Add range_agg with multirange inputs

range_agg for normal ranges already existed.  A lot of code can be
shared.

Author: Paul Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Chapman Flack <chap@anastigmatix.net>
Discussion: https://www.postgresql.org/message-id/flat/007ef255-35ef-fd26-679c-f97e7a7f30c2@illuminatedcomputing.com

doc/src/sgml/func.sgml

@@ -20007,6 +20007,11 @@ SELECT NULLIF(value, '(none)') ...
          <type>anyrange</type> )
         <returnvalue>anymultirange</returnvalue>
        </para>
+       <para role="func_signature">
+        <function>range_agg</function> ( <parameter>value</parameter>
+         <type>anymultirange</type> )
+        <returnvalue>anymultirange</returnvalue>
+       </para>
        <para>
         Computes the union of the non-null input values.
        </para></entry>

src/backend/utils/adt/multirangetypes.c

@@ -1361,6 +1361,9 @@ range_agg_transfn(PG_FUNCTION_ARGS)
 
 /*
  * range_agg_finalfn: use our internal array to merge touching ranges.
+ *
+ * Shared by range_agg_finalfn(anyrange) and
+ * multirange_agg_finalfn(anymultirange).
  */
 Datum
 range_agg_finalfn(PG_FUNCTION_ARGS)
@@ -1396,6 +1399,64 @@ range_agg_finalfn(PG_FUNCTION_ARGS)
 	PG_RETURN_MULTIRANGE_P(make_multirange(mltrngtypoid, typcache->rngtype, range_count, ranges));
 }
 
+/*
+ * multirange_agg_transfn: combine adjacent/overlapping multiranges.
+ *
+ * All we do here is gather the input multiranges' ranges into an array so
+ * that the finalfn can sort and combine them.
+ */
+Datum
+multirange_agg_transfn(PG_FUNCTION_ARGS)
+{
+	MemoryContext aggContext;
+	Oid			mltrngtypoid;
+	TypeCacheEntry *typcache;
+	TypeCacheEntry *rngtypcache;
+	ArrayBuildState *state;
+
+	if (!AggCheckCallContext(fcinfo, &aggContext))
+		elog(ERROR, "multirange_agg_transfn called in non-aggregate context");
+
+	mltrngtypoid = get_fn_expr_argtype(fcinfo->flinfo, 1);
+	if (!type_is_multirange(mltrngtypoid))
+		elog(ERROR, "range_agg must be called with a multirange");
+
+	typcache = multirange_get_typcache(fcinfo, mltrngtypoid);
+	rngtypcache = typcache->rngtype;
+
+	if (PG_ARGISNULL(0))
+		state = initArrayResult(rngtypcache->type_id, aggContext, false);
+	else
+		state = (ArrayBuildState *) PG_GETARG_POINTER(0);
+
+	/* skip NULLs */
+	if (!PG_ARGISNULL(1))
+	{
+		MultirangeType *current;
+		int32		range_count;
+		RangeType **ranges;
+
+		current = PG_GETARG_MULTIRANGE_P(1);
+		multirange_deserialize(rngtypcache, current, &range_count, &ranges);
+		if (range_count == 0)
+		{
+			/*
+			 * Add an empty range so we get an empty result (not a null result).
+			 */
+			accumArrayResult(state,
+							 RangeTypePGetDatum(make_empty_range(rngtypcache)),
+							 false, rngtypcache->type_id, aggContext);
+		}
+		else
+		{
+			for (int32 i = 0; i < range_count; i++)
+				accumArrayResult(state, RangeTypePGetDatum(ranges[i]), false, rngtypcache->type_id, aggContext);
+		}
+	}
+
+	PG_RETURN_POINTER(state);
+}
+
 Datum
 multirange_intersect_agg_transfn(PG_FUNCTION_ARGS)
 {

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202203291
+#define CATALOG_VERSION_NO	202203301
 
 #endif

src/include/catalog/pg_aggregate.dat

@@ -563,6 +563,9 @@
 { aggfnoid => 'range_agg(anyrange)', aggtransfn => 'range_agg_transfn',
   aggfinalfn => 'range_agg_finalfn', aggfinalextra => 't',
   aggtranstype => 'internal' },
+{ aggfnoid => 'range_agg(anymultirange)', aggtransfn => 'multirange_agg_transfn',
+  aggfinalfn => 'multirange_agg_finalfn', aggfinalextra => 't',
+  aggtranstype => 'internal' },
 
