Re: Trivial function query optimized badly

"Craig A. James" <cjames@modgraph-usa.com> writes:
>   CREATE OR REPLACE FUNCTION cansmiles(text) RETURNS text
>   AS '/usr/local/pgsql/lib/libchem.so', 'cansmiles'
>   LANGUAGE 'C' STRICT IMMUTABLE;

Umm ... this is a single-argument function.

> db=> explain analyze select version_id, 'Brc1ccc2nc(cn2c1)C(=O)O' from version where version.isosmiles =
cansmiles('Brc1ccc2nc(cn2c1)C(=O)O',1); 

And this query is invoking some other, two-argument function; which
apparently hasn't been marked IMMUTABLE, else it'd have been folded
to a constant.

            regards, tom lane