Hello 2013/6/25 Szymon Guz <mabew...@gmail.com>: > Hi, > I've got a couple of questions. > > I was using numeric_out like this: > > DatumGetCString(DirectFunctionCall1(numeric_out, d)); > > Why do I have to use DirectFunctionCall1 instead of calling numeric_out?
numeric_out functions doesn't use C calling convention - it use own convention for support NULL values and some other informations. DirectFunctionCall1 is simple function that transform C like call to PostgreSQL call. You can do it directly, but you have to prepare necessary structures. > > > I was suggested to use numeric_send instead of numeric_out, however when > changing the function names in the above example, the whole expression > returns 8. Always 8. I check with: > > char *x = DatumGetCString(DirectFunctionCall1(numeric_send, d)); > PLy_elog(NOTICE, x). > "send" functions are used for binary protocol - so it is nonsense. > > And my main question: is there any documentation about those internal > functions, which use and when etc? source code :( and http://www.postgresql.org/docs/9.2/static/xfunc-c.html src/backend/utils/atd/* is very useful and contains lot of materials for study some examples of usage you can find in contrib examples http://www.postgresql.org/docs/9.2/static/extend.html Regards Pavel > > thanks > Szymon -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
