Re: [GENERAL] Shared Objects (Dynamic loading)

Well, the server side code is in ECPG because thats the easiest choice i
could see.
I really don't know how difficult or beneficial would SPI be. Haven't heard
of SPI before.
I was under the impression that ECPG and libpg are the only two choices a
developer has in postgresql for database related activities.

I am using char in postgres function as an analogue for char* in C. Is this
correct?
The link that you gave says varchar* in C has varchar as its analogue in
postgresql.

Thanks and regards,
Jas

On 8/24/06, Michael Fuhr <mike(at)fuhr(dot)org> wrote:
>
> On Thu, Aug 24, 2006 at 01:03:43AM -0400, Jasbinder Bali wrote:
> > CREATE OR REPLACE FUNCTION sp_trigger_raw_email(int4, text)
> > RETURNS bool AS
> > '/usr/local/pgsql/jsbali/parser', 'parse_email'
> > LANGUAGE 'c' VOLATILE STRICT;
> > ALTER FUNCTION sp_trigger_raw_email(int4,text ) OWNER TO postgres;
> >
> > function parse_email(int caseno, char *rawemail)
> > populates a few global variables first and then
> > call another function parse_header().
> > function parse_header() makes use of the global variables and then
> using
> > ECPG stores values in a table in the database.
>
> Is there a reason this server-side code is using ECPG instead of SPI?
>
> http://www.postgresql.org/docs/8.1/interactive/spi.html
>
> > My question is, when we try to make use of a specific function of a
> shared
> > object dynamically loaded as show above, then
> > would that function be able to access all global variables populated
> > elsewhere in the program or all the global variables can't be accessed
> > inside that function of the shared object.
>
> A function should be able to access any global symbol and any static
> symbol in the same object file. Are you having trouble doing so?
>
> > Also, in the above function definition,
> > the signature of parse_email function is
> > parse_email(int, char*) and i am passing (int4 , text) to int as seen in
> the
> > function code pasted above.
> > Is text in pgsql going to match with char* or i should use some other
> > datatype?
>
> See "C-Language Functions" in the documentation, in particular what
> it says about version 1 calling conventions.
>
> http://www.postgresql.org/docs/8.1/interactive/xfunc-c.html
>
> Is there a reason you're coding in C instead of a higher-level
> language like PL/Perl? If you're parsing email messages then coding
> in Perl, Python, Ruby, etc., would probably be easier than C.
>
> --
> Michael Fuhr
>