Kafka connector for StarRocks
Load data using Kafka connector
StarRocks provides a self-developed connector named Apache Kafka® connector (StarRocks Connector for Apache Kafka®) that continuously consumes messages from Kafka and loads them into StarRocks. The Kafka connector guarantees at-least-once semantics.
The Kafka connector can seamlessly integrate with Kafka Connect, which allows StarRocks better integrated with the Kafka ecosystem. It is a wise choice if you want to load real-time data into StarRocks. Compared with Routine Load, it is recommended to use the Kafka connector in the following scenarios:
- Compared with Routine Load which only supports loading data in CSV, JSON, and Avro formats, Kafka connector can load data in more formats, such as Protobuf. As long as data can be converted into JSON and CSV formats using Kafka Connect's converters, data can be loaded into StarRocks via the Kafka connector.
- Customize data transformation, such as Debezium-formatted CDC data.
- Load data from multiple Kafka topics.
- Load data from Confluent Cloud.
- Need finer control over load batch sizes, parallelism, and other parameters to achieve a balance between load speed and resource utilization.
Preparations
Version requirements
| Connector | Kafka | StarRocks | Java |
|---|---|---|---|
| 1.0.4 | 3.4 | 2.5 and later | 8 |
| 1.0.3 | 3.4 | 2.5 and later | 8 |
Set up Kafka environment
Both self-managed Apache Kafka clusters and Confluent Cloud are supported.
- For a self-managed Apache Kafka cluster, you can refer to Apache Kafka quickstart to quickly deploy a Kafka cluster. Kafka Connect is already integrated into Kafka.
- For Confluent Cloud, make sure that you have a Confluent account and have created a cluster.
Download Kafka connector
Submit the Kafka connector into Kafka Connect:
-
Self-managed Kafka cluster:
Download and extract starrocks-kafka-connector-xxx.tar.gz.
-
Confluent Cloud:
Currently, the Kafka connector is not uploaded to Confluent Hub. You need to download and extract starrocks-kafka-connector-xxx.tar.gz, package it into a ZIP file and upload the ZIP file to Confluent Cloud.
Network configuration
Ensure that the machine where Kafka is located can access the FE nodes of the StarRocks cluster via the http_port (default: 8030) and query_port (default: 9030), and the BE nodes via the be_http_port (default: 8040).
Usage
This section uses a self-managed Kafka cluster as an example to explain how to configure the Kafka connector and the Kafka Connect, and then run the Kafka Connect to load data into StarRocks.
Prepare a dataset
Suppose that JSON-format data exists in the topic test in a Kafka cluster.
{"id":1,"city":"New York"}
{"id":2,"city":"Los Angeles"}
{"id":3,"city":"Chicago"}
Create a table
Create the table test_tbl in the database example_db in the StarRocks cluster according to the keys of the JSON-format data.
CREATE DATABASE example_db;
USE example_db;
CREATE TABLE test_tbl (id INT, city STRING);
Configure Kafka connector and Kafka Connect, and then run Kafka Connect to load data
Run Kafka Connect in standalone mode
-
Configure the Kafka connector. In the config directory under the Kafka installation directory, create the configuration file connect-StarRocks-sink.properties for the Kafka connector, and configure the following parameters. For more parameters and descriptions, see Parameters.
noteThe Kafka connector is a sink connector.
name=starrocks-kafka-connector
connector.class=com.starrocks.connector.kafka.StarRocksSinkConnector
topics=test
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=true
value.converter.schemas.enable=false
# The HTTP URL of the FE in your StarRocks cluster. The default port is 8030.
starrocks.http.url=192.168.xxx.xxx:8030
# If the Kafka topic name is different from the StarRocks table name, you need to configure the mapping relationship between them.
starrocks.topic2table.map=test:test_tbl
# Enter the StarRocks username.
starrocks.username=user1
# Enter the StarRocks password.
starrocks.password=123456
starrocks.database.name=example_db
sink.properties.strip_outer_array=trueNOTICE
If the source data is CDC data, such as data in Debezium format, and the StarRocks table is a Primary Key table, you also need to configure
transformin order to synchronize the source data changes to the Primary Key table. -
Configure and run the Kafka Connect.
