Apache Flink connector docs by kurnoolsaketh · Pull Request #5527 · ClickHouse/clickhouse-docs

kurnoolsaketh · 2026-02-14T00:15:42Z

Summary

Introduce documentation for the official Flink connector. This doc page is adapted from the flink connector repo's README.

vercel · 2026-02-14T00:15:47Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
clickhouse-docs	Ready	Preview, Comment	Mar 3, 2026 1:18am
clickhouse-docs-jp	Building	Preview, Comment	Mar 3, 2026 1:18am

3 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
clickhouse-docs-ko	Ignored	Preview	Mar 3, 2026 1:18am
clickhouse-docs-ru	Ignored	Preview	Mar 3, 2026 1:18am
clickhouse-docs-zh	Ignored	Preview	Mar 3, 2026 1:18am

alexfrancoeur · 2026-02-15T19:26:09Z

The docs look great! A couple of small pieces of feedback, but lgtm overall. I can't wait to get these in there

I reviewed this preview on mobile: https://clickhouse-docs-9zj3bpftf-clickhouse.vercel.app/docs/integrations/apache-flink

The apache flink icon in the integrations view links to the repo still, we'll need to update in the CMS to link to these docs and make it consistent across the different entry points
I feel like we should link to the repo explicitly early in the docs with the connector name
I don't know if we need the "to be filled out later" section for the table api. We could probably just remove until it's added

mshustov · 2026-02-16T08:28:09Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+This is the official Apache Flink Sink Connector supported by ClickHouse. It is built using Flink's [AsyncSinkBase](https://cwiki.apache.org/confluence/display/FLINK/FLIP-171%3A+Async+Sink) and the official ClickHouse [java client](https://github.com/ClickHouse/clickhouse-java).
+
+The connector supports Apache Flink's DataStream API. Table API support is planned for a future release.


Table API support is planned for a future release.

we can link to an issue to follow and upvote or delete the note

i'll link the issue and remove the ## Using the Table API section

mshustov · 2026-02-16T08:30:24Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+### Table API Connection Options {#table-api-connection-options}
+
+Planned for a future release — this section will be updated once available.


I'm not sure what immediate value the note gives, I'd consider removing it

understood, i'll remove these sections

mshustov · 2026-02-16T08:31:06Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+Notes:
+* A `ZoneId` must be provided when performing date operations.
+* Precision and scale must be provided when performing decimal operations.


do we have an example to link to?

yeah - i will link directly to CH docs

docs/integrations/data-ingestion/apache-flink/flink-connector.md

mshustov · 2026-02-16T08:34:11Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+## ClickHouse Version Compatibility and Security {#compatibility-and-security}
+
+- All artifacts and versions of the connector are tested with all [active LTS versions](https://github.com/ClickHouse/ClickHouse/pulls?q=is%3Aopen+is%3Apr+label%3Arelease) of ClickHouse.


active and LTS?

Suggested change

- All artifacts and versions of the connector are tested with all [active LTS versions](https://github.com/ClickHouse/ClickHouse/pulls?q=is%3Aopen+is%3Apr+label%3Arelease) of ClickHouse.

- All artifacts and versions of the connector are tested with all [active and LTS versions](https://github.com/ClickHouse/ClickHouse/pulls?q=is%3Aopen+is%3Apr+label%3Arelease) of ClickHouse.

BentsiLeviav

Left a few comments. In addition, can we go over the repo and find relevant locations where Flink is mentioned, and make sure we link them to this page?

Found these locations, but we might have more:

clickhouse-docs/docs/data-modeling/denormalization.md

Line 374 in 86362ae

    
           You may alternatively wish to perform this outside of ClickHouse, prior to insertion, using streaming technologies such as [Apache Flink](https://flink.apache.org/). Alternatively, incremental [materialized views](/guides/developer/cascading-materialized-views) can be used to perform this process as data is inserted.

clickhouse-docs/docs/best-practices/minimize_optimize_joins.md

Line 22 in 86362ae

    
           - You have the capability to shift processing out of ClickHouse into upstream systems like Flink, where real-time enrichment or flattening can be managed.

BentsiLeviav · 2026-02-16T11:35:07Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+ClickHouseClientConfig clickHouseClientConfig = new ClickHouseClientConfig(url, username, password, database, tableName);
+```
+
+Let's say you want to insert RAW CSV data as is:


Can you change this example to be copy-pastable like we have here?

