Re: Faster setup_param_list() in plpgsql

I wrote:
> What this patch does is to remove setup_param_list() overhead for the
> common case of PLPGSQL_DTYPE_VAR variables (ie, any non-composite type).
> It does that by the expedient of keeping the ParamExternData image of such
> a variable valid at all times. That adds a few cycles to assignments to
> these variables, but removes more cycles from each use of them. Unless
> you believe that common plpgsql functions contain lots of dead stores,
> this is a guaranteed win overall.

> I'm seeing about 10% overall speedup (vs HEAD, with casserts off) for
> realistic simple plpgsql logic, such as this test case:

Here is a version that is rebased up to HEAD. Dunno if anyone wants
to re-review this, if not I'll go commit it.

regards, tom lane