livetime of a variable defined in a c-procedure

hi all,

I want to build sub-sums of an column (rechnr, for example). this field
should be incremented, whenever the field "baust" changes.
I'm able to increment a field by a function:

create function add_intsum(varchar,int8) returns int8 as' update sum_table set intsum=((intsum )+ ($2))where key1 = $1;
     select max(intsum) from sum_table where key1 = $1;'
 
language 'sql';

sum_table ist delared as: 
create table sum_table(key1 varchar,moneysum money,realsum real,intsum
int8);
insert into sum_table values('baust','0',0,0);
insert into sum_table values('contanz',  '0',0,0);
insert into sum_table values('rechnr',   '0',0,0);

now "select add_intsum('rechnr',1);" will increment "rechnr" in
"sum_table" and return this field. this works - but there are 2 problems:

a) its not very fast
b) I can't do a conditional-increment, depending on the value of another field

so I've don the following:

int4    rechnr=0;
int4    baust=0;

int4    add_rechnr(int4 val)
{rechnr=rechnr+val;return rechnr;}

int4    add_baust(int4 val)
{baustelle=baust+val;return baust;}

int4    init_rechnr(int4 val)
{rechnr=val;return rechnr;}

int4    init_baust(int4 val)
{baust=val;return baust;}


this works and I'm able to include conditions into the c-code. But what I
not fully understand is the followinf behaviour:

CREATE FUNCTION add_rechnr(int4) RETURNS int4             AS '/usr/local/pgsql/lib/modules/funcs.so' LANGUAGE 'c';

whenever I add a value to rechnr, the correct result is returned. but if I
copy the save file "funcs.so" into the direcotry while the backend is
running an a connection is established, I'll get this error:

pqReadData() -- backend closed the channel unexpectedly.
.....

So I suppose, the backend will load the lib whenever a lib-function is
invoced. But if so, why does he remember the last value of the variables
defined in this lib?

Any ideas ?

best regards

wicki ;*)