[GitHub] [flink] FangYongs commented on a diff in pull request #13081: [FLINK-18590][json] Support json array explode to multi messages

["FangYongs (via GitHub)" <gi...@apache.org>]

FangYongs commented on code in PR #13081:
URL: https://github.com/apache/flink/pull/13081#discussion_r1119548371


##########
docs/content/docs/connectors/table/formats/json.md:
##########
@@ -241,6 +241,41 @@ The following table lists the type mapping from Flink type to JSON type.
     </tbody>
 </table>
 
+Features
+--------
 
+### Allow top-level JSON Arrays
 
+Usually, we assume the top-level of json string is a json object. Then the json object is converted to one SQL row.
 
+There are some cases that, the top-level of json string is a json array, and we want to explode the array to
+multiple records, each one of the array is a json object which is converted to one row. Flink JSON Format supports
+read such data implicitly.
+
+For example, for the following SQL DDL:
+<div class="codetabs" markdown="1">
+<div data-lang="SQL" markdown="1">
+{% highlight sql %}
+CREATE TABLE user_behavior (
+  col1 BIGINT,
+  col2 DOUBLE,
+  col3 VARCHAR,
+  col4 BOOLEAN
+) WITH (
+ 'format' = 'json',
+ ...
+)
+{% endhighlight %}
+</div>
+</div>
+
+Flink JSON Format will produce 2 rows `(123, "a")` and `(456, "b")` with both of following two json string.
+The top-level is JSON Array:
+{% highlight json %}
+[{"col1": 123, "col2": "a"}, {"col1": 456, "col2": "b"}]
+{% endhighlight %}
+The top-level is JSON Object:
+{% highlight json %}
+{"col1": 123, "col2": "a"}
+{"col1": 456, "col2": "b"}

Review Comment:
   I cannot see the top-level JSON Object here, they are just two JSON Object here?



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