GitHub user sunjincheng121 opened a pull request:
https://github.com/apache/flink/pull/4652
[FLINK-7465][table]Add cardinality count for tableAPI and SQL.
## What is the purpose of the change
*In this PR. we want add add CARDINALITY_COUNT for tableAPI and SQL.(Using
`HyperLogLog` algorithm).
The implementation of HyperLogLog (HLL) algorithm from this paper:
http://algo.inria.fr/flajolet/Publications/FlFuGaMe07.pdf
As we know there are still some improved algorithms, such as:
HyperLogLog++, HyperBitBit etc.
But `HyperLogLog` is a classic algorithm that has been massively verified,
so I chose to use the `HyperLogLog` algorithm as the first version of
cardinality to achieve. And we can improve the algorithm at any time If we need.
*
## Brief change log
- *Add Java implementation of `HyperLogLog`(base on stream-lib)*
- *Add MURMURHASH See more: http://murmurhash.googlepages.com/*
- *Add build-in `CardinalityCountAggFunction`*
- *Add some test case for the validation*
- *Add documentation for TableAPI&SQL*
## Verifying this change
This change added tests and can be verified as follows:
- *Added SQL/TableAPI integration tests for `cardinality_count`*
- *Added `CardinalityCountAggFunctionTest` test case for verify the AGG
logic.*
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (no)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (no)
- The serializers: (no)
- The runtime per-record code paths (performance sensitive): (no)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
## Documentation
- Does this pull request introduce a new feature? (yes)
- If yes, how is the feature documented? (docs / JavaDocs)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/sunjincheng121/flink FLINK-7465-PR
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/4652.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #4652
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commit bc1166ad88538bdcdd6df685c750359aadff3950
Author: é竹 <[email protected]>
Date: 2017-09-05T10:21:10Z
[FLINK-7465][table]Add cardinality count for tableAPI and SQL.
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