[jira] [Created] (PARQUET-128) Optimize the parquet RecordReader implementation when filterpredicate is pushed down

["Yash Datta (JIRA)" <ji...@apache.org>]

Yash Datta created PARQUET-128:
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             Summary: Optimize the parquet RecordReader implementation when filterpredicate is pushed down 
                 Key: PARQUET-128
                 URL: https://issues.apache.org/jira/browse/PARQUET-128
             Project: Parquet
          Issue Type: Improvement
          Components: parquet-mr
    Affects Versions: 1.6.0rc2
            Reporter: Yash Datta
             Fix For: parquet-mr_1.6.0


The RecordReader implementation currently will read all the columns before applying the filter predicate and deciding whether to keep the row or discard it.
We can have a RecordReader which will only assemble the columns on which filters are applied (which are usually a few), then apply the filter and decide whether to keep the row or not , and then goes on to assemble the remaining columns or skip the remaining columns accordingly.

The performance improvement by this change is seen to be significant , and is better in case smaller number of rows are returned by filtering (which is usually the case) and there are many number of columns



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