On 8/3/19 7:27 AM, Tom Lane wrote:
Tomas Vondra <tomas.von...@2ndquadrant.com> writes:
There seems to be a consensus that this this not a pg_basebackup issue
(i.e. duplicate values don't make the file invalid), and it should be
handled in ALTER SYSTEM.
Yeah. I doubt pg_basebackup is the only actor that can create such
situations.
The proposal seems to be to run through the .auto.conf file, remove any
duplicates, and append the new entry at the end. That seems reasonable.
+1
There was a discussion whether to print warnings about the duplicates. I
personally see not much point in doing that - if we consider duplicates
to be expected, and if ALTER SYSTEM has the license to rework the config
file any way it wants, why warn about it?
Personally I agree that warnings are unnecessary.
Having played around with the pg.auto.conf stuff for a while, my feeling is
that ALTER SYSTEM does indeed have a license to rewrite it (which is what
currently happens anyway, with comments and include directives [1] being
silently
removed) so it seems reasonable to remove duplicate entries and ensure
the correct one is processed.
[1] suprisingly any include directives present are honoured, which seems crazy
to me, see:
https://www.postgresql.org/message-id/flat/8c8bcbca-3bd9-dc6e-8986-04a5abdef142%402ndquadrant.com
The main issue however is that no code was written yet.
Seems like it ought to be relatively simple ... but I didn't look.
The patch I originally sent does exactly this.
The thread then drifted off into a discussion about providing ways for
applications to properly write to pg.auto.conf while PostgreSQL is not
running; I have a patch for that which I can submit later (though it
is a thing of considerable ugliness).
Regards
Ian Barwick
--
Ian Barwick https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