 # json
 { aggfnoid => 'json_agg', aggtransfn => 'json_agg_transfn',

src/include/catalog/pg_proc.dat

@@ -10688,6 +10688,17 @@
   proname => 'range_agg', prokind => 'a', proisstrict => 'f',
   prorettype => 'anymultirange', proargtypes => 'anyrange',
   prosrc => 'aggregate_dummy' },
+{ oid => '8205', descr => 'aggregate transition function',
+  proname => 'multirange_agg_transfn', proisstrict => 'f', prorettype => 'internal',
+  proargtypes => 'internal anymultirange', prosrc => 'multirange_agg_transfn' },
+{ oid => '8206', descr => 'aggregate final function',
+  proname => 'multirange_agg_finalfn', proisstrict => 'f',
+  prorettype => 'anymultirange', proargtypes => 'internal anymultirange',
+  prosrc => 'range_agg_finalfn' },
+{ oid => '8207', descr => 'combine aggregate input into a multirange',
+  proname => 'range_agg', prokind => 'a', proisstrict => 'f',
+  prorettype => 'anymultirange', proargtypes => 'anymultirange',
+  prosrc => 'aggregate_dummy' },
 { oid => '4388', descr => 'range aggregate by intersecting',
   proname => 'multirange_intersect_agg_transfn', prorettype => 'anymultirange',
   proargtypes => 'anymultirange anymultirange',

src/test/regress/expected/multirangetypes.out

@@ -2784,6 +2784,67 @@ FROM    (VALUES
  {[a,f],[g,j)}
 (1 row)
 
+-- range_agg with multirange inputs
+select range_agg(nmr) from nummultirange_test;
+ range_agg 
+-----------
+ {(,)}
+(1 row)
+
+select range_agg(nmr) from nummultirange_test where false;
+ range_agg 
+-----------
+ 
+(1 row)
+
+select range_agg(null::nummultirange) from nummultirange_test;
+ range_agg 
+-----------
+ 
+(1 row)
+
+select range_agg(nmr) from (values ('{}'::nummultirange)) t(nmr);
+ range_agg 
+-----------
+ {}
+(1 row)
+
+select range_agg(nmr) from (values ('{}'::nummultirange), ('{}'::nummultirange)) t(nmr);
+ range_agg 
+-----------
+ {}
+(1 row)
+
+select range_agg(nmr) from (values ('{[1,2]}'::nummultirange)) t(nmr);
+ range_agg 
+-----------
+ {[1,2]}
+(1 row)
+
+select range_agg(nmr) from (values ('{[1,2], [5,6]}'::nummultirange)) t(nmr);
+   range_agg   
+---------------
+ {[1,2],[5,6]}
+(1 row)
+
+select range_agg(nmr) from (values ('{[1,2], [2,3]}'::nummultirange)) t(nmr);
+ range_agg 
+-----------
+ {[1,3]}
+(1 row)
+
+select range_agg(nmr) from (values ('{[1,2]}'::nummultirange), ('{[5,6]}'::nummultirange)) t(nmr);
+   range_agg   
+---------------
+ {[1,2],[5,6]}
+(1 row)
+
+select range_agg(nmr) from (values ('{[1,2]}'::nummultirange), ('{[2,3]}'::nummultirange)) t(nmr);
+ range_agg 
+-----------
+ {[1,3]}
+(1 row)
+
 --
 -- range_intersect_agg function
 --

src/test/regress/expected/opr_sanity.out

@@ -201,7 +201,8 @@ ORDER BY 1, 2;
  timestamp without time zone | timestamp with time zone
  bit                         | bit varying
  txid_snapshot               | pg_snapshot
-(4 rows)
+ anyrange                    | anymultirange
+(5 rows)
 
 SELECT DISTINCT p1.proargtypes[2]::regtype, p2.proargtypes[2]::regtype
 FROM pg_proc AS p1, pg_proc AS p2

src/test/regress/sql/multirangetypes.sql

@@ -572,6 +572,18 @@ FROM    (VALUES
           ('[h,j)'::textrange)
         ) t(r);
 
+-- range_agg with multirange inputs
+select range_agg(nmr) from nummultirange_test;
+select range_agg(nmr) from nummultirange_test where false;
+select range_agg(null::nummultirange) from nummultirange_test;
+select range_agg(nmr) from (values ('{}'::nummultirange)) t(nmr);
+select range_agg(nmr) from (values ('{}'::nummultirange), ('{}'::nummultirange)) t(nmr);
+select range_agg(nmr) from (values ('{[1,2]}'::nummultirange)) t(nmr);
+select range_agg(nmr) from (values ('{[1,2], [5,6]}'::nummultirange)) t(nmr);
+select range_agg(nmr) from (values ('{[1,2], [2,3]}'::nummultirange)) t(nmr);
+select range_agg(nmr) from (values ('{[1,2]}'::nummultirange), ('{[5,6]}'::nummultirange)) t(nmr);
+select range_agg(nmr) from (values ('{[1,2]}'::nummultirange), ('{[2,3]}'::nummultirange)) t(nmr);
+
 --
 -- range_intersect_agg function
 --