-
Configure the Kafka Connect. In the configuration file config/connect-standalone.properties in the config directory, configure the following parameters. For more parameters and descriptions, see Running Kafka Connect.
# The addresses of Kafka brokers. Multiple addresses of Kafka brokers need to be separated by commas (,).
# Note that this example uses PLAINTEXT as the security protocol to access the Kafka cluster. If you are using other security protocol to access the Kafka cluster, you need to configure the relevant information in this file.
bootstrap.servers=<kafka_broker_ip>:9092
offset.storage.file.filename=/tmp/connect.offsets
offset.flush.interval.ms=10000
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=true
value.converter.schemas.enable=false
# The absolute path of the starrocks-kafka-connector after extraction. For example:
plugin.path=/home/kafka-connect/starrocks-kafka-connector-1.0.3 -
Run the Kafka Connect.
CLASSPATH=/home/kafka-connect/starrocks-kafka-connector-1.0.3/* bin/connect-standalone.sh config/connect-standalone.properties config/connect-starrocks-sink.properties
-
Run Kafka Connect in distributed mode
-
Configure and run the Kafka Connect.
-
Configure the Kafka Connect. In the configuration file
config/connect-distributed.propertiesin the config directory, configure the following parameters. For more parameters and descriptions, refer to Running Kafka Connect.# The addresses of Kafka brokers. Multiple addresses of Kafka brokers need to be separated by commas (,).
# Note that this example uses PLAINTEXT as the security protocol to access the Kafka cluster. If you are using other security protocol to access the Kafka cluster, you need to configure the relevant information in this file.
bootstrap.servers=<kafka_broker_ip>:9092
offset.storage.file.filename=/tmp/connect.offsets
offset.flush.interval.ms=10000
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=true
value.converter.schemas.enable=false
# The absolute path of the starrocks-kafka-connector after extraction. For example:
plugin.path=/home/kafka-connect/starrocks-kafka-connector-1.0.3 -
Run the Kafka Connect.
CLASSPATH=/home/kafka-connect/starrocks-kafka-connector-1.0.3/* bin/connect-distributed.sh config/connect-distributed.properties
-
-
Configure and create the Kafka connector. Note that in distributed mode, you need to configure and create the Kafka connector through the REST API. For parameters and descriptions, see Parameters.
noteThe Kafka connector is a sink connector.
curl -i http://127.0.0.1:8083/connectors -H "Content-Type: application/json" -X POST -d '{
"name":"starrocks-kafka-connector",
"config":{
"connector.class":"com.starrocks.connector.kafka.StarRocksSinkConnector",
"topics":"test",
"key.converter":"org.apache.kafka.connect.json.JsonConverter",
"value.converter":"org.apache.kafka.connect.json.JsonConverter",
"key.converter.schemas.enable":"true",
"value.converter.schemas.enable":"false",
"starrocks.http.url":"192.168.xxx.xxx:8030",
"starrocks.topic2table.map":"test:test_tbl",
"starrocks.username":"user1",
"starrocks.password":"123456",
"starrocks.database.name":"example_db",
"sink.properties.strip_outer_array":"true"
}
}'infoIf the source data is CDC data, such as data in Debezium format, and the StarRocks table is a Primary Key table, you also need to configure
transformin order to synchronize the source data changes to the Primary Key table.
Query StarRocks table
Query the target StarRocks table test_tbl.
MySQL [example_db]> select * from test_tbl;
+------+-------------+
| id | city |
+------+-------------+
| 1 | New York |
| 2 | Los Angeles |
| 3 | Chicago |
+------+-------------+
3 rows in set (0.01 sec)
The data is successfully loaded when the above result is returned.
