Added documentation for the json_size function

trinodb · Jun 30, 2014 · 1e12b6e · 1e12b6e
1 parent 0171c54
commit 1e12b6e
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/presto-docs/src/main/sphinx/functions/json.rst b/presto-docs/src/main/sphinx/functions/json.rst
@@ -53,3 +53,13 @@ JSON Functions
         SELECT json_array_get('[]', 0); => null
         SELECT json_array_get('["a", "b", "c"]', 10); => null
         SELECT json_array_get('["c", "b", "a"]', -10); => null
+
+.. function:: json_size(json, json_path) -> bigint
+
+    Like :func:`json_extract`, but returns the size of the value.  The size of
+    an object value is the number of fields and the size of an array is the
+    number of elements. The size of a scalar value is zero. For example: ::
+
+        SELECT json_size('{ "x": {"a": 1, "b": 2} }', '$.x'); => 2
+        SELECT json_size('{ "x": [1, 2, 3] }', '$.x'); => 2
+        SELECT json_size('{ "x": {"a": 1, "b": 2} }', '$.x.a'); => 0