GENERATE CHANGELOG DDL

Syntax

GENERATE CHANGLEOG DDL changelog_name WITH(stream_parameter = value [, ...]);

GENERATE CHANGLEOG DDL changelog_name PRIMARY KEY(pk_name) WITH(stream_parameter = value [, ...]);

Description

This command generates a CREATE DDL for CHANGELOG from a given schema or data — for example, Data Store — that has corresponding Protocol Buffers and Descriptors. The command specially simplifies creating DDL for complex descriptors.

You can generate DDL if the current role has USAGE privileges on the Data Store.

Changelog Parameters

Parameter Name	Description
changelog_name	The name of the new changelog.
primary key	If you provide the primary key names they are added to the DDL. Otherwise, this is empty. Required? No.
topic	Name of the Kafka topic whose assigned data schema you're using (for Protobuf descriptor and Avro schema from SchemaRegistry). Required? Yes, for AVRO, PROTOBUF
value.format	AVRO, PROTOBUF, JSON Required? Yes.
key.format	AVRO, PROTOBUF, JSON Required? No.
data.json.value.content	A string containing one or more JSON objects separated by commas. It serves as a data sample you use to infer the schema of the value field in Kafka. Required? Required only for JSON
data.json.key.content	A string containing one or more JSON objects separated by commas. It serves as a data sample you used to infer the schema of the key in Kafka. Required? Only for JSON

Generating "Create Changelog" DDL examples

Generate a "create changelog" ddl for an entity in the current store, which includes a protobuf descriptor.

GENERATE CHANGELOG DDL myChangelog with('topic'='pageviews_pb', 'value.format'='protobuf', 
'key.format'='protobuf');

The output would be:

CREATE CHANGELOG myChangelog(
 "viewtime" BIGINT NOT NULL,
  "userid" VARCHAR NOT NULL,
  "pageid" VARCHAR NOT NULL,
  PRIMARY KEY()  
 ) WITH ('key.format'='protobuf', 'key.type'='STRUCT<"userid" VARCHAR>', 'topic'='pageviews_pb', 'value.format'='protobuf');

Generate a "create changelog" ddl for an entity in the current store, which includes AVRO in the Confluent Schema Registry.

GENERATE CHANGELOG DDL myChangelog with('topic'='pageviews_avro', 'value.format'='avro', 
'key.format'='avro');

The output would be

CREATE CHANGELOG myChangelog(
 "viewtime" BIGINT ,
  "userid" VARCHAR ,
  "pageid" VARCHAR ,
  PRIMARY KEY() 
) WITH ('key.format'='avro', 'key.type'='STRUCT<"userid" VARCHAR>', 'topic'='pageviews_avro', 'value.format'='avro');     

Generate a "create changelog" ddl for an entity whose content is JSON.

GENERATE CHANGELOG DDL myChangelog with ('value.format'='json', 'data.json.value.content'='{"viewtime":1629453600000,"userid":"user_123","pageid":"page_1"},{"viewtime":1629457200000,"userid":"user_456","pageid":"page_2"},{"viewtime":1629460800000,"userid":"user_789","pageid":"page_3"}' );

The output would be

CREATE CHANGELOG myChangelog(
 "viewtime" BIGINT,
 "userid" VARCHAR,
 "pageid" VARCHAR,
  PRIMARY KEY() 
) WITH ('value.format'='json');