION-ALL > FIXED TABLE (FULL) OF X$KDNSSF (Cost=10 > Card=1 Bytes=94) > FIXED TABLE (FULL) OF X$KSQEQ (Cost=10 > Card=1 Bytes=94) > FIXED TABLE (FULL) OF X$KTADM (Cost=10 > Card=1 Bytes=94) > FIXED TABLE (FULL) OF X$KTCXB (Cost=10 > Card=1 Bytes=94) > > If it jams, force it. If it breaks, it needed > replacing anyway. --John F > Duval > > -- > Please see the official ORACLE-L FAQ: > http://www.orafaq.com > -- > Author: Kirsch, Walter J (Northrop Grumman) > 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).