GitHub user clockfly opened a pull request:
https://github.com/apache/spark/pull/14753
[SPARK-17187][SQL] Supports using arbitrary Java object as internal
aggregation buffer object
## What changes were proposed in this pull request?
This PR introduces an abstract class `TypedImperativeAggregate` so that an
aggregation function of TypedImperativeAggregate can use **arbitrary**
user-defined Java object as intermediate aggregation buffer object.
**This has advantages like:**
1. It now can support larger category of aggregation functions. For
example, it will be much easier to implement aggregation function
`percentile_approx`, which has a complex aggregation buffer definition.
2. It can be used to avoid doing serialization/de-serialization for every
call of `update` or `merge` when converting domain specific aggregation object
to internal Spark-Sql storage format.
3. It is easier to integrate with other existing monoid libraries like
algebird, and supports more aggregation functions with high performance.
Please see Java doc of `TypedImperativeAggregate` and Jira ticket
SPARK-17187 for more information.
## How was this patch tested?
Unit tests.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/clockfly/spark object_aggregation_buffer_try_2
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/14753.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 #14753
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commit 6efddadcb8e6d48e9898a8980f4dcceee4894ebc
Author: Sean Zhong <seanzh...@databricks.com>
Date: 2016-08-19T16:34:56Z
object aggregation buffer
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