Fastest way to check database's existence

One way would be to just attempt making a connection to it, trapping any errors upon failure (with eval), or discarding the connection upon success.

This approach has the added benefit of also checking the accessibility of the database to the user running the code, but for this application this added benefit is not necessary.  Checking existence is all that matters.

Is there an even faster way to check for a database's existence that does not require establishing a connection?

(Maybe this question would be more suitable for the pgsql-performance list?)

TIA!

~kynn