junegunn commented on code in PR #8001:
URL: https://github.com/apache/hbase/pull/8001#discussion_r3036225452
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hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/querymatcher/NormalUserScanQueryMatcher.java:
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@@ -70,9 +95,31 @@ public MatchCode match(ExtendedCell cell) throws IOException
{
seePastDeleteMarkers ? tr.withinTimeRange(timestamp) :
tr.withinOrAfterTimeRange(timestamp);
if (includeDeleteMarker) {
this.deletes.add(cell);
+ // A DeleteColumn or DeleteFamily masks all remaining cells for this
column/family.
+ // Seek past them instead of skipping one cell at a time, but only
after seeing
+ // enough consecutive markers for the same column to justify the seek
overhead.
+ // Only safe with plain ScanDeleteTracker. Not safe with
newVersionBehavior (sequence
+ // IDs determine visibility), visibility labels (delete/put label
mismatch), or
+ // seePastDeleteMarkers (KEEP_DELETED_CELLS).
+ if (
+ canSeekOnDeleteMarker && (typeByte ==
KeyValue.Type.DeleteFamily.getCode()
+ || (typeByte == KeyValue.Type.DeleteColumn.getCode() &&
cell.getQualifierLength() > 0))
+ ) {
+ if (lastDelete != null && !CellUtil.matchingQualifier(cell,
lastDelete)) {
+ rangeDeleteCount = 0;
+ }
+ lastDelete = cell;
+ if (++rangeDeleteCount >= SEEK_ON_DELETE_MARKER_THRESHOLD) {
+ rangeDeleteCount = 0;
+ return columns.getNextRowOrNextColumn(cell);
+ }
+ } else {
+ rangeDeleteCount = 0;
+ }
Review Comment:
Good point! I felt it was easier to reason about the code when it's inside
this block, but on second thought, it should be safe to move it out of it, and
it can actually provide performance benefit in some very rare cases. No cons I
can think of. Let me see if I can come up with a contrived benchmark scenario
to show the difference.
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