If needed, you can add comments in between explaining each step.

BentsiLeviav · 2026-02-16T11:45:00Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+For more detailed instructions, see the [Example Guide](https://github.com/ClickHouse/flink-connector-clickhouse/blob/main/examples/README.md)
+
+### DataStream API Connection Options {#datastream-api-connection-options}
+#### Clickhouse Client Options {#client-options}


Can you elaborate on how to set Java Client options? https://github.com/ClickHouse/flink-connector-clickhouse/blob/main/flink-connector-clickhouse-1.17/src/main/java/org/apache/flink/connector/clickhouse/sink/ClickHouseClientConfig.java#L79

BentsiLeviav · 2026-02-16T11:48:03Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+For more detailed instructions, see the [Example Guide](https://github.com/ClickHouse/flink-connector-clickhouse/blob/main/examples/README.md)
+
+### DataStream API Connection Options {#datastream-api-connection-options}


Can we add a section explaining how to add ClickHouse settings to the queries? https://github.com/ClickHouse/flink-connector-clickhouse/blob/main/flink-connector-clickhouse-1.17/src/main/java/org/apache/flink/connector/clickhouse/sink/ClickHouseClientConfig.java#L33

addressed by the previous comment

Tnx. Can you make it more explicit?
There are two types of settings users can tune:

Java client options https://clickhouse.com/docs/integrations/language-clients/java/client#configuration

ClickHouse session settings https://clickhouse.com/docs/operations/settings/settings

With the existing phrasing, the only indication forthe clickhouse settings is by this line
Map.of(), // serverSettings.

BentsiLeviav · 2026-02-16T12:21:12Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+## Limitations {#limitations}
+
+* Currently, the sink does not support exactly-once semantics.


In reference to what @mshustov said earlier, let's make sure we have a point and a linked issue for each of these:

Exactly once semantics

DLQ

TableAPI

A link for each one of these will allow the community/user to vote and give us feedback

BentsiLeviav · 2026-02-16T12:31:35Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+### Table API Connection Options {#table-api-connection-options}
+
+Planned for a future release — this section will be updated once available.


kurnoolsaketh · 2026-02-17T01:53:07Z

In addition, can we go over the repo and find relevant locations where Flink is mentioned, and make sure we link them to this page?

@BentsiLeviav yes - i confirmed the locations you identified are the only other mentions of flink in the repo besides the same pages in japanese & other languages. Should I update those as well?

kurnoolsaketh · 2026-02-17T15:43:16Z

thanks @alexfrancoeur!

The apache flink icon in the integrations view links to the repo still, we'll need to update in the CMS to link to these docs and make it consistent across the different entry points

i've updated the flink icon link to point to the new docs page 👍

I feel like we should link to the repo explicitly early in the docs with the connector name

sure will do

I don't know if we need the "to be filled out later" section for the table api. We could probably just remove until it's added

yup, it's removed now

docs/integrations/data-ingestion/apache-flink/flink-connector.md

BentsiLeviav · 2026-02-18T11:21:51Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+The following options come directly from Flink's `AsyncSinkBase`:
+
+| Parameters             | Description                                                                                                 | Default Value |


All options' default values are marked with N/A. If there truly are no defaults and users must always provide them, it would be worth adding a note saying these are all required (like was done in the client options section

yeah that's a good callout - I think we should set sane defaults for these options, but that can be a followup.

it would be worth adding a note saying these are all required

done

BentsiLeviav · 2026-02-18T11:34:54Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+
+## ClickHouse Version Compatibility and Security {#compatibility-and-security}
+
+- All artifacts and versions of the connector are tested with all [active and LTS versions](https://github.com/ClickHouse/ClickHouse/pulls?q=is%3Aopen+is%3Apr+label%3Arelease) of ClickHouse.


Given that the CH versions are static in our workflows and not yet fully automated to be updated, we should consider being more accurate, maybe something like:

Suggested change

- All artifacts and versions of the connector are tested with all [active and LTS versions](https://github.com/ClickHouse/ClickHouse/pulls?q=is%3Aopen+is%3Apr+label%3Arelease) of ClickHouse.

