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Re: redo copy "sleep rate" is this a problem?

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Thu, 18 Nov 1999 19:09:43 -0000
Message-ID: <942953006.1821.0.nnrp-12.9e984b29@news.demon.co.uk>

If you've got the script you might also have the book. Page 29 points out that the sleep rate on the redo copy latch is always high since redo copy is rarely taken in 'willing to wait' mode.

--

Jonathan Lewis
Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk

Greg Stark wrote in message
<87hfikmnsk.fsf_at_HSE-Montreal-ppp19485.qc.sympatico.ca>...
>
>
>I ran one of the reports from Oracle Internals and see one thing that jumps
>out at me, the redo copy has a "sleep rate" of nearly 90%. What does this
>mean?
>
>Do we need more rollback segments? bigger segments? Is there a particular
type
>of query that would be a problem? Is this even a problem?
>
>LATCH TYPE IMPACT SLEEP RATE WAITS_HOLDING_LATCH LEVEL#
>------------------------------ ----------- ---------- ------------------- -



>redo copy 21551 89.58% 0 5
>
>
>
>
>
>The entire report is below, in case anyone spots anything strange:
>
>LATCH TYPE IMPACT SLEEP RATE WAITS_HOLDING_LATCH LEVEL#
>------------------------------ ----------- ---------- ------------------- -


>cache buffers chains 193859 0.00% 47829 1
>library cache 192286 0.14% 333955 5
>cache buffers lru chain 167315 4.93% 151758 3
>virtual circuit queues 99488 0.03% 98592 8
>shared pool 48845 0.04% 313381 7
>virtual circuits 39824 0.04% 125260 8
>redo writing 34698 0.07% 114821 5
>enqueue hash chains 30060 0.05% 135 4
>Checkpoint queue latch 24730 0.01% 162065 7
>redo allocation 21567 0.03% 56580 6
>redo copy 21551 89.58% 0 5
>
>LATCH TYPE IMPACT SLEEP RATE WAITS_HOLDING_LATCH LEVEL#
>------------------------------ ----------- ---------- ------------------- -


>transaction allocation 19077 0.04% 23514 8
>session idle bit 17965 0.01% 0 1
>undo global data 14390 0.03% 12053 5
>session allocation 12642 0.05% 35032 5
>enqueues 11625 0.02% 12704 5
>virtual circuit buffers 10602 0.00% 8976 0
>dml lock allocation 5747 0.02% 0 3
>messages 3112 0.01% 79128 8
>list of block allocation 2993 0.01% 0 3
>sequence cache 2745 0.02% 4531 8
>multiblock read objects 492 0.01% 2190 3
>
>LATCH TYPE IMPACT SLEEP RATE WAITS_HOLDING_LATCH LEVEL#
>------------------------------ ----------- ---------- ------------------- -


>latch wait list 225 0.09% 0 9
>modify parameter values 143 0.06% 212 0
>cache buffer handles 56 0.00% 172 3
>row cache objects 18 0.00% 193 4
>user lock 13 0.01% 17 3
>Token Manager 5 0.00% 6 6
>Active checkpoint queue latch 3 0.00% 16 5
>
>
>--
>greg
Received on Thu Nov 18 1999 - 13:09:43 CST

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