Create a JDBC Sink Connector

You can use a JDBC Sink connector to export structured data from Redpanda to a relational database.

Prerequisites

Before you can create a JDBC Sink connector in the Redpanda Cloud, you must have a:

  • Relational database instance that is accessible from the JDBC Sink connector instance

  • Database user

Limitations

The JDBC Sink connector has the following limitations:

  • Only JSON or AVRO formats can be used as a value converter.

  • Only the following databases are supported:

    • MySQL 5.7 and 8.0

    • PostgreSQL 8.2 and higher using the version 3.0 of the PostgreSQL® protocol

    • SQLite

    • SQL Server - Microsoft SQL versions: Azure SQL Database, Azure Synapse Analytics, Azure SQL Managed Instance, SQL Server 2014, SQL Server 2016, SQL Server 2017, SQL Server 2019

Create a JDBC Sink connector

To create the JDBC Sink connector:

  1. In Redpanda Cloud, click Connectors in the navigation menu, and then click Create Connector.

  2. Select Export to JDBC.

  3. On the Create Connector page, specify the following required connector configuration options:

    Property name Property key Description

    Topics to export

    topics

    Comma-separated list of the cluster topics you want to replicate.

    Topics regex

    topics.regex

    Java regular expression of topics to replicate. For example: specify .* to replicate all available topics in the cluster. Applicable only when Use regular expressions is selected.

    JDBC URL

    connection.url

    The database connection JDBC URL.

    User

    connection.user

    Name of the database user to be used when connecting to the database.

    Password

    connection.password

    Password of the database user to be used when connecting to the database.

    Redpanda message key format

    key.converter

    Format of the key in the Redpanda topic. BYTES is the default.

    Redpanda message value format

    value.converter

    Format of the value in the Redpanda topic. JSON is the default.

    Auto-create

    auto.create

    When enabled, automatically creates the destination table (if it is missing) based on the record schema (issues a CREATE). The default is disabled.

    Max Tasks

    tasks.max

    Maximum number of tasks to use for this connector. The default is 1. Each task replicates exclusive set of partitions assigned to it.

    Connector name

    name

    Globally-unique name to use for this connector.

  4. Click Next. Review the connector properties specified, then click Create.

Advanced JDBC Sink connector configuration

In most instances, the preceding basic configuration properties are sufficient. If you require additional property settings, then specify any of the following optional advanced connector configuration properties by selecting Show advanced options on the Create Connector page:

Property name Property key Description

Include fields

fields.whitelist

List of comma-separated record value field names. If the value of this property is empty, the connector uses all fields from the record to migrate to a database. Otherwise, the connector uses only the record fields that are specified (in a comma-separated format). Note that Primary Key Fields is applied independently in the context of which fields form the primary key columns in the destination database, while this configuration is applicable for the other columns.

Topics to tables mapping

topics.to.tables.mapping

Kafka topics to database tables mapping. Comma-separated list of topic to table mapping in the format: topic_name:table_name. If the destination table is found in the mapping, then it overrides the generated one defined in table.name.format.

Table name format

table.name.format

A format string for the destination table name, which may contain ${topic} as a placeholder for the original topic name. For example, kafka_${topic} for the topic orders maps to the table name kafka_orders. The default is ${topic}.

Table name normalize

table.name.normalize

Specifies whether or not to normalize destination table names for topics. When enabled, the alphanumeric characters (a-z, A-Z, 0-9) and remain as is, others (such as .) are replaced with . By default, is disabled.

Quote SQL identifiers

sql.quote.identifiers

Specifies whether or not to delimit (in most databases, a quote with double quotation marks) identifiers (for example, table names and column names) in SQL statements. By default, enabled.

Auto-evolve

auto.evolve

Whether to automatically add columns in the table schema when found to be missing relative to the record schema by issuing ALTER.

Batch size

batch.size

Specifies how many records to attempt to batch together for insertion into the destination table, when possible. The default is 3000.

DB time zone

db.timezone

Name of the JDBC timezone that should be used in the connector when querying with time-based criteria. Default is UTC.

