Create a GUC parameter temp_tablespaces that allows selection of the

tablespace(s) in which to store temp tables and temporary files.  This is a
list to allow spreading the load across multiple tablespaces (a random list
element is chosen each time a temp object is to be created).  Temp files are
not stored in per-database pgsql_tmp/ directories anymore, but per-tablespace
directories.

Jaime Casanova and Albert Cervera, with review by Bernd Helmle and Tom Lane.

src/backend/utils/misc/postgresql.conf.sample

@@ -408,6 +408,8 @@
 #search_path = '"$user",public'		# schema names
 #default_tablespace = ''		# a tablespace name, '' uses
 					# the default
+#temp_tablespaces = ''			# a list of tablespace names,
+					# '' uses only default tablespace
 #check_function_bodies = on
 #default_transaction_isolation = 'read committed'
 #default_transaction_read_only = off