RE: Buffer Sort explanation
- From: "Lex de Haan" <lex.de.haan@xxxxxxxxxxxxxx>
- To: <sharmakdeep_oracle@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 4 Aug 2005 10:47:06 +0200
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 ...
additions/corrections welcome,
kind regards,
Lex.
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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Deepak Sharma
Sent: Wednesday, August 03, 2005 23:31
To: oracle-l@xxxxxxxxxxxxx
Subject: Buffer Sort explanation
What does the 'BUFFER SORT' step mean and how does it get calculated, say in
below example? It is out of a tkprof output of a star transformation query.
105 BITMAP MERGE
351549 BITMAP KEY ITERATION
127009880 BUFFER SORT
1607720 TABLE ACCESS FULL SYS_TEMP_4254956840
351549 BITMAP INDEX RANGE SCAN OBJ#(3441108)
PARTITION: 1 177 (object id 3441108)
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