ALTER TABLESPACE -- change the definition of a tablespace
ALTER TABLESPACE name RENAME TO newname
ALTER TABLESPACE changes the definition of a tablespace.
name
The name of an existing tablespace.
newname
The new name of the tablespace. The new name cannot begin with pg_, as such names are reserved for system tablespaces.
Rename tablespace empspace to employee_space:
ALTER TABLESPACE empspace RENAME TO employee_space;