Re: BUG #5273: Unexpected function behavior/failure

On Tue, Jan 12, 2010 at 7:45 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "Vee" <sefer(at)hotmail(dot)com> writes:
>> -- The problem query
>> select data, regexp_matches(data, '(h..l)')
>> from test;
>
>>> hello        {hell}
>
>> Since I have no "where" clause, I would expect to see all the rows in the
>> result of the second case, with possibly a NULL value for the non-matched
>> rows.
>
> No.  regexp_matches() returns setof something, meaning a row per match.
> When you have no match, you get no rows.  And that in turn means that
> the calling select produces no rows --- just as it could also produce
> more than one row from a given table row.
>
> I think the behavior you are after is probably more like that of
> substring().

Or maybe the ~ operator.

...Robert