From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Pavel Stehule <pavel.stehule@gmail.com>,
        Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>,
        Michael Paquier <michael.paquier@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: IF (NOT) EXISTS in psql-completion
In-reply-to: 
 <CA+TgmoaOrwTjMtAbwb5Vd43APi-hFbA8XRJSyqvKui7qqwim=Q@mail.gmail.com>
References: 
 <CAFj8pRAHCwdwe+NRTQ9JrtMO2OdUWtp1demmv_jGBU2tRRs-CQ@mail.gmail.com>
 <20170203.171712.150614683.horiguchi.kyotaro@lab.ntt.co.jp>
 <CAFj8pRD85cnxEEgLtOoqL-Bda2XpzvHB3a6Mr+bvf+OKpiq3Eg@mail.gmail.com>
 <20170214.195152.59283261.horiguchi.kyotaro@lab.ntt.co.jp>
 <CAFj8pRAgwABQUVkbLVnEjDp+OgLWwK3w5P9pC985xfTz+Qbqug@mail.gmail.com>
 <CA+TgmoaOrwTjMtAbwb5Vd43APi-hFbA8XRJSyqvKui7qqwim=Q@mail.gmail.com>
Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Mon, 27 Feb 2017 00:13:34 +0530"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <19656.1488140516.1@sss.pgh.pa.us>
Date: Sun, 26 Feb 2017 15:21:56 -0500
Message-ID: <19657.1488140516@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org

Robert Haas <robertmhaas@gmail.com> writes:
> Yeah, maybe, but we'd need a committer to take more of an interest in
> this patch series.  Personally, I'm wondering why we need a series of
> 19 patches to add tab completion support for IF NOT EXISTS.  The
> feature which is the subject of this thread arrives in patch 0017, and
> a lot of the patches which come before that seem to change a lot of
> stuff without actually improving much that would really benefit users.

FWIW, one reason this committer hasn't jumped in is that we already
rewrote tab-complete.c pretty completely in 9.6.  If we accept a patch
that completely rewrites it again, we're going to be faced with
maintaining three fundamentally different implementations for the next
three-plus years (until 9.5 dies).  Admittedly, we don't back-patch
fixes in tab-complete.c every week, but a look at the git history says
we do need to do that several times a year.

Also, the nature of the primary refactoring (changing the big else-chain
into standalone ifs, if I read it correctly) is particularly bad from a
back-patching standpoint because all you have to do is insert an "else",
or fail to insert one, to silently and almost completely break either
one or the other branch.  And I don't really understand why that's a good
idea anyway: surely we can return at most one set of completions, so how
is turning the function into a lot of independent actions a win?

So I'd be a whole lot happier if it didn't do that.  Can we really not
add the desired features in a more localized fashion?

			regards, tom lane


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers