From: | Ryan Lambert <ryan(at)rustprooflabs(dot)com> |
---|---|
To: | pgsql-bugs(at)lists(dot)postgresql(dot)org |
Subject: | EXPLAIN ANALYZE not displaying recheck condition |
Date: | 2019-11-07 22:04:38 |
Message-ID: | CAN-V+g9caiKmU88Q9fx+7xdboCqRk=HKEe-yFmAQsU09GUEk2A@mail.gmail.com |
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Lists: | pgsql-bugs |
Hello,
In Pg12 I noticed the output from EXPLAIN ANALYZE no longer displays the
recheck condition when using GIST indexes, such as:
Recheck Cond: (b.way ~ way)
Was this intentional? I double checked the release notes and didn't find
any changes that indicate this was expected.
An example is a query such as:
EXPLAIN (ANALYZE)
SELECT r.highway, r.ref, r.way
FROM osm.boundary_polygon b
INNER JOIN osm.road_line r ON ST_Contains(b.way, r.way)
WHERE b.name = 'Jefferson County'
;
Output from PG11 shows the recheck cond:
Nested Loop (cost=29.28..2610.82 rows=220 width=237) (actual
time=20.466..1900.878 rows=62585 loops=1)
-> Seq Scan on boundary_polygon b (cost=0.00..132.16 rows=1 width=5627)
(actual time=0.206..0.323 rows=1 loops=1)
Filter: (name = 'Jefferson County'::text)
Rows Removed by Filter: 492
-> Bitmap Heap Scan on road_line r (cost=29.28..2476.45 rows=220
width=237) (actual time=20.251..1879.286 rows=62585 loops=1)
Recheck Cond: (b.way ~ way)
Filter: _st_contains(b.way, way)
Rows Removed by Filter: 8803
Heap Blocks: exact=2273
-> Bitmap Index Scan on gix_osm_road_line (cost=0.00..29.23
rows=659 width=0) (actual time=14.517..14.517 rows=71388 loops=1)
Index Cond: (b.way ~ way)
Planning Time: 0.213 ms
Execution Time: 1910.810 ms
Output from Pg12 does not show recheck:
Nested Loop (cost=29.24..18887.33 rows=39206 width=234) (actual
time=12.757..1064.333 rows=62585 loops=1)
-> Seq Scan on boundary_polygon b (cost=0.00..109.16 rows=1 width=5627)
(actual time=0.169..0.238 rows=1 loops=1)
Filter: (name = 'Jefferson County'::text)
Rows Removed by Filter: 492
-> Bitmap Heap Scan on road_line r (cost=29.24..18777.51 rows=66
width=234) (actual time=12.578..1055.015 rows=62585 loops=1)
Filter: st_contains(b.way, way)
Rows Removed by Filter: 8803
Heap Blocks: exact=2505
-> Bitmap Index Scan on gix_osm_road_line (cost=0.00..29.23
rows=659 width=0) (actual time=11.285..11.285 rows=71388 loops=1)
Index Cond: (way @ b.way)
Planning Time: 0.613 ms
Execution Time: 1068.370 ms
Thanks,
*Ryan Lambert*
RustProof Labs
www.rustprooflabs.com
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