Hi Jiayi Liao, I have answered the similar question here: http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/Why-documentation-always-say-checkpoint-does-not-support-Flink-specific-features-like-rescaling-td23982.html#a23983 <http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/Why-documentation-always-say-checkpoint-does-not-support-Flink-specific-features-like-rescaling-td23982.html#a23983>
This link might be also useful: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Can-I-only-use-checkpoints-instead-of-savepoints-in-production-td22538.html <http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Can-I-only-use-checkpoints-instead-of-savepoints-in-production-td22538.html> I would recommend to use explicit savepoints at the moment for rescaling. Best, Andrey > On 13 Sep 2018, at 20:29, bupt_ljy <bupt_...@163.com> wrote: > > Thanks for your answer, but I still have some questions. > Could you tell me why the checkpoint cannot be used for rescaling? From my > perspective, the difference between checkpoint and savepoint is nullable > externalSavepointLocation. And from this doc: > https://flink.apache.org/features/2017/07/04/flink-rescalable-state.html > <https://flink.apache.org/features/2017/07/04/flink-rescalable-state.html>, > it talked about rescaling based on the checkpointing. Do I confuse these two > things? > > Original Message > Sender: 杨力<bill.le...@gmail.com> > Recipient: 廖嘉逸<bupt_...@163.com> > Cc: user<user@flink.apache.org> > Date: Friday, Sep 14, 2018 02:03 > Subject: Re: Can rocksDBBackend handle rescaling? > > A checkpoint cannot be used for rescaling. You should take a savepoint, stop > the application, and resume from the savepoint with a new parallelism. > > https://ci.apache.org/projects/flink/flink-docs-release-1.6/ops/state/savepoints.html > > <https://ci.apache.org/projects/flink/flink-docs-release-1.6/ops/state/savepoints.html> > > > On Fri, Sep 14, 2018 at 1:50 AM 廖嘉逸 <bupt_...@163.com > <mailto:bupt_...@163.com>> wrote: > Hi, all > I’m using Flink 1.6 and I’m goint to use RocksDBBackend as the checkpoint > state backend. Before that, I need to make sure that the checkpoint can > handle rescale. From the docs on Apache Flink > https://ci.apache.org/projects/flink/flink-docs-release-1.6/ops/state/checkpoints.html > > <https://ci.apache.org/projects/flink/flink-docs-release-1.6/ops/state/checkpoints.html>, > it says that the checkpoint do not support Flink’s rescaling, however, from > the source code, the rescaling logic seems not to be related to the state > backend if the substask’s states are restored from files successfully. > Could anyone explain this? Or tell me if I miss something? > > Best, Jiayi Liao > > >
