From: Tom Lane Date: Sat, 4 Apr 2009 04:53:34 +0000 (+0000) Subject: Rewrite interval_hash() so that the hashcodes are equal for values that X-Git-Tag: REL8_3_8~66 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=fd8589c1f81fd9497b22e5b051426580b3e42910;p=postgresql 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". --- diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c index 5a08e584d9..74b56631ae 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 1.184.2.1 2008/07/07 18:09:53 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.184.2.2 2009/04/04 04:53:34 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -2029,32 +2029,36 @@ 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); } @@ -2121,31 +2125,28 @@ interval_cmp(PG_FUNCTION_ARGS) PG_RETURN_INT32(interval_cmp_internal(interval1, interval2)); } +/* + * 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; - uint32 mhash; - /* - * To avoid any problems with padding bytes in the struct, we figure the - * field hashes separately and XOR them. This also provides a convenient - * framework for dealing with the fact that the time field might be either - * double or int64. - */ #ifdef HAVE_INT64_TIMESTAMP thash = DatumGetUInt32(DirectFunctionCall1(hashint8, - Int64GetDatumFast(key->time))); + Int64GetDatumFast(span))); #else thash = DatumGetUInt32(DirectFunctionCall1(hashfloat8, - Float8GetDatumFast(key->time))); + Float8GetDatumFast(span))); #endif - thash ^= DatumGetUInt32(hash_uint32(key->day)); - /* Shift so "k days" and "k months" don't hash to the same thing */ - mhash = DatumGetUInt32(hash_uint32(key->month)); - thash ^= mhash << 24; - thash ^= mhash >> 8; + PG_RETURN_UINT32(thash); } diff --git a/src/test/regress/expected/interval.out b/src/test/regress/expected/interval.out index 72a031df5f..5f3531430b 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 d081bf1ffe..3541d68cc8 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;