Re: an aggregate to return max() - 1 value?

SELECT col FROM tab ORDER BY col DESC OFFSET 1 LIMIT 1

In 8.4 OLAP window functions provide more standard and flexibility
method but in this case it wouldn't perform as well:

postgres=# select i from (select i, rank() over (order by i desc) as r
from i) as x where r = 2;i
----99
(1 row)

postgres=# select i from (select i, dense_rank() over (order by i
desc) as r from i) as x where r = 2;i
----99
(1 row)

-- 
greg