On Sun, Jul 13, 2014 at 2:27 AM, Mitsumasa KONDO <kondo.mitsum...@gmail.com> wrote: > I still agree with Fabien-san. I cannot understand why our logical proposal > isn't accepted...
Well, I think the feedback has been pretty clear, honestly. Here's what I'm unhappy about: I can't understand what these options are actually doing. And this isn't helping me a bit: > [nttcom@localhost postgresql]$ contrib/pgbench/pgbench --exponential=10 > starting vacuum...end. > transaction type: Exponential distribution TPC-B (sort of) > scaling factor: 1 > exponential threshold: 10.00000 > > decile percents: 63.2% 23.3% 8.6% 3.1% 1.2% 0.4% 0.2% 0.1% 0.0% 0.0% > highest/lowest percent of the range: 9.5% 0.0% I don't have a clue what that means. None. Here is an example of an explanation that would make sense to me. This is not the actual behavior of your patch, I'm quite sure, so this is just an example of the *kind* of explanation that I think is needed: The --exponential option causes pgbench to select lower-numbered account IDs exponentially more frequently than higher-numbered account IDs. The argument to --exponential controls the strength of the preference for lower-numbered account IDs, with a smaller value indicating a stronger preference. Specifically, it is the percentage of the total number of account IDs which will receive half the total accesses. For example, with --exponential=10, half the accesses will be to the smallest 10 percent of the account IDs; half the remaining accesses will be to the next-smallest 10 percent of account IDs, and so on. --exponential=50 therefore represents a completely flat distribution; larger values are not allowed. -- 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