Re: Unable to ALTER table after SELECT data from table

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "Keary Suska" <hierophant(at)pcisys(dot)net>
Cc: "Postgres General" <pgsql-general(at)postgresql(dot)org>
Subject: Re: Unable to ALTER table after SELECT data from table
Date: 2007-12-10 21:27:52
Message-ID: dcc563d10712101327we238a2ao27f3caaad4ece30d@mail.gmail.com
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On Dec 10, 2007 2:48 PM, Keary Suska <hierophant(at)pcisys(dot)net> wrote:
> on 12/10/07 12:15 PM, Thomas-Carsten(dot)Franke(at)brunel(dot)de purportedly said:
>
> > To work around this I add an dbCon.rollBack() after select statement
> > above in good and in bad times. After that ALTER works.
> > Can someone explain me why I need this rollback ?
>
> You only need the rollback when the SELECT statement fails. When an error
> occurs within a transaction, the transaction is aborted but not rolled back.
> There are likely reasons why the rollback isn't automatic, but I don't know
> them.

I think you confuse postgresql with some other database. Without
setting a savepoint, any error during a transaction and roll it back
upon connection close | rollback | commit.

I.e. the rollback IS automatic. Just not necessarily immediate.

> Your choice is either to run the commands in an "autocommit" mode or, as you
> are doing, rollback (or commit, if there was no error) after the SELECT.

You can commit with an error. It'll do the same thing as a rollback;

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