Re: Undocumented functions

Hi

so 7. 9. 2024 v 20:58 odesílatel Marcos Pegoraro <marcos(at)f10(dot)com(dot)br> napsal:

> Some days ago Tom Lane said ...
>
> SELECT events & 4 != 0 AS can_upd, events & 8 != 0 AS can_ins, events & 16
> != 0 AS can_del FROM
> pg_catalog.pg_relation_is_updatable('_pessoa'::regclass, false) t(events);
>
> Well, I didn't find that function on DOCs and then I thought, are there
> other functions which are not documented ? Why ?
> Then if I get all functions from pg_catalog
> select string_agg(distinct format('"%s"',proname),',') from pg_proc where
> pronamespace::regnamespace::text = 'pg_catalog'
>
> using PowerShell declare a variable, on the SGML folder I use ...
>
> $vv = (result of that select)
> foreach ($v in $vv) {if (!((Get-Content . | %{$_ -match $v}) -contains
> $true)) {
> Write-Host $v}}
>
> I'll get all functions which are on pg_catalog but not on SGML files, so
> are not documented.
>
> Example, elem_contained_by_range is not documented. I know I can use
> select 2 <@ '[1,3]'::int4range
> But why is that function not documented ?
> select elem_contained_by_range(2,'[1,3]'::int4range);
>
> And what other functions are cool to use but are not documented ?
>

there are lot of useful undocumented functions - see queries from
https://github.com/postgres/postgres/blob/master/src/bin/psql/describe.c

I see the main reason for the existence of undocumented functions inside
Postgres or MSSQL is a missing guarantee of stability or existence.

Everything in the pg_catalog schema can be different with every major
release. pg_relation_is_updatable is part of FDW support, it is not
designed for users.

Regards

Pavel

> regards
> Marcos
>