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From Yassine MARZOUGUI <y.marzou...@mindlytix.com>
Subject Re: Externalized Checkpoints vs Periodic Checkpoints
Date Thu, 02 Feb 2017 14:38:19 GMT
Thank you Till for the clarification, that was helpful.

Best,
Yassine

2017-02-02 15:31 GMT+01:00 Till Rohrmann <trohrmann@apache.org>:

> Hi Yassine,
>
> a periodic checkpoint is checkpoint which will be triggered periodically
> by Flink. The checkpoint itself can have multiple properties and one of
> them is whether the checkpoint is externalized or not.
>
> An externalized checkpoint is a checkpoint for which Flink writes the meta
> information into a target directory. In contrast to that, for a
> non-externalized checkpoint Flink will store the checkpoint meta
> information only in memory. The former has the advantage that you don't
> lose the checkpoints if you shutdown your cluster. They behave similar to
> savepoints and in fact savepoints are externalized checkpoints with some
> more properties.
>
> At the moment, Flink's checkpoint coordinator only retains the last
> successfully completed checkpoint. This means that whenever a new
> checkpoint completes then the last completed checkpoint will be discarded.
> This also applies to externalized checkpoints.
>
> Cheers,
> Till
>
> On Wed, Feb 1, 2017 at 2:03 PM, Yassine MARZOUGUI <
> y.marzougui@mindlytix.com> wrote:
>
>> Hi all,
>>
>> Could someone clarify the difference between externalized checkpoints[1]
>> and regular periodic checkpoints[2]?
>> Moreover, I have a question regarding the retention of checkpoints: For
>> regular checkpoints, does the last checkpoint discard the previous ones? If
>> yes, is that the case too for the externalized checkpoints? Thank you.
>>
>> Best,
>> Yassine
>>
>> [1] : https://ci.apache.org/projects/flink/flink-docs-release-1.2/
>> setup/checkpoints.html
>> [2] : https://ci.apache.org/projects/flink/flink-docs-release-1.
>> 2/dev/stream/checkpointing.html
>>
>
>

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