Parameters
name
Required: YES
Default value:
Description: Name for this Kafka connector. It must be globally unique among all Kafka connectors within this Kafka Connect cluster. For example, starrocks-kafka-connector.
connector.class
Required: YES
Default value:
Description: Class used by this Kafka connector's sink. Set the value to com.starrocks.connector.kafka.StarRocksSinkConnector.
topics
Required: YES
Default value:
Description: One or more topics to subscribe to, where each topic corresponds to a StarRocks table. By default, StarRocks assumes that the topic name matches the name of the StarRocks table. So StarRocks determines the target StarRocks table by using the topic name. Please choose either to fill in topics or topics.regex (below), but not both.However, if the StarRocks table name is not the same as the topic name, then use the optional starrocks.topic2table.map parameter (below) to specify the mapping from topic name to table name.
topics.regex
Required:
Default value: Regular expression to match the one or more topics to subscribe to. For more description, see topics. Please choose either to fill in topics.regexor topics (above), but not both.
Description:
starrocks.topic2table.map
Required: NO
Default value:
Description: The mapping of the StarRocks table name and the topic name when the topic name is different from the StarRocks table name. The format is <topic-1>:<table-1>,<topic-2>:<table-2>,....
starrocks.http.url
Required: YES
Default value:
Description: The HTTP URL of the FE in your StarRocks cluster. The format is <fe_host1>:<fe_http_port1>,<fe_host2>:<fe_http_port2>,.... Multiple addresses are separated by commas (,). For example, 192.168.xxx.xxx:8030,192.168.xxx.xxx:8030.
starrocks.database.name
Required: YES
Default value:
Description: The name of StarRocks database.
starrocks.username
Required: YES
Default value:
Description: The username of your StarRocks cluster account. The user needs the INSERT privilege on the StarRocks table.
starrocks.password
Required: YES
Default value:
Description: The password of your StarRocks cluster account.
key.converter
Required: NO
Default value: Key converter used by Kafka Connect cluster
Description: This parameter specifies the key converter for the sink connector (Kafka-connector-starrocks), which is used to deserialize the keys of Kafka data. The default key converter is the one used by Kafka Connect cluster.
value.converter
Required: NO
Default value: Value converter used by Kafka Connect cluster
Description: This parameter specifies the value converter for the sink connector (Kafka-connector-starrocks), which is used to deserialize the values of Kafka data. The default value converter is the one used by Kafka Connect cluster.
key.converter.schema.registry.url
Required: NO
Default value:
Description: Schema registry URL for the key converter.
value.converter.schema.registry.url
Required: NO
Default value:
Description: Schema registry URL for the value converter.
tasks.max
Required: NO
Default value: 1
Description: The upper limit for the number of task threads that the Kafka connector can create, which is usually the same as the number of CPU cores on the worker nodes in the Kafka Connect cluster. You can tune this parameter to control load performance.
bufferflush.maxbytes
Required: NO
Default value: 94371840(90M)
Description: The maximum size of data that can be accumulated in memory before being sent to StarRocks at a time. The maximum value ranges from 64 MB to 10 GB. Keep in mind that the Stream Load SDK buffer may create multiple Stream Load jobs to buffer data. Therefore, the threshold mentioned here refers to the total data size.
bufferflush.intervalms
Required: NO
Default value: 1000
Description: Interval for sending a batch of data which controls the load latency. Range: [1000, 3600000].
connect.timeoutms
Required: NO
Default value: 1000
Description: Timeout for connecting to the HTTP URL. Range: [100, 60000].
sink.properties.*
Required:
Default value:
Description: Stream Load parameters o control load behavior. For example, the parameter sink.properties.format specifies the format used for Stream Load, such as CSV or JSON. For a list of supported parameters and their descriptions, see STREAM LOAD.
sink.properties.format
Required: NO
Default value: json
Description: The format used for Stream Load. The Kafka connector will transform each batch of data to the format before sending them to StarRocks. Valid values: csv and json. For more information, see CSV parameters and JSON parameters.
sink.properties.partial_update
Required: NO
Default value: FALSE
Description: Whether to use partial updates. Valid values: TRUE and FALSE. Default value: FALSE, indicating to disable this feature.
sink.properties.partial_update_mode
Required: NO
Default value: row
Description: Specifies the mode for partial updates. Valid values: row and column.
