Re: Compression and on-disk sorting

[Simon Riggs <simon(at)2ndquadrant(dot)com>]

On Fri, 2006-05-26 at 14:47 -0500, Jim C. Nasby wrote:

> But the meat is:
>                                         -- work_mem --
>                         Scale           2000    20000
> not compressed          150             805.7   797.7
> not compressed          3000            17820   17436
> compressed              150             371.4   400.1
> compressed              3000            8152    8537
> compressed, no headers  3000            7325    7876

Since Tom has committed the header-removing patch, we need to test

	not compressed, no headers v compressed, no headers

There is a noticeable rise in sort time with increasing work_mem, but
that needs to be offset from the benefit that in-general comes from
using a large Heap for the sort. With the data you're using that always
looks like a loss, but that isn't true with all input data orderings.

-- 
  Simon Riggs
  EnterpriseDB          http://www.enterprisedb.com