junegunn commented on code in PR #8001:
URL: https://github.com/apache/hbase/pull/8001#discussion_r3036328156
##########
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/querymatcher/NormalUserScanQueryMatcher.java:
##########
@@ -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:
So here it is:
```ruby
# The minimum timestamp of GET and SCAN will be set to this value
future = (Time.now.to_i + 3600) * 1000
benchmark(:DeleteColumnOldTimestamps, future) do |i|
T.put(Put.new(ROW).addColumn(CF, CQ, future, VALUE)) if i.zero?
T.delete(DC)
flush 't' if (i % 100_000).zero? && i.positive?
end
```
- This benchmark code will `setTimeRange(future, MAX)` both for GET and SCAN
- If we don't put an actual cell within the range, the scanner will be
skipped entirely, so we "put" with the future timestamp
This is a very contrived scenario, to be honest, but anyway, moving the
block out of `includeDeleteMarker` condition (`HBASE-29039-alt-n10-mod`) helps
a lot in this case.
<img width="2304" height="1920" alt="image"
src="https://github.com/user-attachments/assets/ba5782c2-19ff-4967-8db7-31ee7335d8fa";
/>
I updated the code and added a test case in 5b8afdc0fe.
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