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    Realtime Compute for Apache Flink:Manage DLF-Legacy catalogs

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    Realtime Compute for Apache Flink:Manage DLF-Legacy catalogs

    Last Updated:Aug 13, 2026

    After configuring a DLF-Legacy catalog, you can directly access its tables from the Realtime Compute for Apache Flink console. This eliminates the need to manually register Data Lake Formation (DLF) tables, improving development efficiency and ensuring data integrity. This topic describes how to create, view, use, and delete a DLF-Legacy catalog.

    Note

    This topic applies only to DLF-Legacy. We recommend that you use the latest version of Data Lake Formation (DLF) instead of DLF-Legacy. For more information about how to use the new version of DLF, see Manage Paimon catalogs.

    Background information

    Alibaba Cloud Data Lake Formation (DLF) is a unified metadata management service. You can use DLF to manage tables in open source formats, such as Iceberg, Hudi, Delta, Parquet, ORC, and Avro.

    Prerequisites

    The DLF-Legacy service has been activated

    Limitations

    In a DLF-Legacy catalog, Flink can manage only tables in the Iceberg and Hudi data lake formats.

    Create a DLF-Legacy catalog

    You can create a DLF-Legacy catalog using the UI or SQL commands. We recommend using the UI.

    Use the UI

    1. Go to the Catalogs page.

      1. Log on to the Realtime Compute for Apache Flink console.

      2. In the Actions column of the target workspace, click Console.

      3. Click Catalogs.

    2. Click Create Catalog, select DLF, and then click Next.

    3. Create the DLF-Legacy catalog.

      1. Configure the catalog parameters.

        Parameter

        Description

        Required

        Remarks

        catalogname

        The name of the DLF-Legacy catalog.

        Yes

        Enter a custom name in English.

        access.key.id

        The AccessKey ID to access Object Storage Service (OSS).

        Yes

        For more information, see Obtain an AccessKey pair.

        access.key.secret

        The AccessKey Secret to access Object Storage Service (OSS).

        Yes

        For more information, see Obtain an AccessKey pair.

        warehouse

        The default OSS path where tables in the DLF-Legacy catalog are stored.

        Yes

        Both OSS and OSS-HDFS are supported.

        • OSS path format: oss://<bucket>/<object>

        • OSS-HDFS path format: oss://<bucket>.<oss-hdfs-endpoint>/<object>

        The placeholders are described as follows:

        • bucket: The name of your OSS bucket. You can view the bucket name in the OSS console.

        • object: The path where your data is stored. You can view the path in the OSS console.

        • oss-hdfs-endpoint: The endpoint of the OSS-HDFS service. In the OSS console, on the Overview page of a bucket, view the endpoint of the HDFS service in the Access Ports section.

        Note

        This parameter can be set to an OSS-HDFS path only in VVR 8.0.3 and later.

        oss.endpoint

        The endpoint of Alibaba Cloud OSS. For example, oss-cn-hangzhou-internal.aliyuncs.com.

        Yes

        Both OSS and OSS-HDFS are supported.

        • OSS service endpoint. For more information, see Regions and endpoints.

        • OSS-HDFS service endpoint. In the OSS console, on the Overview page of a bucket, view the endpoint of the HDFS service in the Access Ports section.

        Note

        • We recommend that you set the oss.endpoint parameter to a VPC endpoint for OSS. For example, if you are in the China (Hangzhou) region, set oss.endpoint to oss-cn-hangzhou-internal.aliyuncs.com.

        • If you need to access OSS across VPCs, see How do I access other services across VPCs?.

        dlf.endpoint

        The endpoint of the Alibaba Cloud DLF service.

        Yes

        Note

        • We recommend that you set the dlf.endpoint parameter to a VPC endpoint for DLF. For example, if you are in the China (Hangzhou) region, set the dlf.endpoint parameter to dlf-vpc.cn-hangzhou.aliyuncs.com.

        • If you need to access DLF across VPCs, see Workspace management and operations.

        dlf.region-id

        The region ID of the Alibaba Cloud DLF service.

        Yes

        Note

        Make sure that the region ID is consistent with the region of the dlf.endpoint.

