# Sink connector - Add key in separate column

**URL:** <https://forum.confluent.io/t/sink-connector-add-key-in-separate-column/8350>\
**Category:** Kafka Connect\
**Created:** [20 July 2023 07:34 UTC](https://forum.confluent.io/t/sink-connector-add-key-in-separate-column/8350 "2023-07-20T07:34:16Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![victorrogue](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.confluent.io/victorrogue/32/3120_2.png) [@victorrogue](https://forum.confluent.io/u/victorrogue)\
**Post date:** [20 July 2023 07:34 UTC](https://forum.confluent.io/t/sink-connector-add-key-in-separate-column/8350/1 "2023-07-20T07:34:16Z")

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Hello!  
In kafka I have a message with key “id”  
How can I add this key to a separate column when setting up the sink connector

{  
“schema”:{  
“type”:“struct”  
“fields”:[  
0:{  
“type”:“int32”  
“optional”:false  
“field”:“id”  
}  
]  
“optional”:false  
“name”:“ba\_update\_test.public.update\_test.Key”  
}  
“payload”:{  
“id”:2  
}  
}

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<div class="post-metadata">

**Author:** ![OneCricketeer](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.confluent.io/onecricketeer/32/1551_2.png) [@OneCricketeer](https://forum.confluent.io/u/OneCricketeer)\
**Post date:** [25 July 2023 23:22 UTC](https://forum.confluent.io/t/sink-connector-add-key-in-separate-column/8350/2 "2023-07-25T23:22:12Z")

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Is that the value schema? Have you tried using the ValueToKey transform with fields set to id?

> **[ValueToKey | Confluent Documentation](https://docs.confluent.io/platform/current/connect/transforms/valuetokey.html)**
>
> This document provides usage information for the Apache Kafka SMT org.apache.kafka.connect.transforms.ValueToKey.

And not clear what connector you’re using, but JDBC sink can already write keys to columns

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<div class="post-metadata">

**Author:** ![victorrogue](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.confluent.io/victorrogue/32/3120_2.png) [@victorrogue](https://forum.confluent.io/u/victorrogue)\
**Post date:** [26 July 2023 07:44 UTC](https://forum.confluent.io/t/sink-connector-add-key-in-separate-column/8350/3 "2023-07-26T07:44:01Z")

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I solved this case.  
I used Custom transform based InsertField transform and added new type record.key().toString()

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex019/uploads/confluentcommunity/original/1X/c49438c90c9df282e9996fdf6971be890c71b65a.svg) [@system](https://forum.confluent.io/u/system)\
**Post date:** [25 August 2023 07:44 UTC](https://forum.confluent.io/t/sink-connector-add-key-in-separate-column/8350/4 "2023-08-25T07:44:46Z")

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