(DEPRECATED) Apache Flink User Mailing List archive.

Incremental state with purging

Classic

List

Threaded

5 messages Options

Annemarie Burger

Incremental state with purging

Hi,

I'm trying to implement the most efficient way to incrementally put incoming
DataStream elements in my (map)state, while removing old elements (older
that x) from that same state. I then want to output the state every y
seconds. I've looked into using the ProcessFunction with onTimer, or
building my own Trigger for a window function, but I struggle with putting
all this together in a logical and efficient way. Since the state is very
big I don't want to duplicate it over multiple (sliding)windows. Does
anybody know the best way to achieve this? Some pseudo code would be very
helpful.

Thanks!

--
Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/

Yun Tang

Re: Incremental state with purging

From your description: "output the state every y seconds and remove old elements", I think TTL [1] is the proper solution for your scenario. And you could define the ttl of your state as y seconds so that processfunction could only print elements in the last y seconds.

[1] https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/state/state.html#state-time-to-live-ttl

Best

Yun Tang

From: Annemarie Burger <[hidden email]>
Sent: Wednesday, May 13, 2020 2:46
To: [hidden email] <[hidden email]>
Subject: Incremental state with purging

Congxian Qiu

Re: Incremental state with purging

From your description, you want to do two things:

1 update state and remote the state older than x

2 output the state every y second

From my side, the first can be done by using TTL state as Yun said,

the second can be done by using KeyedProcessFunction[1]

If you want to have complex logic to remove the older state in step 1, maybe you can also use the KeyedProcessFunction and timer()

[1] https://ci.apache.org/projects/flink/flink-docs-release-1.10/dev/stream/operators/process_function.html#the-keyedprocessfunction

Best,

Congxian

Yun Tang <[hidden email]> 于2020年5月13日周三下午7:42写道：

Hi

From your description: "output the state every y seconds and remove old elements", I think TTL [1] is the proper solution for your scenario. And you could define the ttl of your state as y seconds so that processfunction could only print elements in the last y seconds.

[1] https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/state/state.html#state-time-to-live-ttl

Best

Yun Tang

From: Annemarie Burger <[hidden email]>
Sent: Wednesday, May 13, 2020 2:46
To: [hidden email] <[hidden email]>
Subject: Incremental state with purging

Hi,

I'm trying to implement the most efficient way to incrementally put incoming
DataStream elements in my (map)state, while removing old elements (older
that x) from that same state. I then want to output the state every y
seconds. I've looked into using the ProcessFunction with onTimer, or
building my own Trigger for a window function, but I struggle with putting
all this together in a logical and efficient way. Since the state is very
big I don't want to duplicate it over multiple (sliding)windows. Does
anybody know the best way to achieve this? Some pseudo code would be very
helpful.

Thanks!

--
Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/

Annemarie Burger

Re: Incremental state with purging

Hi,

Thanks for your suggestions!
However, as I'm reading the docs for queryable state, it says that it can
only be used for Processing time, and my windows are defined using event
time. So, I guess this means I should use the KeyedProcessFunction. Could
you maybe suggest a rough implementation for this? I can't seem to get the
implementation working right.

Best,
Annemarie

--
Sent from: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/

Thomas Huang

Re: Incremental state with purging

I’m wondering that why you use a beta feature for production. Why not push the latest state into down sink like redis or hbase with Apache phoenix .

From: Annemarie Burger <[hidden email]>
Sent: Monday, May 18, 2020 11:19:23 PM
To: [hidden email] <[hidden email]>
Subject: Re: Incremental state with purging