From: | Noah Misch <noah(at)leadboat(dot)com> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Chapman Flack <chap(at)anastigmatix(dot)net>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
Subject: | Re: libpq should not look up all host addresses at once |
Date: | 2018-08-12 06:26:15 |
Message-ID: | 20180812062615.GA2619236@rfd.leadboat.com |
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Lists: | pgsql-hackers |
On Thu, Aug 09, 2018 at 02:32:58PM -0400, Tom Lane wrote:
> Chapman Flack <chap(at)anastigmatix(dot)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
https://c-ares.haxx.se/ is the async DNS API that I've experienced. It works
well if you really need such a thing, but I haven't needed it in libpq.
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