godfreyhe commented on code in PR #21789:
URL: https://github.com/apache/flink/pull/21789#discussion_r1101023309
##########
docs/content.zh/docs/connectors/table/hive/hive_functions.md:
##########
@@ -73,6 +73,34 @@ Some Hive built-in functions in older versions have [thread
safety issues](https
We recommend users patch their own Hive to fix them.
{{< /hint >}}
+## Use Native Hive Aggregate Functions
+
+If [HiveModule]({{< ref "docs/dev/table/modules" >}}#hivemodule) is loaded
with a higher priority than CoreModule, Flink will try to use the Hive built-in
function first. And then for Hive built-in aggregation function,
+Flink currently uses sort-based aggregation strategy. Compared to hash-based
aggregation strategy, the performance is one to two times worse, so from Flink
1.17, we have implemented some of Hive's aggregation functions natively in
Flink.
Review Comment:
If no specific scenario is given, it is best not to give specific
performance results here.
##########
docs/content.zh/docs/connectors/table/hive/hive_functions.md:
##########
@@ -73,6 +73,34 @@ Some Hive built-in functions in older versions have [thread
safety issues](https
We recommend users patch their own Hive to fix them.
{{< /hint >}}
+## Use Native Hive Aggregate Functions
+
+If [HiveModule]({{< ref "docs/dev/table/modules" >}}#hivemodule) is loaded
with a higher priority than CoreModule, Flink will try to use the Hive built-in
function first. And then for Hive built-in aggregation function,
+Flink currently uses sort-based aggregation strategy. Compared to hash-based
aggregation strategy, the performance is one to two times worse, so from Flink
1.17, we have implemented some of Hive's aggregation functions natively in
Flink.
+These functions will use the hash-agg strategy to improve performance.
Currently, only five functions are supported, namely sum/count/avg/min/max, and
more aggregation functions will be supported in the future.
Review Comment:
for the fix length agg buffer, we can use hash-agg, otherwise sort-agg will
be chosed
Another performance improvement is code gen
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