Firebird: how to find SQL queries which use bad index?

In the first part of our optimization story (“How to ruin Firebird performance…“) we mentioned that indices should be analyzed before dropping, even if they appeared to be very bad in IBAnalyst in terms of garbage and number of unique values.

In essence, we need to log all queries used in applications, get their execution plans and check, how indices are used.

For this we need to log all SQL traffic between applications and Firebird database.