Norbert Luksa has uploaded this change for review. ( 
http://gerrit.cloudera.org:8080/15051


Change subject: IMPALA-9226: Improve string allocations of the ORC scanner
......................................................................

WIP: IMPALA-9226: Improve string allocations of the ORC scanner

Currently the OrcColumnReader copies values from the
orc::StringVectorBatch one-by-one. Since ORC 1.6, the blob which
contains the pointed values is moved to the StringVectorBatch,
so we can copy it.

This commit beside the above improvement also enables the
LazyEncoding option for the ORC reader. This way, for stripes
with DICTIONARY_ENCODING[_V2], EncodedStringVectorBatch contains
the data in a dictionaryBlob from which the data can be aquired
with the given indices and lengths.

Tests:
 * TODO: performance tests.

Change-Id: If2d975946fb6f4104d8dc98895285b3a0c6bef7f
---
M be/src/exec/hdfs-orc-scanner.cc
M be/src/exec/orc-column-readers.cc
M be/src/exec/orc-column-readers.h
3 files changed, 118 insertions(+), 49 deletions(-)



  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/51/15051/1
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: If2d975946fb6f4104d8dc98895285b3a0c6bef7f
Gerrit-Change-Number: 15051
Gerrit-PatchSet: 1
Gerrit-Owner: Norbert Luksa <[email protected]>
Gerrit-Reviewer: Norbert Luksa <[email protected]>
Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]>

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