RE: OLTP compression slow update
- From: Yong Huang <yong321@xxxxxxxxx>
- To: Joel.Patterson@xxxxxxxxxxx
- Date: Thu, 27 Dec 2012 13:20:13 -0800 (PST)
> The reason being is that every session is contributing to the numbers
> -- like enqueues, latches, mutexes, or runtime.
Some but not all these metrics can be broken down into sessions. V$sesstat has
session-specific 'enqueue waits'. You can also use event 10704 to trace a
session's enqueue gets along the way. V$mutex_sleep_history has columns for
requesting and blocking sessions, but you need to make sure these *historical*
stats are really for the session you're interested in. V$sesstat has 'CPU used
by this session' and 'CPU used when call started'.
Oracle never breaks latch statistics into sessions. You may frequently sample a
specific server process with some tools for its calls to latch related
functions, kslgetl etc. V$latchholder shows the sessions holding the latch
right at the moment only. If there's latch wait, of course you'll have numbers
in v$session(_wait) and related views for 'latch free' event which is
session-specific.
Yong Huang
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