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https://issues.apache.org/jira/browse/HIVE-24403?focusedWorklogId=519148&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-519148
]
ASF GitHub Bot logged work on HIVE-24403:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 02/Dec/20 17:40
Start Date: 02/Dec/20 17:40
Worklog Time Spent: 10m
Work Description: pvargacl commented on a change in pull request #1688:
URL: https://github.com/apache/hive/pull/1688#discussion_r534357567
##########
File path:
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/txn/TxnHandler.java
##########
@@ -390,6 +404,42 @@ public void setConf(Configuration conf){
}
}
+ /**
+ * Check if min_history_level table is usable
+ * @return
+ * @throws MetaException
+ */
+ private boolean checkMinHistoryLevelTable(boolean configValue) throws
MetaException {
+ if (!configValue) {
+ // don't check it if disabled
+ return false;
+ }
+ Connection dbConn = null;
+ boolean tableExists = true;
+ try {
+ dbConn = getDbConn(Connection.TRANSACTION_READ_COMMITTED);
+ try (Statement stmt = dbConn.createStatement()) {
+ // Dummy query to see if table exists
+ try (ResultSet rs = stmt.executeQuery("SELECT
MIN(\"MHL_MIN_OPEN_TXNID\") FROM \"MIN_HISTORY_LEVEL\"")) {
Review comment:
fixed
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Issue Time Tracking
-------------------
Worklog Id: (was: 519148)
Time Spent: 3h 20m (was: 3h 10m)
> change min_history_level schema change to be compatible with previous version
> -----------------------------------------------------------------------------
>
> Key: HIVE-24403
> URL: https://issues.apache.org/jira/browse/HIVE-24403
> Project: Hive
> Issue Type: Improvement
> Components: Metastore
> Reporter: Peter Varga
> Assignee: Peter Varga
> Priority: Major
> Labels: pull-request-available
> Time Spent: 3h 20m
> Remaining Estimate: 0h
>
> In some configurations the HMS backend DB is used by HMS services with
> different versions.
> HIVE-23107 dropped the min_history_level table from the backend DB making
> the new schema version incompatible with the older HMS services.
> It is possible to modify that change to keep the compatibility
> * Keep the min_history_level table
> * Add the new fields for the compaction_queue the same way
> * Create a feature flag for min_history_level and if it is on
> * Keep the logic inserting to the table during openTxn
> * Keep the logic removing the records at commitTxn and abortTxn
> * Change the logic in the cleaner, to get the highwatermark the old way
> * But still change it to not start the cleaning before that
> * The txn_to_write_id table cleaning can work the new way in the new version
> and the old way in the old version
> * This feature flag can be automatically setup based on the existence of the
> min_history level table, this way if the table will be dropped all HMS-s can
> switch to the new functionality without restart
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