Insert mode

insert.mode

The insertion mode to use. The supported modes are:

  • INSERT: standard SQL INSERT statements

  • MULTI: multi-row INSERT statements

  • UPSERT: use the appropriate upsert semantics for the target database if it is supported by the connector; for example, INSERT .. ON CONFLICT .. DO UPDATE SET ..

  • UPDATE: use the appropriate update semantics for the target database if it is supported by the connector; for example, UPDATE.

Primary key mode

pk.mode

The primary key mode to use. Supported modes are:

  • NONE: no keys utilized

  • kafka: Kafka coordinates (the topic, partition, and offset) are used as the primary key

  • RECORD_KEY: fields from the record key are used, which may be a primitive or a struct

  • RECORD_VALUE: fields from the record value are used, which must be a struct.

Primary key fields

pk.fields

Comma-separated list of primary key field names. The runtime interpretation of this configuration depends on the pk.mode. Supported modes are:

  • none: ignored because no fields are used as primary key in this mode.

  • kafka: must be a trio representing the Kafka coordinates (the topic, partition, and offset). Defaults to connect_topic,connect_partition,__connect_offset if empty.

  • record_key: if empty, all fields from the key struct will be used, otherwise used to extract the desired fields. For primitive key, only a single field name must be configured.

  • record_value: if empty, all fields from the value struct will be used, otherwise used to extract the desired fields.

Maximum retries

max.retries

The maximum number of times to retry on errors before failing the task. The default is 10.

Retry backoff (ms)

retry.backoff.ms

The time in milliseconds to wait before a retry attempt is made following an error. The default is 3000.

Database dialect

dialect.name

The name of the database dialect that should be used for this connector. By default. the connector automatically determines the dialect based upon the JDBC connection URL. Use if you want to override that behavior and specify a specific dialect.

Error tolerance

errors.tolerance

Error tolerance response during connector operation. Default value is none and signals that any error will result in an immediate connector task failure. Value of all changes the behavior to skip over problematic records.

Dead letter queue topic name

errors.deadletterqueue.topic.name

The name of the topic to be used as the dead letter queue (DLQ) for messages that result in an error when processed by this sink connector, its transformations, or converters. The topic name is blank by default, which means that no messages are recorded in the DLQ.

Dead letter queue topic replication factor

errors.deadletterqueue.topic .replication.factor

Replication factor used to create the dead letter queue topic when it doesn’t already exist.

Enable error context headers

errors.deadletterqueue.context .headers.enable

When true, adds a header containing error context to the messages written to the dead letter queue. To avoid clashing with headers from the original record, all error context header keys, start with __connect.errors.

Map data

Use the appropriate key or value converter (input data format) for your data as follows:

  • Use the default Redpanda message value format = JSON (org.apache.kafka.connect.json.JsonConverter) property in your configuration.

  • Topics should contain data in JSON format with a defined JSON schema. For example:

    {
   "schema": {
     "type": "struct",
     "fields": [
     ]
   },
   "payload": {
   }
}

Test the connection

After the connector is created, ensure that:

  • There are no errors in logs and in Redpanda Console.

  • Database tables contain data from Redpanda topics.

Troubleshoot

JDBC Sink connector issues are reported as failed tasks. Select Show Logs to view error details.

Message Action

PSQLException: FATAL: database "invalid-database" does not exist

Make sure the JDBC URL specifies an existing database name.

UnknownHostException: invalid-host

Make sure the JDBC URL specifies a valid database host name.

PSQLException: Connection to postgres:1234 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections

Make sure the JDBC URL specifies a valid database host name and port, and that the port is accessible.

PSQLException: FATAL: password authentication failed for user "postgres"

Verify that the User and Password are correct.

ConnectException: topic_name.Value (STRUCT) type doesn’t have a mapping to the SQL database column type

The JDBC Sink connector is not compatible with the Debezium PostgreSQL Source connector. Kafka Connect JSON produced by the Debezium Connector is not compatible with what the JDBC Sink Connector is expecting. Try changing a topic name. The JDBC Source connector is compatible with the JDBC Sink connector, and can be used as an alternative for a Debezium PostgreSQL source connector.