Citus 在我的测试环境中没有横向扩展

Question

I have setup a Citus environment: (Citus 7.2.2, Postgres 10.12) 1) 1x coordinator node 2) 5x worker nodes 3) (2GB mem and 2cores VM's for each of the 6 nodes)

I used pgbench with built-in sql (eg simple-update, select-only, tpc-b). As I added worker nodes from one to 5 the tps only increase about less than 1-10% (depends on # of client and WAL on hdd or ssd).

When benchmarking with SELECT, the coordinator VM load can go up to 60+, with other 2 type of SQL the load is only 2 or so. The worker nodes load always about 1 and disk io is between 500 and 2000 io/sec

Does this result sound right? Anything I can do to improve the performance?

Thanks, David

Answer 1

For a scale factor of 1 the tables will have:

table                   # of rows
---------------------------------
pgbench_branches        1
pgbench_tellers         10
pgbench_accounts        100000
pgbench_history         0

https://www.postgresql.org/docs/current/pgbench.html

So scaling factor 30 will have 3M rows in pgbench_accounts, which will probably fit into memory of a single node as suggested by jjanes.

And you have 5 worker nodes so you can definitely increase the scaling factor much more. When the data doesn't fit to a memory of a single node, you should see the difference with citus.