- The connector is tested against a range of recent ClickHouse versions, including latest and head, via a daily CI workflow. The tested versions are updated periodically as new ClickHouse releases become active.

Adding a link to the matrix might be useful as well, so users would get an accurate status. https://github.com/ClickHouse/flink-connector-clickhouse/blob/main/.github/workflows/tests-nightly.yaml#L15

thank you, i've updated this line

docs/integrations/data-ingestion/apache-flink/flink-connector.md

mzitnik · 2026-02-18T15:29:33Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+<Tabs groupId="client_options_example">
+<TabItem value="Java" label="Java" default>
+
+```java


I think best would be best if we give some network options as example configurations as an example (I think it will be more useful)

docs/integrations/data-ingestion/apache-flink/flink-connector.md

kurnoolsaketh · 2026-02-27T20:46:03Z

docs/integrations/data-ingestion/apache-flink/flink-connector.md

+## Advanced and recommended usage {#advanced-and-recommended-usage}
+
+- For optimal performance, ensure your DataStream element type is **not** a Generic type - see [here for Flink's type distinction](https://nightlies.apache.org/flink/flink-docs-release-2.2/docs/dev/datastream/fault-tolerance/serialization/types_serialization/#flinks-typeinformation-class). Non-generic elements will avoid the serialization overhead incurred by Kryo and improve throughput to ClickHouse.
+- We recommend setting `maxBatchSize` to at least 1000 and ideally between 10,000 to 100,000. See [this guide on bulk inserts](https://clickhouse.com/docs/optimize/bulk-inserts) for more information.


items 12 and 15 in the doc matrix

docs/integrations/data-ingestion/apache-flink/flink-connector.md

Co-authored-by: Bentsi Leviav <bentsi.997@gmail.com>

Blargian · 2026-03-02T06:12:58Z

In addition, can we go over the repo and find relevant locations where Flink is mentioned, and make sure we link them to this page?

@BentsiLeviav yes - i confirmed the locations you identified are the only other mentions of flink in the repo besides the same pages in japanese & other languages. Should I update those as well?

@kurnoolsaketh no need to update any of the translations, there is a bot which will open a PR after this gets merged with any updates to translations.

vercel bot had a problem deploying to Preview – clickhouse-docs February 14, 2026 00:17 Failure

kurnoolsaketh force-pushed the flink-connector-docs branch from 507aa28 to d416e81 Compare February 14, 2026 00:25

vercel bot deployed to Preview – clickhouse-docs February 14, 2026 00:54 View deployment

kurnoolsaketh marked this pull request as ready for review February 14, 2026 19:33

kurnoolsaketh requested review from a team as code owners February 14, 2026 19:33

kurnoolsaketh requested review from BentsiLeviav and mzitnik February 14, 2026 19:33

vercel bot deployed to Preview – clickhouse-docs February 14, 2026 19:43 View deployment

BentsiLeviav requested review from alexfrancoeur and laeg February 15, 2026 07:29

alexfrancoeur approved these changes Feb 15, 2026

View reviewed changes

mshustov reviewed Feb 16, 2026

View reviewed changes

docs/integrations/data-ingestion/apache-flink/flink-connector.md Outdated Show resolved Hide resolved

mshustov reviewed Feb 16, 2026

View reviewed changes

BentsiLeviav requested changes Feb 16, 2026

View reviewed changes

vercel bot had a problem deploying to Preview – clickhouse-docs February 17, 2026 00:30 Failure

kurnoolsaketh force-pushed the flink-connector-docs branch from d37e53d to 5d8487b Compare February 17, 2026 00:31

vercel bot had a problem deploying to Preview – clickhouse-docs February 17, 2026 00:32 Failure

kurnoolsaketh force-pushed the flink-connector-docs branch from 5d8487b to c211779 Compare February 17, 2026 01:49

kurnoolsaketh requested a review from BentsiLeviav February 17, 2026 01:49

vercel bot deployed to Preview – clickhouse-docs February 17, 2026 02:00 View deployment

vercel bot deployed to Preview – clickhouse-docs February 17, 2026 02:18 View deployment

kurnoolsaketh force-pushed the flink-connector-docs branch from 9a10228 to 2a9c54a Compare February 17, 2026 18:52

vercel bot deployed to Preview – clickhouse-docs February 17, 2026 19:04 View deployment

