Re: "could not open relation 1663/16384/16584: No such file or directory" in a specific combination of transactions with temp tables

From: "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com>
To: "Bruce Momjian" <bruce(at)momjian(dot)us>
Cc: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "John Smith" <sodgodofall(at)gmail(dot)com>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: "could not open relation 1663/16384/16584: No such file or directory" in a specific combination of transactions with temp tables
Date: 2008-03-05 10:02:48
Message-ID: 47CE6FC8.8040306@enterprisedb.com
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Bruce Momjian wrote:
> Tom Lane wrote:
>> "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> writes:
>>> John Smith wrote:
>>>> [3] I am not certain how widespread they might be, but I think there
>>>> may be some backward compatibility concerns with the patch you are
>>>> proposing.
>>> Well, the current behavior is certainly broken, so an application
>>> relying on it is in trouble anyway :-(. Even if we came up with a patch
>>> for 8.4 to relax the limitation, I doubt it would be safe enough to
>>> backport to stable branches.
>> As Heikki pointed out later, PG 8.1 correctly enforces the restriction
>> against preparing a transaction that has dropped a temp table. It's
>> only 8.2.x and 8.3.0 that (appear to) allow this. So I'm not persuaded
>> by backwards-compatibility arguments.
>>
>> I've applied Heikki's new patch, and I think that's as much as we can do
>> for 8.2 and 8.3. Any improvement in the functionality would be new
>> development (and not trivial development, either) for 8.4 or later.
>
> Is there a TODO here?

Yes, please:

"Allow two-phase commit when a temporary table is created and dropped in
the same transaction, or when an ON COMMIT DELETE ROWS temporary table
is accessed"

Hmm. If we can do that, I guess we could allow read-only queries on temp
tables as well.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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