Karen Coppage created HIVE-24302:
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             Summary: Cleaner should not mark compaction queue entry as cleaned 
if it doesn't remove obsolete files
                 Key: HIVE-24302
                 URL: https://issues.apache.org/jira/browse/HIVE-24302
             Project: Hive
          Issue Type: Bug
            Reporter: Karen Coppage
            Assignee: Karen Coppage


Example:
 # open txn 5, leave it open (maybe it's a long-running compaction)
 # insert into table t in txns 6, 7 with writeids 1, 2
 # compactor.Worker runs on table t and compacts writeids 1, 2
 # compactor.Cleaner picks up the compaction queue entry, but doesn't delete 
any files because the min global open txnid is 5, which cannot see writeIds 1, 
2.
 # Cleaner marks the compactor queue entry as cleaned and removes the entry 
from the queue.

delta_1 and delta_2 will remain in the file system until another compaction is 
run on table t.

Step 5 should not happen, we should skip calling markCleaned() and leave it in 
the queue in "ready to clean" state. MarkCleaned() should be called only after 
txn 5 is closed and, following that, the cleaner runs successfully.

This will potentially slow down the cleaner, but on the other hand it won't 
silently "fail" i.e. not do its job.



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