Clover.ETL chooses proper database type depending on the format set on the data field. When format contains date symbols only (GyMwWDdFE), type is "translated" to DATE, when it contains time symbols only (aHhKkmsSzZ) , type is "translated" to TIME, in other cases (format contains both symbols or is not set at all) type is "translated" to TIMESTAMP. This is general rule for default jdbc configuration. In addition, for different jdbc configurations (jdbcSpecific attribute in db connection configuration), rules can be slightly changed, eg. for Oracle, only fields with format containing only date symbols are treated as DATE type, other fields are treated as TIMESTAMPs.