wuchong opened a new pull request #14160:
URL: https://github.com/apache/flink/pull/14160
<!--
*Thank you very much for contributing to Apache Flink - we are happy that
you want to help us improve Flink. To help the community review your
contribution in the best possible way, please go through the checklist below,
which will get the contribution into a shape in which it can be best reviewed.*
*Please understand that we do not do this to make contributions to Flink a
hassle. In order to uphold a high standard of quality for code contributions,
while at the same time managing a large number of contributions, we need
contributors to prepare the contributions well, and give reviewers enough
contextual information for the review. Please also understand that
contributions that do not follow this guide will take longer to review and thus
typically be picked up with lower priority by the community.*
## Contribution Checklist
- Make sure that the pull request corresponds to a [JIRA
issue](https://issues.apache.org/jira/projects/FLINK/issues). Exceptions are
made for typos in JavaDoc or documentation files, which need no JIRA issue.
- Name the pull request in the form "[FLINK-XXXX] [component] Title of the
pull request", where *FLINK-XXXX* should be replaced by the actual issue
number. Skip *component* if you are unsure about which is the best component.
Typo fixes that have no associated JIRA issue should be named following
this pattern: `[hotfix] [docs] Fix typo in event time introduction` or
`[hotfix] [javadocs] Expand JavaDoc for PuncuatedWatermarkGenerator`.
- Fill out the template below to describe the changes contributed by the
pull request. That will give reviewers the context they need to do the review.
- Make sure that the change passes the automated tests, i.e., `mvn clean
verify` passes. You can set up Azure Pipelines CI to do that following [this
guide](https://cwiki.apache.org/confluence/display/FLINK/Azure+Pipelines#AzurePipelines-Tutorial:SettingupAzurePipelinesforaforkoftheFlinkrepository).
- Each pull request should address only one issue, not mix up code from
multiple issues.
- Each commit in the pull request has a meaningful commit message
(including the JIRA id)
- Once all items of the checklist are addressed, remove the above text and
this checklist, leaving only the filled out template below.
**(The sections below can be removed for hotfixes of typos)**
-->
## What is the purpose of the change
Usually, CDC tools deliver change events to message queue in an
**at-least-once** semantic. There might be duplicate INSERT/UPDATE/DELETE
messages for the same primary key. However, when appling TopN query on this
created source table, the TopN operator will thrown exception: `Caused by:
java.lang.RuntimeException: Can not retract a non-existent record`.
We introduced a configuration
`table.exec.source.cdc-events-duplicate=true|false` to indicate whether the cdc
source produce duplicate messages that require the framework to deduplicate. By
default, the value is false (for backward-compatibility). When it is set to
true, it requires to set a primary key on the source, and the framework will
this the primary key to deduplicate/normalize the changelog (using the
ChangelogNormalize operator).
This option only take effect on the cdc sources which will produce full
changelog, including INSERT/UPDATE_BEFORE/UPDATE_AFTER/DELETE events. So it
doesn't affect the upsert sources, because upsert sources always generate a
ChangelogNormalize operator after it.
This pull request also fixes FLINK-20205 to not send `UPDATE_BEFORE`
messages if the downstream doesn't need it for CDC sources.
## Brief change log
- Add validation if the configuration is enabled but primary key is not
defined.
- Generate ChangelogNormalize node after CDC source if
`table.exec.source.cdc-events-duplicate=true`.
- Drop `UPDATE_BEFORE` messages for CDC source if downstream doesn't need
it, because `ChangelogNormalize` also doesn't need the before messages.
## Verifying this change
- Added plan tests for the configuration is enabled.
- Added IT cases for the configuration is enabled.
- Added unit tests for metadata handler tests for the new
`StreamExecDropUpdateBefore` node.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / **no**)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (yes / **no**)
- The serializers: (yes / **no** / don't know)
- The runtime per-record code paths (performance sensitive): (yes / **no**
/ don't know)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / **no** / don't know)
- The S3 file system connector: (yes / **no** / don't know)
## Documentation
- Does this pull request introduce a new feature? (yes / **no**)
- If yes, how is the feature documented? (**not applicable** / docs /
JavaDocs / not documented)
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
