Обсуждение: [GSoC] create type questions

Charles Cui <charles.cui1984@gmail.com> writes:
>    I have a new type defined like this
> CREATE TYPE thrift_binary (
>     INPUT = thrift_binary_in,
>     OUTPUT = thrift_binary_out,
>     LIKE = bytea
> );

> in thrift_binary_in, it accepts cstring and returns thrift_binary.

OK, that's what it should do.

> And in
> this function I returned a bytea because the create type tells the system
> thrift_binary and bytea are the same.

Sure, PG_RETURN_BYTEA_P() would work in the C code.  I think it might be
worth inventing a macro PG_RETURN_THRIFT_BINARY_P that's a thin wrapper
around that, just for clarity's sake, but it doesn't matter functionally.

> However, the test passes only when I
> explicitly tell thrift_binary_in to return a bytea (change the return type
> from thrift_binary to bytea), and it does not work when returns
> thrift_binary.

What do you mean by "the test passes" (or doesn't pass)?  What do you
mean by "tell thrift_binary_in to return a bytea"?  You just said you
were already doing that.

This works for me:

regression=# create type thrift_binary;
CREATE TYPE
regression=# create function thrift_binary_in(cstring) returns thrift_binary
regression-# strict immutable language internal as 'byteain';
NOTICE:  return type thrift_binary is only a shell
CREATE FUNCTION
regression=# create function thrift_binary_out(thrift_binary) returns cstring
regression-# strict immutable language internal as 'byteaout';
NOTICE:  argument type thrift_binary is only a shell
CREATE FUNCTION
regression=# CREATE TYPE thrift_binary (
regression(# INPUT = thrift_binary_in,
regression(# OUTPUT = thrift_binary_out,
regression(# LIKE = bytea
regression(# );
CREATE TYPE

I cheated here by pointing to byteain/byteaout instead of C functions
that'd actually do what you want, but CREATE TYPE doesn't know that.

I suspect you may have forgotten the initial dummy creation of
thrift_binary as a "shell type".

            regards, tom lane

>>>>> "Charles" == Charles Cui <charles.cui1984@gmail.com> writes:

 Charles> Hi Tom,
 Charles>    Thanks for your comments, I do forget create type shell.
 Charles> But even if I add this line still does not work.
 Charles> Here is the commit that can demo my bug (
 Charles> https://github.com/charles-cui/pg_thrift/commit/8b43f3e2172f4a1b4e61211f7d76b061a90c38f7
 Charles> )
 Charles> To see it, download the repo and do make install && make installcheck.
 Charles> It cannot return a bytea as expected.

Your output function isn't doing anything, and in particular it's not
returning any value (just dropping off the end), so as soon as pg tries
to output a query result containing a thrift_binary value, it either
outputs garbage or crashes.

-- 
Andrew (irc:RhodiumToad)