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https://issues.apache.org/jira/browse/HIVE-12352?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15092913#comment-15092913
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Alan Gates commented on HIVE-12352:
-----------------------------------
CompactionTxnHandler, line 347:
{code}
if (info.partName != null) {
s += " and ctc_partition = '" + info.partName + "'" +
(info.highestTxnId == null ? "" : " and ctc_txnid <= " + info.highestTxnId);
}
{code}
Shouldn't that "and ctc_txnid <=... go outside this if? Don't you want it to
apply for tables and partitions?
----------------
I don't understand this code, also in CompactionTxnHandler
{code}
638 highWater = minOpenTxn == Long.MAX_VALUE ? highWater : minOpenTxn -
1;
639 return new ValidCompactorTxnList(exceptions, -1, highWater);
{code}
Why is this change necessary?
> CompactionTxnHandler.markCleaned() may delete too much
> ------------------------------------------------------
>
> Key: HIVE-12352
> URL: https://issues.apache.org/jira/browse/HIVE-12352
> Project: Hive
> Issue Type: Bug
> Components: Transactions
> Affects Versions: 1.0.0
> Reporter: Eugene Koifman
> Assignee: Eugene Koifman
> Priority: Blocker
> Attachments: HIVE-12352.patch
>
>
> Worker will start with DB in state X (wrt this partition).
> while it's working more txns will happen, against partition it's
> compacting.
> then this will delete state up to X and since then. There may be new
> delta files created
> between compaction starting and cleaning. These will not be compacted
> until more
> transactions happen. So this ideally should only delete
> up to TXN_ID that was compacted (i.e. HWM in Worker?) Then this can also
> run
> at READ_COMMITTED. So this means we'd want to store HWM in
> COMPACTION_QUEUE when
> Worker picks up the job.
> Actually the problem is even worse (but also solved using HWM as above):
> Suppose some transactions (against same partition) have started and aborted
> since the time Worker ran compaction job.
> That means there are never-compacted delta files with data that belongs to
> these aborted txns.
> Following will pick up these aborted txns.
> s = "select txn_id from TXNS, TXN_COMPONENTS where txn_id = tc_txnid and
> txn_state = '" +
> TXN_ABORTED + "' and tc_database = '" + info.dbname + "' and
> tc_table = '" +
> info.tableName + "'";
> if (info.partName != null) s += " and tc_partition = '" +
> info.partName + "'";
> The logic after that will delete relevant data from TXN_COMPONENTS and if one
> of these txns becomes empty, it will be picked up by cleanEmptyAbortedTxns().
> At that point any metadata about an Aborted txn is gone and the system will
> think it's committed.
> HWM in this case would be (in ValidCompactorTxnList)
> if(minOpenTxn > 0)
> min(highWaterMark, minOpenTxn)
> else
> highWaterMark
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