swapna267 opened a new pull request, #28115: URL: https://github.com/apache/flink/pull/28115
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## What is the purpose of the change
This pull request adds a new avro-variant-confluent deserialization format
that reads Avro binary data from Confluent Schema Registry and converts it into
Flink's VARIANT type. Unlike the existing avro-confluent format which requires
a fixed reader schema at table creation time, this format uses the writer
schema
dynamically per record — enabling schema-agnostic ingestion where the Avro
schema varies across records.
Example usage:
```
CREATE TABLE kafka_source (
data VARIANT,
avro_schema STRING METADATA FROM 'schema'
) WITH (
'connector' = 'kafka',
'topic' = 'my-topic',
'properties.bootstrap.servers' = 'server1',
'format' = 'avro-variant-confluent',
'avro-variant-confluent.url' = ''
);
```
## Brief change log
- Added RegistryWriterAvroDeserializationSchema that deserializes Avro
binary using the writer schema as both reader and writer, preserving all fields
as-is
- Added AvroVariantDeserializationSchema that converts GenericRecord to
Variant with an LRU converter cache keyed by writer schema
- Added AvroVariantDecodingFormat with support for optional schema
metadata column exposing the writer schema string
- Added ConfluentRegistryAvroVariantFormatFactory as the SPI entry point
(identifier: avro-variant-confluent), deserialization only
- Added test utility fixedRoundRobinSchemaCoderProvider for testing
multi-schema scenarios
## Verifying this change
This change added tests and can be verified as follows:
- AvroVariantDeserializationSchemaTest — parameterized deserialization
with/without schema metadata, converter cache eviction, null message handling
- RegistryWriterAvroDeserializationSchemaTest — verifies
writer-schema-preserving deserialization of GenericRecord
- ConfluentRegistryAvroVariantFormatFactoryTest — SPI discovery, optional
SSL/auth properties, missing URL validation, schema metadata column via format
readable metadata
- RegistryAvroVariantDeserializationSchemaTest — end-to-end serialize
(RowData→Avro) then deserialize (Avro→Variant) with MockSchemaRegistryClient,
schema evolution across v1/v2, parameterized with/without schema metadata
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
@Public(Evolving): no
- The serializers: no
- The runtime per-record code paths (performance sensitive): yes (new
deserialization path for VARIANT type)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? yes
- If yes, how is the feature documented? JavaDocs , Will add to Flink docs
similar to avro-confluent format page, once this PR is reviewed and ready.
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Generated-by: Claude Code (Claude Opus 4.6)
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