From 394d51731495794655f95b5580adb757d7a9bbe2 Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Fri, 27 Oct 2023 17:57:11 +0200 Subject: [PATCH] Fix calculation in brin_minmax_multi_distance_date When calculating the distance between date values, make sure to subtract them in the right order, i.e. (larger - smaller). The distance is used to determine which values to merge, and is expected to be a positive value. The code unfortunately did the subtraction in the opposite order, i.e. (smaller - larger), thus producing negative values and merging values the most distant values first. The resulting index is correct (i.e. produces correct results), but may be significantly less efficient. This affects all minmax-multi indexes on date columns. Backpatch to 14, where minmax-multi indexes were introduced. Reported-by: Ashutosh Bapat Reviewed-by: Ashutosh Bapat, Dean Rasheed Backpatch-through: 14 Discussion: https://postgr.es/m/eef0ea8c-4aaa-8d0d-027f-58b1f35dd170@enterprisedb.com --- src/backend/access/brin/brin_minmax_multi.c | 7 ++++++- src/test/regress/expected/brin_multi.out | 20 ++++++++++++++++++++ src/test/regress/sql/brin_multi.sql | 18 ++++++++++++++++++ 3 files changed, 44 insertions(+), 1 deletion(-) diff --git a/src/backend/access/brin/brin_minmax_multi.c b/src/backend/access/brin/brin_minmax_multi.c index 8c72a0a036..7e63dda14f 100644 --- a/src/backend/access/brin/brin_minmax_multi.c +++ b/src/backend/access/brin/brin_minmax_multi.c @@ -2081,13 +2081,18 @@ brin_minmax_multi_distance_uuid(PG_FUNCTION_ARGS) Datum brin_minmax_multi_distance_date(PG_FUNCTION_ARGS) { + float8 delta = 0; DateADT dateVal1 = PG_GETARG_DATEADT(0); DateADT dateVal2 = PG_GETARG_DATEADT(1); if (DATE_NOT_FINITE(dateVal1) || DATE_NOT_FINITE(dateVal2)) PG_RETURN_FLOAT8(0); - PG_RETURN_FLOAT8(dateVal1 - dateVal2); + delta = (float8) dateVal2 - (float8) dateVal1; + + Assert(delta >= 0); + + PG_RETURN_FLOAT8(delta); } /* diff --git a/src/test/regress/expected/brin_multi.out b/src/test/regress/expected/brin_multi.out index c18d9764c1..465f93f55f 100644 --- a/src/test/regress/expected/brin_multi.out +++ b/src/test/regress/expected/brin_multi.out @@ -836,5 +836,25 @@ SELECT '294276-12-01 00:00:01'::timestamptz + (i || ' seconds')::interval FROM generate_series(1,30) s(i); CREATE INDEX ON brin_timestamp_test USING brin (a timestamptz_minmax_multi_ops) WITH (pages_per_range=1); DROP TABLE brin_timestamp_test; +-- test overflows during CREATE INDEX with extreme date values +CREATE TABLE brin_date_test(a DATE); +-- insert values close to date minimum +INSERT INTO brin_date_test SELECT '4713-01-01 BC'::date + i FROM generate_series(1, 30) s(i); +-- insert values close to date minimum +INSERT INTO brin_date_test SELECT '5874897-12-01'::date + i FROM generate_series(1, 30) s(i); +CREATE INDEX ON brin_date_test USING brin (a date_minmax_multi_ops) WITH (pages_per_range=1); +SET enable_seqscan = off; +-- make sure the ranges were built correctly and 2023-01-01 eliminates all +EXPLAIN (ANALYZE, TIMING OFF, COSTS OFF, SUMMARY OFF) +SELECT * FROM brin_date_test WHERE a = '2023-01-01'::date; + QUERY PLAN +------------------------------------------------------------------------- + Bitmap Heap Scan on brin_date_test (actual rows=0 loops=1) + Recheck Cond: (a = '2023-01-01'::date) + -> Bitmap Index Scan on brin_date_test_a_idx (actual rows=0 loops=1) + Index Cond: (a = '2023-01-01'::date) +(4 rows) + +DROP TABLE brin_date_test; RESET enable_seqscan; RESET datestyle; diff --git a/src/test/regress/sql/brin_multi.sql b/src/test/regress/sql/brin_multi.sql index 847bb5aa01..88ccf0bc65 100644 --- a/src/test/regress/sql/brin_multi.sql +++ b/src/test/regress/sql/brin_multi.sql @@ -605,5 +605,23 @@ SELECT '294276-12-01 00:00:01'::timestamptz + (i || ' seconds')::interval CREATE INDEX ON brin_timestamp_test USING brin (a timestamptz_minmax_multi_ops) WITH (pages_per_range=1); DROP TABLE brin_timestamp_test; +-- test overflows during CREATE INDEX with extreme date values +CREATE TABLE brin_date_test(a DATE); + +-- insert values close to date minimum +INSERT INTO brin_date_test SELECT '4713-01-01 BC'::date + i FROM generate_series(1, 30) s(i); + +-- insert values close to date minimum +INSERT INTO brin_date_test SELECT '5874897-12-01'::date + i FROM generate_series(1, 30) s(i); + +CREATE INDEX ON brin_date_test USING brin (a date_minmax_multi_ops) WITH (pages_per_range=1); + +SET enable_seqscan = off; + +-- make sure the ranges were built correctly and 2023-01-01 eliminates all +EXPLAIN (ANALYZE, TIMING OFF, COSTS OFF, SUMMARY OFF) +SELECT * FROM brin_date_test WHERE a = '2023-01-01'::date; + +DROP TABLE brin_date_test; RESET enable_seqscan; RESET datestyle; -- 2.39.5