In Talend Studio, there are two data types in the database component schema: the Talend type and the database type. When retrieving the table schema, there is always a default Talend type to map to the real database type, and there is a default database type to map to the Talend type on the database schema, when linking a non-database component to a database output component.
A Talend type is an intermediate Java type, mapped for each data type of different databases. These default data type mappings are configured in an XML file. Each kind of database has a separate mapping configuration file. For example, the file mapping_Mysql.xml maps MySQL data types to Talend types.
By editing the mapping file, you can modify any default data type mapping for your project rather than changing it manually every time, and add new type mappings to server your needs.