[PR] HBASE-30351 ROWS_SCANNED scan metric double-counts rows passing the filter when the scan uses the joined heap [hbase]

["eomiks (via GitHub)" <gi...@apache.org>]

eomiks opened a new pull request, #8596:
URL: https://github.com/apache/hbase/pull/8596

   Fixes the ROWS_SCANNED server-side scan metric double-counting rows that pass the filter when the scan uses the joined heap, i.e. `Scan#setLoadColumnFamiliesOnDemand(true)` with a filter marking some families as non-essential (`Filter#isFamilyEssential`).
   
   `RegionScannerImpl#populateResult` increments the metric whenever the given heap finishes the current row, and `populateFromJoinedHeap` goes through the same method for the non-essential families, so a row passing the filter was counted twice (once for the store heap, once for the joined heap). The row-scanned event is now recorded only when populating from the store heap.
   
   The new test in `TestServerSideScanMetricsFromClientSide` reproduces the issue with stock filters (`SingleColumnValueFilter` with `setFilterIfMissing(true)` on a two-family table): before the fix ROWS_SCANNED reported 15 for a scan over 10 rows with 5 matching, after the fix it reports 10.
   
   Details: https://issues.apache.org/jira/browse/HBASE-30351
   


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Re: [PR] HBASE-30351 ROWS_SCANNED scan metric double-counts rows passing the filter when the scan uses the joined heap [hbase]

["junegunn (via GitHub)" <gi...@apache.org>]

junegunn merged PR #8596:
URL: https://github.com/apache/hbase/pull/8596


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