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PARALLELISM not working for SELECT query

1048827Oct 14 2016 — edited Oct 17 2016

DB version: 11.2.0.4

OS : Oracle Linux 6.5

I am trying to run a SELECT with parallelism 50 from an SQL*Plus script. But, no slave processes are being created.

PARALLEL_MAX_SERVERS for this 2-node RAC DB is set to 2600 and PARALLEL_DEGREE_POLICY is set to MANUAL

I tried the below mentioned 4 methods to enable parallelism. But, none of them worked (confirmed by querying GV$PX_SESSION ). Any idea why ?

Attempt1.

  alter session enable parallel query;

   select  /*+ PARALLEL(50) */ distinct ..... ;

Attempt2:

  alter session enable parallel query;

  ALTER SESSION FORCE PARALLEL QUERY PARALLEL;

  select  /*+ PARALLEL(50) */ distinct ..... ;

Attempt3:

  ALTER SESSION FORCE PARALLEL QUERY PARALLEL 50;

  select /*+ PARALLEL */ distinct ..... ;

Attempt4:

Since PARALLEL_DEGREE_POLICY was set to MANUAL , I tried to set it to AUTO at session level. But, this didn't help either

   alter session set parallel_degree_policy = auto;

  ALTER SESSION FORCE PARALLEL QUERY PARALLEL 50;

  select /*+ PARALLEL */ distinct .....   ;

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