Chapman Flack <c...@anastigmatix.net> writes: > On 08/09/2018 11:05 AM, Tom Lane wrote: >> So I think what this code should do is (1) look up each hostname as it >> needs it, not all at once, and (2) proceed on to the next hostname >> if it gets a DNS lookup failure, not fail the whole connection attempt >> immediately. As attached.
> Would it be worth the complexity to be a little async about it, > fling a few DNS requests out, and try the hosts in the order the > responses come back? It would be nice if an async connection request didn't have to block during DNS lookups ... but I don't know of any portable library API for async DNS requests, and it's most certainly not worth the trouble for us to write our own version of getaddrinfo(3). In practice, I think the async connection mode is mostly a legacy API at this point anyway; surely most people who need that sort of behavior are handling it nowadays by invoking libpq on a separate thread. So I just don't see it being worth a huge amount of work and maintenance effort to get that to happen. (Having said that, at least moving the lookup from connectDBStart into PQconnectPoll, as this patch does, is a step in the right direction.) Now that I think about it, there may be some text in the libpq docs claiming that the lookup happens in PQconnectStart not PQconnectPoll; that would need adjustment. regards, tom lane