On 10/22/13, Rémi Cura <remi.cura@xxxxxxxxx> wrote:
> But it is immensely easier and sometimes mandatory to use instead
> a plpgsql function using cursor (or cursors).
>
> It would be something like that in plpgsql :
>
> cursor on table of letter ordered
> accum = 0;
> loop on rows of table ordered
>
> if letter = previous letter, new_id = accum
> else accum ++ ; new_id = accum
>
> old letter = new_letter
> new letter = next letter;
>
> end of loop,
Shouldn't it be possible to do that with a FOR loop without a cursor?
It might be that procedural is the way to go. But I still believe
that relational algebra can handle this, even without a window
function. Something like:
SELECT event e, COUNT(
SELECT event oe ... WHERE oe.event_time > e.event_time AND NOT EXISTS (
SELECT event te WHERE te.event_time > e.event_time AND
te.event_time < oe.event_time))
.
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