How many database connections?

Could you please help me with 2 questions?
1: If there are several ignition clients on the shopfloor should i consider creating separate database connection for each client (to the same database)? Would it be more robust solution or would not matter?
2: If transaction manager is used to interact with the database is it the most robust way of communication to the database as it is using transactions so no chance of bad data which could the case of SQL code without rollback ? If data is deleted after 1 day automatically by transaction manager there is even no need to maintain database - is it right?