Note also how: enqueue gets and releases = 23M db block gets = 23 M execute count = 23M You can't help feeling that that's not a complete coincidence. I think your trigger theory sounds quite good at the moment, only a) I'd like to find that 23M executions in v$sql. Why isn't it appearing in statspack ? b) There's no redo generated to match the volume of locking. I'd like to see the snapshot of x$ksqst One thought - for parallel DML, maybe there are lots of DX locks being taken and dropped. Regards Jonathan Lewis http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/seminar.html Public Appearances - schedule updated Dec 23rd 2004 ----- Original Message ----- From: "Riyaj Shamsudeen" <rshamsud@xxxxxxxxxxxx> To: <oracle.unix@xxxxxxxxx>; <jonathan@xxxxxxxxxxxxxxxxxx> Cc: <oracle-l@xxxxxxxxxxxxx> Sent: Sunday, January 09, 2005 9:09 PM Subject: RE: what's mean of "enqueue hash chains" latch? Eygle Looking at the excel spreadsheet, one of the child latch has 2.4 Billion gets and other child latches have less then 76K latch gets. So, sessions are contending to lock one table. Looking at the statspack report, you have numerous enqueue gets and releases too. Is there any foreign key constraint on this table ? If yes, do you have any index on that foreign key column ? Further, what mode locks are being acquired ? do you have any triggers on this table, by any chance ? Thanks Riyaj "Re-yas" Shamsudeen Certified Oracle DBA -- //www.freelists.org/webpage/oracle-l