Oleksandr Diachenko created HAWQ-1404:
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Summary: PXF to leverage file-level stats of ORC file and emit
records for COUNT(*)
Key: HAWQ-1404
URL: https://issues.apache.org/jira/browse/HAWQ-1404
Project: Apache HAWQ
Issue Type: Improvement
Components: PXF
Reporter: Oleksandr Diachenko
Assignee: Ed Espino
For cases when user issues COUNT(*) queries without WHERE clause PXF should be
able to leverage file-level stats for a ORC file and emit given number of
records back to HAWQ, avoiding reading actual tuples from disk. This should be
a first step in enabling PXF to use ORC stats(file, stripe and row group
levels) so we can improve a wider range of aggregate queries.
So whenever PXF receives "count" as AGG-TYPE parameters value - it should
optimize it by emitting tuples using ORC file-level stats.
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