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Commitd1740e1

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Fix calculation in brin_minmax_multi_distance_date
When calculating the distance between date values, make sure to subtractthem in the right order, i.e. (larger - smaller).The distance is used to determine which values to merge, and is expectedto be a positive value. The code unfortunately did the subtraction inthe opposite order, i.e. (smaller - larger), thus producing negativevalues and merging values the most distant values first.The resulting index is correct (i.e. produces correct results), but maybe significantly less efficient. This affects all minmax-multi indexeson date columns.Backpatch to 14, where minmax-multi indexes were introduced.Reported-by: Ashutosh BapatReviewed-by: Ashutosh Bapat, Dean RasheedBackpatch-through: 14Discussion:https://postgr.es/m/eef0ea8c-4aaa-8d0d-027f-58b1f35dd170@enterprisedb.com
1 parent90c4da6 commitd1740e1

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3 files changed

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3 files changed

+44
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‎src/backend/access/brin/brin_minmax_multi.c

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2075,13 +2075,18 @@ brin_minmax_multi_distance_uuid(PG_FUNCTION_ARGS)
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Datum
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brin_minmax_multi_distance_date(PG_FUNCTION_ARGS)
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{
2078+
float8delta=0;
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DateADTdateVal1=PG_GETARG_DATEADT(0);
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DateADTdateVal2=PG_GETARG_DATEADT(1);
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20812082
if (DATE_NOT_FINITE(dateVal1)||DATE_NOT_FINITE(dateVal2))
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PG_RETURN_FLOAT8(0);
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2084-
PG_RETURN_FLOAT8(dateVal1-dateVal2);
2085+
delta= (float8)dateVal2- (float8)dateVal1;
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Assert(delta >=0);
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PG_RETURN_FLOAT8(delta);
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}
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/*

‎src/test/regress/expected/brin_multi.out

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -479,5 +479,25 @@ SELECT '294276-12-01 00:00:01'::timestamptz + (i || ' seconds')::interval
479479
FROM generate_series(1,30) s(i);
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CREATE INDEX ON brin_timestamp_test USING brin (a timestamptz_minmax_multi_ops) WITH (pages_per_range=1);
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DROP TABLE brin_timestamp_test;
482+
-- test overflows during CREATE INDEX with extreme date values
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CREATE TABLE brin_date_test(a DATE);
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-- insert values close to date minimum
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INSERT INTO brin_date_test SELECT '4713-01-01 BC'::date + i FROM generate_series(1, 30) s(i);
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-- insert values close to date minimum
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INSERT INTO brin_date_test SELECT '5874897-12-01'::date + i FROM generate_series(1, 30) s(i);
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CREATE INDEX ON brin_date_test USING brin (a date_minmax_multi_ops) WITH (pages_per_range=1);
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SET enable_seqscan = off;
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-- make sure the ranges were built correctly and 2023-01-01 eliminates all
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EXPLAIN (ANALYZE, TIMING OFF, COSTS OFF, SUMMARY OFF)
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SELECT * FROM brin_date_test WHERE a = '2023-01-01'::date;
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QUERY PLAN
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-------------------------------------------------------------------------
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Bitmap Heap Scan on brin_date_test (actual rows=0 loops=1)
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Recheck Cond: (a = '2023-01-01'::date)
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-> Bitmap Index Scan on brin_date_test_a_idx (actual rows=0 loops=1)
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Index Cond: (a = '2023-01-01'::date)
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(4 rows)
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DROP TABLE brin_date_test;
482502
RESET enable_seqscan;
483503
RESET datestyle;

‎src/test/regress/sql/brin_multi.sql

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -440,5 +440,23 @@ SELECT '294276-12-01 00:00:01'::timestamptz + (i || ' seconds')::interval
440440
CREATEINDEXON brin_timestamp_test USING brin (a timestamptz_minmax_multi_ops) WITH (pages_per_range=1);
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DROPTABLE brin_timestamp_test;
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-- test overflows during CREATE INDEX with extreme date values
444+
CREATETABLEbrin_date_test(aDATE);
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-- insert values close to date minimum
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INSERT INTO brin_date_testSELECT'4713-01-01 BC'::date+ iFROM generate_series(1,30) s(i);
448+
449+
-- insert values close to date minimum
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INSERT INTO brin_date_testSELECT'5874897-12-01'::date+ iFROM generate_series(1,30) s(i);
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CREATEINDEXON brin_date_test USING brin (a date_minmax_multi_ops) WITH (pages_per_range=1);
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SET enable_seqscan= off;
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-- make sure the ranges were built correctly and 2023-01-01 eliminates all
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EXPLAIN (ANALYZE, TIMING OFF, COSTS OFF, SUMMARY OFF)
458+
SELECT*FROM brin_date_testWHERE a='2023-01-01'::date;
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460+
DROPTABLE brin_date_test;
443461
RESET enable_seqscan;
444462
RESET datestyle;

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