Обсуждение: Implementation of aggregate functions

Hello all,
I am doing a project as a part of a course work in
database implementation in which we are required to
implement some feature in postGres or extend some of
the existing functionality.
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,

Thanks in advance for all the help.



Best regards,
  Sayali

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  The degree of technical competence is
  inversely proportional to the level of management.
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On Thu, 2007-20-09 at 06:49 +0100, 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,

stddev() already exists. Take a look at the implementation of the
existing aggregate functions, which can be found in
src/backend/utils/adt (float.c, numeric.c, etc.) There is no need to
modify the core Postgres backend code to add new aggregate functions, of
course.

I suggest doing a modicum of research first, and then asking on
pgsql-hackers if you have more specific questions about Postgres
internals.

-Neil

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


--
  Euler Taveira de Oliveira
  http://www.timbira.com/

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


--
Euler Taveira de Oliveira
http://www.timbira.com/