gustavodemorais commented on code in PR #28688:
URL: https://github.com/apache/flink/pull/28688#discussion_r3630790690
##########
docs/data/sql_functions.yml:
##########
@@ -1223,7 +1218,51 @@ json:
-- [{"nested_json":{"value":42}}]
JSON_ARRAY(JSON('{"nested_json": {"value": 42}}'))
```
-
+ - sql: JSON_LENGTH(json_doc[, path])
+ table: jsonLength(jsonObject[, path])
+ description: |
+ Returns the number of elements in a JSON document, or the length of the
value at the specified path if one is provided.
+ Returns NULL if the argument is NULL, the json is invalid, or the path
does not locate a value.
+ eg.
+ -- 2
+ JSON_LENGTH('{"1": "hello", "2": "bye bye"}')
+
+ -- 5
+ JSON_LENGTH('[1,2,3,4,5]')
+
+ -- 1
+ JSON_LENGTH('"hello"')
+
+ -- 1
+ JSON_LENGTH('{"1": "hello", "2": "bye bye"}', '$.2')
+
+ -- NULL
+ JSON_LENGTH('{"1": "hello", "2": "BAD SYNTAX ->"', '$.2')
+
+
+ The length is determined as follows:
+
+ - Scalar values (number, string, boolean): has length 1.
+ - Array: has a length equal to the number of its elements.
+ - Object: has a length equal to the number of its key-value pairs.
+
+ The path argument uses the form:
+
+ path ::= '$' ( '.' `field` | '[' `index` ']' )*
+ field ::= a key in a JSON object
+ index ::= a zero-based position in a JSON array
+
+ For example: `$.author.address` or `$.metadata.tags[0]`.
Review Comment:
Path is reused in multiple json functions and not specific for this
function. Just checked the docs and we already have some documentation on it at
the top `The special character $ denotes the root node in a JSON path. Paths
can access properties ($.a), array elements ($.a[0].b), or branch over all
elements in an array ($.a[*].b).`
If you want to improve that, change it there so it's visible for all
functions. Otherwise, just delete it from here
```suggestion
```
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