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apache / impala / 827070b473c02da480f3a9d77c59f7031f9070c2
commit827070b473c02da480f3a9d77c59f7031f9070c2[log] [tgz]
authorShant Hovsepian <shant@cloudera.com>Fri Aug 21 23:39:20 2020 -0400
committerTim Armstrong <tarmstrong@cloudera.com>Mon Aug 31 18:34:07 2020 +0000
treed8fc59a02fb82432188c909b1c3a151e0741c401
parent578933fe74d8c320431148f9a458a0051afafb17 [diff]
IMPALA-10099: Push down DISTINCT in Set operations

INTERSECT/EXCEPT are not duplicate preserving operations. The distinct
aggregations can happen in each operand, the leftmost operand only, or
after all the operands in a separate aggregation step. Except for a
couple special cases we would use the last strategy most often.

This change pushes the distinct aggregation down to the leftmost operand
in cases where there are no analytic functions, or when a distinct or
grouping operation already eliminates duplicates.

In general DISTINCT placement such as in this case should be done
throughout the entire plan tree in a cost based manner as described in
IMPALA-5260

Testing:
 * TpcdsPlannerTest
 * PlannerTest
 * TPC-DS 30TB Perf run for any affected queries
   - Q14-1 180s -> 150s
   - Q14-2 109s -> 90s
   - Q8 no significant change
 * SetOperation Planner Tests
 * Analyzer tests
 * Tpcds Functional Workload

Change-Id: Ia248f1595df2ab48fbe70c778c7c32bde5c518a5
Reviewed-on: http://gerrit.cloudera.org:8080/16350
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Reviewed-by: Tim Armstrong <tarmstrong@cloudera.com>
6 files changed
tree: d8fc59a02fb82432188c909b1c3a151e0741c401
  1. be/
  2. bin/
  3. cmake_modules/
  4. common/
  5. docker/
  6. docs/
  7. ext-data-source/
  8. fe/
  9. impala-parent/
  10. infra/
  11. lib/
  12. query-event-hook-api/
  13. security/
  14. shaded-deps/
  15. shell/
  16. ssh_keys/
  17. testdata/
  18. tests/
  19. www/
  20. .clang-format
  21. .clang-tidy
  22. .gitattributes
  23. .gitignore
  24. buildall.sh
  25. CMakeLists.txt
  26. EXPORT_CONTROL.md
  27. LICENSE.txt
  28. LOGS.md
  29. NOTICE.txt
  30. README-build.md
  31. README.md
  32. setup.cfg
README.md

Welcome to Impala

Lightning-fast, distributed SQL queries for petabytes of data stored in Apache Hadoop clusters.

Impala is a modern, massively-distributed, massively-parallel, C++ query engine that lets you analyze, transform and combine data from a variety of data sources:

  • Best of breed performance and scalability.
  • Support for data stored in HDFS, Apache HBase, Apache Kudu, Amazon S3, Azure Data Lake Storage, Apache Hadoop Ozone and more!
  • Wide analytic SQL support, including window functions and subqueries.
  • On-the-fly code generation using LLVM to generate lightning-fast code tailored specifically to each individual query.
  • Support for the most commonly-used Hadoop file formats, including Apache Parquet and Apache ORC.
  • Support for industry-standard security protocols, including Kerberos, LDAP and TLS.
  • Apache-licensed, 100% open source.

More about Impala

To learn more about Impala as a business user, or to try Impala live or in a VM, please visit the Impala homepage. Detailed documentation for administrators and users is available at Apache Impala documentation.

If you are interested in contributing to Impala as a developer, or learning more about Impala's internals and architecture, visit the Impala wiki.

Supported Platforms

Impala only supports Linux at the moment.

Export Control Notice

This distribution uses cryptographic software and may be subject to export controls. Please refer to EXPORT_CONTROL.md for more information.

Build Instructions

See Impala's developer documentation to get started.

Detailed build notes has some detailed information on the project layout and build.