[Bug] kafka_fdw foreign table returns zero rows: Feature not supported: Foreign Data

[ehkim12]

Description:

I have successfully created and configured the kafka_fdw extension and a foreign table to read from a Kafka topic. However, when querying the foreign table, it returns zero rows with the following log message:

NOTICE: "Feature not supported: Foreign Data"

This seems to indicate the foreign table was created correctly but data retrieval is blocked or unsupported by the executor.

Steps to Reproduce:

Installed and enabled kafka_fdw:

CREATE EXTENSION kafka_fdw;

Set up Kafka/Zookeeper using Docker:

version: '2'
networks:
test:
services:
zookeeper:
image: confluentinc/cp-zookeeper:5.5.0
ports: [ "2181:2181" ]
environment:
ZOOKEEPER_CLIENT_PORT: 2181
ZOOKEEPER_TICK_TIME: 2000
kafka:
image: confluentinc/cp-kafka:5.5.0
ports: [ "9092:9092" ]
environment:
KAFKA_BROKER_ID: 1
KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
KAFKA_LISTENERS: PLAINTEXT://0.0.0.0:9092
KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://192.168.222.51:9092
KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1

Created server and foreign table:

CREATE SERVER kafka_server
FOREIGN DATA WRAPPER kafka_fdw
OPTIONS (brokers 'localhost:9092');

CREATE USER MAPPING FOR PUBLIC SERVER kafka_server;
CREATE USER MAPPING FOR gpadmin SERVER kafka_server;

CREATE FOREIGN TABLE kafka_test (
part int OPTIONS (partition 'true'),
offs bigint OPTIONS (offset 'true'),
some_int int,
some_text text,
some_date date,
some_time timestamp
)
SERVER kafka_server
OPTIONS (format 'csv', topic 'contrib_regress', batch_size '30', buffer_delay '100');

Ran query:

SELECT * FROM kafka_test LIMIT 1;

Expected Behavior:
Should return rows from the Kafka topic contrib_regress.

Actual Behavior:
Returns zero rows with notice:

NOTICE: "Feature not supported: Foreign Data"

Environment:

OS: Docker container

Kafka: 5.5.0 (also tried 7.4.0)

kafka_fdw: latest build from GitHub

Database: CloudberryDB / GreenplumDB

FDW server created with broker localhost:9092

Additional Context:

Kafka topic contrib_regress is successfully created. Using command-line tools, I can publish and consume messages. Seems like the FDW is skipping execution due to unsupported features.

Please advise on how to enable execution or whether a fix is available.

[roseduan]

I tried to reproduce this issue but it seems no problem.

I use your docker script to start a kafka server and the data can be returned correctly.