Using unnest function on multi-dimensional array.

Hi,

Can anybody highlight how to use unnest function from postgres 8.4 on multi-dimensional array?

Below is the sample table structure:

Table "public.multi_array_test"
 Column  |   Type   | Modifiers
---------+----------+-----------
 id      | integer  |
 user_id | bigint[] |

Sample data:

  1 | {{3567559397,0},{3020933367,1},{2479094216,2},{3310282955,3}}

Regards,
Nimesh.