        Configurations

        Additional DLF settings. For example, to specify multiple DLF catalogs, enter each on a new line.

        No

        For example: dlf.catalog.id:my_catalog.

      2. Click Confirm.

    4. After the catalog is created, you can view it in the Catalogs section.

    Use SQL commands

    1. In the text editor on the Scripts page, enter the command to create a DLF-Legacy catalog.

      CREATE CATALOG <yourcatalogname> WITH (
   'type' = 'dlf',
   'access.key.id' = '<YourAliyunAccessKeyId>',
   'access.key.secret' = '<YourAliyunAccessKeySecret>',
   'warehouse' = '<YourAliyunOSSLocation>',
   'oss.endpoint' = '<YourAliyunOSSEndpoint>',
   'dlf.region-id' = '<YourAliyunDLFRegionId>',
   'dlf.endpoint' = '<YourAliyunDLFEndpoint>'
);

      Parameter

      Description

      Required

      Remarks

      yourcatalogname

      A custom name for the DLF-Legacy catalog.

      Yes

      Enter a custom name in English.

      Important

      After you replace the parameter with your catalog name, remove the angle brackets (<>). Otherwise, a syntax error occurs.

      type

      The type of the catalog.

      Yes

      Set this parameter to dlf.

      access.key.id

      The AccessKey ID of your Alibaba Cloud account.

      Yes

      For more information, see Obtain an AccessKey pair.

      access.key.secret

      The AccessKey Secret of your Alibaba Cloud account.

      Yes

      For more information, see Obtain an AccessKey pair.

      warehouse

      The default OSS path for tables in the DLF-Legacy catalog.

      Yes

      The format is oss://<bucket>/<object>. The placeholders are described as follows:

      • bucket: The name of your OSS bucket.

      • object: The path where your data is stored.

      Note

      You can view your bucket and object names in the OSS console.

      oss.endpoint

      The endpoint of Alibaba Cloud OSS.

      Yes

      For more information, see Regions and endpoints.

      Note

      • We recommend that you set the oss.endpoint parameter to a VPC endpoint for OSS. For example, if you are in the China (Hangzhou) region, set oss.endpoint to oss-cn-hangzhou-internal.aliyuncs.com.

      • If you need to access OSS across VPCs, see Workspace management and operations.

      dlf.endpoint

      The endpoint of the Alibaba Cloud DLF service.

      Yes

      Note

      • We recommend that you set the dlf.endpoint parameter to a VPC endpoint for DLF. For example, if you are in the China (Hangzhou) region, set the dlf.endpoint parameter to dlf-vpc.cn-hangzhou.aliyuncs.com.

      • If you need to access DLF across VPCs, see Workspace management and operations.

      dlf.region-id

      The region ID of the Alibaba Cloud DLF service.

      Yes

      Note

      Make sure that the region ID is consistent with the region of the dlf.endpoint.

    2. Select the statement and click Run.

    3. In the Catalogs section on the left, view the created catalog.

    View a DLF-Legacy catalog

    After creating a DLF-Legacy catalog, you can view its metadata.

    1. Go to the Catalogs page.

      1. Log on to the Realtime Compute for Apache Flink console.

      2. In the Actions column of the target workspace, click Console.

      3. Click Catalogs.

    2. On the Catalog list page, you can view the Name and Type.

      Note

      To view the databases and tables in a catalog, click View.

    Use a DLF-Legacy catalog

    Manage DLF databases

    In the text editor on the Scripts page, enter the following statements. Select a statement and click Run. After the database is created or deleted, you can verify the result in the Catalogs section on the left side of the SQL Editor page.

    • Create a database

      CREATE DATABASE dlf.dlf_testdb;

    • Delete a database

      DROP DATABASE dlf.dlf_testdb;

    Manage DLF tables

    • Create a table

      • Create a table by using a connector

        SQL

        In the text editor on the Scripts page, enter a statement. Select the statement and click Run. After the table is created, you can view it in the Catalogs section on the left side of the SQL Editor page.

