Revise API for partition_rbound_cmp/partition_rbound_datum_cmp.

Instead of passing the PartitionKey, pass just the required bits of
it.  This allows these functions to be used without needing the
PartitionKey to be available, which is important for several
pending patches.

Ashutosh Bapat, reviewed by Amit Langote, with a comment tweak
by me.

Discussion: http://postgr.es/m/3d835ed1-36ab-f06d-0ce8-a76a2bbf7677@lab.ntt.co.jp
Discussion: http://postgr.es/m/b4d88995-094b-320c-b614-2282fae0bf6c@lab.ntt.co.jp

src/backend/catalog/partition.c

@@ -165,10 +165,12 @@ static PartitionRangeBound *make_one_range_bound(PartitionKey key, int index,
 					 List *datums, bool lower);
 static int32 partition_hbound_cmp(int modulus1, int remainder1, int modulus2,
 					 int remainder2);
-static int32 partition_rbound_cmp(PartitionKey key,
-					 Datum *datums1, PartitionRangeDatumKind *kind1,
-					 bool lower1, PartitionRangeBound *b2);
-static int32 partition_rbound_datum_cmp(PartitionKey key,
+static int32 partition_rbound_cmp(int partnatts, FmgrInfo *partsupfunc,
+					 Oid *partcollation, Datum *datums1,
+					 PartitionRangeDatumKind *kind1, bool lower1,
+					 PartitionRangeBound *b2);
+static int32 partition_rbound_datum_cmp(FmgrInfo *partsupfunc,
+						   Oid *partcollation,
 						   Datum *rb_datums, PartitionRangeDatumKind *rb_kind,
 						   Datum *tuple_datums, int n_tuple_datums);
 
@@ -1113,8 +1115,9 @@ check_new_partition_bound(char *relname, Relation parent,
 				 * First check if the resulting range would be empty with
 				 * specified lower and upper bounds
 				 */
-				if (partition_rbound_cmp(key, lower->datums, lower->kind, true,
-										 upper) >= 0)
+				if (partition_rbound_cmp(key->partnatts, key->partsupfunc,
+										 key->partcollation, lower->datums,
+										 lower->kind, true, upper) >= 0)
 				{
 					ereport(ERROR,
 							(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
@@ -1174,7 +1177,10 @@ check_new_partition_bound(char *relname, Relation parent,
 							kind = boundinfo->kind[offset + 1];
 							is_lower = (boundinfo->indexes[offset + 1] == -1);
 
-							cmpval = partition_rbound_cmp(key, datums, kind,
+							cmpval = partition_rbound_cmp(key->partnatts,
+														  key->partsupfunc,
+														  key->partcollation,
+														  datums, kind,
 														  is_lower, upper);
 							if (cmpval < 0)
 							{
@@ -2618,6 +2624,7 @@ get_partition_for_tuple(Relation relation, Datum *values, bool *isnull)
 																 key->partnatts,
 																 values,
 																 &equal);
+
 					/*
 					 * The bound at bound_offset is less than or equal to the
 					 * tuple value, so the bound at offset+1 is the upper
@@ -2811,7 +2818,9 @@ qsort_partition_rbound_cmp(const void *a, const void *b, void *arg)
 	PartitionRangeBound *b2 = (*(PartitionRangeBound *const *) b);
 	PartitionKey key = (PartitionKey) arg;
 
-	return partition_rbound_cmp(key, b1->datums, b1->kind, b1->lower, b2);
+	return partition_rbound_cmp(key->partnatts, key->partsupfunc,
+								key->partcollation, b1->datums, b1->kind,
+								b1->lower, b2);
 }
 
 /*
@@ -2820,6 +2829,10 @@ qsort_partition_rbound_cmp(const void *a, const void *b, void *arg)
  * Return for two range bounds whether the 1st one (specified in datums1,
  * kind1, and lower1) is <, =, or > the bound specified in *b2.
  *
+ * partnatts, partsupfunc and partcollation give the number of attributes in the
+ * bounds to be compared, comparison function to be used and the collations of
+ * attributes, respectively.
+ *
  * Note that if the values of the two range bounds compare equal, then we take
  * into account whether they are upper or lower bounds, and an upper bound is
  * considered to be smaller than a lower bound. This is important to the way
@@ -2828,7 +2841,7 @@ qsort_partition_rbound_cmp(const void *a, const void *b, void *arg)
  * two contiguous partitions.
  */
 static int32
-partition_rbound_cmp(PartitionKey key,
+partition_rbound_cmp(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 					 Datum *datums1, PartitionRangeDatumKind *kind1,
 					 bool lower1, PartitionRangeBound *b2)
 {
@@ -2838,7 +2851,7 @@ partition_rbound_cmp(PartitionKey key,
 	PartitionRangeDatumKind *kind2 = b2->kind;
 	bool		lower2 = b2->lower;
 
-	for (i = 0; i < key->partnatts; i++)
+	for (i = 0; i < partnatts; i++)
 	{
 		/*
 		 * First, handle cases where the column is unbounded, which should not
@@ -2859,8 +2872,8 @@ partition_rbound_cmp(PartitionKey key,
 			 */
 			break;
 
-		cmpval = DatumGetInt32(FunctionCall2Coll(&key->partsupfunc[i],
-												 key->partcollation[i],
+		cmpval = DatumGetInt32(FunctionCall2Coll(&partsupfunc[i],
+												 partcollation[i],
 												 datums1[i],
 												 datums2[i]));
 		if (cmpval != 0)
@@ -2884,9 +2897,14 @@ partition_rbound_cmp(PartitionKey key,
  *
  * Return whether range bound (specified in rb_datums, rb_kind, and rb_lower)
  * is <, =, or > partition key of tuple (tuple_datums)
+ *
+ * n_tuple_datums, partsupfunc and partcollation give number of attributes in
+ * the bounds to be compared, comparison function to be used and the collations
+ * of attributes resp.
+ *
  */
 static int32
-partition_rbound_datum_cmp(PartitionKey key,
+partition_rbound_datum_cmp(FmgrInfo *partsupfunc, Oid *partcollation,
 						   Datum *rb_datums, PartitionRangeDatumKind *rb_kind,
 						   Datum *tuple_datums, int n_tuple_datums)
 {
@@ -2900,8 +2918,8 @@ partition_rbound_datum_cmp(PartitionKey key,
 		else if (rb_kind[i] == PARTITION_RANGE_DATUM_MAXVALUE)
 			return 1;
 
-		cmpval = DatumGetInt32(FunctionCall2Coll(&key->partsupfunc[i],
-												 key->partcollation[i],
+		cmpval = DatumGetInt32(FunctionCall2Coll(&partsupfunc[i],
+												 partcollation[i],
 												 rb_datums[i],
 												 tuple_datums[i]));
 		if (cmpval != 0)
@@ -2978,7 +2996,8 @@ partition_range_bsearch(PartitionKey key,
 		int32		cmpval;
 
 		mid = (lo + hi + 1) / 2;
-		cmpval = partition_rbound_cmp(key,
+		cmpval = partition_rbound_cmp(key->partnatts, key->partsupfunc,
+									  key->partcollation,
 									  boundinfo->datums[mid],
 									  boundinfo->kind[mid],
 									  (boundinfo->indexes[mid] == -1),
@@ -3022,7 +3041,8 @@ partition_range_datum_bsearch(PartitionKey key,
 		int32		cmpval;
 
 		mid = (lo + hi + 1) / 2;
-		cmpval = partition_rbound_datum_cmp(key,
+		cmpval = partition_rbound_datum_cmp(key->partsupfunc,
+											key->partcollation,
 											boundinfo->datums[mid],
 											boundinfo->kind[mid],
 											values,