On 30th of July, Andrew Dunstan committed patch: Add IF NOT EXISTS processing to ALTER TABLE ADD COLUMN Fabrízio de Royes Mello, reviewed by Payal Singh, Alvaro Herrera and Michael Paquier.

On 25th Robert Haas committed patch which adds first of 'CREATE IF NOT EXISTS' commands: Log Message: ----------- CREATE TABLE IF NOT EXISTS. Reviewed by Bernd Helmle.