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Posted to issues@flink.apache.org by GitBox <gi...@apache.org> on 2022/04/27 02:45:01 UTC
[GitHub] [flink-table-store] JingsongLi commented on a diff in pull request #104: [FLINK-27336] Avoid merging when there is only one record
JingsongLi commented on code in PR #104:
URL: https://github.com/apache/flink-table-store/pull/104#discussion_r859320053
##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/mergetree/SortBufferMemTable.java:
##########
@@ -166,19 +169,31 @@ private void advanceIfNeeded() {
if (previousRow == null) {
return;
}
- mergeFunction.reset();
- mergeFunction.add(previous.getReusedKv().value());
+ boolean hasOne = true;
while (readOnce()) {
if (keyComparator.compare(
previous.getReusedKv().key(), current.getReusedKv().key())
!= 0) {
break;
}
+ // avoid merging when there is only one record
+ if (hasOne) {
+ mergeFunction.reset();
+ mergeFunction.add(previous.getReusedKv().value());
+ hasOne = false;
+ }
mergeFunction.add(current.getReusedKv().value());
swapSerializers();
}
- result = mergeFunction.getValue();
+ RowData previousValue = previous.getReusedKv().value();
+ result =
+ hasOne
+ ? mergeFunction instanceof ValueCountMergeFunction
Review Comment:
I think we can ignore that count is zero for `ValueCountMergeFunction`.
Because if there is no merge, the count should never be zero.
##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/mergetree/SortBufferMemTable.java:
##########
@@ -166,19 +169,31 @@ private void advanceIfNeeded() {
if (previousRow == null) {
return;
}
- mergeFunction.reset();
- mergeFunction.add(previous.getReusedKv().value());
+ boolean hasOne = true;
Review Comment:
`hasOne = true` -> `mergeFuncInitialized = false`?
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