Re: PG function call - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: PG function call
Date
Msg-id 20051006143037.GA7044@surnet.cl
Whole thread Raw
In response to PG function call  ("smile khmer" <khmersmile@email.com>)
Responses How PG_FUNCTION_ARG works in PG
List pgsql-hackers
On Thu, Oct 06, 2005 at 09:06:59AM -0500, smile khmer wrote:
> Dear all,
> 
> Does anyone know how index searching work in PG. I've explored the 
> source code of PG, for btree, for searching, it will call the 
> functions in file btcompare.c. As I've made a printf in the functions 
> of the file btcompare.c. When I compile and run PG, it get into 
> loop,..... the messages are printed and printed .....

Not a loop -- the function may just be called a lot of times.

> I want to know how the function called happen in Postgres, 
> it seems that it doesn't call the function directly ! 

The code gets function pointers through the catalogs, so they will be
called even if you don't see a direct function call.  At some time the
code will ask for the equality function for such-and-such datatype, then
call it.

-- 
Alvaro Herrera                 http://www.amazon.com/gp/registry/CTMLCN8V17R4
"Acepta los honores y aplausos y perderás tu libertad"


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