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what is the process queue reference latch?

From: Tony van Lingen <>
Date: Sat, 02 Dec 2006 10:33:08 +1000
Message-ID: <>

Morning all,

Does any-one know what the process queue reference latch does? I've never seen it pop up in my monitors, but this morning in one database it has an appalling miss rate:

NAME                                                  WW        IMM 
--------------------------------------------- ---------- ---------- 
-------------- ----------------
process queue reference                       .020905483 
187.158241        2390210          4473475

(from v$latch: ww - miss ratio of willing-to-wait type gets, imm - miss ratio of immediate gets, both in %)

This database is an Oracle 64bit on Solaris 9. Today only a handful of users are logged on and they are perfoming some sort of system test - they complain that the system is running like a dog and this is the only anomality I could find.

I found some hint on google that this has something to do with parallel execution., but I've checked for parallel execution, but can't find a trace of any. None has been defined as far as I know. Can Oracle decide to use parallellism anyway even if the degree on all tables is 1 and the parallel_* init vars are all default?


Tony van Lingen

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Received on Fri Dec 01 2006 - 18:33:08 CST

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