A query $$Find the names of the customers who are $23$ years old from Buckingham$$ is performed on the table above. If the whole table for customers can be loaded into the RAM, which of the following relational algebraic expressions is quicker to evaluate and why?

$($i$)\backslash$pi name$(\backslash$sigma age $=23$ and City $=$Buckingham$($Customers$))$

$($ii$)\backslash$pi name$(\backslash$sigma age $=23(\backslash$sigma City $=$Buckingham$($Customers$)))$

What about if the whole table is too big to be accommodated in RAM?