- The value
row(default) means partial updates in row mode, which is more suitable for real-time updates with many columns and small batches. - The value
columnmeans partial updates in column mode, which is more suitable for batch updates with few columns and many rows. In such scenarios, enabling the column mode offers faster update speeds. For example, in a table with 100 columns, if only 10 columns (10% of the total) are updated for all rows, the update speed of the column mode is 10 times faster.
Usage Notes
Flush Policy
The Kafka connector will buffer the data in memory, and flush them in batch to StarRocks via Stream Load. The flush will be triggered when any of the following conditions are met:
- The bytes of buffered rows reaches the limit
bufferflush.maxbytes. - The elapsed time since the last flush reaches the limit
bufferflush.intervalms. - The interval at which the connector tries committing offsets for tasks is reached. The interval is controlled by the Kafka Connect configuration
offset.flush.interval.ms, and the default values is60000.
For lower data latency, adjust these configurations in the Kafka connector settings. However, more frequent flushes will increase CPU and I/O usage.
Limits
- It is not supported to flatten a single message from a Kafka topic into multiple data rows and load into StarRocks.
- The Kafka connector's sink guarantees at-least-once semantics.
Best practices
Load Debezium-formatted CDC data
Debezium is a popular Change Data Capture (CDC) tool that supports monitoring data changes in various database systems and streaming these changes to Kafka. The following example demonstrates how to configure and use the Kafka connector to write PostgreSQL changes to a Primary Key table in StarRocks.
Step 1: Install and start Kafka
NOTE
You can skip this step if you have your own Kafka environment.
-
Download the latest Kafka release from the official site and extract the package.
tar -xzf kafka_2.13-3.7.0.tgz
cd kafka_2.13-3.7.0 -
Start the Kafka environment.
Generate a Kafka cluster UUID.
KAFKA_CLUSTER_ID="$(bin/kafka-storage.sh random-uuid)"Format the log directories.
bin/kafka-storage.sh format -t $KAFKA_CLUSTER_ID -c config/kraft/server.propertiesStart the Kafka server.
bin/kafka-server-start.sh config/kraft/server.properties
Step 2: Configure PostgreSQL
-
Make sure the PostgreSQL user is granted
REPLICATIONprivileges. -
Adjust PostgreSQL configuration.
Set
wal_leveltologicalin postgresql.conf.wal_level = logicalRestart the PostgreSQL server to apply changes.
pg_ctl restart -
Prepare the dataset.
Create a table and insert test data.
CREATE TABLE customers (
id int primary key ,
first_name varchar(65533) NULL,
last_name varchar(65533) NULL ,
email varchar(65533) NULL
);
INSERT INTO customers VALUES (1,'a','a','a@a.com'); -
Verify the CDC log messages in Kafka.
