Subject: Userland copy of pg_statistic - is there a solution?

From: Vinícius Abrahão <[email-masked]>
Date: Mon, 30 Sep 2024 08:31:06 +0100

Morning,

postgres=# create table backup_pg_statistic as select * from pg_statistic;
2024-09-30 08:25:56 BST [7400]:
user=vinnix,db=postgres,app=psql,client=[local] ERROR:  column "stavalues1"
has pseudo-type anyarray
2024-09-30 08:25:56 BST [7400]:
user=vinnix,db=postgres,app=psql,client=[local] STATEMENT:  create table
backup_pg_statistic as select * from pg_statistic;
ERROR:  column "stavalues1" has pseudo-type anyarray
Time: 9.544 ms
postgres=# create table test_array(a anyarray);
2024-09-30 08:26:40 BST [7400]:
user=vinnix,db=postgres,app=psql,client=[local] ERROR:  column "a" has
pseudo-type anyarray
2024-09-30 08:26:40 BST [7400]:
user=vinnix,db=postgres,app=psql,client=[local] STATEMENT:  create table
test_array(a anyarray);
ERROR:  column "a" has pseudo-type anyarray
Time: 9.137 ms
Is there a solution for this simple problem?

Cheers,
Vinícius

---

From: Laurenz Albe <[email-masked]>
Date: Mon, 30 Sep 2024 12:05:52 +0200

On Mon, 2024-09-30 at 08:31 +0100, Vinícius Abrahão wrote:
> 2024-09-30 08:25:56 BST [7400]: user=vinnix,db=postgres,app=psql,client=[local] ERROR:  column "stavalues1" has pseudo-type anyarray
> 2024-09-30 08:25:56 BST [7400]: user=vinnix,db=postgres,app=psql,client=[local] STATEMENT:  create table backup_pg_statistic as select * from pg_statistic;
> 2024-09-30 08:26:40 BST [7400]: user=vinnix,db=postgres,app=psql,client=[local] ERROR:  column "a" has pseudo-type anyarray
> 2024-09-30 08:26:40 BST [7400]: user=vinnix,db=postgres,app=psql,client=[local] STATEMENT:  create table test_array(a anyarray);

Use a text[] for your copy of the stavalues* columns.

Yours,
Laurenz Albe

---

From: Vinícius Abrahão <[email-masked]>
Date: Thu, 3 Oct 2024 12:29:50 +0100

> Is there a solution for this simple problem?

Following up my own question - I could overcome this limitation observing
the parameter allow_system_table_mods

postgres=# set allow_system_table_mods to on;
SET
Time: 5.190 ms
postgres=# create table a(a anyarray) ;
CREATE TABLE
Time: 132.959 ms

This is verified at heap_create_with_catalog(...). PostgreSQL code
https://github.com/postgres/postgres/blob/master/src/backend/catalog/heap.c#L1151

If someone needs a patch let me know to make it work for other users. We
can work on this together.

--
vinnix
aka: Vinícius Abrahão Bazana Schmidt
twitter.com/vischmidt