RE: db file scattered/sequential read wait
- From: Wolfgang Breitling <breitliw@xxxxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Wed, 16 Jun 2004 11:21:04 -0700
Just a word of caution. You don't want to run this query every time you want to
find out the object for a db file read. That alone could bring your system to
its knees, especially if you have LMTs - and if not, why not? (those who still
manage Oracle 7 and lower systems are excused).
I run something like that in the wee hours of the morning when there is spare
capacity and load the response into a table indexed by file# and block#. This
way I don't go after the catalog tables and the response is immediate. Sure, I
risk missing the occasional block (hasn't happened yet) if the object went into
a new extent after I ran my report.
Quoting "Mark W. Farnham" <mwf@xxxxxxxx>:
> I think you want a minus one in the second term.
>
> Let's see, if block_id = 1 and you read 8 blocks, then 1...9, is *not* what
> you want, so yeah, (block_id+blocks-1)
> would tighten up that predicate.
>
> mwf
>
--
regards
Wolfgang Breitling,
Oracle 7,8,8i,9i OCP DBA; Oaktable member
Centrex Consulting Corporation
www.centrexcc.com
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