Re: attndims, typndims still not enforced, but make the value within a sane threshold

Bruce Momjian <bruce(at)momjian(dot)us> writes:
> Using the queries in that URL, I see:

> CREATE TABLE test (data integer, data_array integer[5][5]);
> CREATE TABLE test2 (LIKE test);
> CREATE TABLE test3 AS SELECT * FROM test;
> SELECT relname, attndims
> FROM pg_class JOIN pg_attribute ON (pg_attribute.attrelid = pg_class.oid)
> WHERE attname = 'data_array';
> relname | attndims
> ---------+----------
> test | 2
> --> test2 | 0
> --> test3 | 0

Yeah, that's not great. We don't have the ability to extract a
number-of-dimensions from a result column of a SELECT, but we could
at least take care to make attndims be 1 not 0 for an array type.
And CREATE TABLE LIKE can easily do better. See attached draft.
(We could simplify it a little bit if we decide to store only 1 or 0
in all cases.)

> Interestingly, if I dump and restore with:
> $ createdb test2; pg_dump test | sql test2
> and run the query again I get:
> relname | attndims
> ---------+----------
> test | 1
> test2 | 1
> test3 | 1

I looked at getting a better result here and decided that it didn't
look very promising. pg_dump uses format_type() to build the type
name to put in CREATE TABLE, and that doesn't have access to attndims.

regards, tom lane