Can't use pgRouting functions in PostgreSQL 9.2 - postgresql

Question

I have 3 pgRouting sql files,
routing_core
routing_core_wrappers
routing_topology
And I run the code in the first one in PostgreSQL 9.2, I got this error,
PS. although there are already pgRouting functions in extensions of 9.2, I still can't run the following code,
ALTER TABLE tc_2000_w_area ADD COLUMN source integer;
ALTER TABLE tc_2000_w_area ADD COLUMN target integer;
SELECT assign_vertex_id('tc_2000_w_area', 0.0001, 'the_geom', 'gid')
got the error,
>>>
Traceback (most recent call last):
File "C:/Users/Heinz/Desktop/python_test/any_test.py", line 12, in <module>
cur.execute(query)
ProgrammingError: 錯誤: 函式 assign_vertex_id(unknown, numeric, unknown, unknown) 不存在
LINE 4: SELECT assign_vertex_id('tc_2000_w_area', 0.0001, 'the_g...
^
HINT: 沒有符合指定之名稱和參數型別的函式。您可能需要加入明確型別轉換。
So I think to run the above 3 sql files first.
But I can run all 3 sql files in PostgreSQL 8.4
I am working with PostgreSQL 9.2, PostgreSQL 8.4 under Windows 8.1 x64.
UPDATE#1
I run the code below, but shows error message,
create extension pgrouting;
錯誤: 擴充功能 "pgrouting" 已存在
********** 錯誤 **********
錯誤: 擴充功能 "pgrouting" 已存在
SQL 狀態: 42710
the error message means the pgRouting extension already exists, but if I directly use the code in my original post, got the same error as I posted.

Answer 1

You have to install postgis before pgrouting.
create extension postgis;
create extension pgrouting;
Then you should be able to use it.