enqueue waits

Hi,

I am running Oracle 8.0.5 on AIX. I have a question about enqueue waits. The instance has 10 rollback segments, 10 MB each (thanks to shrinking back to the optimal size), and 1 LARGE RBS (rbslarge) that is about 2.5 times large than the regular ones.

I was logged into the database as UserA, and issued a set transaction use rollback segment rbslarge;, then issued a truncate table TableA (which lives in tablespaceA). About the same time, UserB issued an insert into TableB (which lives in tablespaceB), and encountered a wait situation. UserB waited. and waited. and waited some more. v$session_wait showed about a dozen 'enqueue' wait events.

As soon as my truncate finished, UserB's insert finished and the enqueue waits went away. My question is this ... I did not create the rbslarge as a private rbs, so I assume it defaults to public, meaning anybody can hit it in the round-robin rbs cycle. Is it possible that both me and UserB grabbed rbslarge, and even though his data was in a separate table, in a separate tablespace, on a separate disk than mine, we were contending for rollback? There are no entries in the alert log or trace files indicating any type of rollback contention.

Any info is appreciated ... I'm still fuzzy on the whole enqueue thing.

Thanks,
Roy

Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't. Received on Thu Sep 23 1999 - 16:18:18 CDT