On Wed, Jun 23, 2010 at 1:50 AM, Ralph Heinkel <ralph.hein...@web.de> wrote: > Hi, > > we are about upgrading our sqlalchemy library from 0.4.8 to something newer > and during this process we have detected that the LIMIT/OFFSET support for > oracle has been changed, from using “ROW NUMBER OVER...” to a wrapped > subquery approach in conjunction with ROWNUM as described in > http://www.sqlalchemy.org/docs/reference/dialects/oracle.html#limit-offset-support > > > Unfortunately this approch is about 10 times slower for large tables which > is mainly related to the fact that the innermost subquery has to sort the > entire table with a plain 'order by'. > Interestingly the > ROW_NUMBER() OVER (ORDER BY some db fields) > is so much more efficient than the normal order by approach.
Do you have benchmarks to back that up? In Django, we switched from using row_number to rownum after a contributor convinced me that rownum was faster. See: http://code.djangoproject.com/ticket/9136 Thanks, Ian -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
