pgbench on UNLOGGED table(s)

To satisfy my curiosity, I just tried a quick run for pgbench with UNLOGGED tables.

Under the pgbench transaction model, a kind of tpc-b, changing the history table attribute to "UNLOGGED" did not contribute to the performance.

However, changing all tables to "UNLOGGED" improved the performance *substantially*. :)

The results shown in the right image are averages of running pgbench 10 times each.

Here is the steps to make this test:

• Start PostgreSQL 9.1.
• Create `testdb' to run a regular pgbench.
• Dump schemas with `pg_dump --schema-only testdb' into a schema file.
• Dump data with `pg_dump --data-only testdb' into a data file.
• Edit the schema file, by hands, to create the UNLOGGED table(s).
• Create another database `testdb_nologged'.
• Import the schemas with using the schema file into `testdb_nologged'.
• Import the data with using the data file into `testdb_nologged'.
• Run pgbench against `testdb' and 'testdb_nologged'.

In addition, this test was executed on the following server:

• NEC Express5800/GT110b
• Dual Core Celeron @ 2.27GHz
• Physical Memory 12GB
• WDC WD1602ABYS-19B7A0 (SATA)
• Red Hat Enterprise Linux 6.0

and with the following PostgreSQL configuration:

• Shared Buffers : 2048MB
• Checkpoint Segments : 32
• WAL Buffers : 1024kB
• Pgbench: Scale factor 10, 1,000 Transactions * 32 Clients

That's all. Thanks for reading! I need to back to work! :)