[7.0.2] node type 17 not supported ...

I have a database where, periodically, I get a query that is producing
pg_noname files that are >1gig in size ... according to syslog, for that
process:

Sep  7 18:36:39 pgsql postgres[47078]: DEBUG:  ExecRestrPos: node type 17 not supported
Sep  7 18:36:39 pgsql postgres[47078]: DEBUG:  ExecRestrPos: node type 17 not supported
Sep  7 18:36:40 pgsql postgres[47078]: DEBUG:  ExecRestrPos: node type 17 not supported
Sep  7 18:36:56 pgsql postgres[47078]: DEBUG:  ExecMarkPos: node type 17 not supported
%

the query that appears to be causing this, in this particular case, is:

SELECT distinct s.gid, s.created ,       geo_distance(pd.location, '(-97.4382912597586,37.7021126098755)')  FROM status
s,personal_data pd, relationship_wanted rw,       personal_ethnicity pe, personal_religion pr, personal_bodytype pb,
 personal_smoking ps WHERE s.active   AND s.status != 0                  AND (s.gid = pd.gid AND pd.gender = 0)  AND
(s.gid= rw.gid AND rw.gender = 1)                  AND geo_distance(pd.location,
'(-97.4382912597586,37.7021126098755)')<= 500
 
ORDER BY geo_distance( pd.location, '(-97.4382912597586,37.7021126098755)'),          s.created desc;

now, its a reasonable oft run query, and from a debugging log that I keep,
it normally takes <1sec to run:

[0.38 secs]: SELECT distinct s.gid, s.created , geo_distance(pd.location, '(-97.4382912597586,37.7021126098755)')
     FROM status s, personal_data pd, relationship_wanted rw            WHERE s.active AND s.status != 0
AND(s.gid = pd.gid AND pd.gender = 0)              AND (s.gid = rw.gid AND rw.gender = 1 )              AND
geo_distance(pd.location, '(-97.4382912597586,37.7021126098755)' ) <= 500         ORDER BY geo_distance( pd.location,
'(-97.4382912597586,37.7021126098755)'), s.created desc;
 

So, I'm curious as to why it periodically just hangs ... how do you debug
something like this? :(  Its been happening ~once per day, so should be
reasonably debugging (unless, of course, now that I mention something it
never comes back *sigh*) ...

Thoughts? 

Marc G. Fournier                   ICQ#7615664               IRC Nick: Scrappy
Systems Administrator @ hub.org 
primary: scrappy@hub.org           secondary: scrappy@{freebsd|postgresql}.org