Fix minmax-multi distance for extreme interval values

When calculating distance for interval values, the code mostly mimicked
interval_mi, i.e. it built a new interval value for the difference.
That however does not work for sufficiently distant interval values,
when the difference overflows the interval range.

Instead, we can calculate the distance directly, without constructing
the intermediate (and unnecessary) interval value.

Backpatch to 14, where minmax-multi indexes were introduced.

Reported-by: Dean Rasheed
Reviewed-by: Ashutosh Bapat, Dean Rasheed
Backpatch-through: 14
Discussion: https://postgr.es/m/eef0ea8c-4aaa-8d0d-027f-58b1f35dd170@enterprisedb.com

Author: tvondra

src/backend/access/brin/brin_minmax_multi.c

@@ -2160,45 +2160,20 @@ brin_minmax_multi_distance_interval(PG_FUNCTION_ARGS)
 
 	Interval   *ia = PG_GETARG_INTERVAL_P(0);
 	Interval   *ib = PG_GETARG_INTERVAL_P(1);
-	Interval   *result;
 
 	int64		dayfraction;
 	int64		days;
 
-	result = (Interval *) palloc(sizeof(Interval));
-
-	result->month = ib->month - ia->month;
-	/* overflow check copied from int4mi */
-	if (!SAMESIGN(ib->month, ia->month) &&
-		!SAMESIGN(result->month, ib->month))
-		ereport(ERROR,
-				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-				 errmsg("interval out of range")));
-
-	result->day = ib->day - ia->day;
-	if (!SAMESIGN(ib->day, ia->day) &&
-		!SAMESIGN(result->day, ib->day))
-		ereport(ERROR,
-				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-				 errmsg("interval out of range")));
-
-	result->time = ib->time - ia->time;
-	if (!SAMESIGN(ib->time, ia->time) &&
-		!SAMESIGN(result->time, ib->time))
-		ereport(ERROR,
-				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-				 errmsg("interval out of range")));
-
 	/*
 	 * Delta is (fractional) number of days between the intervals. Assume
 	 * months have 30 days for consistency with interval_cmp_internal. We
 	 * don't need to be exact, in the worst case we'll build a bit less
 	 * efficient ranges. But we should not contradict interval_cmp.
 	 */
-	dayfraction = result->time % USECS_PER_DAY;
-	days = result->time / USECS_PER_DAY;
-	days += result->month * INT64CONST(30);
-	days += result->day;
+	dayfraction = (ib->time % USECS_PER_DAY) - (ia->time % USECS_PER_DAY);
+	days = (ib->time / USECS_PER_DAY) - (ia->time / USECS_PER_DAY);
+	days += (int64) ib->day - (int64) ia->day;
+	days += ((int64) ib->month - (int64) ia->month) * INT64CONST(30);
 
 	/* convert to double precision */
 	delta = (double) days + dayfraction / (double) USECS_PER_DAY;

src/test/regress/expected/brin_multi.out

@@ -915,3 +915,32 @@ SELECT * FROM brin_date_test WHERE a = '1900-01-01'::date;
 DROP TABLE brin_date_test;
 RESET enable_seqscan;
 RESET datestyle;
+-- test handling of overflow for interval values
+CREATE TABLE brin_interval_test(a INTERVAL);
+INSERT INTO brin_interval_test SELECT (i || ' years')::interval FROM generate_series(-178000000, -177999980) s(i);
+INSERT INTO brin_interval_test SELECT (i || ' years')::interval FROM generate_series( 177999980,  178000000) s(i);
+CREATE INDEX ON brin_interval_test USING brin (a interval_minmax_multi_ops) WITH (pages_per_range=1);
+SET enable_seqscan = off;
+EXPLAIN (ANALYZE, TIMING OFF, COSTS OFF, SUMMARY OFF)
+SELECT * FROM brin_interval_test WHERE a = '-30 years'::interval;
+                                 QUERY PLAN                                  
+-----------------------------------------------------------------------------
+ Bitmap Heap Scan on brin_interval_test (actual rows=0 loops=1)
+   Recheck Cond: (a = '@ 30 years ago'::interval)
+   ->  Bitmap Index Scan on brin_interval_test_a_idx (actual rows=0 loops=1)
+         Index Cond: (a = '@ 30 years ago'::interval)
+(4 rows)
+
+EXPLAIN (ANALYZE, TIMING OFF, COSTS OFF, SUMMARY OFF)
+SELECT * FROM brin_interval_test WHERE a = '30 years'::interval;
+                                 QUERY PLAN                                  
+-----------------------------------------------------------------------------
+ Bitmap Heap Scan on brin_interval_test (actual rows=0 loops=1)
+   Recheck Cond: (a = '@ 30 years'::interval)
+   ->  Bitmap Index Scan on brin_interval_test_a_idx (actual rows=0 loops=1)
+         Index Cond: (a = '@ 30 years'::interval)
+(4 rows)
+
+DROP TABLE brin_interval_test;
+RESET enable_seqscan;
+RESET datestyle;

src/test/regress/sql/brin_multi.sql

@@ -664,3 +664,24 @@ SELECT * FROM brin_date_test WHERE a = '1900-01-01'::date;
 DROP TABLE brin_date_test;
 RESET enable_seqscan;
 RESET datestyle;
+
+-- test handling of overflow for interval values
+CREATE TABLE brin_interval_test(a INTERVAL);
+
+INSERT INTO brin_interval_test SELECT (i || ' years')::interval FROM generate_series(-178000000, -177999980) s(i);
+
+INSERT INTO brin_interval_test SELECT (i || ' years')::interval FROM generate_series( 177999980,  178000000) s(i);
+
+CREATE INDEX ON brin_interval_test USING brin (a interval_minmax_multi_ops) WITH (pages_per_range=1);
+
+SET enable_seqscan = off;
+
+EXPLAIN (ANALYZE, TIMING OFF, COSTS OFF, SUMMARY OFF)
+SELECT * FROM brin_interval_test WHERE a = '-30 years'::interval;
+
+EXPLAIN (ANALYZE, TIMING OFF, COSTS OFF, SUMMARY OFF)
+SELECT * FROM brin_interval_test WHERE a = '30 years'::interval;
+
+DROP TABLE brin_interval_test;
+RESET enable_seqscan;
+RESET datestyle;