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ASF GitHub Bot logged work on HIVE-26882: ----------------------------------------- Author: ASF GitHub Bot Created on: 03/Jan/23 13:47 Start Date: 03/Jan/23 13:47 Worklog Time Spent: 10m Work Description: pvary commented on code in PR #3888: URL: https://github.com/apache/hive/pull/3888#discussion_r1060600376 ########## standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/HiveAlterHandler.java: ########## @@ -187,6 +187,16 @@ public void alterTable(RawStore msdb, Warehouse wh, String catName, String dbnam TableName.getQualified(catName, dbname, name) + " doesn't exist"); } + String expectedKey = environmentContext != null && environmentContext.getProperties() != null ? + environmentContext.getProperties().get(hive_metastoreConstants.EXPECTED_PARAMETER_KEY) : null; + String expectedValue = environmentContext != null && environmentContext.getProperties() != null ? + environmentContext.getProperties().get(hive_metastoreConstants.EXPECTED_PARAMETER_VALUE) : null; + if (expectedKey != null && expectedValue != null + && !expectedValue.equals(oldt.getParameters().get(expectedKey))) { + throw new MetaException("The table has been modified. The parameter value for key '" + expectedKey + "' is '" Review Comment: It turns out, that you have been right. We use `READ_COMMITTED` isolation level for our commits. Because of this, we could commit concurrently, and lose data. I had to set the isolation level for these transactions to `REPEATABLE_READ` explicitly. @szehon-ho and @prasanthj could you please check it if you are back from holidays? Thanks, Peter Issue Time Tracking ------------------- Worklog Id: (was: 836617) Time Spent: 1h 20m (was: 1h 10m) > Allow transactional check of Table parameter before altering the Table > ---------------------------------------------------------------------- > > Key: HIVE-26882 > URL: https://issues.apache.org/jira/browse/HIVE-26882 > Project: Hive > Issue Type: Improvement > Components: Standalone Metastore > Reporter: Peter Vary > Priority: Major > Labels: pull-request-available > Time Spent: 1h 20m > Remaining Estimate: 0h > > We should add the possibility to transactionally check if a Table parameter > is changed before altering the table in the HMS. > This would provide an alternative, less error-prone and faster way to commit > an Iceberg table, as the Iceberg table currently needs to: > - Create an exclusive lock > - Get the table metadata to check if the current snapshot is not changed > - Update the table metadata > - Release the lock > After the change these 4 HMS calls could be substituted with a single alter > table call. > Also we could avoid cases where the locks are left hanging by failed processes -- This message was sent by Atlassian Jira (v8.20.10#820010)