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https://issues.apache.org/jira/browse/HIVE-24291?focusedWorklogId=506627&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-506627
]
ASF GitHub Bot logged work on HIVE-24291:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 30/Oct/20 10:21
Start Date: 30/Oct/20 10:21
Worklog Time Spent: 10m
Work Description: deniskuzZ commented on a change in pull request #1592:
URL: https://github.com/apache/hive/pull/1592#discussion_r514997057
##########
File path:
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/txn/TxnHandler.java
##########
@@ -2228,38 +2235,45 @@ public void addWriteNotificationLog(AcidWriteEvent
acidWriteEvent)
public void performWriteSetGC() throws MetaException {
Connection dbConn = null;
Statement stmt = null;
- ResultSet rs = null;
try {
dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
stmt = dbConn.createStatement();
-
- long minOpenTxn;
- rs = stmt.executeQuery("SELECT MIN(\"TXN_ID\") FROM \"TXNS\" WHERE
\"TXN_STATE\"=" + TxnStatus.OPEN);
- if (!rs.next()) {
- throw new IllegalStateException("Scalar query returned no rows?!?!!");
- }
- minOpenTxn = rs.getLong(1);
- if (rs.wasNull()) {
- minOpenTxn = Long.MAX_VALUE;
- }
- long lowWaterMark = getOpenTxnTimeoutLowBoundaryTxnId(dbConn);
- /**
- * We try to find the highest transactionId below everything was
committed or aborted.
- * For that we look for the lowest open transaction in the TXNS and the
TxnMinTimeout boundary,
- * because it is guaranteed there won't be open transactions below that.
- */
- long commitHighWaterMark = Long.min(minOpenTxn, lowWaterMark + 1);
- LOG.debug("Perform WriteSet GC with minOpenTxn {}, lowWaterMark {}",
minOpenTxn, lowWaterMark);
+ long commitHighWaterMark = getMinOpenTxnIdWaterMark(dbConn);
Review comment:
Question to getOpenTxnTimeoutLowBoundaryTxnId. If we need min open txn
why we are doing:
SELECT MAX(TXN_ID) FROM TXNS WHERE TXN_STARTED < (sysdate -
openTxnTimeOutMillis)
shouldn't in be MIN() ?
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Issue Time Tracking
-------------------
Worklog Id: (was: 506627)
Time Spent: 1h 50m (was: 1h 40m)
> 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
> Priority: Major
> Labels: pull-request-available
> Time Spent: 1h 50m
> Remaining Estimate: 0h
>
> 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)
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