On Mon, Oct 19, 2009 at 8:56 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Greg Stark <gsstark@mit.edu> writes:
>> The run-time of CLUSTER doesn't vary very much based on whether the
>> data is already in index order or not. The number of passes only grows
>> like log(n) of the size of your data and if you set
>> maintenance_work_mem large enough (somewhere around 100MB-1GB) the
>> constants are small enough that you're unlikely to even outgrow a
>> single pass (plus a final merge though)
>
> Uh ... what? It's not based on the sort code, unless someone rewrote it
> since I looked last. It's an index scan and will definitely depend on
> the index ordering.
Er, uh, of course. I wonder what I was thinking.
Sorry
--
greg