This value is only relevant for the plan operationPX 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