Specifies the shared memory implementation that the server should use for the main shared memory region that holds PostgreSQL's shared buffers and other shared data. Possible values are
mmap (for anonymous shared memory allocated using mmap),
sysv (for System V shared memory allocated via shmget) and
windows (for Windows shared memory). Not all values are supported on all platforms; the first supported option is the default for that platform. The use of the
sysv option, which is not the default on any platform, is generally discouraged because it typically requires non-default kernel settings to allow for large allocations (see sysvipc).