Re: [Fwd: Re: Transactions and temp tables]

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Emmanuel Cecchet <manu(at)asterdata(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [Fwd: Re: Transactions and temp tables]
Date: 2009-01-21 21:18:39
Message-ID: 200901212118.n0LLId111559@momjian.us
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Heikki Linnakangas wrote:
> Emmanuel Cecchet wrote:
> > I just saw that this new patch was not considered because the previous
> > version ended being rejected.
> > Note that this version of the patch aims at supporting ONLY temp tables
> > that are created AND dropped in the same transaction. We need to be able
> > to use temp tables in transactions that are doing 2PC, but the temp
> > table lifespan does not need to cross transaction boundaries.
> >
> > Please let me know if this patch could be integrated in 8.4.
>
> IMHO, this is just getting too kludgey. We came up with pretty good
> ideas on how to handle temp tables properly, by treating the same as
> non-temp tables. That should eliminate all the problems the latest patch
> did, and also the issues with sequences, and allow all access to temp
> tables, not just a limited subset. I don't think it's worthwhile to
> apply the kludge as a stopgap measure, let's do it properly in 8.5.
>
> As a workaround, you can use a regular table instead of a temporary one.
> If you create and drop the regular table in the same transaction (that's
> the same limitation that latest patch has), you won't end up with a
> bogus table in your database if the connection is dropped unexpectedly.
> If your application uses multiple connections simultaenously, you'll
> need a little bit of code in the application so that you don't try to
> create a table with the same name in all backends. You could also create
> a different schema for each connection, and do "set
> search_path='semitempschemaX, public'", so that you can use the same
> table name and still have separate tables for each connections.

Can someone tell me how this should be worded as a TODO item?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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