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https://issues.apache.org/jira/browse/BEAM-9320?focusedWorklogId=387516&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-387516
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ASF GitHub Bot logged work on BEAM-9320:
----------------------------------------
Author: ASF GitHub Bot
Created on: 14/Feb/20 17:58
Start Date: 14/Feb/20 17:58
Worklog Time Spent: 10m
Work Description: dpmills commented on pull request #10862: [BEAM-9320]
Add AlwaysFetched annotation
URL: https://github.com/apache/beam/pull/10862#discussion_r379566634
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/DoFn.java
##########
@@ -397,6 +397,47 @@ public Duration getAllowedTimestampSkew() {
String value();
}
+ /////////////////////////////////////////////////////////////////////////////
+
+ /**
+ * Annotation for declaring that a state parameter is always fetched.
+ *
+ * <p>A DoFn might not fetch a state value on every element, and for that
reason runners may
+ * choose to defer fetching state until read() is called. Annotating a state
argument with this
+ * parameter provides a hint to the runner that the state is always fetched.
This may cause the
+ * runner to prefetch all the state before calling the processElement or
processTimer method,
+ * improving performance. See the following code for an example:
Review comment:
Add a comment that the annotation only works for ReadableState
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Issue Time Tracking
-------------------
Worklog Id: (was: 387516)
Time Spent: 20m (was: 10m)
> Add an annotation to State to indicate it should always be fetched
> ------------------------------------------------------------------
>
> Key: BEAM-9320
> URL: https://issues.apache.org/jira/browse/BEAM-9320
> Project: Beam
> Issue Type: Improvement
> Components: sdk-java-core
> Reporter: Daniel Mills
> Assignee: Reuven Lax
> Priority: Minor
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently, if you have several StateIds that always need to be fetched for a
> stateful DoFn, you have to have a block of .readLater() calls at the
> beginning of each method. It would be nicer to have an nnotation on the
> processElement/processTimer call params to indicate that the value should
> always be fetched.
> Something like:
> @ProcessElement
> void process(@RequiredStateId("foo") ValueState foo, E element) \{...}
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