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Re: Re: BUG #6050: Dump and restore of view after a schema change: can't restore the view

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Greg Stark <gsstark(at)gmail(dot)com>
Cc: pgsql-bugs(at)postgresql(dot)org, Daniel Cristian Cruz <danielcristian(at)gmail(dot)com>
Subject: Re: Re: BUG #6050: Dump and restore of view after a schema change: can't restore the view
Date: 2011-06-07 14:33:05
Message-ID: 12928.1307457185@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-bugs
Greg Stark <gsstark(at)gmail(dot)com> writes:
> On Jun 3, 2011 4:20 PM, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I'm inclined to write this off as "so don't do that".  There's nothing
>> that pg_dump can do to make this work: it has to use the USING syntax
>> for the join, and that doesn't offer any way to qualify the column name
>> on just one side.

> There's nothing stopping us from adding a nonstandard syntax to cover
> precisely the information needed to resolve this case when dumping.

> For example we could support USING (a.a=b.a) or ON (a.a=b.a as a)

1. "Nonstandard syntax" is widely seen as "vendor lock-in".  I don't
think that people would appreciate such a fix, especially for an issue
so obscure that we've never seen it before.

2. I don't believe your proposal covers all cases.  For instance, there
are cases where there is no valid qualified name for a column, ie, it's
a merged column from an alias-less JOIN.  (The existence of such cases
is another reason why USING sucks, but I digress.)

> We could use it only in this case where there's ambiguity too so it wouldn't
> clutter people's dumps.

No, because the problem case is where ambiguity gets added after the
fact.

			regards, tom lane

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