Gabor Kaszab created IMPALA-8809:
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Summary: Refresh a subset of partitions for ACID tables
Key: IMPALA-8809
URL: https://issues.apache.org/jira/browse/IMPALA-8809
Project: IMPALA
Issue Type: Improvement
Affects Versions: Impala 3.3.0
Reporter: Gabor Kaszab
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partition-level writeIds and reload only the ones that are out-of-date locally.
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