On Mon, 2021-03-08 at 14:39 +0900, Tatsuo Ishii wrote: > Currently pgbench uses plain COPY to populate pgbench_accounts > table. With adding FREEZE option to COPY, the time to perform "pgbench > -i" will be significantly reduced. > > Curent master: > pgbench -i -s 100 > : > : > done in 70.78 s (drop tables 0.21 s, create tables 0.02 s, client-side > generate 12.42 s, vacuum 51.11 s, primary keys 7.02 s). > > Using FREEZE: > done in 16.86 s (drop tables 0.20 s, create tables 0.01 s, client-side > generate 11.86 s, vacuum 0.25 s, primary keys 4.53 s). > > As you can see total time drops from 70.78 seconds to 16.86 seconds, > that is 4.1 times faster. This is mainly because vacuum takes only > 0.25 seconds after COPY FREEZE while unpatched pgbench takes 51.11 > seconds, which is 204 times slower. > > Thanks for the COPY FREEZE patch recently committed: > https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=7db0cd2145f2bce84cac92402e205e4d2b045bf2 > > Attached is one line patch for this.
That is indeed low hanging fruit and an improvement. > - res = PQexec(con, "copy pgbench_accounts from stdin"); > + res = PQexec(con, "copy pgbench_accounts from stdin freeze"); I think it would be better to use the official syntax and put the "freeze" in parentheses. Perhaps the old syntax will be desupported some day. Yours, Laurenz Albe
