"Jimmy Choi" <yhjchoi@xxxxxxxxx> writes: > select > metric_type, > case metric_type > when 0 then > sum (1 / val) > when 1 then > sum (val) > end as result > from metrics > group by metric_type The reason this does not work is that the aggregate functions are aggregated without any knowledge of how they might ultimately be used in the final output row. The fact that the CASE might not actually demand the value of an aggregate at the end doesn't stop the system from having to compute it. You could use a CASE *inside* the SUM() to prevent division by zero while forming the sum, but on the whole this query seems rather badly designed. Consider SELECT 0, sum(1/val) FROM metrics WHERE metric_type = 0 UNION ALL SELECT 1, sum(val) FROM metrics WHERE metric_type = 1 UNION ALL ... regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
