Re: SELECTing every Nth record for better performance

On Thu, Dec 3, 2009 at 9:26 PM, Tom <tom(at)cstcomposites(dot)com> wrote:

> I
> want run a query that skips every nth record and returns a managable
> dataset that still gives a correct overview of the data without
> slowing the programme down. Is there an easy way to do this that I
> have overlooked? I looked at:

I've played with datalogging. It was very easy to find nth records
when using date_trunc() on a timestamp. The only minor problem with
data_trunc was that I couldn't create arbitrary granularity. For
example it is easy to date_trunc() on an year, month, week, day, hour
or a minute but I wanted 5, 10 and 15 minute increments. I bet there
could be a solution to this, but I never looked into it.

To improve the select performance, I created functional indexes using
different data_trunc() granularities.

--
Regards,
Richard Broersma Jr.

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