Обсуждение: Java app and SPI functions

Hi everybody!

I'm new to PostgreSQL with JDBC. What I want to do is to connect an
already implemented Java application to my postgresql server.I want to
be able to pass arguments from the java application to some function
I've written in C (that uses SPI functions) and receive tuples to
display in the Java GUI.

Any hints on where to start from?

Richard Huxton at the General list kindly pointed me to the PL/Java
project. Is this where I should focus?

Thanks in advance,
Ntinos Katsaros

Hi Ntinos,

    You don't need to use PL/Java - you can call the SPI functions
through standard SQL. I have C functions that return tuples and call
them with executeQuery(...).

The function in question is defined as

CREATE TYPE correlation_type AS
(
        id INTEGER,
        num_points INTEGER,
        correlation FLOAT8
);

CREATE OR REPLACE FUNCTION
   max_min_correlation(int,smallint,smallint,int,int)
RETURNS SETOF correlation_type
AS '$libdir/contrib/my_func.so','max_min_correlation'
LANGUAGE 'C' STABLE STRICT;

and then I call it with

ResultSet results = st
                    .executeQuery("SELECT * FROM
max_min_correlation("+var+")");

and work through the result set.

Good luck,

Adriaan

Katsaros Kwn/nos wrote:

>Hi everybody!
>
>I'm new to PostgreSQL with JDBC. What I want to do is to connect an
>already implemented Java application to my postgresql server.I want to
>be able to pass arguments from the java application to some function
>I've written in C (that uses SPI functions) and receive tuples to
>display in the Java GUI.
>
>Any hints on where to start from?
>
>Richard Huxton at the General list kindly pointed me to the PL/Java
>project. Is this where I should focus?
>
>Thanks in advance,
>Ntinos Katsaros
>
>
>
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