[IMPALA-3788] Add Kudu support for read-your-writes scan consistency

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Kudu_Impala
• Fix Version/s: Impala 2.8.0
• Component/s: Backend, Frontend
• Labels: kudu
• Target Version: Kudu_Impala
• Assignee: Matthew Jacobs
• Reporter: Mike Percy
• Created: 24/Jun/16 21:39
• Updated: 07/Dec/16 05:38
• Resolved: 07/Dec/16 05:38

Description

Impala currently distributes Kudu scan load across Kudu replicas. However, this means that it will read from replicas who may be out of date with the leader replica. This results in observable consistency abberations where the read history may be delayed from the write history.

It would be useful to provide options or keywords in Impala so that read-your-writes consistency can be achieved.

It is already possible to get this behavior with the Kudu C++ client API, so it's achievable today in Impala. See https://issues.apache.org/jira/browse/KUDU-1497 for the Kudu feature being tracked to make this API consistent across client implementations and more user friendly.