EungsopYoo commented on code in PR #6557:
URL: https://github.com/apache/hbase/pull/6557#discussion_r1921798704
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hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/querymatcher/NormalUserScanQueryMatcher.java:
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@@ -71,15 +84,42 @@ public MatchCode match(ExtendedCell cell) throws
IOException {
if (includeDeleteMarker) {
this.deletes.add(cell);
}
- return MatchCode.SKIP;
+ // In some cases, optimization can not be done
+ if (!canOptimizeReadDeleteMarkers()) {
+ return MatchCode.SKIP;
+ }
}
- returnCode = checkDeleted(deletes, cell);
- if (returnCode != null) {
+ // optimization when prevCell is Delete or DeleteFamilyVersion
+ if ((returnCode = checkDeletedEffectively(cell, prevCell)) != null) {
+ return returnCode;
+ }
+ if ((returnCode = checkDeleted(deletes, cell)) != null) {
return returnCode;
}
return matchColumn(cell, timestamp, typeByte);
}
+ // If prevCell is a delete marker and cell is a delete marked Put or delete
marker,
+ // it means the cell is deleted effectively.
+ // And we can do SEEK_NEXT_COL.
+ private MatchCode checkDeletedEffectively(ExtendedCell cell, ExtendedCell
prevCell) {
+ if (
+ prevCell != null && canOptimizeReadDeleteMarkers()
+ && CellUtil.matchingRowColumn(prevCell, cell) &&
CellUtil.matchingTimestamp(prevCell, cell)
+ && (PrivateCellUtil.isDeleteType(prevCell)
+ || PrivateCellUtil.isDeleteFamilyVersion(prevCell))
+ ) {
+ return MatchCode.SEEK_NEXT_COL;
+ }
+ return null;
+ }
+
+ private boolean canOptimizeReadDeleteMarkers() {
+ // for simplicity, optimization works only for these cases
+ return !seePastDeleteMarkers && scanMaxVersions == 1 &&
!visibilityLabelEnabled
+ && getFilter() == null && !(deletes instanceof
NewVersionBehaviorTracker);
+ }
Review Comment:
@virajjasani
I have reviewed Dual File Compaction you mentioned. This PR and Dual File
Compaction have something in common, especially handling delete markers. But I
think there some differences.
This PR focuses on the accumulated delete markers of the same row or cell,
but that handles delete marker of different rows or columns. And this PR can
optimize read from both of MemStore and StoreFiles, but that can optimize read
from StoreFiles only.
So I think they are complementary and can be used all together.
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