        CREATE TABLE dlf.dlf_testdb.iceberg (
  id    BIGINT,
  data  STRING,
  dt    STRING
) PARTITIONED BY (dt) WITH(
  'connector' = 'iceberg'
);
CREATE TABLE dlf.dlf_testdb.hudi (
  id    BIGINT PRIMARY KEY NOT ENFORCED,
  data  STRING,
  dt    STRING
) PARTITIONED BY (dt) WITH(
  'connector' = 'hudi'
);

        UI

        1. Go to the Catalogs page.

          1. Log on to the Realtime Compute for Apache Flink console.

          2. In the Actions column of the target workspace, click Console.

          3. Click Catalogs.

        2. In the Actions column of the target catalog, click View.

        3. In the Actions column of the target database, click View.

        4. Click Create Table.

        5. On the Built-in tab, click Connection Type and select a table type.

        6. Click Next.

        7. Enter the table creation statement and configure the parameters. The following code provides an example.

          CREATE TABLE dlf.dlf_testdb.iceberg (
  id    BIGINT,
  data  STRING,
  dt    STRING
) PARTITIONED BY (dt) WITH(
  'connector' = 'iceberg'
);
CREATE TABLE dlf.dlf_testdb.hudi (
  id    BIGINT PRIMARY KEY NOT ENFORCED,
  data  STRING,
  dt    STRING
) PARTITIONED BY (dt) WITH(
  'connector' = 'hudi'
);

        8. Click Confirm.

      • Create a table with a matching schema (This method is supported only for Iceberg tables.)

        In the text editor on the Scripts page, enter the following statement. Select the statement and click Run.

        CREATE TABLE iceberg_table_like LIKE iceberg_table;

    • Delete a table

      DROP TABLE iceberg_table;

    Modify Iceberg table schema

    In the text editor on the Scripts page, enter the required command. Select the command and click Run.

    Actions

    Example

    Change table properties

    		 
    ALTER TABLE iceberg_table SET ('write.format.default'='avro');

    Rename a table

    		 
    ALTER TABLE iceberg_table RENAME TO new_iceberg_table;

    Rename a column

    		 
    ALTER TABLE iceberg_table RENAME id TO index;
    Note

    This feature is supported only in VVR 8.0.7 and later.

    Change a data type

    		 
    ALTER TABLE iceberg_table MODIFY (id, BIGINT)

    The following rules apply when you change the data type of a column:

    • INT -> BIGINT

    • Float -> Double

    • Decimal -> Decimal

    Note

    This feature is supported only in VVR 8.0.7 and later.

    Write data

    INSERT INTO dlf.dlf_testdb.iceberg VALUES (1, 'AAA', '2022-02-01'), (2, 'BBB', '2022-02-01');
INSERT INTO dlf.dlf_testdb.hudi VALUES (1, 'AAA', '2022-02-01'), (2, 'BBB', '2022-02-01');

    Read data

    SELECT * FROM dlf.dlf_testdb.iceberg LIMIT 2;
SELECT * FROM dlf.dlf_testdb.hudi LIMIT 2;

    Delete a DLF-Legacy catalog

    Warning

    Deleting a DLF-Legacy catalog does not affect running deployments. However, deployments that use the catalog may fail upon restart or republication because they can no longer find the tables. Proceed with caution.

    You can delete a DLF-Legacy catalog using the UI or SQL commands. We recommend using the UI.

    Use the UI

    1. Go to the Catalogs page.

      1. Log on to the Realtime Compute for Apache Flink console.

      2. In the Actions column of the target workspace, click Console.

      3. Click Catalogs.

    2. On the Catalog list page, click Delete in the Actions column of the target catalog.

    3. In the confirmation message that appears, click Delete.

    4. In the Catalogs section on the left, verify that the target catalog has been deleted.

    Use SQL commands

    1. In the text editor on the Scripts page, enter the following command.

      DROP CATALOG ${catalog_name}

      Replace ${catalog_name} with the name of the DLF-Legacy catalog to delete.

    2. Select the command and click Run.

    3. In the Catalogs section on the left, verify that the target catalog has been deleted.

    Related documents

    • For more information about how to use the Iceberg connector, see Iceberg connector.

    • For more information about how to use the Hudi connector, see Hudi connector (retiring).

    • If the built-in catalogs do not meet your business requirements, you can create a custom catalog. For more information, see Manage custom catalogs.