How to reset sequence in postgres and fill id column with new data?

Question

I have a table with over million rows. I need to reset sequence and reassign id column with new values (1, 2, 3, 4... etc...). Is any easy way to do that?

Answer 1

With PostgreSQL 8.4 or newer there is no need to specify the WITH 1 anymore. The start value that was recorded by CREATE SEQUENCE or last set by ALTER SEQUENCE START WITH will be used (most probably this will be 1).

Reset the sequence:

ALTER SEQUENCE seq RESTART;

Then update the table's ID column:

UPDATE foo SET id = DEFAULT;

Source: PostgreSQL Docs