[Dbix-class] coercing Result objects

[Len Jaffe]

On Mon, Nov 26, 2012 at 11:38 AM, Ben Tilly <btilly at gmail.com> wrote:
>
> Random tip in case you don't know it.  A union has an implicit dedupe
> in it, which is quite expensive.  If ou can, you really want to make
> that a UNION ALL instead.
>
> (Database people all know this, developers generally don't.)
>

Expensive bacause dedupe is typically implemented using either a sort, or
the building of a hash table. Both are order N (or worse) operations.


-- =

lenjaffe at jaffesystems.com   614-404-4214             www.volunteerable.net
Proprietor: http://www.theycomewithcheese.com/ - An Homage to Fromage
Greenbar <http://www.greenbartraining.org/>: Grubmaster: 2012-2009, Grub
Asst: 2008, Trained: 2007.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.scsys.co.uk/pipermail/dbix-class/attachments/20121126/0fe=
ac6ca/attachment.htm