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|Reported by||Allison Kaptur|
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The following bug has been logged on the website: Bug reference: 15580 Logged by: Allison Kaptur Email address: (redacted) PostgreSQL version: 9.6.2 Operating system: Any Description: An ALTER TABLE that both (a) adds a primary key on an existing column and (b) adds a new not-null column fails with "column 'new_col' contains null values". Tom Lane helpfully boiled down my original problem to a smaller repro: 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 Tom adds (on pgsql-general): > 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. Two workarounds that do not trigger the bug: 1. Setting NOT NULL in a separate step from adding the column ALTER TABLE t1 ADD COLUMN b int UNIQUE DEFAULT random(), ADD PRIMARY KEY (a), ALTER COLUMN b SET NOT NULL; 2. Splitting the command into two ALTER TABLE statements ALTER TABLE t1 ADD COLUMN b int UNIQUE NOT NULL DEFAULT random(); ALTER TABLE new_table ADD PRIMARY KEY (a); These two workarounds leave me with the same theory as Tom: postgres seems to be rewriting the order of the ALTER steps so that NOT NULL is applied to the new column before the default values are supplied.
|2019-01-07 19:40:45+00||=?utf-8?q?PG_Bug_reporting_form?=||BUG #15580: ALTER TABLE with new column and ADD PRIMARY KEY throws spurious "column contains null values"|