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Re: latch free and hot blocks

From: hrishy <>
Date: 3 Jun 2004 02:45:49 -0700
Message-ID: <>

Hi Jonathan

Thank you very much for clear are you comming out with a 10g book :-) just like the one you had for 8i :-)..8i one is cool..i liked the book a lot specifically

1)Inline views (i knew they existed but didnt know when to use them)
2)Analytical functions
3)explanation about mult-versioning (hope u do that for undo
tablespaces too)
4)and the alter table intricacies

Srivenu thanks for your sql..i am on i need to look upto the sql statements..i liked the clear cut explanation form you.


"Jonathan Lewis" <> wrote in message news:<c9k6su$42d$>...
> First take a look at srivenu's note.
> There is a bug in some versions of 8.1.7 which
> puts excess pressure on the latches covering
> root blocks of indexes. Are any of your hot
> index blocks the root block. (Check dba_segments
> for the location of the segment header block, the
> index root block is always the block after the
> segment header block).
> There is no reason why a hot block has to be a
> table block. In fact, for latching reasons, index
> blocks are more likely to get hot than table blocks
> if the tables are popular lookup tables. (There are
> more table blocks than index blocks usually, so the
> so visits are spread out more thinly across the table).
> If the problem is the root block problem, you may
> need to upgrade. The other option is to find out why
> you are doing so many lookups, and reduce the amount
> of work. Index-related latch contention is sometimes
> an indication of excessive reliance on indexed access
> paths when the occasional tablescan might be more
> cost-effective.
> --
> Regards
> Jonathan Lewis
> The Co-operative Oracle Users' FAQ
> Optimising Oracle Seminar - schedule updated May 1st
> "hrishy" <> wrote in message
> > Hi Jonathan
> >
> > whe i run your query i see the hot blocks are for indexes..i was
> > expecting tables what i am kind of lost
> >
> > regards
> > Hrishy
> >
Received on Thu Jun 03 2004 - 04:45:49 CDT

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