Allison Kaptur <allison.kaptur@xxxxxxxxx> writes: > I encountered a surprising error when writing a migration that both added a > primary key to a table and added a new NOT NULL column. It threw the error " > column "col_d" contains null values", even though I supplied a default. The > migration looks like this: > CREATE TABLE new_table AS SELECT col_a, col_b, col_c from existing_table; > ALTER TABLE new_table > ADD COLUMN col_d UUID UNIQUE NOT NULL DEFAULT uuid_generate_v4(), > ADD PRIMARY KEY (col_a, col_b, col_c); Hm, this can be made a good deal more self-contained: regression=# create table t1 (a int); CREATE TABLE regression=# insert into t1 values(1); INSERT 0 1 regression=# alter table t1 add column b float8 not null default random(), add primary key(a); ERROR: column "b" contains null values It fails like that as far back as I tried (8.4). I'm guessing that we're doing the ALTER steps in the wrong order, but haven't looked closer than that. Interestingly, in v11 and HEAD it works if you use a constant default, suggesting that the fast-default feature is at least adjacent to the problem. regards, tom lane
