Re: [HACKERS] concat_ws

Tom Lane wrote:
> Yeah.  The problem is that the SQL function inliner generates an
> enormous expression tree from this function definition.  7.3 had no
> inliner so no problem.

But I wonder why it isn't at all a problem when the function is also
defined STRICT?

I also looked back at the greatest() example -- similar behavior. If
defined
   ...language sql;
or
   ...language sql IMMUTABLE STRICT;
it works great.

But when defined
   ...language sql IMMUTABLE;
it dies a horrible recursive death.

In case 1 above, the function doesn't get inlined at all, right? But in
both case 2 and 3, it should get inlined -- why does 2 work fine when 3
doesn't?

> I am not sure what to do about it --- the only idea that comes to mind
> is to put an arbitrary limit (of, say, 5 or 10 function calls) on the
> depth of inlining expansion.  That seems like a pretty ugly answer
> ... anyone have a better one?

But as above, case 2 is inlined (I think) and works fine -- why restrict it.

> Your definition of concat_ws bears some passing resemblance to the
> infamous Ackermann's function, btw.

I always knew I was destined to be infamous ;-)

Joe