Support dynamic table routing via kafka message header 'table.name.format'

[OZOOOOOH]

Problem

#960
#1208
#1194

Multiple table sink support has been requested in several issues.
Currently, JDBC sink connector only supports routing all records to a single table or using topic-based routing, which limits flexibility for complex data pipeline requirements.

Solution

This PR implements a simple and non-intrusive approach to support multiple table sinks by leveraging Kafka message headers.

I am currently operating a data pipeline in production using this feature, successfully routing data from a single Kafka topic through a single connector to over 100 different tables. This demonstrates the scalability and reliability of this approach for complex, multi-table data ingestion scenarios.

Key Implementation Details:

• When table.name.format is set to __RECORD_HEADER__, the connector activates header-based table routing
• The connector reads the table name from the Kafka message header with key table.name.format
• This approach preserves existing functionality while adding new capabilities
• No breaking changes to current configurations or behavior

How it works:

1. Configure the connector with table.name.format=__RECORD_HEADER__
2. Kafka producers include a header with key table.name.format and target table name as value
3. The connector dynamically routes each record to the specified table

Does this solution apply anywhere else?

• yes
• no

If yes, where?

Test Strategy

Testing done:

• Unit tests
• Integration tests
• System #tests
• Manual tests

Release Plan

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[Copilot]

Pull Request Overview

Adds support for dynamic table routing based on a Kafka message header (table.name.format).
Key changes:

• Extended JdbcSinkConfig with a special constant and updated documentation for header-based table routing.
• Updated JdbcDbWriter to determine destination tables from record headers when configured.
• Added unit tests in JdbcSinkTaskTest covering header-based routing with different PK modes and invalid headers.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/main/java/io/confluent/connect/jdbc/sink/JdbcSinkConfig.java	Added TABLE_NAME_FORMAT_RECORD_HEADER, enhanced docstring for header routing.
src/main/java/io/confluent/connect/jdbc/sink/JdbcDbWriter.java	Implemented determineTableId and header extraction logic.
src/test/java/io/confluent/connect/jdbc/sink/JdbcSinkTaskTest.java	New tests for header-based routing (Kafka PK, record-key PK, invalid header).

Comments suppressed due to low confidence (2)

src/main/java/io/confluent/connect/jdbc/sink/JdbcSinkConfig.java:132

• There's a missing space between the closing parenthesis and the next sentence in the docstring. Consider changing to "a header key ('table.name.format') that contains..." for readability.

      + "a header key ('table.name.format')"

src/test/java/io/confluent/connect/jdbc/sink/JdbcSinkTaskTest.java:575

• In the Kafka PK mode test, only the kafka_offset field is asserted. Consider adding assertions for kafka_topic and kafka_partition to fully validate all configured primary key columns.

                assertEquals(44, rs.getLong("kafka_offset"));