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Updating Configs

Overview​

Fluss allows you to update cluster or table configurations dynamically without requiring a cluster restart or table recreation. This section demonstrates how to modify and apply such configurations.

Updating Cluster Configs​

From Fluss version 0.8 onwards, some of the server configs can be updated without restarting the server.

Currently, the supported dynamically updatable server configurations include:

  • datalake.format: Enable lakehouse storage by specifying the lakehouse format, e.g., paimon, iceberg.
  • Options with prefix datalake.${datalake.format}
  • kv.rocksdb.shared-rate-limiter.bytes-per-sec: Control RocksDB flush and compaction write rate shared across all RocksDB instances on the TabletServer. The rate limiter is always enabled. Set to a lower value (e.g., 100MB) to limit the rate, or a very high value to effectively disable rate limiting.

You can update the configuration of a cluster with Java client or Flink Procedures.

Using Java Client​

Here is a code snippet to demonstrate how to update the cluster configurations using the Java Client:

// Enable lakehouse storage with Paimon format
admin.alterClusterConfigs(
        Collections.singletonList(
                new AlterConfig(DATALAKE_FORMAT.key(), "paimon", AlterConfigOpType.SET)));

// Disable lakehouse storage
admin.alterClusterConfigs(
        Collections.singletonList(
                new AlterConfig(DATALAKE_FORMAT.key(), "paimon", AlterConfigOpType.DELETE)));

// Set RocksDB shared rate limiter to 200MB/sec
admin.alterClusterConfigs(
        Collections.singletonList(
                new AlterConfig(KV_SHARED_RATE_LIMITER_BYTES_PER_SEC.key(), "200MB", AlterConfigOpType.SET)));

The AlterConfig class contains three properties:

  • key: The configuration key to be modified (e.g., datalake.format)
  • value: The configuration value to be set (e.g., paimon)
  • opType: The operation type, either AlterConfigOpType.SET or AlterConfigOpType.DELETE

For certain configurations, Fluss provides convenient Flink stored procedures that can be called directly from Flink SQL. See Procedures for detailed documentation on using get_cluster_config and set_cluster_config procedures.

Updating Table Configs​

The connector options on a table including Storage Options can be updated dynamically by ALTER TABLE ... SET statement. See the example below:

-- Enable lakehouse storage for the given table
ALTER TABLE my_table SET ('table.datalake.enabled' = 'true');