Loads a shared library file into the PostgreSQL backend's address
space. If the file had been loaded previously, it is first
unloaded. This command is primarily useful to unload and reload a
shared library file that has been changed since the backend first
loaded it. To make use of the
shared library, function(s) in it need to be declared using the CREATE FUNCTION command.
The file name is specified in the same way as for shared library
names in CREATE FUNCTION; in particular, one
may rely on a search path and automatic addition of the system's standard
shared library file name extension. See the
Programmer's Guide for more detail.