[development] Why do we avoid auto-incrementing db columns?
sammys-drupal at synerger.com
Mon Apr 30 07:20:25 UTC 2007
And to clarify, what i've been explaining above is different to what is
explained in this post. This post is about modifing db_next_id() to stop
using the sequences table for MySQL. My post was about PostgreSQL.
The use of db_next_id() or db_insert_id() can't be removed for obvious
reasons. The implementation can be changed.
Thanks Dries for bringing up these posts.
Synerger Pty Ltd
On 26-Apr-07 07:53, Dries Buytaert wrote:
> On 25 Apr 2007, at 18:53, Sammy Spets wrote:
> >Sure there are two different use cases for insertions: those where you
> >need the ID afterwards (e.g node) and those you don't (e.g watchdog).
> >If you want to write code without the use of db_next_id() then do an
> >INSERT and omit the id column. I don't see anyone wanting to spend
> >effort patching Drupal core to gain 0.01% efficiency across the
> Overall, I think it would be good if we could get rid of db_next_id
> (). Related patches:
> + http://drupal.org/node/49836
> + http://drupal.org/node/118066
> * Drupal's db_next_id() was introduced in 2002 by Marco Molinari, who
> used to be a top-contributor. Parts of the relevant discussion can
> be found at:
> We introduced it because it was hard to reproduce the (correct) last
> ID on non MySQL databases -- we felt this was a more portable way to
> get the last ID. As this has been a while, the original motivation
> might no longer be relevant, or it might have been incorrect all the
> way. We had less database expertise/experts than we have now, and
> lack of experience probably made db_next_id() feel like a portable
> and safe choice ...
> * I don't think it has been mentioned already but the fact we do not
> use auto_increment make it difficult/impossible to setup Drupal in a
> master-master configuration. MySQL 5 introdeced a
> "auto_increment_increment" and "auto_increment_offset" which can't be
> used until we get rid of db_next_id(). See http://dev.mysql.com/doc/
> * The table lock in db_next_id() has been shown to be a problem in
> certain setups.
> * table locking, as used in db_next_id(), is not always supported by
> cheap webhosts.
> * http://drupal.org/node/49836#comment-74275 suggests that most/all
> database support something like auto_increment.
> That's 5 reasons why we could remove db_next_id() ... ;-)
> Dries Buytaert :: http://www.buytaert.net/
More information about the development