Refactor code creating PartitionBoundInfo

The code building PartitionBoundInfo based on the constituent partition
data read from catalogs has been located in partcache.c, with a specific
set of routines dedicated to bound types, like sorting or bound data
creation.  All this logic is moved to partbounds.c and relocates all the
bound-specific logistic into it, with partition_bounds_create() as
principal entry point.

Author: Amit Langote
Reviewed-by: Michael Paquier, Álvaro Herrera
Discussion: https://postgr.es/m/3f289da8-6d10-75fe-814a-635e8b191d43@lab.ntt.co.jp

src/include/partitioning/partbounds.h

@@ -75,40 +75,14 @@ typedef struct PartitionBoundInfoData
 #define partition_bound_accepts_nulls(bi) ((bi)->null_index != -1)
 #define partition_bound_has_default(bi) ((bi)->default_index != -1)
 
-/*
- * When qsort'ing partition bounds after reading from the catalog, each bound
- * is represented with one of the following structs.
- */
-
-/* One bound of a hash partition */
-typedef struct PartitionHashBound
-{
-	int			modulus;
-	int			remainder;
-	int			index;
-} PartitionHashBound;
-
-/* One value coming from some (index'th) list partition */
-typedef struct PartitionListValue
-{
-	int			index;
-	Datum		value;
-} PartitionListValue;
-
-/* One bound of a range partition */
-typedef struct PartitionRangeBound
-{
-	int			index;
-	Datum	   *datums;			/* range bound datums */
-	PartitionRangeDatumKind *kind;	/* the kind of each datum */
-	bool		lower;			/* this is the lower (vs upper) bound */
-} PartitionRangeBound;
-
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
+extern PartitionBoundInfo partition_bounds_create(List *boundspecs,
+						PartitionKey key,
+						int **mapping);
 extern bool partition_bounds_equal(int partnatts, int16 *parttyplen,
 					   bool *parttypbyval, PartitionBoundInfo b1,
 					   PartitionBoundInfo b2);
@@ -120,14 +94,6 @@ extern void check_default_partition_contents(Relation parent,
 								 Relation defaultRel,
 								 PartitionBoundSpec *new_spec);
 
-extern PartitionRangeBound *make_one_partition_rbound(PartitionKey key, int index,
-						  List *datums, bool lower);
-extern int32 partition_hbound_cmp(int modulus1, int remainder1, int modulus2,
-					 int remainder2);
-extern int32 partition_rbound_cmp(int partnatts, FmgrInfo *partsupfunc,
-					 Oid *partcollation, Datum *datums1,
-					 PartitionRangeDatumKind *kind1, bool lower1,
-					 PartitionRangeBound *b2);
 extern int32 partition_rbound_datum_cmp(FmgrInfo *partsupfunc,
 						   Oid *partcollation,
 						   Datum *rb_datums, PartitionRangeDatumKind *rb_kind,
@@ -136,10 +102,6 @@ extern int partition_list_bsearch(FmgrInfo *partsupfunc,
 					   Oid *partcollation,
 					   PartitionBoundInfo boundinfo,
 					   Datum value, bool *is_equal);
-extern int partition_range_bsearch(int partnatts, FmgrInfo *partsupfunc,
-						Oid *partcollation,
-						PartitionBoundInfo boundinfo,
-						PartitionRangeBound *probe, bool *is_equal);
 extern int partition_range_datum_bsearch(FmgrInfo *partsupfunc,
 							  Oid *partcollation,
 							  PartitionBoundInfo boundinfo,