This command loads a shared library file into the PostgreSQL server's address space. If the file has been loaded already, the command does nothing. Shared library files that contain C functions are automatically loaded whenever one of their functions is called. Therefore, an explicit LOAD is usually only needed to load a library that modifies the server's behavior through "hooks" rather than providing a set of functions.
The file name is specified in the same way as for shared library names in CREATE FUNCTION; in particular, one can rely on a search path and automatic addition of the system's standard shared library file name extension. See Section 36.9 for more information on this topic.
Non-superusers can only apply LOAD to library files located in $libdir/plugins/ — the specified filename must begin with exactly that string. (It is the database administrator's responsibility to ensure that only "safe" libraries are installed there.)
Read the upstream documentation. For corrections, first check the current version.