GitHub user zsxwing opened a pull request:
https://github.com/apache/spark/pull/16970
[SPARK-19497][SS]Implement streaming deduplication
## What changes were proposed in this pull request?
This PR adds a special streaming deduplication operator to support
`dropDuplicates` with `aggregation` and watermark. It reuses the
`dropDuplicates` API but creates new logical plan `Deduplication` and new
physical plan `DeduplicationExec`.
The following cases are supported:
- dropDuplicates() (one `dropDuplicates` with any output mode)
- withWatermark(...).dropDuplicates().groupBy(...)....outputMode("append")
- dropDuplicates().groupBy(...)....outputMode("update")
Not supported cases:
- dropDuplicates().dropDuplicates() (multiple `dropDuplicates`s)
- groupBy(...).dropDuplicates() (`dropDuplicates` after `aggregation`)
- dropDuplicates().groupBy(...)....outputMode("complete")
## How was this patch tested?
The new unite tests.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/zsxwing/spark dedup
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16970.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 #16970
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commit 63a7f4c62b2da32351d008f9719d513e14562e56
Author: Shixiong Zhu <shixi...@databricks.com>
Date: 2017-02-15T19:01:57Z
Implement deduplication
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