Slow query after upgrade to 8.4

Hello postgres wizards,

We recently upgraded from 8.1.5 to 8.4
We have a query (slow_query.sql) which took about 9s on 8.1.5
On 8.4, the same query takes 17.7 minutes.

The code which generated this query is written to support the
calculation of arbitrary arithmetic expressions across "variables" and
"data" within our application.  The example query is a sum of three
"variables", but please note that because the code supports arbitrary
arithmetic, we do not use an aggregate function like sum()

We have collected as much information as we could and zipped it up here:

http://pgsql.privatepaste.com/download/a3SdI8j2km

Thank you very much in advance for any suggestions you may have,
Jared Beck

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Jared Beck
Web Developer
Singlebrook Technology
(607) 330-1493
jared(at)singlebrook(dot)com