maheshk114 commented on a change in pull request #684: HIVE-21880 : Enable
flaky test
TestReplicationScenariosAcidTablesBootstrap.testBootstrapAcidTablesDuringIncrementalWithConcurrentWrites.
URL: https://github.com/apache/hive/pull/684#discussion_r298916973
##########
File path:
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/ObjectStore.java
##########
@@ -10000,17 +10000,25 @@ private void prepareQuotes() throws SQLException {
}
}
- private void lockForUpdate() throws MetaException {
- String selectQuery = "select \"NEXT_EVENT_ID\" from
\"NOTIFICATION_SEQUENCE\"";
- String selectForUpdateQuery = sqlGenerator.addForUpdateClause(selectQuery);
- new RetryingExecutor(conf, () -> {
- prepareQuotes();
- Query query = pm.newQuery("javax.jdo.query.SQL", selectForUpdateQuery);
- query.setUnique(true);
- // only need to execute it to get db Lock
- query.execute();
- query.closeAll();
- }).run();
+ private void lockNotificationSequenceForUpdate() throws MetaException {
+ if (sqlGenerator.getDbProduct() == DatabaseProduct.DERBY && directSql !=
null) {
+ // Derby doesn't allow FOR UPDATE to lock the row being selected (See
https://db.apache
+ // .org/derby/docs/10.1/ref/rrefsqlj31783.html) . So lock the whole
table. Since there's
+ // only one row in the table, this shouldn't cause any performance
degradation. Also we not
+ // suggest Derby to be used in production so that's fine.
+ directSql.lockDbTable("NOTIFICATION_SEQUENCE");
Review comment:
if it can have only one records ..does select for update makes any sense ?
can we make it lock table for other kind of db also ?
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