Jeff Janes escribió:
> On Tue, Jun 18, 2013 at 11:20 AM, Svenne Krap <svenne.lists@krap.dk> wrote:
> > As I have no real idea of what "~<~" is for an operator (I have looked
> > it up as scalarltjoinsel), but I cannot find any semantics for it in the
> > docs*... So I have no way of manually checking the expected result.
>
> Yes, it does seem to be entirely undocumented. Using:
> git grep '~<~', I found the code comment "character-by-character (not
> collation order) comparison operators for character types"
To look up an operator you can search in pg_operator.h (where you'd also
see the DESCR() line nearby containing a description) or the pg_operator
catalog. The pg_operator row contains a reference to the pg_proc entry
that implements the operator. The pg_proc row, in turn, refers to a
(typically) C-language function that implements the function. Normally
looking at the function and surrounding code you can figure out what the
operator is about.
In this case you should probably be able to find the operator referenced
in pg_amop as well, as part of the "*_pattern_ops" opclasses.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
