On Tue, Jul 21, 2015 at 4:06 PM, Peter Geoghegan <p...@heroku.com> wrote: > Design considerations and consequences > --------------------------------------------------------
Good write-up. > I'm not concerned about synchronized scans breaking my assumption of a > physical ordering of heaptuples being fed to tuplesort.c. I think that > it is unlikely to ever be worth seriously considering this case. Why not? > I have a hard time imagining anything (beyond synchronous scans) > breaking my assumption that index tuplesorts receive tuples in heap > physical order. If anything was to break that in the future (e.g. > parallelizing the heap scan for index builds), then IMV the onus > should be on that new case to take appropriate precautions against > breaking my assumption. I'm very dubious about that. There are lots of reasons why we might want to read tuples out of order; for example, suppose we want a parallel sequential scan to feed the sort. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers