Don't lock the table while migrate your db

migration_00001.sql

-- dont force update all table with default value
ALTER TABLE TB_A
    ADD COLUMN new_coumn boolean;

-- add constaint for new records
ALTER TABLE public.TB_A
    ALTER COLUMN new_coumn SET DEFAULT false;

-- while not return 0 update the table
do $$
    counter interger := 1;
begin
    while counter > 0 loop
        UPDATE TB_A SET new_coumn = false WHERE id IN (SELECT id FROM TB_A WHERE new_coumn is NULL LIMIT 10000);
        counter := row_count
    end loop;
end$$