QuoteDBI::connect_cached.
Die Doku von DBI sagt dazu:
Quoteconnect_cached is like connect, except that the database handle returned is also stored in a hash associated with the given parameters. If another call is made to connect_cached with the same parameter values, then the corresponding cached $dbh will be returned if it is still valid. The cached database handle is replaced with a new connection if it has been disconnected or if the ping method fails.
Es werde nur die Handles gecached, keine Inhalte der DB.