Re: regexp_matches() quantified-capturing-parentheses oddity

Julian Mehnle <julian@mehnle.net> writes:
> So far, so good.  However, can someone please explain the following to me?
>   wisu-dev=# SELECT regexp_matches('quux@foo@bar.zip', '([@.]|[^@.]+)+', 'g');
>   wisu-dev=# SELECT regexp_matches('quux@foo@bar.zip', '([@.]|[^@.]+){1,2}', 'g');
>   wisu-dev=# SELECT regexp_matches('quux@foo@bar.zip', '([@.]|[^@.]+){1,3}', 'g');

These might be a bug, but the behavior doesn't seem to me that it'd be
terribly well defined in any case.  The function should be pulling the
match to the parenthesized subexpression, but here that subexpression
has got multiple matches --- which one would you expect to get?

Instead of (foo)+ I'd try
    ((foo+))    if you want all the matches
    (foo)(foo)*    if you want the first one
    (?:foo)*(foo)    if you want the last one

            regards, tom lane