LOAD — load a shared library file
LOAD 'filename'
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 library file name is typically given as just a bare file name, which is sought in the server's library search path (set by dynamic_library_path). Alternatively it can be given as a full path name. In either case the platform's standard shared library file name extension may be omitted. See Section 36.10.1 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.)
LOAD is a PostgreSQL extension.
Read the upstream documentation. For corrections, first check the current version.