Hello: I have a large table (40 million+ rows) that I generated with "copy into" statements using several 1g txt files. The table was subsequently subjected to an "order asc" statement and now I need to add a sequence column to it and there I have a problem. A simple test table illustrates the problem as follows: sql-> create table test (name varchar(10)); sql->alter table test add column seq serial; Error: ALTER TABLE ADD COLUMN: adding column with key constraint not implemented I have tried several different ways to generate a sequence that work from me in postgres but I continuously run into an error like "primary key constraint violated". The only way I can get it to work is by adding one row at a time. Sorry about my ignorance, but can someone lend a hand? Thanks, George H