Re: Timestamps in trace files (and other trace file oddities)

Hi!

About the second one, you see the first read started from 6041 and was 18 blocks, the second one which was executed 7 minutes later, started from 6042 and was 17 blocks. Probably the extent boundary is at block 6059. Multiblock reads don't cross extent boundaries.

So, probably your query acquired block 6041 with FTS and by the time it needed next block, the blocks were already out of buffer cache (LRU list) and another multiblock read was needed. Maybe you should look at keep buffer pool, but since the time interval was long, it might not be necessary anyway...

Tanel.
----- Original Message -----
From: "Henry Poras" <hporas_at_etal.uri.edu> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Thursday, July 24, 2003 6:04 PM
Subject: RE: Timestamps in trace files (and other trace file oddities)

> (Tried sending this yesterday. I'll try again)
>
> Dan,
> I was running a 10046 (level 12) trace on an awful piece of PeopleSoft SQL
> today and got some really odd results in my trace file (8.1.7).
>
> *** 2003-07-23 15:40:59.149
> WAIT #1: nam='db file scattered read' ela= 0 p1=65 p2=6041 p3=18
> *** 2003-07-23 15:46:06.340
> WAIT #1: nam='latch free' ela= 1 p1=813986232 p2=66 p3=0
> *** 2003-07-23 15:47:53.851
> WAIT #1: nam='db file scattered read' ela= 0 p1=65 p2=6042 p3=17
>
> Two things struck me (three if it takes me too long to write this and I
get
> home late). First, the timestamps show an elapsed time of ~7 minutes, but
> the trace file has ela=1 (one onehundredth of a second). The 7 minutes is
> closer to reality. Huh???
>
> Secondly, the first scattered read reads 18 blocks starting at 6041. Why
> does the next scattered read start at block# 6042?
>
> Any ideas?
>
> Henry
>
>
>
> -----Original Message-----
> Daniel Fink
> Sent: Wednesday, July 23, 2003 11:04 AM
> To: Multiple recipients of list ORACLE-L
>
>
> Gudmundur,
> Where is this documented (so I can RTFM)?
> The one piece of this I don't quite understand is that the timestamp is
not
> emitted twice in a row. If the long time is the triggering event, why do I
> see a gap of 90 minutes (in another trace file)?
>
> Daniel
>
> Gudmundur Bjarni Josepsson wrote:
> >
> > Daniel,
> >
> > Perhaps someone else can explain this better but the documentation I've
> > got on this says that the Oracle kernel emits timestamps when a long
> > time has elapsed since the last line was emitted to the trace file.
> > Long time is defined as tens of seconds.
> >
> > Gudmundur
> >
> > > -----Original Message-----
> > > From: ml-errors_at_fatcity.com [mailto:ml-errors_at_fatcity.com] On
> > > Behalf Of Daniel Fink
> > > Sent: 22. júlí 2003 21:19
> > > To: Multiple recipients of list ORACLE-L
> > > Subject: Timestamps in trace files
> > >
> > >
> > > I was perusing a 10046 trace file and I noticed that
> > > timestamps are written to the trace file. Sometimes they were
> > > very regular (3 minutes apart give or take 30 seconds) while
> > > other times they were hours apart. I have noticed that two
> > > timestamps are never written without any intervening
> > > activity. Anyone have any idea on the reasoning behind the
> > > timestamps and the 'triggering event'?
> > >
> > > Daniel
> > >
> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Gudmundur Bjarni Josepsson
> > INET: gbj_at_index.is
> >
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Henry Poras
> INET: hporas_at_etal.uri.edu
>
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Received on Thu Jul 24 2003 - 10:06:36 CDT