RE: Latching / Oracle support problems

Hi Tom,

The latch wait list and its latches are explained on page 27 of my book. The others are all associated with parallel execution. These miss rates are probably not of concern. It is of the nature of parallel execution that several processes tend to want the same latches at the same time. In any event, as with all latching, it is the number of sleeps that you should be concerned with, not the number of misses.

@ Regards,
@ Steve Adams
@ http://www.ixora.com.au/
@ http://www.christianity.net.au/
@
@ Going to OpenWorld?
@ Catch the Ixora performance tuning seminar too!
@ See http://www.ixora.com.au/seminars/ for details.

-----Original Message-----
From: Terrian, Thomas [mailto:Thomas.Terrian_at_standardregister.com] Sent: Thursday, 31 August 2000 23:20
To: 'Steve Adams'; Terrian, Thomas; Multiple recipients of list ORACLE-L Subject: RE: Latching / Oracle support problems

Steve,

I guess that I am applying the standard broad brush that latches with a %miss rate of over 1% are bad and something should be done to fix them. I certainly could be in error.

In Oracle Performance Tuning - Tips and Techniques by Niemiec, on page 182 he states that "If the number of immediate misses is more than 1 percent .... you may have a contention problem." Therefore, I have assumed that I have a contention problem.

Do you have an idea of what these latches mean? Are the miss rates OK and nothing to worry about? We have seen some intermittent bad response times in production so I am trying to tune it up as best I can.

Tom
-----Original Message-----
From: Steve Adams [mailto:steve.adams_at_ixora.com.au] Sent: Thursday, August 31, 2000 8:51 AM
To: Terrian, Thomas; Multiple recipients of list ORACLE-L Subject: RE: Latching / Oracle support problems

Hi Tom,

What makes you think that there is a problem here?

@ Regards,
@ Steve Adams
@ http://www.ixora.com.au/
@ http://www.christianity.net.au/
@
@ Going to OpenWorld?
@ Catch the Ixora performance tuning seminar too!
@ See http://www.ixora.com.au/seminars/ for details.

-----Original Message-----
From: Terrian, Thomas [mailto:Thomas.Terrian_at_standardregister.com] Sent: Thursday, 31 August 2000 23:09
To: Multiple recipients of list ORACLE-L Subject: Latching / Oracle support problems

AIX 4.3.2
Oracle 8.1.6
No OPS

Does anyone know what the following latches mean and more importantly how to fix them?

Latch                       Gets Misses %misses
--------------------       ----- ------ -------
latch wait list              5754   368  6.39%
parallel query alloc buffer 27083 10653 39.33%
parallel query stats         1003   453 45.16%
process queue                9979   113  1.13%
process queue reference   4157244 61439  1.47%
queryserver freelists       16348   522  3.19%

Also for your enjoyment -- I log a TAR for this on Aug 18, 13 days ago. So far, no help from Oracle. I love it!!! - Gold support, production system, problem priority 2 -- and still no good answers from Oracle. Oh yea, baby. Received on Thu Aug 31 2000 - 08:35:20 CDT