Selina Zhang created HIVE-10596:
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Summary: Further optimize metadata only query
Key: HIVE-10596
URL: https://issues.apache.org/jira/browse/HIVE-10596
Project: Hive
Issue Type: Improvement
Components: Query Planning
Reporter: Selina Zhang
Assignee: Selina Zhang
Currently with NullScan optimizer we skip the full table scan for metadata only
query. However, further step can be taken: writing metadata info to a HDFS temp
file and replace the original table info with the temp table info. In this way
we will not calculate the mapper number according the original files. Users
like to run metadata only query for facts table; calculates splits and
allocates resources for this type of query seems unnecessary.
We had this patch and it has been running for a while. Will upload it soon.
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