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https://issues.apache.org/jira/browse/BEAM-5427?focusedWorklogId=146639&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-146639
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ASF GitHub Bot logged work on BEAM-5427:
----------------------------------------
Author: ASF GitHub Bot
Created on: 21/Sep/18 23:34
Start Date: 21/Sep/18 23:34
Worklog Time Spent: 10m
Work Description: HuangLED commented on a change in pull request #6439:
[BEAM-5427] Fix and update sample code for CombineFn.
URL: https://github.com/apache/beam/pull/6439#discussion_r219650411
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Combine.java
##########
@@ -289,6 +305,21 @@ private Combine() {
* arbitrary tree structure. Commutativity is required because any order of
the input values is
* ignored when breaking up input values into groups.
*
+ * <h3>Note on Data Encoding</h3>
+ *
+ * <p>Data encoding is required to make CombineFn work. The sample code
above implements {@code
+ * java.io.Serializable} so that CombineFn in consequence makes use of
SerializableCoder to encode
+ * the data. In many cases though, relying on Serializable could be less
preferred for efficiency
+ * considerations. In addition, Serializable may not be applicable in all
situations. There are
+ * two alternatives to make data encoding work for AverageFn:
+ *
+ * <ul>
+ * <li>Generic Coder class. Implement an encoder class explicitly and use
{@code @DefaultCoder}
+ * tag.
+ * <li>{@link CombineFn} Specific way. While extending {@link CombineFn},
overwrite both {@link
+ * #getAccumulatorCoder} and {@link #getDefaultOutputCoder}.
+ * </ul>
+ *
Review comment:
oops. I was trying to consolidate commits for cleaner history. But looks
like history is now gone.
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Issue Time Tracking
-------------------
Worklog Id: (was: 146639)
Time Spent: 2h (was: 1h 50m)
> Fix sample code (AverageFn) in Combine.java
> -------------------------------------------
>
> Key: BEAM-5427
> URL: https://issues.apache.org/jira/browse/BEAM-5427
> Project: Beam
> Issue Type: Improvement
> Components: examples-java
> Reporter: Ruoyun Huang
> Assignee: Ruoyun Huang
> Priority: Minor
> Time Spent: 2h
> Remaining Estimate: 0h
>
> Sample code missing coder.
> In its current state, job run fails with Coder missing error.
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