Re: CLUSTER and synchronized scans and pg_dump et al

>>> On Mon, Jan 28, 2008 at  9:00 AM, in message <479DEDF5.4090909@dunslane.net>,
Andrew Dunstan <andrew@dunslane.net> wrote:
> Kevin Grittner wrote:
>>>>> On Sun, Jan 27, 2008 at  9:02 AM, in message
>> <87odb7s45i.fsf@oxford.xeocode.com>, Gregory Stark <stark@enterprisedb.com>
>> wrote:
>>
>>> Perhaps we should have some form of escape hatch for pg_dump to request real
>>> physical order when dumping clustered tables.
>>
>> It would seem reasonable to me for pg_dump to use ORDER BY to select
>> data from clustered tables.
>
> What will be the performance hit from doing that?
If the rows actually are in order of the clustered index, it
shouldn't add much more than the time needed to sequentially pass
the clustered index, should it?  Even so, perhaps there should be a
command-line option on pg_dump to control whether it does this.
-Kevin