RE: Uneven distribution of latches - what's next?

From: Parker, Matthew <matthewp_at_amazon.com>
Date: Fri, 24 Dec 2004 11:01:27 -0800
Message-ID: <F385925F530F6C4081F1659F71640EB301CC7499@ex-mail-sea-04.ant.amazon.com>

 Before answering it would be nice to know about your query and it's = execution rate.

-----Original Message-----
From: oracle-l-bounce_at_freelists.org =
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Boris Dali Sent: Friday, December 24, 2004 6:30 AM
To: oracle-l_at_freelists.org
Subject: Uneven distribution of latches - what's next?

The subject says it all.
The distribution below (from v$latch_children for latch# 157 - library = cache):

CHILD# GETS MISSES SLEEPS WAIT_TIME ------ ---------- ---------- ---------- ----------

     2   16597807      72387        333    1674350
     1   34475788     203781       1254    4801328
     7   27065517     241493       1284    5753591
     8   33897775     440298       1718   14570006
     4   60799550     676421       1833   11250799
    10   62099645     922629       2881   11083064
     6   52733583     818465       3384   21322498
     3   56602708     883077       9150   49110401
     9   65188664    1275753      10214   64507786
    11  117460816    3227510      24170  133460244
     5 3643740682 3001597195   23020516 6.2108E+12

So child latch 5 is the one getting hit the most by far. I know exactly = the reason/query that gets soft-reparsed over and over, but is there = **anything** that can be done from a system/DB configuration = perfspective to:
- ease the load on CPUs pegging at a 100%

• make the distribution more even (would it improve anything, e.g. = decrease response time and/or overall system load?)? Why child latch 5?=20 =20 Thanks, Boris Dali.

        =09

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Received on Fri Dec 24 2004 - 12:56:48 CST