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authorTomas Vondra2023-10-27 15:57:11 +0000
committerTomas Vondra2023-10-27 16:15:37 +0000
commit394d51731495794655f95b5580adb757d7a9bbe2 (patch)
treea6b424108cf83140d5ad9974aa547f5d17d7b7fb
parentb5489b75c6ce9517ab5f9d6f1d98bc928f6d5bd5 (diff)
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
-rw-r--r--src/backend/access/brin/brin_minmax_multi.c7
-rw-r--r--src/test/regress/expected/brin_multi.out20
-rw-r--r--src/test/regress/sql/brin_multi.sql18
3 files changed, 44 insertions, 1 deletions
diff --git a/src/backend/access/brin/brin_minmax_multi.c b/src/backend/access/brin/brin_minmax_multi.c
index 8c72a0a0366..7e63dda14f4 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 c18d9764c1c..465f93f55f1 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 847bb5aa016..88ccf0bc654 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;