problem with coalesce

Hi there,

I don't understand why this select doesn't works:

regression=# select coalesce(
tp_rewrite_substitute(ARRAY[query, test.target, test.sample]),
query)
from test,to_tsquery('new2 & york2 & hotel') as query
where query @ test.target;

ERROR: column "query.query" must appear in the GROUP BY clause or be used in an aggregate function

as a workaround I could explicitly specify query, but this doesn't looks
nice

regression=# select coalesce(
tp_rewrite_substitute(ARRAY[query, test.target, test.sample]),
to_tsquery('new2 & york2 & hotel'))
from test,to_tsquery('new2 & york2 & hotel') as query
where query @ test.target;

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83