An asynchronous connection method is to use a function like PQconnectStart() instead of a function like PQconnectdb (). PQconnectStart() returns without synchronizing the completion of the connection to the database. The user application must then monitor the sockets returned by PQsocket() to be readable or writable, for example by using the poll() system call, according to the values required by the return value of PQconnectPoll().

With the Connection Manager, the socket returned by PQsocket() may change after a call to PQconnectPoll(), so be sure to reacquire the socket that you want to give to the poll() system call using PQsocket(). This behavior is similar to simply specifying multiple hosts in the connection string without using the Connection Manager.