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authorTom Lane <tgl@sss.pgh.pa.us>2009-04-04 04:53:43 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2009-04-04 04:53:43 +0000
commit9462a22ab61ff49a79eeac860b66bb0dd6405266 (patch)
treef99bf2687ef18bdefc56d1967c3a69ccc9049c83
parentdf3a497603c2a6ce296ed49d10a40243068ebb19 (diff)
downloadpostgresql-9462a22ab61ff49a79eeac860b66bb0dd6405266.tar.gz
postgresql-9462a22ab61ff49a79eeac860b66bb0dd6405266.zip
Rewrite interval_hash() so that the hashcodes are equal for values that
interval_eq() considers equal. I'm not sure how that fundamental requirement escaped us through multiple revisions of this hash function, but there it is; it's been wrong since interval_hash was first written for PG 7.1. Per bug #4748 from Roman Kononov. Backpatch to all supported releases. This patch changes the contents of hash indexes for interval columns. That's no particular problem for PG 8.4, since we've broken on-disk compatibility of hash indexes already; but it will require a migration warning note in the next minor releases of all existing branches: "if you have any hash indexes on columns of type interval, REINDEX them after updating".
-rw-r--r--src/backend/utils/adt/timestamp.c66
-rw-r--r--src/test/regress/expected/interval.out13
-rw-r--r--src/test/regress/sql/interval.sql6
3 files changed, 57 insertions, 28 deletions
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index acbb2e1d2e9..2941a762488 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.169.2.2 2008/07/07 18:10:03 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.169.2.3 2009/04/04 04:53:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1728,32 +1728,36 @@ timestamptz_cmp_timestamp(PG_FUNCTION_ARGS)
*
* collate invalid interval at the end
*/
-static int
-interval_cmp_internal(Interval *interval1, Interval *interval2)
-{
#ifdef HAVE_INT64_TIMESTAMP
- int64 span1,
- span2;
+typedef int64 TimeOffset;
#else
- double span1,
- span2;
+typedef double TimeOffset;
#endif
- span1 = interval1->time;
- span2 = interval2->time;
+static inline TimeOffset
+interval_cmp_value(const Interval *interval)
+{
+ TimeOffset span;
+
+ span = interval->time;
#ifdef HAVE_INT64_TIMESTAMP
- span1 += interval1->month * INT64CONST(30) * USECS_PER_DAY;
- span1 += interval1->day * INT64CONST(24) * USECS_PER_HOUR;
- span2 += interval2->month * INT64CONST(30) * USECS_PER_DAY;
- span2 += interval2->day * INT64CONST(24) * USECS_PER_HOUR;
+ span += interval->month * INT64CONST(30) * USECS_PER_DAY;
+ span += interval->day * INT64CONST(24) * USECS_PER_HOUR;
#else
- span1 += interval1->month * ((double) DAYS_PER_MONTH * SECS_PER_DAY);
- span1 += interval1->day * ((double) HOURS_PER_DAY * SECS_PER_HOUR);
- span2 += interval2->month * ((double) DAYS_PER_MONTH * SECS_PER_DAY);
- span2 += interval2->day * ((double) HOURS_PER_DAY * SECS_PER_HOUR);
+ span += interval->month * ((double) DAYS_PER_MONTH * SECS_PER_DAY);
+ span += interval->day * ((double) HOURS_PER_DAY * SECS_PER_HOUR);
#endif
+ return span;
+}
+
+static int
+interval_cmp_internal(Interval *interval1, Interval *interval2)
+{
+ TimeOffset span1 = interval_cmp_value(interval1);
+ TimeOffset span2 = interval_cmp_value(interval2);
+
return ((span1 < span2) ? -1 : (span1 > span2) ? 1 : 0);
}
@@ -1821,20 +1825,28 @@ interval_cmp(PG_FUNCTION_ARGS)
}
/*
- * interval, being an unusual size, needs a specialized hash function.
+ * Hashing for intervals
+ *
+ * We must produce equal hashvals for values that interval_cmp_internal()
+ * considers equal. So, compute the net span the same way it does,
+ * and then hash that, using either int64 or float8 hashing.
*/
Datum
interval_hash(PG_FUNCTION_ARGS)
{
- Interval *key = PG_GETARG_INTERVAL_P(0);
+ Interval *interval = PG_GETARG_INTERVAL_P(0);
+ TimeOffset span = interval_cmp_value(interval);
+ uint32 thash;
- /*
- * Specify hash length as sizeof(double) + sizeof(int4), not as
- * sizeof(Interval), so that any garbage pad bytes in the structure won't
- * be included in the hash!
- */
- return hash_any((unsigned char *) key,
- sizeof(key->time) + sizeof(key->day) + sizeof(key->month));
+#ifdef HAVE_INT64_TIMESTAMP
+ thash = DatumGetUInt32(DirectFunctionCall1(hashint8,
+ Int64GetDatumFast(span)));
+#else
+ thash = DatumGetUInt32(DirectFunctionCall1(hashfloat8,
+ Float8GetDatumFast(span)));
+#endif
+
+ PG_RETURN_UINT32(thash);
}
/* overlaps_timestamp() --- implements the SQL92 OVERLAPS operator.
diff --git a/src/test/regress/expected/interval.out b/src/test/regress/expected/interval.out
index 72a031df5f1..5f3531430bb 100644
--- a/src/test/regress/expected/interval.out
+++ b/src/test/regress/expected/interval.out
@@ -349,3 +349,16 @@ SELECT '5.5 seconds 3 milliseconds'::interval; -- error
ERROR: invalid input syntax for type interval: "5.5 seconds 3 milliseconds"
SELECT '1:20:05 5 microseconds'::interval; -- error
ERROR: invalid input syntax for type interval: "1:20:05 5 microseconds"
+-- check that '30 days' equals '1 month' according to the hash function
+select '30 days'::interval = '1 month'::interval as t;
+ t
+---
+ t
+(1 row)
+
+select interval_hash('30 days'::interval) = interval_hash('1 month'::interval) as t;
+ t
+---
+ t
+(1 row)
+
diff --git a/src/test/regress/sql/interval.sql b/src/test/regress/sql/interval.sql
index d081bf1ffed..3541d68cc8b 100644
--- a/src/test/regress/sql/interval.sql
+++ b/src/test/regress/sql/interval.sql
@@ -126,4 +126,8 @@ SELECT '3 days 5 milliseconds'::interval;
SELECT '1 second 2 seconds'::interval; -- error
SELECT '10 milliseconds 20 milliseconds'::interval; -- error
SELECT '5.5 seconds 3 milliseconds'::interval; -- error
-SELECT '1:20:05 5 microseconds'::interval; -- error \ No newline at end of file
+SELECT '1:20:05 5 microseconds'::interval; -- error
+
+-- check that '30 days' equals '1 month' according to the hash function
+select '30 days'::interval = '1 month'::interval as t;
+select interval_hash('30 days'::interval) = interval_hash('1 month'::interval) as t;