{
"schema": {
"type": "struct",
"fields": [
{
"type": "struct",
"fields": [
{
"type": "int32",
"optional": false,
"field": "id"
},
{
"type": "string",
"optional": true,
"field": "first_name"
},
{
"type": "string",
"optional": true,
"field": "last_name"
},
{
"type": "string",
"optional": true,
"field": "email"
}
],
"optional": true,
"name": "test.public.customers.Value",
"field": "before"
},
{
"type": "struct",
"fields": [
{
"type": "int32",
"optional": false,
"field": "id"
},
{
"type": "string",
"optional": true,
"field": "first_name"
},
{
"type": "string",
"optional": true,
"field": "last_name"
},
{
"type": "string",
"optional": true,
"field": "email"
}
],
"optional": true,
"name": "test.public.customers.Value",
"field": "after"
},
{
"type": "struct",
"fields": [
{
"type": "string",
"optional": false,
"field": "version"
},
{
"type": "string",
"optional": false,
"field": "connector"
},
{
"type": "string",
"optional": false,
"field": "name"
},
{
"type": "int64",
"optional": false,
"field": "ts_ms"
},
{
"type": "string",
"optional": true,
"name": "io.debezium.data.Enum",
"version": 1,
"parameters": {
"allowed": "true,last,false,incremental"
},
"default": "false",
"field": "snapshot"
},
{
"type": "string",
"optional": false,
"field": "db"
},
{
"type": "string",
"optional": true,
"field": "sequence"
},
{
"type": "string",
"optional": false,
"field": "schema"
},
{
"type": "string",
"optional": false,
"field": "table"
},
{
"type": "int64",
"optional": true,
"field": "txId"
},
{
"type": "int64",
"optional": true,
"field": "lsn"
},
{
"type": "int64",
"optional": true,
"field": "xmin"
}
],
"optional": false,
"name": "io.debezium.connector.postgresql.Source",
"field": "source"
},
{
"type": "string",
"optional": false,
"field": "op"
},
{
"type": "int64",
"optional": true,
"field": "ts_ms"
},
{
"type": "struct",
"fields": [
{
"type": "string",
"optional": false,
"field": "id"
},
{
"type": "int64",
"optional": false,
"field": "total_order"
},
{
"type": "int64",
"optional": false,
"field": "data_collection_order"
}
],
"optional": true,
"name": "event.block",
"version": 1,
"field": "transaction"
}
],
"optional": false,
"name": "test.public.customers.Envelope",
"version": 1
},
"payload": {
"before": null,
"after": {
"id": 1,
"first_name": "a",
"last_name": "a",
"email": "a@a.com"
},
"source": {
"version": "2.5.3.Final",
"connector": "postgresql",
"name": "test",
"ts_ms": 1714283798721,
"snapshot": "false",
"db": "postgres",
"sequence": "[\"22910216\",\"22910504\"]",
"schema": "public",
"table": "customers",
"txId": 756,
"lsn": 22910504,
"xmin": null
},
"op": "c",
"ts_ms": 1714283798790,
"transaction": null
}
}
Step 3: Configure StarRocks
Create a Primary Key table in StarRocks with the same schema as the source table in PostgreSQL.
CREATE TABLE `customers` (
`id` int(11) COMMENT "",
`first_name` varchar(65533) NULL COMMENT "",
`last_name` varchar(65533) NULL COMMENT "",
`email` varchar(65533) NULL COMMENT ""
) ENGINE=OLAP
PRIMARY KEY(`id`)
DISTRIBUTED BY hash(id) buckets 1
PROPERTIES (
"bucket_size" = "4294967296",
"in_memory" = "false",
"enable_persistent_index" = "false",
"replicated_storage" = "true",
"fast_schema_evolution" = "true"
);
Step 4: Install connector
-
Download the connectors and extract the packages in the plugins directory.
mkdir plugins
tar -zxvf debezium-debezium-connector-postgresql-2.5.3.zip -C plugins
tar -zxvf starrocks-kafka-connector-1.0.3.tar.gz -C pluginsThis directory is the value of the configuration item
plugin.pathin config/connect-standalone.properties.plugin.path=/path/to/kafka_2.13-3.7.0/plugins -
Configure the PostgreSQL source connector in pg-source.properties.
{
"name": "inventory-connector",
"config": {
"connector.class": "io.debezium.connector.postgresql.PostgresConnector",
"plugin.name": "pgoutput",
"database.hostname": "localhost",
"database.port": "5432",
"database.user": "postgres",
"database.password": "",
"database.dbname" : "postgres",
"topic.prefix": "test"
}
} -
Configure the StarRocks sink connector in sr-sink.properties.
