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
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 (<> ). |
-- Add a column named "v3" to a source named "src1"
ALTER SOURCE src1
ADD COLUMN v3 int;
-
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
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. |
-- Change the name of a source named "src" to "src1"
ALTER SOURCE src
RENAME TO src1;
OWNER TO
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. |
-- Change the owner of the source named "src" to user "user1"
ALTER SOURCE src OWNER TO user1;
SET SCHEMA
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. |
-- 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.
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:
-- 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:
ALTER SOURCE src_user FORMAT PLAIN ENCODE PROTOBUF(
schema.registry = 'http://message_queue:8081',
message = 'test.UserWithMoreFields'
);
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.
ALTER SOURCE source_name REFRESH SCHEMA;
For example, assume we have a source as follows:
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:
ALTER SOURCE src_user REFRESH SCHEMA;
For more details about this example, see our test file.