[Pgpool-general] pgpool II performance

[Tatsuo Ishii]

> I'm running Postgres 8.1.11.   Here are the results of a pgbench test
> pgbench -c 20 -t 1000 testdb
> starting vacuum...end.
> transaction type: TPC-B (sort of)
> scaling factor: 1
> number of clients: 20
> number of transactions per client: 1000
> number of transactions actually processed: 20000/20000
> tps = 731.350579 (including connections establishing)
> tps = 732.860160 (excluding connections establishing)
> 
> I set up another environment with 3 servers 1 pgpool server and 2 masters
> for master-master replication.  Everything on the pgpool functions great but
> the performance is terrible.   Here are the results of the same pgbench test
> run on the pgpool cluster.
> pgbench -p 9999 -c 20 -t 1000 testdb
> starting vacuum...end.
> transaction type: TPC-B (sort of)
> scaling factor: 1
> number of clients: 20
> number of transactions per client: 1000
> number of transactions actually processed: 20000/20000
> tps = 443.242941 (including connections establishing)
> tps = 443.912381 (excluding connections establishing)
> tps = 401.669441 (excluding connections establishing)
> 
> 
> All four servers have exactly the same hardware configuration.
> 
> Is this performance loss normal?

Yes.

I think existing shared-nothing-synchronous-replication softwares
including PGCluster will show more or less same performance.

I should note that while other such replication softwares show the
performance degration almost propotional to the numbers of PostgreSQL
servers, pgpool's performance is not worse than 1/2 of PostgreSQL.

Also please note that READ query performance will increase according
to the numbers of PostgreSQL servers. So you have a chance to get
performance boost if most of your quries are READ. Of course this may
vary to the characteristics of load though.
--
Tatsuo Ishii
SRA OSS, Inc. Japan