Add a cardinality function for arrays.

Unlike our other array functions, this considers the total number of
elements across all dimensions, and returns 0 rather than NULL when the
array has no elements.  But it seems that both of those behaviors are
almost universally disliked, so hopefully that's OK.

Marko Tiikkaja, reviewed by Dean Rasheed and Pavel Stehule

1 files changed, 12 insertions, 0 deletions

diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index d52101663a1..311d0c22f06 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -1740,6 +1740,18 @@ array_length(PG_FUNCTION_ARGS)
 }
 
 /*
+ * array_cardinality:
+ *		returns the total number of elements in an array
+ */
+Datum
+array_cardinality(PG_FUNCTION_ARGS)
+{
+	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	PG_RETURN_INT32(ArrayGetNItems(ARR_NDIM(v), ARR_DIMS(v)));
+}
+
+
+/*
  * array_ref :
  *	  This routine takes an array pointer and a subscript array and returns
  *	  the referenced item as a Datum.  Note that for a pass-by-reference