Boaz Ben-Zvi created DRILL-7069:
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             Summary: Poor performance of transformBinaryInMetadataCache
                 Key: DRILL-7069
                 URL: https://issues.apache.org/jira/browse/DRILL-7069
             Project: Apache Drill
          Issue Type: Improvement
          Components: Metadata
    Affects Versions: 1.15.0
            Reporter: Boaz Ben-Zvi
            Assignee: Boaz Ben-Zvi
             Fix For: 1.16.0


The performance of the method *transformBinaryInMetadataCache* scales poorly as 
the table's numbers of underlying files, row-groups and columns grow. This 
method is invoked during planning of every query using this table.

     A test on a table using 219 directories (each with 20 files), 1 row-group 
in each file, and 94 columns, measured about *1340 milliseconds*.

    The main culprit are the version checks, which take place in *every 
iteration* (i.e., about 400k times in the previous example) and involve 
construction of 6 MetadataVersion objects (and possibly garbage collections).

     Removing the version checks from the loops improved this method's 
performance on the above test down to about *250 milliseconds*.

 



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