Re: 9.2 V$ views

From: Tanel Põder <tanel.poder.003_at_mail.ee>
Date: Tue, 27 Jul 2004 12:14:15 +0300
Message-ID: <3a5001c473ba$1a620800$0a879fd9@porgand>

> See below for a 'select count(*) from dba_extents' on an Apps database
> (total of 217,167) extents sitting on 452 datafiles, and the snapshot of
> V$SESSTAT and V$SESSION_EVENT for that SID. The query too about 13 minutes
> (dev server, slightly slow disk). Interesting stats to note? Look at
> 'revursive calls', 'CPU used%', 'cluster key scans' and 'cluster key block
> gets' stats, 'session logical reads', number of dbfile reads. Most were
> against the C_FILE#_BLOCK#, UET$, SEG$, SYS_IOT_TOP_132603,
I_FILE#_BLOCK#,
> OBJ$, C_TS#, TS$, FET$ objects among others.

Which version of db? Was it fully LMT or only partially? In full LMT configuration you shouldn't have any records in UET$ and FET$ (which contents can be cached in dictionary cache), instead there is IO on x$ktfbue (used extents), which in turn goes to segment headers...

But yeah, select count(*) from dba_extents, especially in Apps like environment kill performance and yet there are monitoring tools around which query it after every five minutes for some reason...

Tanel.

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Received on Tue Jul 27 2004 - 04:11:14 CDT