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Re: 10046 trace: 'latch free' then 'db file seq. read' waits

From: <sjaffarhussain_at_gmail.com>
Date: 14 Jun 2006 06:44:39 -0700
Message-ID: <1150292679.848087.55920@y41g2000cwy.googlegroups.com>


cache buffer chain generally comes when a block accessed in the buffer, i.e. logical read. Since the wait event is 'db file sequential read', I guess this could be index root block hot block issues. Can you give us the explain plan and information about the tabels involved in the query and its statistical information and also index information.
What is the size of buffer cache in the database? Jaffar

Spendius wrote:
> Argh... Forgot to say I'm dealing with an 8i DB, for which
> SQL> select name from v$latch where latch#=66;
> NAME
> ---------------------
> cache buffers chains
>
> Sorry.
>
> > When you find a series of 'latch free' waits with p2=66 in a 10046
> > trace file that are immediately followed by a 'db file sequential read'
> > wait (and then again 'latch free' p2=66 lines until another 'db file
> > seq. read' line with different file#/block# values etc etc.) does it
> > mean that Oracle now shows a wait for a seq. read on this very
> > p1=file# and p2=block# on which it was trying to get a 'cache buffer
> > chain' latch a second before ?
> >
Received on Wed Jun 14 2006 - 08:44:39 CDT

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