Since PostgreSQL uses standard files for all its files, there are several parts of the database you can relocate to somewhere else just by moving the associated files and adding a symbolic link to the new location.
Disk layout for PostgreSQL
Symbolic links
Symbolic links (also called symlinks) are just entries in a filesystem directory that point towards another location. UNIX systems originally preferred to use what are called hard links, which link to the new location directly. The entry in the filesystem literally points to another spot on the disk. To make this easier to manage, the normal approach now is to use soft symlinks, which are easily visible. The most common thing to relocate using a symlink in PostgreSQL is...