Fang-Yu Rao created IMPALA-11668:
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Summary: Investigate whether Impala's frontend could still use the
statistics for an empty table with greater-than-zero file size
Key: IMPALA-11668
URL: https://issues.apache.org/jira/browse/IMPALA-11668
Project: IMPALA
Issue Type: Improvement
Components: Frontend
Reporter: Fang-Yu Rao
Assignee: Fang-Yu Rao
In IMPALA-11666, it has been shown that it's possible to create a transactional
ORC table with 0 row but greater-than-zero file size even though there is no
corrupt statistics.
Impala's frontend in this case would compute an estimated number of rows
instead of using the accurate number of rows (0 in this case) in
[HdfsScanNode()#getStatsNumRows()|https://github.com/apache/impala/blob/master/fe/src/main/java/org/apache/impala/planner/HdfsScanNode.java#L1575].
As a result, the returned number of rows is not accurate.
It would be good if Impala's frontend could determine whether or not there is
indeed corrupt statistics associated with a table when its number of row is 0
and its associated file size is greater than 0.
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