Michael Giannakopoulos wrote:
> I would like to ask if there is any way to make an aggregate function
to take a set of tuples as an
> input variable. I know that an actual aggregate function receives each
tuple one at a time and process
> it on the fly. However I want to store tuples in an incremental
fashion so as to process them in a
> batch approach in the finalaggr function. Think for example
implementing logistic regression (which is
> an OLAP query by its nature). I want to support it with the current
features that PostgreSQL provides
> from which the closest feature is an aggregate. However an aggregate
function feeds me one a tuple for
> each call, but I would like to have access to a batch of tuples per
function call. Is there any
> possible way to perform something like this?
If you write in C, there is nothing that keeps you from
storing all the rows that come in in memory allocated in
a suitable MemoryContext and process them all at the end.
You might run out of memory though.
Yours,
Laurenz Albe