Hello Lars Volker, Zoltan Borok-Nagy, Csaba Ringhofer, Alex Behm, Mostafa
Mokhtar, Impala Public Jenkins,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/8319
to look at the new patch set (#21).
Change subject: IMPALA-4123: Columnar decoding in Parquet
......................................................................
IMPALA-4123: Columnar decoding in Parquet
The idea is to optimise the common case where there are long runs of
NULL or non-NULL values (i.e. the def level is repeated). We can
detect this cheaply by keying the decoding loop in the column reader
off the state of the def level RLE decoder - if there's a long run
of repeated levels, we can skip checking the def level for every
value. We still fall back to decoding, caching and reading
value-by-value a batch of def levels whenever the next def level is not
in a repeated run. We still use the old approach for decoding rep
levels. There might be some benefit to using the same approach for rep
levels *if* repeated def and rep level runs line up.
These changes should unlock further optimizations because more time is
spent in simple kernel functions, e.g. UnpackAndDecode32Values() for
dictionary decompression, which is very optimisable using SIMD etc.
Snappy decompression now seems to be the main CPU bottleneck for
decoding snappy-compressed Parquet.
Perf:
Running TPC-H scale factor 60 on uncompressed and snappy parquet
both showed a ~4% speedup overall.
Microbenchmarks on uncompressed parquet show scans only doing
dictionary decoding on uncompressed Parquet is ~75% faster:
set mt_dop=1;
select min(l_returnflag) from lineitem;
Testing:
We have alltypes agg with a mix of null and non-null.
Many tables have long runs of non-null values.
Added new test data and coverage:
* a test table manynulls with long runs of null values.
* a large CHAR test table
* missing coverage for materialising pos slot in flattened nested types
scan.
* Extended dict test to test longer runs.
* A larger version of complextypestbl with interesting collection
shapes - NULL collections, empty collections, etc, particularly runs
of collections with the same shape.
* Test interaction of timestamp validation with conversion
* Ran code coverage build to confirm all code paths are tested
* ASAN and exhaustive runs.
TODO:
* Before merging, run fuzz test for longer
Change-Id: I8c03006981c46ef0dae30602f2b73c253d9b49ef
---
M be/src/exec/hdfs-parquet-scanner.cc
M be/src/exec/parquet-column-readers.cc
M be/src/exec/parquet-column-readers.h
M be/src/exec/parquet-common.h
M be/src/runtime/tuple.cc
M be/src/runtime/tuple.h
M be/src/util/bit-packing.h
M be/src/util/bit-packing.inline.h
M be/src/util/bit-stream-utils.h
M be/src/util/bit-stream-utils.inline.h
M be/src/util/dict-encoding.h
M be/src/util/dict-test.cc
A be/src/util/mem-util.h
M be/src/util/rle-encoding.h
M testdata/bin/generate-schema-statements.py
M testdata/data/README
A testdata/data/out_of_range_timestamp2_hive_211.parquet
A testdata/data/out_of_range_timestamp_hive_211.parquet
M testdata/datasets/functional/functional_schema_template.sql
M testdata/datasets/functional/schema_constraints.csv
M testdata/workloads/functional-query/queries/QueryTest/chars.test
M
testdata/workloads/functional-query/queries/QueryTest/nested-types-scanner-position.test
M testdata/workloads/functional-query/queries/QueryTest/nested-types-tpch.test
A
testdata/workloads/functional-query/queries/QueryTest/out-of-range-timestamp-local-tz-conversion.test
A testdata/workloads/functional-query/queries/QueryTest/scanners-many-nulls.test
M tests/custom_cluster/test_hive_parquet_timestamp_conversion.py
M tests/query_test/test_scanners.py
27 files changed, 884 insertions(+), 133 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/19/8319/21
--
To view, visit http://gerrit.cloudera.org:8080/8319
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I8c03006981c46ef0dae30602f2b73c253d9b49ef
Gerrit-Change-Number: 8319
Gerrit-PatchSet: 21
Gerrit-Owner: Tim Armstrong <tarmstr...@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.b...@cloudera.com>
Gerrit-Reviewer: Csaba Ringhofer <csringho...@cloudera.com>
Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
Gerrit-Reviewer: Lars Volker <l...@cloudera.com>
Gerrit-Reviewer: Mostafa Mokhtar <mmokh...@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com>
Gerrit-Reviewer: Zoltan Borok-Nagy <borokna...@cloudera.com>
