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From Padma Penumarthy <ppenumar...@mapr.com>
Subject Re: Parquet, Arrow, and Drill Roadmap
Date Tue, 02 May 2017 18:46:24 GMT
One thing I want to add is use_new_reader uses reader from parquet-mr library, where as
default one is drill’s native reader which is supposed to be better, performance wise.
But, it does not support complex types and we automatically switch to use reader from parquet
library
when we have to read complex types.

Thanks,
Padma


On May 2, 2017, at 11:09 AM, Jinfeng Ni <jni@apache.org<mailto:jni@apache.org>>
wrote:


- What the two readers are (is one a special drill thing, is the other  a
standard reader from the parquet project?)
- What is the eventual goal here... to be able to use and switch between
both? To provide the option? To have code parity with another project?

Both readers were for reading parquet data into Drill's value vector.
The default one (when store.parquet.use_new_reader is false) was
faster (based on measurements done by people worked on the two
readers), but it could not support complex type like map/array.  The
new reader would be used by Drill either if you change the option to
true, or when the parquet data you are querying contain complex type
(even with the default option being false). Therefore, both readers
might be used by Drill code.

There was a Parquet hackathon some time ago, which aimed to make
people in different projects using parquet work together to
standardize a vectorized reader. I did not keep track of that effort.
People with better knowledge of that may share their inputs.


- Do either of the readers work with Arrow?

For now, neither works with Arrow, since Drill has not integrated with
Arrow yet. See DRILL-4455 for the latest discussion
(https://issues.apache.org/jira/browse/DRILL-4455).  I would expect
Drill's parquet reader will work with Arrow, once the integration is
done.

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