[marcosdumay]

Today I just woke up to find yet another "ORA-01555: snapshot too old" on something I left running overnight.

Honestly, performance isn't as important as the capacity of getting an atomic snapshot of your data with any reliability.

[ComodoHacker]

Avoiding ORA-01555 is a matter of properly sizing your undo.

[marcosdumay]

And a matter of not getting any task that is slower than what you expected.