I create a patch that outputs affected rows in EXPLAIN that occur by INSERT/UPDATE/DELETE.
Despite the fact that commands in EXPLAIN ANALYZE query are executed as usual, EXPLAIN doesn't show outputting affected rows as in these commands.
The patch fixes this problem.
Examples:
explain analyze insert into a values (1);
QUERY PLAN
------------------------------------------------------------------------------------------
Insert on a (cost=0.00..0.01 rows=0 width=0) (actual time=0.076..0.077 rows=0 loops=1)
-> Result (cost=0.00..0.01 rows=1 width=4) (actual time=0.002..0.002 rows=1 loops=1)
Planning Time: 0.025 ms
Execution Time: 0.412 ms
(4 rows)
INSERT 0 1
QUERY PLAN
------------------------------------------------------------------------------------------------------
Update on a (cost=0.00..35.50 rows=0 width=0) (actual time=0.059..0.060 rows=0 loops=1)
-> Seq Scan on a (cost=0.00..35.50 rows=2550 width=10) (actual time=0.012..0.013 rows=7 loops=1)
Planning Time: 0.142 ms
Execution Time: 0.666 ms
(4 rows)
UPDATE 7
explain analyze delete from a where n = 1;
QUERY PLAN
---------------------------------------------------------------------------------------------------
Delete on a (cost=0.00..41.88 rows=0 width=0) (actual time=0.147..0.147 rows=0 loops=1)
-> Seq Scan on a (cost=0.00..41.88 rows=13 width=6) (actual time=0.120..0.123 rows=7 loops=1)
Filter: (n = 1)
Planning Time: 1.073 ms
Execution Time: 0.178 ms
(5 rows)
DELETE 7
EXPLAIN queries without ANALYZE don't affect rows, so the output number is 0.
explain update a set n = 2;
QUERY PLAN
------------------------------------------------------------
Update on a (cost=0.00..35.50 rows=0 width=0)
-> Seq Scan on a (cost=0.00..35.50 rows=2550 width=10)
(2 rows)
UPDATE 0
Maybe there is no need to add this row when EXPLAIN has no ANALYZE. So it is a discussion question.
Also haven't fixed regress tests yet.
Regards,
Damir Belyalov
Postgres Professional