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| author | Etsuro Fujita <efujita@postgresql.org> | 2021-02-05 15:30:02 +0900 |
|---|---|---|
| committer | Etsuro Fujita <efujita@postgresql.org> | 2021-02-05 15:30:02 +0900 |
| commit | 984384129bb8a92481d4f7ddd5dede2d781b191f (patch) | |
| tree | 5af1f50e45cb01e1b347c82b0d339c52f27430ed /contrib | |
| parent | 6467661b6d80122582c9b84f9ae350e5e8073de2 (diff) | |
| download | postgresql-984384129bb8a92481d4f7ddd5dede2d781b191f.tar.gz | |
postgres_fdw: Fix assertion in estimate_path_cost_size().
Commit 08d2d58a2 added an assertion assuming that the retrieved_rows
estimate for a foreign relation, which is re-used to cost pre-sorted
foreign paths with local stats, is set to at least one row in
estimate_path_cost_size(), which isn't correct because if the relation
is a foreign table with tuples=0, the estimate would be set to 0 there
when not using remote estimates.
Per bug #16807 from Alexander Lakhin. Back-patch to v13 where the
aforementioned commit went in.
Author: Etsuro Fujita
Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/16807-9fe4e08fbaa5c7ce%40postgresql.org
Diffstat (limited to 'contrib')
| -rw-r--r-- | contrib/postgres_fdw/expected/postgres_fdw.out | 18 | ||||
| -rw-r--r-- | contrib/postgres_fdw/postgres_fdw.c | 2 | ||||
| -rw-r--r-- | contrib/postgres_fdw/sql/postgres_fdw.sql | 12 |
3 files changed, 31 insertions, 1 deletions
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 747ab40d2f..71ad0e691c 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -602,6 +602,24 @@ SELECT t1."C 1", t2.c1, t3.c1 FROM "S 1"."T 1" t1 full join ft1 t2 full join ft2 RESET enable_hashjoin; RESET enable_nestloop; +-- Test executing assertion in estimate_path_cost_size() that makes sure that +-- retrieved_rows for foreign rel re-used to cost pre-sorted foreign paths is +-- a sensible value even when the rel has tuples=0 +CREATE TABLE loct_empty (c1 int NOT NULL, c2 text); +CREATE FOREIGN TABLE ft_empty (c1 int NOT NULL, c2 text) + SERVER loopback OPTIONS (table_name 'loct_empty'); +INSERT INTO loct_empty + SELECT id, 'AAA' || to_char(id, 'FM000') FROM generate_series(1, 100) id; +DELETE FROM loct_empty; +ANALYZE ft_empty; +EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft_empty ORDER BY c1; + QUERY PLAN +------------------------------------------------------------------------------- + Foreign Scan on public.ft_empty + Output: c1, c2 + Remote SQL: SELECT c1, c2 FROM public.loct_empty ORDER BY c1 ASC NULLS LAST +(3 rows) + -- =================================================================== -- WHERE with remotely-executable conditions -- =================================================================== diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c index ed4e455fcb..6af224fa21 100644 --- a/contrib/postgres_fdw/postgres_fdw.c +++ b/contrib/postgres_fdw/postgres_fdw.c @@ -2810,7 +2810,7 @@ estimate_path_cost_size(PlannerInfo *root, */ if (fpinfo->rel_startup_cost >= 0 && fpinfo->rel_total_cost >= 0) { - Assert(fpinfo->retrieved_rows >= 1); + Assert(fpinfo->retrieved_rows >= 0); rows = fpinfo->rows; retrieved_rows = fpinfo->retrieved_rows; diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index 29c61e7ff4..894724dab8 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -298,6 +298,18 @@ SELECT t1."C 1", t2.c1, t3.c1 FROM "S 1"."T 1" t1 full join ft1 t2 full join ft2 RESET enable_hashjoin; RESET enable_nestloop; +-- Test executing assertion in estimate_path_cost_size() that makes sure that +-- retrieved_rows for foreign rel re-used to cost pre-sorted foreign paths is +-- a sensible value even when the rel has tuples=0 +CREATE TABLE loct_empty (c1 int NOT NULL, c2 text); +CREATE FOREIGN TABLE ft_empty (c1 int NOT NULL, c2 text) + SERVER loopback OPTIONS (table_name 'loct_empty'); +INSERT INTO loct_empty + SELECT id, 'AAA' || to_char(id, 'FM000') FROM generate_series(1, 100) id; +DELETE FROM loct_empty; +ANALYZE ft_empty; +EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft_empty ORDER BY c1; + -- =================================================================== -- WHERE with remotely-executable conditions -- =================================================================== |