It's a general class warning , when ever a Class is created with keys it will expect a table mapping for the class in DB . if it not able to find the mapping in inheritance too , then it will map the class to pr_others by default and store the instances of the class on it .
If you need to overcome "Instances of this class save to the pr_other table which has few properties exposed as columns. Consider mapping to a different table." this warning, create a table in the PegaRules DB ,Column names similar to properties (Pega recommends tables to have pzInskey, pxobjClass and pxInsName for better performance) ans a corresponding Data-Admin-DB-table for the Class and the table.
1. Create new DB table and update database table instance mapping by replacing pr_other with new table name. Create new columns and provide column external mapping at class level if column name is not same as property name or if mapping to embedded properties. For property name same as column no need to provide external mapping explicitly.
2. If you want to use structure of pr_other. Create table with below query and perform other action as mentioned in point no. 1
Create table New_Table_Name AS (Select * from pr_other where pxobjclass="YourclassName");