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Oracle PLAN_TABLE: column DISTRIBUTION

The value of the column distribution in a plan table lists an operation's distribution method in an execution plan of a parallel statement.

This value is only relevant for the plan operation PX SEND. Thus, the following query returns 0:

select
   count(*)
from
   v$sql_plan
where
   distribution is not null and
   operation <> 'PX SEND'
;

In records where distribution is not null (i. e. in PX SEND records), the value of distribution is equal to that of options: the following query return 0:

select
   count(*)
from
   v$sql_plan
where
   distribution is not null and
   nvl(options, 'x') <> distribution
;

select
-- count(*),
   distribution
from
   v$sql_plan
where
   distribution  is not null
group by
   distribution
order by
   distribution
;
--
-- BROADCAST
-- HASH
-- HASH (BLOCK ADDRESS)
-- HASH (NULL RANDOM)
-- QC (ORDER)
-- QC (RANDOM)
-- RANGE
-- ROUND-ROBIN

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