Обсуждение: why does this query not use a parallel query
Have a query:
explain analyze SELECT minion_id FROM mob_player_mob_118 WHERE player_id = 55351078;
QUERY PLAN
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Index Only Scan using mob_player_mob_118_pkey on mob_player_mob_118 (cost=0.44..117887.06 rows=4623076 width=4) (actual time=0.062..3716.105 rows=4625123 loops=1)
Index Cond: (player_id = 55351078)
Heap Fetches: 1152408
Planning time: 0.241 ms
Execution time: 5272.171 ms
If I just get the count it will use a parallel query
explain analyze SELECT count(minion_id) FROM mob_player_mob_118 WHERE player_id = 55351078;
Thanks
Dave Cramer
Dave Cramer <davecramer@gmail.com> writes:
> Have a query:
> explain analyze SELECT minion_id FROM mob_player_mob_118 WHERE player_id =
> 55351078;
> Index Only Scan using mob_player_mob_118_pkey on mob_player_mob_118
> (cost=0.44..117887.06 rows=4623076 width=4) (actual time=0.062..3716.105
> rows=4625123 loops=1)
I don't think we have parallel IOS yet (I might be wrong). If so,
it probably thinks this is cheaper than the best available parallel plan.
> If I just get the count it will use a parallel query
Likely a parallelized aggregation.
regards, tom lane