On Jan 8, 2013, at 6:48 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> The OP didn't
> suggest how many years his data covers, but it's quite possible that
> pulling a full year's worth of data will read enough of the table that
> there's no point in worrying about whether an index could be used
> anyway.
There are only a few years worth of data, 2008 - 2012. However, the data consists of 15 min measurements and when renormalized (un-pivoted) is several hundred million records. It is conceivable that someone will want to query by month, or even hour of the day.