Re: Abbreviated keys for text cost model fix

On Mon, Feb 23, 2015 at 11:17 AM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> So while it's true that for the 3rd query we get much worse results
> compared to the other queries (i.e. we don't get >400% speedup but ~3%
> slowdown compared to master), it's true that master performs
> exceptionally well for this query with small datasets. Once we get to 2M
> rows, the master performance drops significantly but cost-model keeps
> the performance characteristics and the speedup jumps back to ~700%
> which is nice.
>
> These numbers are for the 'ASC + unsorted row' test, but I do get
> exactly the same pattern for the 'random' tests done previously.

Yeah. Looks like you're comparing a case where the old cost model did
the right thing anyway (i.e. used abbreviation). The difference would
then be entirely explainable as noise. Right?

> It would be nice if we could address the 3% regression for the last
> query, but I guess it's not a big deal. The numbers in general are
> absolutely impressive. Kudos.

Thanks.

--
Peter Geoghegan