postgres.git / summary / log / commit / refs
commit 704e393190725f54ddaaaee2cda1a6f3a26bff6d
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat Jul 14 15:59:12 2018 +0000
Fix hashjoin costing mistake introduced with inner_unique optimization.
In final_cost_hashjoin(), commit 9c7f5229a allowed inner_unique cases
to follow a code path previously used only for SEMI/ANTI joins; but it
neglected to fix an if-test within that path that assumed SEMI and ANTI
were the only possible cases. This resulted in a wrong value for
hashjointuples, and an ensuing bad cost estimate, for inner_unique normal
joins. Fortunately, for inner_unique normal joins we can assume the number
of joined tuples is the same as for a SEMI join; so there's no need for
more code, we just have to invert the test to check for ANTI not SEMI.
It turns out that in two contrib tests in which commit 9c7f5229a
changed the plan expected for a query, the change was actually wrong
and induced by this estimation error, not by any real improvement.
Hence this patch also reverts those changes.
Per report from RK Korlapati. Backpatch to v10 where the error was
introduced.
David Rowley
Discussion: https://postgr.es/m/CA+SNy03bhq0fodsfOkeWDCreNjJVjsdHwUsb7AG=jpe0PtZc_g@mail.gmail.com
contrib/citext/expected/citext.out | 2 +-
contrib/citext/expected/citext_1.out | 2 +-
contrib/postgres_fdw/expected/postgres_fdw.out | 19 +++++++++++--------
src/backend/optimizer/path/costsize.c | 6 +++---
4 files changed, 16 insertions(+), 13 deletions(-)
diff --git a/contrib/citext/expected/citext.out b/contrib/citext/expected/citext.out
index 95373182af5..99365c57b01 100644
--- a/contrib/citext/expected/citext.out
+++ b/contrib/citext/expected/citext.out
@@ -2336,8 +2336,8 @@ SELECT *
WHERE t.id IS NULL OR m.id IS NULL;
id | name | id | name
----+------+----+------
- 2 | two | |
| | 2 | Two
+ 2 | two | |
(2 rows)
REFRESH MATERIALIZED VIEW CONCURRENTLY citext_matview;
diff --git a/contrib/citext/expected/citext_1.out b/contrib/citext/expected/citext_1.out
index 855ec3f10b7..8aac72e2268 100644
--- a/contrib/citext/expected/citext_1.out
+++ b/contrib/citext/expected/citext_1.out
@@ -2336,8 +2336,8 @@ SELECT *
WHERE t.id IS NULL OR m.id IS NULL;
id | name | id | name
----+------+----+------
- 2 | two | |
| | 2 | Two
+ 2 | two | |
(2 rows)
REFRESH MATERIALIZED VIEW CONCURRENTLY citext_matview;
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index cf4863c5aa2..1dd8e13f331 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -4233,18 +4233,21 @@ explain (verbose, costs off) select * from ft3 where f2 = 'foo' COLLATE "C";
explain (verbose, costs off) select * from ft3 f, loct3 l
where f.f3 = l.f3 COLLATE "POSIX" and l.f1 = 'foo';
- QUERY PLAN
----------------------------------------------------------
- Nested Loop
+ QUERY PLAN
+-------------------------------------------------------------
+ Hash Join
Output: f.f1, f.f2, f.f3, l.f1, l.f2, l.f3
- Join Filter: ((f.f3)::text = (l.f3)::text)
- -> Index Scan using loct3_f1_key on public.loct3 l
- Output: l.f1, l.f2, l.f3
- Index Cond: (l.f1 = 'foo'::text)
+ Inner Unique: true
+ Hash Cond: ((f.f3)::text = (l.f3)::text)
-> Foreign Scan on public.ft3 f
Output: f.f1, f.f2, f.f3
Remote SQL: SELECT f1, f2, f3 FROM public.loct3
-(9 rows)
+ -> Hash
+ Output: l.f1, l.f2, l.f3
+ -> Index Scan using loct3_f1_key on public.loct3 l
+ Output: l.f1, l.f2, l.f3
+ Index Cond: (l.f1 = 'foo'::text)
+(12 rows)
-- ===================================================================
-- test writable foreign table stuff
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index a2a7e0c5202..31ff618d8fb 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -3457,10 +3457,10 @@ final_cost_hashjoin(PlannerInfo *root, HashPath *path,
clamp_row_est(inner_path_rows / virtualbuckets) * 0.05;
/* Get # of tuples that will pass the basic join */
- if (path->jpath.jointype == JOIN_SEMI)
- hashjointuples = outer_matched_rows;
- else
+ if (path->jpath.jointype == JOIN_ANTI)
hashjointuples = outer_path_rows - outer_matched_rows;
+ else
+ hashjointuples = outer_matched_rows;
}
else
{
[parent: dbd7f4e7c433]