Re: Undocumented functions

Marcos Pegoraro <marcos(at)f10(dot)com(dot)br> writes:
> 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 ?

Functions that are primarily meant to implement operators are
normally not documented separately: we feel it would bloat the
docs without adding a lot. There are pg_description entries for
them, eg

regression=# \df+ elem_contained_by_range
List of functions
Schema | Name | Result data type | Argument data types | Type | Volatility | Parallel | Owner | Security | Access privileges | Language | Internal name | Description
------------+-------------------------+------------------+----------------------+------+------------+----------+----------+----------+-------------------+----------+-------------------------+-------------------------------
pg_catalog | elem_contained_by_range | boolean | anyelement, anyrange | func | immutable | safe | postgres | invoker | | internal | elem_contained_by_range | implementation of <@ operator
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
(1 row)

I think pg_relation_is_updatable is primarily meant as support for the
information_schema views, which may explain why it's not in the docs
either. There's less of a formal policy about functions underlying
system views, but the majority of them probably aren't documented.

regards, tom lane