1 files changed, 106 insertions, 0 deletions

diff --git a/src/backend/utils/adt/multirangetypes.c b/src/backend/utils/adt/multirangetypes.c
index fbcc27d0726..fbbda4af36d 100644
--- a/src/backend/utils/adt/multirangetypes.c
+++ b/src/backend/utils/adt/multirangetypes.c
@@ -34,6 +34,7 @@
 
 #include "access/tupmacs.h"
 #include "common/hashfn.h"
+#include "funcapi.h"
 #include "lib/stringinfo.h"
 #include "libpq/pqformat.h"
 #include "miscadmin.h"
@@ -1068,6 +1069,39 @@ multirange_constructor0(PG_FUNCTION_ARGS)
 	PG_RETURN_MULTIRANGE_P(make_multirange(mltrngtypid, rangetyp, 0, NULL));
 }
 
+/*
+ * Cast multirange to an array of ranges.
+ */
+Datum
+multirange_to_array(PG_FUNCTION_ARGS)
+{
+	ArrayBuildState *astate = NULL;
+	MultirangeType *mr = PG_GETARG_MULTIRANGE_P(0);
+	TypeCacheEntry *typcache;
+	int			i;
+
+	typcache = multirange_get_typcache(fcinfo, MultirangeTypeGetOid(mr));
+
+	astate = initArrayResult(typcache->rngtype->type_id,
+							 CurrentMemoryContext,
+							 false);
+
+	for (i = 0; i < mr->rangeCount; i++)
+	{
+		RangeType  *r;
+
+		r = multirange_get_range(typcache->rngtype, mr, i);
+		astate = accumArrayResult(astate,
+								  RangeTypePGetDatum(r),
+								  false,
+								  typcache->rngtype->type_id,
+								  CurrentMemoryContext);
+	}
+
+	PG_RETURN_ARRAYTYPE_P(makeArrayResult(astate, CurrentMemoryContext));
+}
+
+
 
 /* multirange, multirange -> multirange type functions */
 
@@ -2645,6 +2679,78 @@ range_merge_from_multirange(PG_FUNCTION_ARGS)
 	PG_RETURN_RANGE_P(result);
 }
 
+/* Turn multirange into a set of ranges */
+Datum
+multirange_unnest(PG_FUNCTION_ARGS)
+{
+	typedef struct
+	{
+		MultirangeType *mr;
+		TypeCacheEntry *typcache;
+		int			index;
+	} multirange_unnest_fctx;
+
+	FuncCallContext *funcctx;
+	multirange_unnest_fctx *fctx;
+	MemoryContext oldcontext;
+
+	/* stuff done only on the first call of the function */
+	if (SRF_IS_FIRSTCALL())
+	{
+		MultirangeType *mr;
+
+		/* create a function context for cross-call persistence */
+		funcctx = SRF_FIRSTCALL_INIT();
+
+		/*
+		 * switch to memory context appropriate for multiple function calls
+		 */
+		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+		/*
+		 * Get the multirange value and detoast if needed.  We can't do this
+		 * earlier because if we have to detoast, we want the detoasted copy
+		 * to be in multi_call_memory_ctx, so it will go away when we're done
+		 * and not before.  (If no detoast happens, we assume the originally
+		 * passed multirange will stick around till then.)
+		 */
+		mr = PG_GETARG_MULTIRANGE_P(0);
+
+		/* allocate memory for user context */
+		fctx = (multirange_unnest_fctx *) palloc(sizeof(multirange_unnest_fctx));
+
+		/* initialize state */
+		fctx->mr = mr;
+		fctx->index = 0;
+		fctx->typcache = lookup_type_cache(MultirangeTypeGetOid(mr),
+										   TYPECACHE_MULTIRANGE_INFO);
+
+		funcctx->user_fctx = fctx;
+		MemoryContextSwitchTo(oldcontext);
+	}
+
+	/* stuff done on every call of the function */
+	funcctx = SRF_PERCALL_SETUP();
+	fctx = funcctx->user_fctx;
+
+	if (fctx->index < fctx->mr->rangeCount)
+	{
+		RangeType  *range;
+
+		range = multirange_get_range(fctx->typcache->rngtype,
+									 fctx->mr,
+									 fctx->index);
+		fctx->index++;
+
+		SRF_RETURN_NEXT(funcctx, RangeTypePGetDatum(range));
+	}
+	else
+	{
+		/* do when there is no more left */
+		SRF_RETURN_DONE(funcctx);
+	}
+}
+
 /* Hash support */
 
 /* hash a multirange value */