Re: Latches

From: joel garry <>
Date: Fri, 9 Oct 2009 14:19:05 -0700 (PDT)
Message-ID: <>

On Oct 9, 10:32 am, The Magnet <> wrote:
> Hi,
> Been looking around and reading on latches.  I see references to
> 'parent' and 'child' latches.  I'd like to understand the difference
> but I cannot find any good documentation on them.  The Oracle
> documentation did not really explain why one would be acquired over
> the other.
> Thanks.
> Oh yeah, Sybrand, anything?

Basically, child latches are used to protect SGA memory areas with a finer granularity than in previous versions. For example, the library cache latch serializes access to objects there. If you have a latching problem, and you make the library larger, you just make the latching problem worse (like in O8). So Oracle makes 7 child latches to protect various parts in 9i. Then does more stuff in 10g. Now If you want to dig deep and see some cool examples, search for latch on tanel's blog.


-- is bogus.
Received on Fri Oct 09 2009 - 16:19:05 CDT

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