On 28th of March 2018, Andrew Dunstan committed patch: Fast ALTER TABLE ADD COLUMN with a non-NULL default Currently adding a column to a table with a non-NULL default results in a rewrite of the table. For large tables this can be both ...

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.