[GitHub] [calcite] xy2953396112 commented on a change in pull request #2021: [CALCITE-3929] When deserialize UDAF aggregate call from json string,…

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xy2953396112 commented on a change in pull request #2021:
URL: https://github.com/apache/calcite/pull/2021#discussion_r443085303



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File path: core/src/main/java/org/apache/calcite/rel/externalize/RelJson.java
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@@ -271,7 +271,9 @@ public RelDataType toType(RelDataTypeFactory typeFactory, Object o) {
 
   public Object toJson(AggregateCall node) {
     final Map<String, Object> map = jsonBuilder.map();
-    map.put("agg", toJson(node.getAggregation()));
+    Map<String, Object> aggMap = new HashMap(toJson(node.getAggregation()));
+    aggMap.put("class", node.getAggregation().getClass().getName());

Review comment:
       Thank you for your comments. This is a problem of lack of class information during udaf serialization. When we deserialize udaf, we will try to load udaf function through class attribute[1].If we can't load SqlAggregateFunction correctly, there will be an exception when creating AggregateCall.
   [[1]](https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/externalize/RelJson.java#L680)
   




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