From: Craig Ringer <craig@postnewspapers.com.au>
To: Science <science@misuse.org>
Cc: pgsql-sql@postgresql.org
Subject: Re: Bit by "commands ignored until end of transaction block" again
Date: Mon, 27 Jul 2009 08:00:28 +0800
Message-ID: <1248652828.2303.5.camel@ayaki> (raw)
In-Reply-To: <4A6CE37B.9020709@misuse.org>
References: <4A6CE37B.9020709@misuse.org>
On Sun, 2009-07-26 at 19:15 -0400, Science wrote:
> FWIW, the way the Rails ORM ActiveRecord (another fairly damaged ORM)
> handles this is by allowing you to open any number of transaction
> blocks, but only the outer transaction block commits (in Pg):
>
> Property.transaction { # SQL => 'BEGIN'
> User.transaction {
> Foo.transaction {
> Foo.connection.execute('--some sql code') # SQL => '--some sql code'
> }
> }
> } # SQL => 'COMMIT'
What happens if, Foo.transaction does something that causes an error,
though, or issues a rollback? It's not creating savepoints, so if
Foo.transaction rolls back it throws out the work of User.transaction
and Property.transaction too.
Ugh.
That design would be quite good _IF_ it used savepoints:
Property.transaction { # SQL => 'BEGIN'
User.transaction { # SQL => SAVEPOINT User
Foo.transaction { # SQL => SAVEPOINT Foo
Foo.connection.execute('--some sql code') # SQL => '--some sql code'
} # SQL => RELEASE SAVEPOINT Foo
} # SQL => RELEASE SAVEPOINT User
} # SQL => 'COMMIT'
... so that inner transactions could ROLLBACK TO SAVEPOINT on error ,
and so that asking for a rollback would give you a ROLLBACK TO SAVEPOINT
if the transaction is a subtransaction.
--
Craig Ringer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: craig@postnewspapers.com.au, science@misuse.org
Subject: Re: Bit by "commands ignored until end of transaction block" again
In-Reply-To: <1248652828.2303.5.camel@ayaki>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox