Postgres provides serial and bigserial column types for which it
implicitly creates sequence.
As far as this mechanism is somehow hidden from user, it may be
confusing that table
created with CREATE TABLE LIKE has no associated sequence.
But what is worse, even if experienced user knows that serial types are
implemented in Postgres by specifying
nextval(seq) default value for this column and default values are copied
by CREATE TABLE LIKE only if is it explicitly requested (including all),
then two tables will share the same sequence:
create table t1(x serial primary key, val int);
create table t2(like t1 including all);
postgres=# \d+ t1;
Table "public.t1"
Column | Type | Collation | Nullable | Default | Storage
| Stats target | Description
--------+---------+-----------+----------+-------------------------------+---------+--------------+-------------
x | integer | | not null |
nextval('t1_x_seq'::regclass) | plain | |
val | integer | | | |
plain | |
Indexes:
"t1_pkey" PRIMARY KEY, btree (x)
Access method: heap
postgres=# \d+ t2;
Table "public.t2"
Column | Type | Collation | Nullable | Default | Storage
| Stats target | Description
--------+---------+-----------+----------+-------------------------------+---------+--------------+-------------
x | integer | | not null |
nextval('t1_x_seq'::regclass) | plain | |
val | integer | | | |
plain | |
Indexes:
"t2_pkey" PRIMARY KEY, btree (x)
Access method: heap
Please notice that index is correctly replaced, but sequence - not.
I consider such behavior more like bug than a feature.
And it can be fixed using relatively small patch.
Thoughts?
