This was recently discussed on -docs and I believe a patch was applied
to at least HEAD.
On Mon, Jan 30, 2006 at 10:33:35AM +0000, dueyduey@freemail.hu wrote:
>
> The following bug has been logged online:
>
> Bug reference: 2223
> Logged by:
> Email address: dueyduey@freemail.hu
> PostgreSQL version: 8.1
> Operating system: linux
> Description: Misleading info in docs on volatility level of functions
> Details:
>
> Hi, all!
> The documentation on how to and why declare a function STABLE or IMMUTABLE
> is very laconic. It makes clear what promises I make when determining the
> volatility of my functions but it fails to point out what exactly I can
> expect in turn for my promises.
> See also the discussion on bug#2150 on the pgsql-bugs list.
> Thanks for bothering.
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
>
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461