Re: Bug in ExecModifyTable function and trigger issues for foreign tables

From: Ildus Kurbangaliev <i(dot)kurbangaliev(at)postgrespro(dot)ru>
To: Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>
Cc: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>
Subject: Re: Bug in ExecModifyTable function and trigger issues for foreign tables
Date: 2017-06-15 15:05:48
Message-ID: 20170615180548.5e142ddc@wp.localdomain
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On Mon, 5 Jun 2017 17:25:27 +0900
Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> wrote:

> On 2017/06/02 18:10, Etsuro Fujita wrote:
> > On 2017/05/16 21:36, Etsuro Fujita wrote:
> >> One approach I came up with to fix this issue is to rewrite the
> >> targetList entries of an inherited UPDATE/DELETE properly using
> >> rewriteTargetListUD, when generating a plan for each child table
> >> in inheritance_planner. Attached is a WIP patch for that. Maybe
> >> I am missing something, though.
> >
> > While updating the patch, I noticed the patch rewrites the UPDATE
> > targetList incorrectly in some cases; rewrite_inherited_tlist I
> > added to adjust_appendrel_attrs (1) removes all junk items from the
> > targetList and (2) adds junk items for the child table using
> > rewriteTargetListUD, but it's wrong to drop all junk items in cases
> > where there are junk items for some other reasons than
> > rewriteTargetListUD. Consider junk items containing MULTIEXPR
> > SubLink. One way I came up with to fix this is to change (1) to
> > only remove junk items with resname; since junk items added by
> > rewriteTargetListUD should have resname (note: we would need
> > resname to call ExecFindJunkAttributeInTlist at execution time!)
> > while other junk items wouldn't have resname (see
> > transformUpdateTargetList), we could correctly replace junk items
> > added by rewriteTargetListUD for the parent with ones for the
> > child, by that change. I might be missing something, though.
> > Comments welcome.
> I updated the patch that way. Please find attached an updated
> version.
> Other changes:
> * Moved the initialization for "tupleid" I added in ExecModifyTable
> as discussed before, which I think is essentially the same as
> proposed by Ildus in [1], since I think that would be more consistent
> with "oldtuple".
> * Added regression tests.
> Anyway I'll add this to the next commitfest.
> Best regards,
> Etsuro Fujita
> [1]

Checked the latest patch. Looks good.
Shouldn't this patch be backported to 9.6 and 10beta? The bug
affects them too.

Ildus Kurbangaliev
Postgres Professional:
Russian Postgres Company

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