Multirange datatypes

Multiranges are basically sorted arrays of non-overlapping ranges with
set-theoretic operations defined over them.

Since v14, each range type automatically gets a corresponding multirange
datatype.  There are both manual and automatic mechanisms for naming multirange
types.  Once can specify multirange type name using multirange_type_name
attribute in CREATE TYPE.  Otherwise, a multirange type name is generated
automatically.  If the range type name contains "range" then we change that to
"multirange".  Otherwise, we add "_multirange" to the end.

Implementation of multiranges comes with a space-efficient internal
representation format, which evades extra paddings and duplicated storage of
oids.  Altogether this format allows fetching a particular range by its index
in O(n).

Statistic gathering and selectivity estimation are implemented for multiranges.
For this purpose, stored multirange is approximated as union range without gaps.
This field will likely need improvements in the future.

Catversion is bumped.

Discussion: https://postgr.es/m/CALNJ-vSUpQ_Y%3DjXvTxt1VYFztaBSsWVXeF1y6gTYQ4bOiWDLgQ%40mail.gmail.com
Discussion: https://postgr.es/m/a0b8026459d1e6167933be2104a6174e7d40d0ab.camel%40j-davis.com#fe7218c83b08068bfffb0c5293eceda0
Author: Paul Jungwirth, revised by me
Reviewed-by: David Fetter, Corey Huinker, Jeff Davis, Pavel Stehule
Reviewed-by: Alvaro Herrera, Tom Lane, Isaac Morland, David G. Johnston
Reviewed-by: Zhihong Yu, Alexander Korotkov

1 files changed, 61 insertions, 1 deletions

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 204bcd03c0b..ad92636f7f1 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -2611,6 +2611,16 @@ type_is_range(Oid typid)
 }
 
 /*
+ * type_is_multirange
+ *	  Returns true if the given type is a multirange type.
+ */
+bool
+type_is_multirange(Oid typid)
+{
+	return (get_typtype(typid) == TYPTYPE_MULTIRANGE);
+}
+
+/*
  * get_type_category_preferred
  *
  *		Given the type OID, fetch its category and preferred-type status.
@@ -3308,7 +3318,7 @@ get_namespace_name_or_temp(Oid nspid)
 		return get_namespace_name(nspid);
 }
 
-/*				---------- PG_RANGE CACHE ----------				 */
+/*				---------- PG_RANGE CACHES ----------				 */
 
 /*
  * get_range_subtype
@@ -3361,6 +3371,56 @@ get_range_collation(Oid rangeOid)
 		return InvalidOid;
 }
 
+/*
+ * get_range_multirange
+ *		Returns the multirange type of a given range type
+ *
+ * Returns InvalidOid if the type is not a range type.
+ */
+Oid
+get_range_multirange(Oid rangeOid)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache1(RANGETYPE, ObjectIdGetDatum(rangeOid));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_range rngtup = (Form_pg_range) GETSTRUCT(tp);
+		Oid			result;
+
+		result = rngtup->rngmultitypid;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return InvalidOid;
+}
+
+/*
+ * get_multirange_range
+ *		Returns the range type of a given multirange
+ *
+ * Returns InvalidOid if the type is not a multirange.
+ */
+Oid
+get_multirange_range(Oid multirangeOid)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache1(RANGEMULTIRANGE, ObjectIdGetDatum(multirangeOid));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_range rngtup = (Form_pg_range) GETSTRUCT(tp);
+		Oid			result;
+
+		result = rngtup->rngtypid;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return InvalidOid;
+}
+
 /*				---------- PG_INDEX CACHE ----------				 */
 
 /*