{
"name": "starrocks-kafka-connector",
"config": {
"connector.class": "com.starrocks.connector.kafka.StarRocksSinkConnector",
"tasks.max": "1",
"topics": "test.public.customers",
"starrocks.http.url": "172.26.195.69:28030",
"starrocks.database.name": "test",
"starrocks.username": "root",
"starrocks.password": "StarRocks@123",
"sink.properties.strip_outer_array": "true",
"connect.timeoutms": "3000",
"starrocks.topic2table.map": "test.public.customers:customers",
"transforms": "addfield,unwrap",
"transforms.addfield.type": "com.starrocks.connector.kafka.transforms.AddOpFieldForDebeziumRecord",
"transforms.unwrap.type": "io.debezium.transforms.ExtractNewRecordState",
"transforms.unwrap.drop.tombstones": "true",
"transforms.unwrap.delete.handling.mode": "rewrite"
}
}NOTE
- If the StarRocks table is not a Primary Key table, you do not need to specify the
addfieldtransform. - The unwrap transform is provided by Debezium and is used to unwrap Debezium's complex data structure based on the operation type. For more information, see New Record State Extraction.
- If the StarRocks table is not a Primary Key table, you do not need to specify the
-
Configure Kafka Connect.
Configure the following configuration items in the Kafka Connect configuration file config/connect-standalone.properties.
# The addresses of Kafka brokers. Multiple addresses of Kafka brokers need to be separated by commas (,).
# Note that this example uses PLAINTEXT as the security protocol to access the Kafka cluster.
# If you use other security protocol to access the Kafka cluster, configure the relevant information in this part.
bootstrap.servers=<kafka_broker_ip>:9092
offset.storage.file.filename=/tmp/connect.offsets
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=true
value.converter.schemas.enable=false
# The absolute path of the starrocks-kafka-connector after extraction. For example:
plugin.path=/home/kafka-connect/starrocks-kafka-connector-1.0.3
# Parameters that control the flush policy. For more information, see the Usage Note section.
offset.flush.interval.ms=10000
bufferflush.maxbytes = xxx
bufferflush.intervalms = xxxFor descriptions of more parameters, see Running Kafka Connect.
Step 5: Start Kafka Connect in Standalone Mode
Run Kafka Connect in standalone mode to initiate the connectors.
bin/connect-standalone.sh config/connect-standalone.properties config/pg-source.properties config/sr-sink.properties
Step 6: Verify data ingestion
Test the following operations and ensure the data is correctly ingested into StarRocks.
INSERT
- In PostgreSQL:
postgres=# insert into customers values (2,'b','b','b@b.com');
INSERT 0 1
postgres=# select * from customers;
id | first_name | last_name | email
----+------------+-----------+---------
1 | a | a | a@a.com
2 | b | b | b@b.com
(2 rows)
- In StarRocks:
MySQL [test]> select * from customers;
+------+------------+-----------+---------+
| id | first_name | last_name | email |
+------+------------+-----------+---------+
| 1 | a | a | a@a.com |
| 2 | b | b | b@b.com |
+------+------------+-----------+---------+
2 rows in set (0.01 sec)
UPDATE
- In PostgreSQL:
postgres=# update customers set email='c@c.com';
UPDATE 2
postgres=# select * from customers;
id | first_name | last_name | email
----+------------+-----------+---------
1 | a | a | c@c.com
2 | b | b | c@c.com
(2 rows)
- In StarRocks:
MySQL [test]> select * from customers;
+------+------------+-----------+---------+
| id | first_name | last_name | email |
+------+------------+-----------+---------+
| 1 | a | a | c@c.com |
| 2 | b | b | c@c.com |
+------+------------+-----------+---------+
2 rows in set (0.00 sec)
DELETE
- In PostgreSQL:
postgres=# delete from customers where id=1;
DELETE 1
postgres=# select * from customers;
id | first_name | last_name | email
----+------------+-----------+---------
2 | b | b | c@c.com
(1 row)
- In StarRocks:
MySQL [test]> select * from customers;
+------+------------+-----------+---------+
| id | first_name | last_name | email |
+------+------------+-----------+---------+
| 2 | b | b | c@c.com |
+------+------------+-----------+---------+
1 row in set (0.00 sec)