You are viewing a plain text version of this content. The canonical link for it is here.

Posted to dev@hive.apache.org by "Peter Varga (Jira)" <ji...@apache.org> on 2020/10/20 11:50:00 UTC

[jira] [Created] (HIVE-24291) Compaction Cleaner prematurely cleans up deltas

Peter Varga created HIVE-24291:
----------------------------------

             Summary: Compaction Cleaner prematurely cleans up deltas
                 Key: HIVE-24291
                 URL: https://issues.apache.org/jira/browse/HIVE-24291
             Project: Hive
          Issue Type: Bug
            Reporter: Peter Varga
            Assignee: Peter Varga


Since HIVE-23107 the cleaner can clean up deltas that are still used by running queries.

Example:
 * TxnId 1-5 writes to a partition, all commits
 * Compactor starts with txnId=6
 * Long running query starts with txnId=7, it sees txnId=6 as open in its snapshot
 * Compaction commits
 * Cleaner runs

Previously min_history_level table would have prevented the Cleaner to delete the deltas1-5 until txnId=7 is open, but now they will be deleted and the long running query may fail if its tries to access the files.



Solution could be to not run the cleaner until any txn is open that was opened before the compaction was committed (CQ_NEXT_TXN_ID)



--
This message was sent by Atlassian Jira
(v8.3.4#803005)