Re: Btree Index on PostgreSQL and Wiredtiger (MongoDB3.2)

On Fri, Aug 12, 2016 at 1:40 AM, Mark Kirkwood
<mark.kirkwood@catalyst.net.nz> wrote:
> After examining the benchmark design - I see we are probably not being
> helped by the repeated insertion of keys all of form 'userxxxxxxx' leading
> to some page splitting.

But shouldn't that still leave us with a 75% full index, rather than
slightly over 50% full?

The leaf pages start at 50%, grow to 100%, then split back to 50%,
then grow back to 100%.  So the average should be about 75%.


> However your index rebuild gets you from 5 to 3 GB - does that really help
> performance significantly?

It can make a big difference, depending on how much RAM you have.

Cheers,

Jeff