Information about Data length of baseview of Redbrick in Sagent

The user is upgrading Sagent v6.5 to v6.8(64-bit) and database migration from RedBrick to Oracle. The user want to know why created length is different between RedBrick and Oracle.
 
For example:
When we create BaseView for char/varchar/varchar2 of Oracle, that is created by <actual length> + 1 byte.


 
However, the varchar of RedBrick is created by <actual length> + 2 byte.


 
The user asked for the reason of this behavior. The user wanted to know about the following result when he create Baseview. 

VARCHAR(10)  ? String(12) 
char(10)            ? String(12) 
DATE                ? DATE(21) 
integer              ? Long(5) 
decimal(10)      ? decimal(13) 

This is because SQL Server and Oracle are relational database. 
But RedBrick is OLAP database. 

For example, 
Column length of DTF source is always +1 byte. This 1 byte is reserved for Sagent internal use. 
This is the same for BaseView. Extra 1 byte is reserved for Relational database(SQL Server and Oracle) . 
Extra 2 bytes are reservied OLAP database(RedBrick).