Re: [WIP] Effective storage of duplicates in B-tree index.

On 28 January 2016 at 17:09, Peter Geoghegan <pg@heroku.com> wrote:
> On Thu, Jan 28, 2016 at 9:03 AM, Thom Brown <thom@linux.com> wrote:
>> I'm surprised that efficiencies can't be realised beyond this point.  Your results show a sweet spot at around 1000
/10000000, with it getting slightly worse beyond that.  I kind of expected a lot of efficiency where all the values are
thesame, but perhaps that's due to my lack of understanding regarding the way they're being stored. 
>
> I think that you'd need an I/O bound workload to see significant
> benefits. That seems unsurprising. I believe that random I/O from
> index writes is a big problem for us.

I was thinking more from the point of view of the index size.  An
index containing 10 million duplicate values is around 40% of the size
of an index with 10 million unique values.

Thom