dawidwys commented on a change in pull request #6766: [docs] Improve
documentation of savepoints
URL: https://github.com/apache/flink/pull/6766#discussion_r220867491
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File path: docs/ops/state/savepoints.md
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@@ -25,17 +25,29 @@ under the License.
* toc
{:toc}
-## Overview
+## What is a Savepoint? How is a Savepoint different from a Checkpoint?
-Savepoints are externally stored self-contained checkpoints that you can use
to stop-and-resume or update your Flink programs. They use Flink's
[checkpointing mechanism]({{ site.baseurl
}}/internals/stream_checkpointing.html) to create a (non-incremental) snapshot
of the state of your streaming program and write the checkpoint data and meta
data out to an external file system.
-
-This page covers all steps involved in triggering, restoring, and disposing
savepoints.
-For more details on how Flink handles state and failures in general, check out
the [State in Streaming Programs]({{ site.baseurl
}}/dev/stream/state/index.html) page.
+A Savepoint is a consistent image of the execution state of a streaming job,
created via Flink's [checkpointing mechanism]({{ site.baseurl
}}/internals/stream_checkpointing.html). You can use Savepoints to
stop-and-resume, fork,
+or update your Flink jobs. Savepoints consist of two parts: a directory with
(typically large) binary files on stable storage (e.g. HDFS, S3, ...) and a
(relatively small) meta data file. The files on stable storage represent the
net data of the job's execution state
+image. The meta data file of a Savepoint contains (primarily) pointers to all
file on stable storage that are part of the Savepoint, in form of absolute
paths.
<div class="alert alert-warning">
<strong>Attention:</strong> In order to allow upgrades between programs and
Flink versions, it is important to check out the following section about <a
href="#assigning-operator-ids">assigning IDs to your operators</a>.
</div>
+Flink's Savepoints are different from Checkpoints in a similar way that
backups are different from recovery logs in traditional database systems. The
primary purpose of Checkpoints is the provide a recovery mechanism in case of
Review comment:
is the provide -> is to provide?
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