Tom Lane wrote: > Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> writes: > > On 10.05.2011 20:15, Simon Riggs wrote: > >> I can picture that. Regrettably, I can also picture the accesses to > >> the visibility map, the maintenance operations on the VM that are > >> needed for this and the contention that both of those will cause. > > > I agree that we need to do tests to demonstrate that there's a gain from > > the patch, once we have a patch to test. I would be very surprised if > > there isn't, but that just means the testing is going to be easy. > > I think Simon's point is that showing a gain on specific test cases > isn't a sufficient argument. What we need to know about this sort of > change is what is the distributed overhead that is going to be paid by > *everybody*, whether their queries benefit from the optimization or not. > And what fraction of real-world queries really do benefit, and to what > extent. Isolated test cases (undoubtedly chosen to show off the > optimization) are not adequate to form a picture of the overall cost and > benefit.
Yes, I assume we are going to need the same kind of tests we did for other invasive patches like serializable isolation level and hot standby. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
