Re: In-Memory Parallel Execution (11.2)

  • From: Stefan Koehler <contact@xxxxxxxx>
  • To: ORACLE-L <oracle-l@xxxxxxxxxxxxx>, Hemant-K.Chitale@xxxxxx
  • Date: Thu, 2 Apr 2015 12:27:46 +0200 (CEST)

Hi Hemant,
i am not able to answer all your question, but some of them.

1. Does In-Memory Parallel Execution work in a non-RAC environment ?
Never thought about this (sense ?!?), but the official documentation (
https://docs.oracle.com/cd/E18283_01/server.112/e16541/parallel002.htm#BEICFFGB
) also states about single instance environments: "If the size of the object is
larger than the size of the buffer cache (single instance) or the size
of the buffer cache multiplied by the number of active instances in an Oracle
RAC cluster, then it is read using direct path reads."

2. Does it HAVE to have PARALLEL_DEGREE_POLICY=’AUTO’ or does it work with
MANUAL ?
Yes, it can also kick in with PARALLEL_DEGREE_POLICY=MANUAL. Please check Tanel
Poders' blog post about this and the different options:
http://blog.tanelpoder.com/2013/11/27/when-do-oracle-parallel-execution-slaves-issue-buffered-physical-reads-part-1/

4. How do you determine if In-Memory Parallel Execution has been used ?
Tracing with parameter "_px_trace" for example.

5. Is there another switch (other than PARALLEL_DEGREE_POLICY) to disable it ?
Refer to Tanels' blog post.

Best Regards
Stefan Koehler

Freelance Oracle performance consultant and researcher
Homepage: http://www.soocs.de
Twitter: @OracleSK

"Chitale, Hemant K" <Hemant-K.Chitale@xxxxxx> hat am 2. April 2015 um 10:27
geschrieben:

In-Memory Parallel Execution in 11.2

Questions :
1. Does In-Memory Parallel Execution work in a non-RAC environment ?
2. Does it HAVE to have PARALLEL_DEGREE_POLICY=’AUTO’ or does it work
with MANUAL ?
3. In RAC does it still work if PARALLEL_FORCE_LOCAL is TRUE ?
4. How do you determine if In-Memory Parallel Execution has been used
?
5. Is there another switch (other than PARALLEL_DEGREE_POLICY) to
disable it ?


For some tests I need to
1. Determine if In-Memory Parallel Execution has been used
2. Selectively disable it (or enable it :>)
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