sayali k wrote:
> I am keen in implementing certain additional aggregate
> functions like percentage, standard deviation etc. I
> would like to know the complexity of this and also the
> parts of the code which would have to be modified for
> the same,
>
This is the wrong list to ask this kind of question. Use pgsql-hackers
instead.
Some statistics functions [1] are already implemented in PostgreSQL.
Samples are in utils/adt/float.c.
[1]
http://www.postgresql.org/docs/8.2/static/functions-aggregate.html#FUNCTIONS-AGGREGATE-STATISTICS-TABLE
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Euler Taveira de Oliveira
http://www.timbira.com/