Re: returning value from inside a transaction

From: Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: returning value from inside a transaction
Date: 2001-09-14 20:00:02
Message-ID: Pine.BSF.4.21.0109141250110.43495-100000@megazone23.bigpanda.com
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On Wed, 12 Sep 2001, Matt wrote:

> create table tez (i int);
> insert into tez values(3);
>
> create function tezt0(int) returns int as '
> begin work;
> lock table tez;
> select * from tez as r;
> commit work;
>
> select tez.i;
> ' language 'sql';

It looks to me from testing reasonably recent sources
that the above really isn't safe. Since we don't have nested
transactions, that's not a separate transaction from whatever
it's running in, but instead the begin will NOTICE if you're in a
transaction and the commit will commit it and now you're no longer
in a transaction...
begin;
select tezt0(4);
insert into tez values (4);
rollback;
will end up with tez getting the row and a notice about the fact
you weren't in a transaction from rollback. Is this really reasonable
behavior?

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