Re: BUG #4580: select substring ('a' from '(b)?(a)') returns null

"substring and regular expresssion" <m.mamin@intershop.de> writes:
> substring ('a' from '(b)?(a)') returns 'a' in version 8.2.x,
> but null with 8.3.5.  Comparing this to the bug entry
> http://archives.postgresql.org/pgsql-bugs/2008-11/msg00112.php I guess this
> is not considered as a bug

No, the old behavior was a bug.  Using your example pattern,
substring ('ba' from '(b)?(a)') would return 'b' not 'ba',
so I can hardly see how you failed to notice that it wasn't
behaving consistently.

            regards, tom lane