On 2014-02-18 20:49:06 +0900, MauMau wrote: > From: "Andres Freund" <and...@2ndquadrant.com> > >On 2014-02-18 01:35:52 +0900, MauMau wrote: > >>For example, please see the max latencies of test set 2 (PG 9.3) and test > >>set 4 (xlog scaling with padding). They are 207.359 and 1219.422 > >>respectively. The throughput is of course greatly improved, but I think > >>the > >>response time should not be sacrificed as much as possible. There are > >>some > >>users who are sensitive to max latency, such as stock exchange and online > >>games. > > > >You need to compare both at the same throughput to have any meaningful > >comparison. > > I'm sorry for my lack of understanding, but could you tell me why you think > so? When the user upgrades to 9.4 and runs the same workload, he would > experience vastly increased max latency --- or in other words, greater > variance in response times.
No, the existing data indicates no such thing. When they upgrade they will have the *same* throughput as before. The datapoints you indicate that there's an increase in latency, but it's there while processing several time as much data! The highest throughput of set 2 is 3223, while the highest for set 4 is 14145. To get interesting latency comparison you'd need to use pgbench --rate and use a rate *both* versions can sustain. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers