Alex Behm has posted comments on this change.

Change subject: Optimized ReadValueBatch() for Parquet scalar column readers.
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Patch Set 5:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/2843/5/be/src/exec/hdfs-parquet-scanner.cc
File be/src/exec/hdfs-parquet-scanner.cc:

Line 827:   bool MaterializeValueBatch(MemPool* pool, int max_values, int 
tuple_size,
> instead of calling this for !materialized && !in_collection, it makes more 
That logic is already specialized and in such cases we will stamp out row 
batches with empty tuples directly from the Parquet file metadata.

Added DCHECK and comment.


Line 1566:     valid = Get(&level);
> that's not immediately obvious from the code as is it today. it would be go
I added a comment on the LevelDecoder. Tim, can you check if the statement is 
accurate?


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Gerrit-MessageType: comment
Gerrit-Change-Id: I21fa9b050a45f2dd45cc0091ea5b008d3c0a3f30
Gerrit-PatchSet: 5
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Alex Behm <[email protected]>
Gerrit-Reviewer: Alex Behm <[email protected]>
Gerrit-Reviewer: Marcel Kornacker <[email protected]>
Gerrit-Reviewer: Mostafa Mokhtar <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-HasComments: Yes

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