RE: TC Enqueue waits

PQ slaves uses direct reads bypassing the SGA to read the segment blocks =
which requires waiting to flush all committed
changes in the SGA (dirty buffers) of that object to make sure the PQ =
slaves
will access the most recent version of that object.

Regards,

Waleed

-----Original Message-----
From: Diego Cutrone [mailto:diegocutrone@xxxxxxxxxxxx]
Sent: Friday, April 30, 2004 4:25 PM
To: Oracle List
Subject: TC Enqueue waits


Hi List.
I have detected high enqueue waits in one instance.
After quering x$ksqst I realized most of them were TX and TC enqueues.

I'm on the TX enqueues by tracing some sessions. But I have never heard =
of TC enqueues
I have read that TC enqueue stands for "Thread Checkpoint enqueue".=20

Anybody knows what are they used for? what kind of resources they =
protect?

And I have another quick question:

I'm also seeing Parallel query events like:

PX Deq: Execution Msg
PX Idle Wait
PX qref latch=20
PX Deq: Execute Reply=20
PX Deq: Table Q Normal=20
PX Deq: Parse Reply=20

Does anybody know where I can get a description for them?=20
I'd like to know which ones can be ignored and which ones can't.

Thank you very much
Regards
Diego
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