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From "Alex Behm (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-5304: reduce transfer of Parquet decompression buffers
Date Fri, 12 May 2017 20:53:34 GMT
Alex Behm has posted comments on this change.

Change subject: IMPALA-5304: reduce transfer of Parquet decompression buffers

Patch Set 2:

File be/src/exec/

Line 1029: Status BaseScalarColumnReader::ReadDataPage() {
> We already do that in HdfsParquetScanner::InitColumns() if the file is comp
Ahh right. Thanks.

Line 1037:     decompressed_data_pool_->FreeAll();
> You mean Clear()? I don't want to make that change - it's really difficult 
Makes sense. We could selectively Clear() and FreeAll() depending on the uncompressed_size
of the page and the allocated bytes in the mempool (I think we can safely assume the mempool
only has a single chunk). Change seems easy enough, but fine with me if you want to defer.
File be/src/exec/parquet-column-readers.h:

Line 476:         && slot_desc_ != nullptr && slot_desc_->type().IsVarLenType();
I think checking IsStringType() is more accurate because IsVarLenType() includes collection
types which are not really var len in the sense used here.

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Gerrit-MessageType: comment
Gerrit-Change-Id: I2dbd749f43078b222ff8e1ddcec840986c466de6
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <>
Gerrit-Reviewer: Alex Behm <>
Gerrit-Reviewer: Michael Ho <>
Gerrit-Reviewer: Tim Armstrong <>
Gerrit-HasComments: Yes

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