wuchong commented on a change in pull request #12303:
URL: https://github.com/apache/flink/pull/12303#discussion_r435244412
##########
File path:
flink-table/flink-table-runtime-blink/src/main/java/org/apache/flink/table/runtime/operators/rank/AppendOnlyTopNFunction.java
##########
@@ -210,14 +210,19 @@ private void processElementWithoutRowNumber(RowData
input, Collector<RowData> ou
RowData lastKey = lastEntry.getKey();
List<RowData> lastList = (List<RowData>)
lastEntry.getValue();
// remove last one
- RowData lastElement = lastList.remove(lastList.size() -
1);
- if (lastList.isEmpty()) {
+ int size = lastList.size();
+ RowData lastElement = null;
+ if (size > 0) {
+ lastElement = lastList.get(size - 1);
Review comment:
Remove on the list use index will be more efficient than `buffer.remove`.
##########
File path:
flink-table/flink-table-runtime-blink/src/main/java/org/apache/flink/table/runtime/operators/rank/AppendOnlyTopNFunction.java
##########
@@ -210,14 +210,19 @@ private void processElementWithoutRowNumber(RowData
input, Collector<RowData> ou
RowData lastKey = lastEntry.getKey();
List<RowData> lastList = (List<RowData>)
lastEntry.getValue();
// remove last one
- RowData lastElement = lastList.remove(lastList.size() -
1);
- if (lastList.isEmpty()) {
+ int size = lastList.size();
+ RowData lastElement = null;
+ if (size > 0) {
+ lastElement = lastList.get(size - 1);
+ }
+ if (size <= 1) {
buffer.removeAll(lastKey);
dataState.remove(lastKey);
} else {
+ buffer.remove(lastKey, lastElement);
dataState.put(lastKey, lastList);
Review comment:
```suggestion
dataState.put(lastKey, new
ArrayList<>(lastList));
```
We should do a shallow copy for the `lastList`, see FLINK-17918.
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