RE: Researching latch efficiency
- From: Yong Huang <yong321@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Sat, 21 Jun 2008 06:21:10 -0700 (PDT)
Anjo Kolk's wait event article is still the most complete about documenting
latches. Search for it on Google.
messages
There is a pool of message blocks in the SGA. This pool is controlled by the
init.ora parameter _messages. If a process needs a message it will get the
latch, search a linked list for a free message block, unlink this message block
, put this message on the message queue for the intended process and then
release this latch. The event rdbms ipc message indicates that a process is
waiting for a message to arrive on his message queue. The event rdbms ipc
message reply is used to indicate that a message is expected back by the
sending process.
Why not compare the numbers in Spotlight and sqlplus? If they're close, they
must be referring to the same event.
Yong Huang
> I'm using Quest's Spotlight and wonder if it means "latch: messages". I
> may need to open a ticket with Quest Support to explain the display in
> their GUI.
>
> Not sure if this is the one I'm waiting on. I'll look deeper.
>
> sql> select * from v$event_name where name = 'latch: messages';
>
> The online Oracle doc referenced by Jared (thanks J!) does not have all
> 889 wait events documented for 10.2.0.4. I doubt I'm gonna find it. :-)
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