Norbert Luksa has uploaded a new patch set (#7). ( 
http://gerrit.cloudera.org:8080/15051 )

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

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 acquired
with the given indices and lengths.

Tests:
 * Run ORC scanner tests (query_tests/test_scanners.py::TestOrc)
   and tpch query tests.
 * Tested performance on tpch.lineitem table with scale=25,
   running queries that selects min of string columns.
   Some results:
   col_name     | encoding | before | after | speedup
   =============================================================
   l_comment      DIRECT     16.42s   14.38s  14%
   l_shipinstruct DICTIONARY 5.26s    3.80s   32%
   l_commitdate   DICTIONARY 5.46s    5.19s   5%
   all string col BOTH       39.06s   32.18s  21%

   The queries were run on a desktop PC with MT_DOP and NUM_NODES
   set to 1.
 * Also run TPC-H queries on the TPC-H benchmark where some
   queries' runtime improved by around 10-15%, while there were
   no regression for the others.

Change-Id: If2d975946fb6f4104d8dc98895285b3a0c6bef7f
---
M be/src/exec/hdfs-orc-scanner.cc
M be/src/exec/hdfs-orc-scanner.h
M be/src/exec/orc-column-readers.cc
M be/src/exec/orc-column-readers.h
4 files changed, 135 insertions(+), 42 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/51/15051/7
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: If2d975946fb6f4104d8dc98895285b3a0c6bef7f
Gerrit-Change-Number: 15051
Gerrit-PatchSet: 7
Gerrit-Owner: Norbert Luksa <[email protected]>
Gerrit-Reviewer: Csaba Ringhofer <[email protected]>
Gerrit-Reviewer: Daniel Becker <[email protected]>
Gerrit-Reviewer: Gabor Kaszab <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Norbert Luksa <[email protected]>
Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]>

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