Index: timestamp.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/adt/timestamp.c,v
retrieving revision 1.197
diff -c -r1.197 timestamp.c
*** timestamp.c	15 Mar 2009 20:31:19 -0000	1.197
--- timestamp.c	3 Apr 2009 21:34:51 -0000
***************
*** 2047,2052 ****
--- 2047,2053 ----
  	TimeOffset	span1,
  				span2;
  
+ 	/* If you change this, see also interval_hash() */
  	span1 = interval1->time;
  	span2 = interval2->time;
  
***************
*** 2131,2158 ****
  Datum
  interval_hash(PG_FUNCTION_ARGS)
  {
! 	Interval   *key = PG_GETARG_INTERVAL_P(0);
  	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)));
  #else
  	thash = DatumGetUInt32(DirectFunctionCall1(hashfloat8,
! 											 Float8GetDatumFast(key->time)));
  #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);
  }
  
--- 2132,2162 ----
  Datum
  interval_hash(PG_FUNCTION_ARGS)
  {
! 	Interval   *interval = PG_GETARG_INTERVAL_P(0);
! 	TimeOffset	span;
  	uint32		thash;
  
  	/*
! 	 * 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.
  	 */
+ 	span = interval->time;
+ 
  #ifdef HAVE_INT64_TIMESTAMP
+ 	span += interval->month * INT64CONST(30) * USECS_PER_DAY;
+ 	span += interval->day * INT64CONST(24) * USECS_PER_HOUR;
+ 
  	thash = DatumGetUInt32(DirectFunctionCall1(hashint8,
! 											   Int64GetDatumFast(span)));
  #else
+ 	span += interval->month * ((double) DAYS_PER_MONTH * SECS_PER_DAY);
+ 	span += interval->day * ((double) HOURS_PER_DAY * SECS_PER_HOUR);
+ 
  	thash = DatumGetUInt32(DirectFunctionCall1(hashfloat8,
! 											   Float8GetDatumFast(span)));
  #endif
! 
  	PG_RETURN_UINT32(thash);
  }