Yu-Wen Lai created HIVE-23846:
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Summary: Avoid unnecessary serialization and deserialization of
bitvectors
Key: HIVE-23846
URL: https://issues.apache.org/jira/browse/HIVE-23846
Project: Hive
Issue Type: Bug
Components: Standalone Metastore
Reporter: Yu-Wen Lai
Assignee: Yu-Wen Lai
In the method *getNdvEstimator* of <datatype>*ColumnStatsDataInspector*, it
will call isSetBitVectors(), in which it serializes the bitvectors again when
we already have deserialized bitvectors _ndvEstimator_. For example, we can see
this pattern from
[LongColumnStatsDataInspector|[https://github.com/apache/hive/blob/master/standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/columnstats/cache/LongColumnStatsDataInspector.java#L106]].
This method could check if the _ndvEstimator_ is set first so that it won't
need to serialize and deserialize back.
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