On Aug 16, 2011, at 14:29, Merlin Moncure <mmonc...@gmail.com> wrote:
> On Tue, Aug 16, 2011 at 8:33 AM, Harald Fuchs <hari.fu...@gmail.com> wrote: >> In article >> <cakwofmjwz3znxcj9radn4ov+krsa-133968yvag3l8m3w3z...@mail.gmail.com>, >> Lauri Kajan <lauri.ka...@gmail.com> writes: >> >>> I have also tried: >>> select >>> *, getAttributes(a.id) >>> from >>> myTable a >> >>> That works almost. I'll get all the fields from myTable, but only a >>> one field from my function type of attributes. >>> myTable.id | myTable.name | getAttributes >>> integer | character | attributes >>> 123 | "record name" | (10,20) >> >>> What is the right way of doing this? >> >> If you want the attributes parts in extra columns, use >> >> SELECT *, (getAttributes(a.id)).* FROM myTable a > > This is not generally a good way to go. If the function is volatile, > you will generate many more function calls than you were expecting (at > minimum one per column per row). The best way to do this IMO is the > CTE method (as david jnoted) or, if and when we get it, 'LATERAL'. > >From your statement is it correct to infer that a function defined as "stable" >does not exhibit this effect? More specifically would the function only be >evaluated once for each set of distinct parameters and the resulting >records(s) implicitly cached just like the CTE does explicitly? David J. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
