Re: B-tree fan-out

On Fri, Jun 22, 2007 at 09:32:30PM +0200, cluster wrote:
> What is the fan-out (number of child nodes) on each B-tree node in
> postgresql? Is it dependent of the size of the keys being indexed? If
> so: How?

In postgres, everything is done in pages, so how ever many keys fit in
a page. Bigs keys mean less. For integers you can fit an awful lot of
keys.

> In B-trees all non-leaf nodes have a bunch of pointers to its child
> nodes. What is the size of such a pointer?

I imagine it's a page number, probably just a 32-bit integer.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.