Check the documentation about using composite-type arguments in C http://www.postgresql.org/docs/8.2/static/xfunc-c.html#AEN37402
You can use GetAttributeByNum() or GetAttributeByName() to get each value from your custom type. You will need to get the HeapTupleHeader first by calling PG_GETARG_HEAPTUPLEHEADER(). A quick google search brought up this tutorial that might help http://linuxgazette.net/142/peterson.html
Cheers
My problem is, how do I access this type in my function (in C), and how do I create a new object of this type to return from the function? I need to store both a text and an int, to avoid doing an extra query around the result of this aggregate (to get the corresponding text value), which is what I'm currently doing. Any ideas?
