[IMPALA-8809] Refresh a subset of partitions for ACID tables

• Type: Improvement
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Affects Version/s: Impala 3.3.0
• Component/s: Frontend
• Labels: impala-acid
• Epic Color: ghx-label-2
• Assignee: Unassigned
• Reporter: Gabor Kaszab
• Created: 30/Jul/19 15:30
• Updated: 09/Apr/24 09:18

Description

Enhancing REFRESH logic to handle ACID tables was covered by this change: https://issues.apache.org/jira/browse/IMPALA-8600
Basically each user initiated REFRESH PARTITION is rejected meanwhile the REFRESH_PARTITION event in event processor are actually doing a full table load for ACID tables.

There is room for improvement: When a full table refresh is being executed on an ACID table we can have 2 scenarios:

• If there was some schema changes then reload the full table. Identify such a scenario should be possible by checking the table-level writeId. However, there is a bug in Hive that it doesn't update that field for partitioned tables (https://issues.apache.org/jira/browse/HIVE-22062). This would be the desired way but could also be workarounded by checking other fields lik lastDdlChanged or such.
• If a full table refresh is not needed then we should fetch the partition-level writeIds and reload only the ones that are out-of-date locally.

Issue Links

• Blocked: HIVE-22062 WriteId is not updated for a partitioned ACID table when schema changes