Crazy query plan.
От | Oleg Serov |
---|---|
Тема | Crazy query plan. |
Дата | |
Msg-id | cec7c6df0911130325q3df937cel9cbec500179f7a5a@mail.gmail.com обсуждение исходный текст |
Ответы |
Re: Crazy query plan.
|
Список | pgsql-bugs |
SQL: CREATE TABLE test (id BIGINT, id2 BIGINT, id3 BIGINT, id4 BIGINT); INSERT INTO test SELECT i, i, i, i FROM generate_series(0, 9) i; EXPLAIN ANALYZE SELECT ((SELECT tmp::test FROM (SELECT * FROM test LIMIT 1) tmp)::test).*; WILL: QUERY PLAN Result (cost=0.11..0.12 rows=1 width=0) (actual time=0.076..0.078 rows=1 loops=1) InitPlan -> Subquery Scan tmp (cost=0.00..0.03 rows=1 width=32) (actual time=0.014..0.019 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=32) (actual time=0.008..0.009 rows=1 loops=1) -> Seq Scan on test (cost=0.00..23.10 rows=1310 width=32) (actual time=0.005..0.005 rows=1 loops=1) -> Subquery Scan tmp (cost=0.00..0.03 rows=1 width=32) (actual time=0.008..0.013 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=32) (actual time=0.005..0.006 rows=1 loops=1) -> Seq Scan on test (cost=0.00..23.10 rows=1310 width=32) (actual time=0.002..0.002 rows=1 loops=1) -> Subquery Scan tmp (cost=0.00..0.03 rows=1 width=32) (actual time=0.008..0.012 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=32) (actual time=0.005..0.006 rows=1 loops=1) -> Seq Scan on test (cost=0.00..23.10 rows=1310 width=32) (actual time=0.003..0.003 rows=1 loops=1) -> Subquery Scan tmp (cost=0.00..0.03 rows=1 width=32) (actual time=0.009..0.013 rows=1 loops=1) -> Limit (cost=0.00..0.02 rows=1 width=32) (actual time=0.005..0.006 rows=1 loops=1) -> Seq Scan on test (cost=0.00..23.10 rows=1310 width=32) (actual time=0.002..0.002 rows=1 loops=1) Total runtime: 0.138 ms One subquery for each column. wtf?
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