Re: pl/python invalidate functions with composite arguments

On Wed, Feb 9, 2011 at 02:09, Jan Urbański <wulczer(at)wulczer(dot)org> wrote:
> On 27/01/11 22:42, Jan Urbański wrote:
>> On 23/12/10 14:50, Jan Urbański wrote:
>>> Here's a patch implementing properly invalidating functions that have
>>> composite type arguments after the type changes, as mentioned in
>>> http://archives.postgresql.org/pgsql-hackers/2010-12/msg01991.php. It's
>>> an incremental patch on top of the plpython-refactor patch sent eariler.
>>
>> Updated to master.
>
> Again.

Looks good, it works as described, the code is clean and well
documented and it passes the added regression tests.

I took the liberty of looking at the other pls to see how they handled
this to find they don't cache them in the first place. For fun, I
hacked plpython to not cache to see if there was any performance
difference pre patch, post patch and in the non-cached cases. I
couldn't find any probably due to:
1) my simple test case (select
count(test_composite_table_input('(John, 100, "(10)")')) FROM
generate_series(1, 1000000);)
2) things being cached
3) cache invalidation having to do most of the work that the non
caching cache does. I think there is one or two more SearchSysCall's.
4) overhead from cassert

It seems a bit heavy handed to invalidate and remake the entire
plpython function whenever we hit this case. I think we could get away
with setting ->is_rowtype = 2 in PLy_procedure_valid() instead. I
suppose it should be fairly rare case anyway so... *shrug*.