[IMPALA-11028] Table loading could fail if metastore cleans up old events

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Impala 4.1.0
• Epic Color: ghx-label-12
• Assignee: Vihang Karajgaonkar
• Reporter: Vihang Karajgaonkar
• Created: 18/Nov/21 23:32
• Updated: 02/Dec/21 16:54
• Resolved: 02/Dec/21 16:54

Description

After IMPALA-10502, Catalogd tracks the table's create event id. When the table is loaded for the first time, it updates the create event id of the table. But if the table is loaded for the first time after a long delay (after 24 hrs) it is possible the metastore cleans up old notification logs entries which are required by catalogd during the table load.

See this snippet from TableLoader.java

      if (eventId != -1 && catalog_.isEventProcessingActive()) {
        // If the eventId is not -1 it means this table was likely created by Impala.
        // However, since the load operation of the table can happen much later, it is
        // possible that the table was recreated outside Impala and hence the eventId
        // which is stored in the loaded table needs to be updated to the latest.
        // we are only interested in fetching the events if we have a valid eventId
        // for a table. For tables where eventId is unknown are not created by
        // this catalogd and hence the self-event detection logic does not apply.
        events = MetastoreEventsProcessor.getNextMetastoreEvents(catalog_, eventId,
            notificationEvent -> CreateTableEvent.CREATE_TABLE_EVENT_TYPE
                .equals(notificationEvent.getEventType())
                && notificationEvent.getDbName().equalsIgnoreCase(db.getName())
                && notificationEvent.getTableName().equalsIgnoreCase(tblName));
      }

getNextMetastoreEvents method can throw the following exception if the metastore has cleaned up older entries (by default 24 hrs). This is controlled by configuration hive.metastore.event.db.listener.timetolive on the metastore side.

I could reproduce the problem setting the following metastore configs.

hive.metastore.event.db.listener.clean.interval=10s
hive.metastore.event.db.listener.timetolive=120s

Now run the following Impala script

create table t1 (c1 int);
create table t2 (c1 int);
select sleep(240000);
create table t3 (c1 int);
select * from t1;

Issue Links

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