Re: Document that server will start even if it's unable to open some TCP/IP ports

On Sat, May 27, 2023 at 03:17:21PM -0700, Gurjeet Singh wrote:
> Upon further testing, I saw that server will not start only if it is
> unable to open the port on _all_ the interfaces/addresses. It it's
> able to open the port on at least one, the server will start.

This surprised me.  I would've expected the server to fail to start if it
failed for anything in listen_addresses.  After some digging, I found what
I believe is the original justification [0] as well as a follow-up thread
[1] that seems to call out kernel support for IPv6 as the main objection.
Perhaps it is time to reevaluate this decision.

> If listen_addresses is empty, then server won't try to open any TCP/IP
> ports. The patch does not change any language related to that.

Your proposed change notes that the server only starts if it can listen on
at least one TCP/IP address, which I worry might lead folks to think that
the server won't start if listen_addresses is empty.

[0] https://postgr.es/m/6739.1079384078%40sss.pgh.pa.us
[1] https://postgr.es/m/200506281149.51696.peter_e%40gmx.net

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Nathan Bossart
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