ALTER SOURCE

The ALTER SOURCE command modifies the definition of a source.

Syntax

ALTER SOURCE current_source_name 
    alter_option;

alter_option depends on the operation you want to perform on the source. For all supported clauses, see the sections below.

Clause

ADD COLUMN

Syntax

ALTER SOURCE source_name 
    ADD COLUMN col_name data_type;

Parameter or clause	Description
ADD COLUMN	This clause adds a column to the specified source.
col_name	The name of the new column you want to add to the source.
data_type	The data type of the newly added column. With the struct data type, you can create a nested table. Elements in a nested table need to be enclosed with angle brackets ("<>").

Example

-- Add a column named "v3" to a source named "src1" 
ALTER SOURCE src1 
    ADD COLUMN v3 int;

note

• To alter columns in a source created with a schema registry, see FORMAT and ENCODE options.

• You cannot add a primary key column to a source or table in RisingWave. To modify the primary key of a source or table, you need to recreate the table.

• You cannot remove a column from a source in RisingWave. If you intend to remove a column from a source, you'll need to drop the source and create the source again.

RENAME TO

Syntax

ALTER SOURCE source_name 
    RENAME TO new_source_name;

Parameter or clause	Description
RENAME TO	This clause changes the name of the source.
new_source_name	The new name of the source.

Example

-- Change the name of a source named "src" to "src1"
ALTER SOURCE src 
   RENAME TO src1;

OWNER TO

Syntax

ALTER SOURCE current_source_name 
    OWNER TO new_user;

Parameter or clause	Description
OWNER TO	This clause changes the owner of the source.
new_user	The new owner you want to assign to the source.

Example

-- Change the owner of the source named "src" to user "user1"
ALTER SOURCE src OWNER TO user1;

SET SCHEMA

Syntax

ALTER SOURCE current_source_name
    SET SCHEMA schema_name;

Parameter or clause	Description
SET SCHEMA	This clause moves the source to a different schema.
schema_name	The name of the schema to which the source will be moved.

Example

-- Move the source named "test_source" to the schema named "test_schema"
ALTER SOURCE test_source SET SCHEMA test_schema;

FORMAT and ENCODE options

At present, combined with the ALTER SOURCE command, you can refresh the schema registry of a source by refilling the FORMAT and ENCODE options. For more details about these options, see FORMAT and ENCODE parameters.

Syntax

ALTER SOURCE source_name FORMAT data_format ENCODE data_encode [ (
    message='message',
    schema.location='location', ...) ];

Here is an example. Let's assume the original FORMAT and ENCODE options are as follows:

Example

-- Create a source.
CREATE SOURCE src_user WITH (
    connector = 'kafka',
    topic = 'sr_pb_test',
    properties.bootstrap.server = 'message_queue:29092',
    scan.startup.mode = 'earliest'
)
FORMAT PLAIN ENCODE PROTOBUF(
    schema.registry = 'http://message_queue:8081',
    message = 'test.User');

Then you can refresh the schema registry by the following command:

Example

ALTER SOURCE src_user FORMAT PLAIN ENCODE PROTOBUF(
    schema.registry = 'http://message_queue:8081',
    message = 'test.UserWithMoreFields'
);

note

Currently, it is not supported to modify the data_format and data_encode. Furthermore, when refreshing the schema registry of a source, it is not allowed to drop columns or change types.

Another way of refreshing the schema is using the REFRESH SCHEMA clause.

REFRESH SCHEMA

This is another way of refreshing the schema of sources when the FORMAT and ENCODE options are not changed.

Syntax

ALTER SOURCE source_name REFRESH SCHEMA;

For example, assume we have a source as follows:

Create a source

CREATE SOURCE src_user WITH (
    connector = 'kafka',
    topic = 'sr_pb_test',
    properties.bootstrap.server = 'message_queue:29092',
    scan.startup.mode = 'earliest'
)
FORMAT PLAIN ENCODE PROTOBUF(
    schema.registry = 'http://message_queue:8081',
    message = 'test.User'
);

Then we can refresh its schema with the following statement:

Refresh schema

ALTER SOURCE src_user REFRESH SCHEMA;

For more details about this example, see our test file.