On Mon, Aug 1, 2011 at 10:18 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Mon, Aug 1, 2011 at 11:04 AM, David Fetter <david@fetter.org> wrote:
>> SQL is Turing-complete, so the chances are excellent that it's
>> possible to express that algorithm in it. ;)
>>
>> Look into common table expressions for iteration/recursion, and
>> windowing functions, commonly used for time series.
>>
>> http://www.postgresql.org/docs/current/static/queries-with.html
>> http://www.postgresql.org/docs/current/static/tutorial-window.html
>
> That doesn't guarantee that it can be expressed efficiently, though.
> I think the OP may be going overboard by trying to bypass SPI, but
> putting the logic inside the server seems like it could well be
> worthwhile.
I think David is probably right and this can be handled in pure sql
simply and easily (perhaps in a function, perhaps not). The SPI
interface is great, but the sql and plpgsql languages are very
powerful and should always be preferred over a C solution all else
being equal.
merlin
