pgbench on UNLOGGED table(s), Round 2

As one pointed out in a comment in the last post, I have tried additional pgbench runs for "synchronous_commit = off" and "fsync = off".

The results are shown in the right pic.

It shows that "sync_commit = off" and "fsync = off" are almost the same, and these are faster as much as "UNLOGGED", except a tiny behind.

I think the tiny behind means the difference between "sync_commit = off (or fsync = off)" and "UNLOGGED" that the WAL records would be eventually written, or not.

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:

xlogdump 0.5.0 released

Hi, pg folks,

xlogdump is a tool for extracting data from WAL segment files. I'm pleased to announce the latest version of xlogdump, 0.5.0, after a few weeks from the previous release 0.4.0.

I think xlogdump would be helpful to understand PostgreSQL behaviors, and you can enjoy brand-new features in this version, so please try it if you're interested in it.

In this version 0.5.0, xlogdump is able to show not only xlog records itself, but also the statistics of xlog records as the right pic.

xlogdump 0.4.0

I'm pleased to announce the latest release of xlogdump. xlogdump is a tool for extracting data from WAL segment files.

Here is xlogdump README:
https://github.com/snaga/xlogdump/blob/master/README.xlogdump

xlogdump was originally developed by Tom Lane and Diogo Biazus around five years ago, but not be maintained these few years.

PostgreSQL Query Cache - "pqc"

I would like to introduce a new open source software, PostgreSQL Query Cache, which enables to improve query performance extremely (10x~100x) by caching query results in front of backends.

PostgreSQL Query Cache:

• waits connections on the different port from the clients.
• delegates queries in front of the backends, like a proxy.
• intercepts and caches SELECT query results.
• also manages lifecycle of the query cache.