GitHub user zsxwing opened a pull request:
https://github.com/apache/spark/pull/16251
[SPARK-18826][SS]Add 'newestFirst' option to FileStreamSource
## What changes were proposed in this pull request?
When starting a stream with a lot of backfill and maxFilesPerTrigger, the
user could often want to start with most recent files first. This would let you
keep low latency for recent data and slowly backfill historical data.
This PR adds a new option `newestFirst` to control this behavior. When it's
true, `FileStreamSource` will sort the files by the modified time from newest
to oldest, and take the first `maxFilesPerTrigger` files as a new batch.
## How was this patch tested?
The added test.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/zsxwing/spark newest-first
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16251.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 #16251
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commit 58a57d4004c45ff2290b95ec8c70ef95828d379b
Author: Shixiong Zhu <shixi...@databricks.com>
Date: 2016-12-12T05:15:10Z
Add 'newestFirst' option to FileStreamSource
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