Re: Vacuum, Freeze and Analyze: the big picture

On 06/04/2013 05:27 AM, Peter Geoghegan wrote:
> On Mon, Jun 3, 2013 at 5:03 AM, Craig Ringer <craig@2ndquadrant.com> wrote:
>> I've seen cases on Stack Overflow and elsewhere in which disk merge
>> sorts perform vastly better than in-memory quicksort, so the user
>> benefited from greatly *lowering* work_mem.
> I've heard of that happening on Oracle, when the external sort is
> capable of taking advantage of I/O parallelism, but I have a pretty
> hard time believing that it could happen with Postgres under any
> circumstances.
IIRC it's usually occurred with very expensive comparison operations.

I'll see if I can find one of the SO cases.

-- Craig Ringer                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services