Coskan’s Approach to Oracle

June 28, 2007

Sub Latch Wait Events with weak documentation

Filed under: RAC — coskan @ 8:57 am

Prior to Oracle Database 10g, all latch waits show up as the latch free wait event . In Oracle Database 10g, common latches are broken out and have independent wait event names and statistics but documentation about this independent wait event statistics are forgotten.

Yesterday I saw long waits of “latch: KCL gc element parent latch ” event on 10046 trace output of one of our sqls. I searched the documentation, metalink and google, all I have found is 15 bug pages on metalink, no page on documentation, 6 pages on google and all of this pages are not talking about defintion of event. They only show that this event has a place on the tkproof outputs. But my sql is suffering from this event what should I do now to lower this long waits???.

I hope documentation about latch sub events will be more definitive on upcoming 11G.

Ps: Any comment about definition of this wait event will be welcome.

The Silver is the New Black Theme. Blog at


Get every new post delivered to your Inbox.

Join 234 other followers