1. A method of storing data into a database, the method comprising: a loader application receiving data; determining one or more routines that are associated with a type of said data, wherein said one or more routines are implemented by a program that is external to both said loader application and a database server that manages said database; said program registering, with said loader application, said one or more routines, which are not implemented by said loader application; in response to said program registering said one or more routines with said loader application, said loader application adding, to a dispatch table, an entry that indicates an association between said one or more routines and an opaque type implemented by said program; invoking said one or more routines; in response to said one or more routines being invoked, said program performing steps comprising: creating a data structure that has one or more elements that correspond to one or more attributes of said type; and populating said one or more elements with one or more values that are specified in said data, wherein said one or more values correspond to said one or more attributes; generating, based on said data structure, a data stream that conforms to a format of data blocks of said database; and writing said data into one or more data blocks in said database.