Re: [HACKERS] hash index on unlogged tables doesn't behave asexpected

At Thu, 21 Sep 2017 20:35:01 -0400, Robert Haas <robertmhaas@gmail.com> wrote in
<CA+TgmobXYq1ht8R76RTvun0pY85-=Oov8EY2Fv8nhNnM7Gdzxg@mail.gmail.com>
> On Thu, Sep 21, 2017 at 8:16 PM, Kyotaro HORIGUCHI
> <horiguchi.kyotaro@lab.ntt.co.jp> wrote:
> > Though I don't see it's bug and agree that the message is not
> > proper, currently we can create hash indexes without no warning
> > on unlogged tables and it causes a problem with replication.
> 
> That's true, but I don't believe it's a sufficient reason to make a change.
> 
> Before 84aa8ba128a08e6fdebb2497c7a79ebf18093e12 (2014), we didn't
> issue a warning about hash indexes in any case whatsoever; we relied
> on people reading the documentation to find out about the limitations
> of hash indexes.  They can still do that in any cases that the warning
> doesn't adequately cover.  I really don't think it's worth kibitzing
> the cases where this message is emitted in released branches, or the
> text of the message, just as we didn't back-patch the message itself
> into older releases that are still supported.  We need a compelling
> reason to change things in stable branches, and the fact that a
> warning message added in 2014 doesn't cover every limitation of a
> pre-1996 hash index implementation is not an emergency.  Let's save
> back-patching for actual bugs, or we'll forever be fiddling with
> things in stable branches that would be better left alone.

Sorry for annoying you and thank you. I agree with that after
just knowing the reason is not precisely (3) (we already have
WARNING for the problematic ops).

regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center



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