You can use the schema discovery feature to discover external schemas and create CCL schemas based on the format of the data from the datasource connected to an adapter.
Every row in a stream or window must have the same structure, or schema, which includes the column names, the column datatypes, and the order in which the columns appear. Multiple streams or windows may use the same schema, but a stream or window can only have one schema.
Rather than manually creating a new schema, you can use schema discovery to discover and automatically create a schema based on the format of the data from the datasource connected to your adapter. For example, for the Database Input adapter, you can discover a schema that corresponds to a specific table from a database the adapter is connected to.
While using discovery is a convenient way to create your CCL schema, pay particular attention to the datatypes your CCL columns inherit from the external data source. For example, whenever possible, discovery maintains the same level of precision or greater when mapping source data types to ESP data types. Some databases, such as Sybase IQ, support microsecond precision for the SQL_TIMESTAMP and SQL_TYPE_TIMESTAMP data types. As such, discovery maps these types to the ESP data type bigdatetime, which also supports microsecond precision. If your ESP project does not require this level of precision, you can, after generating your schema through discovery, modify the schema to use a lower-precision data type such as timestamp (millisecond precision).
To discover a schema, you need to first configure the adapter properties. Each adapter that supports schema discovery has unique properties that must be set to enable schema discovery.