Re: BUG #13960: plpython fails with certain function names

On 2/14/16 6:49 PM, Tom Lane wrote:
> Jim.Nasby@BlueTreble.com writes:
>> If a Postgres function contains characters that are illegal for python
>> identifiers, compilation fails. Error message is not very helpful either:
>
> Hm, how much do we really care?  The example seems kinda artificial.

I did run across it creating cast functions programmatically, roughly as

format( 'CREATE FUNCTION "ndarray_to_%1s"', input_type::regtype )

which blows up when you feed it something like float. The actual example
was doing something similar but for an array.

I agree it's not exactly a high priority thing to support, but the error
text is completely useless unless you happen to know that plpython is
creating an actual python function.

>> One possibility is to simply strip out invalid characters[1].
>
> No, because then you would get collisions, ie function names that look
> different to PG would look the same to python.  Bad news.

IIRC we append the regproc OID to ensure it's unique.

> (Actually, don't we have that issue anyway because of schemas?  I wonder
> why we are exposing the PG name of the function to python at all.)

Not sure. Maybe useful in a call stack inside python? I can't really
think of what else you'd use it for. (I assume you're suggesting just
call the function names something like plpython_<regproc::oid>.)
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com