BentsiLeviav requested changes Feb 18, 2026

View reviewed changes

mzitnik reviewed Feb 18, 2026

View reviewed changes

kurnoolsaketh force-pushed the flink-connector-docs branch from f455e1f to 9a4861b Compare February 19, 2026 01:22

kurnoolsaketh requested review from BentsiLeviav and mzitnik February 19, 2026 01:23

vercel bot deployed to Preview – clickhouse-docs February 19, 2026 01:40 View deployment

vercel bot had a problem deploying to Preview – clickhouse-docs February 24, 2026 18:39 Failure

kurnoolsaketh added 10 commits February 24, 2026 12:40

first stab at flink connector docs

7345975

linting fix

ce0e555

fix CI

0e9525d

update data ingestion index

f0f699d

fix CI 2

0641d72

make metric names code lines

5ba7454

review comments round 1

7ce3308

update integrations-fallback

ec45a7d

reviews round 2

a135407

update client options table and description

78c12c7

kurnoolsaketh force-pushed the flink-connector-docs branch from a2f55b4 to 78c12c7 Compare February 24, 2026 18:40

vercel bot deployed to Preview – clickhouse-docs February 24, 2026 18:51 View deployment

add items 10 and 15 in the doc matrix, minor case refactoring

71957c3

kurnoolsaketh commented Feb 27, 2026

View reviewed changes

docs/integrations/data-ingestion/apache-flink/flink-connector.md Show resolved Hide resolved

vercel bot deployed to Preview – clickhouse-docs February 27, 2026 20:53 View deployment

Apply suggestion from @BentsiLeviav

ca42e8a

Co-authored-by: Bentsi Leviav <bentsi.997@gmail.com>

vercel bot deployed to Preview – clickhouse-docs March 2, 2026 06:05 View deployment

add troubleshooting section

d8b302f

vercel bot deployed to Preview – clickhouse-docs March 3, 2026 01:18 View deployment


		This is the official Apache Flink Sink Connector supported by ClickHouse. It is built using Flink's [AsyncSinkBase](https://cwiki.apache.org/confluence/display/FLINK/FLIP-171%3A+Async+Sink) and the official ClickHouse [java client](https://github.com/ClickHouse/clickhouse-java).

		The connector supports Apache Flink's DataStream API. Table API support is planned for a future release.


		### Table API Connection Options {#table-api-connection-options}

		Planned for a future release — this section will be updated once available.


		## ClickHouse Version Compatibility and Security {#compatibility-and-security}

		- All artifacts and versions of the connector are tested with all [active LTS versions](https://github.com/ClickHouse/ClickHouse/pulls?q=is%3Aopen+is%3Apr+label%3Arelease) of ClickHouse.


		For more detailed instructions, see the [Example Guide](https://github.com/ClickHouse/flink-connector-clickhouse/blob/main/examples/README.md)

		### DataStream API Connection Options {#datastream-api-connection-options}


		## Limitations {#limitations}

		* Currently, the sink does not support exactly-once semantics.


		The following options come directly from Flink's `AsyncSinkBase`:

		\| Parameters \| Description \| Default Value \|

	- All artifacts and versions of the connector are tested with all [active and LTS versions](https://github.com/ClickHouse/ClickHouse/pulls?q=is%3Aopen+is%3Apr+label%3Arelease) of ClickHouse.
	- The connector is tested against a range of recent ClickHouse versions, including latest and head, via a daily CI workflow. The tested versions are updated periodically as new ClickHouse releases become active.

Conversation

kurnoolsaketh commented Feb 14, 2026

Summary

Uh oh!

vercel bot commented Feb 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

alexfrancoeur commented Feb 15, 2026

Uh oh!

Choose a reason for hiding this comment

Uh oh!

kurnoolsaketh Feb 16, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

BentsiLeviav left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

kurnoolsaketh commented Feb 17, 2026

Uh oh!

kurnoolsaketh commented Feb 17, 2026

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

kurnoolsaketh Feb 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

vercel bot commented Feb 14, 2026 •

edited

Loading

kurnoolsaketh Feb 16, 2026 •

edited

Loading

kurnoolsaketh Feb 27, 2026 •

edited

Loading