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Home -> Community -> Mailing Lists -> Oracle-L -> 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_at_yahoo.com.ar]
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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