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Posted to dev@flink.apache.org by lonely Feb <lo...@gmail.com> on 2016/03/26 09:15:22 UTC

watermark in fault tolerance

I wonder if stream source task which extract timestamps and watermark from
source element fail and restart with fault tolerance, what kind of
watermark it would emit?

Re: watermark in fault tolerance

Posted by Aljoscha Krettek <al...@apache.org>.

Hi,
the current watermark position is not persisted. The sources will start
emitting based on the elements that they are seeing. So if the source is
reset to some previous reading position (say with Kafka). Then it will emit
the watermarks based on those earlier elements again.

Cheers,
Aljoscha

On Sat, 26 Mar 2016 at 09:16 lonely Feb <lo...@gmail.com> wrote:

> I wonder if stream source task which extract timestamps and watermark from
> source element fail and restart with fault tolerance, what kind of
> watermark it would emit?
>