
> > (who really selects nearly all rows from a 5M row
> >    table?).

I have to comment here from a practical standpoint.  My company does the above
dozens of times per day using Oracle 7 under Solaris.  This is a *VERY*
common operation in data processing organizations (like mine) running large
batch jobs in tight time windows.  At least under Oracle 7 (not sure about
ProgreSQL, still running tests), it is impractical to sort an extraction
using ORDER BY, but *MUCH* cheaper to index the fields wanted and then
artificially constrain the query
to convince the oprimizer to use the index for extraction.  You can
get the whole dataset in any order you want with few resources.  Again, we
do it all the time.

Marty

Thu, 15 Oct 1998 10:32:52 -0600
Martin <marty@outputservices.com>
Re: [HACKERS] Re: order by and index path