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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Buffer Sort explanation
that's indeed how I understand it. obviously, there must be some cut off number
or threshold value -- and obviously, it is highly undocumented; I don't have a
clue :-)
by the way, even if I would have a clue, these algorithms are typically fine-tuned by Oracle development with every release, without letting us know...
kind regards,
Lex.
-----Original Message-----
Hi Lex,
If Oracle determines that if a block will be accessed multiple times by the _same_ SQL, then it moves it to PGA. If the same can be accessed multiple times by _different_ SQL statements it ends up in SGA? Is there a cut off number for accessing the data block above which Oracle places it to PGA?
On 8/4/05, Lex de Haan <lex.de.haan_at_naturaljoin.nl> wrote:
> a BUFFER SORT typically means that Oracle reads data blocks into
> private memory, because the block will be accessed multiple times in
> the context of the SQL statement execution. in other words, Oracle
> sacrifies some extra memory to reduce the overhead of accessing blocks
> multiple times in shared memory. this has nothing to do with sorting ...
-- http://www.freelists.org/webpage/oracle-lReceived on Sun Aug 07 2005 - 13:08:36 CDT
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