Postgres on Evan Hoffman

Setting user Postgres passwords via MD5

Wed, 12 Feb 2014 11:06:07 +0000

Say you want to create a Postgres account for a user but you don’t want them to have to reset it after logging in, and you don’t want to do the “come type in a password on my computer” routine. Well, here’s one way around this.

Have the user generate an MD5 of their password on their local computer. Postgres uses the username as the salt for the hash, so the command to generate the md5 on a Mac would be (assuming a username of ’ehoffman’ and a password of ‘abcdefg’):

Goodbye, pg_dump

Thu, 26 Sep 2013 09:12:05 +0000

I’ve been a Postgres user and administrator for a while. Over the years, my views on backups have evolved.

Originally, like most people, I started out with good old pg_dump. With a reasonably small database (under 50 GB) dumping to a flat text file is a fine option. I’d generally do something like pg_dump -Upostgres dbname | gzip > dbname.sql.gz to compress it on the fly and save space. For years this seemed perfect: dumping the entire database in a single transaction into a single file that can be restored anywhere.

Problems with PostgreSQL 9.0 on CentOS 6.3 with a 2.6.32-series kernel

Tue, 25 Sep 2012 13:20:36 +0000

Note: this is cross-posted from the Yodle Tech Blog. We recently migrated our Postgres database to a significantly more powerful machine. While our existing server was doing okay load-wise, we were approaching 90% full on its Postgres volume. We’d also recently acquired an awesome new PureStorage SSD-based SAN and were excited to move our database onto it. For comparison, here are the the specs for the two systems:


	Old server	New server
Nickname	DB1	DB2
CPU	2x 6-core Xeon X5690 CPUs at 3.47GHz	2x 8-core E5-2690 CPUs at 2.90 GHz
Memory	96 GB 1333 MHz	128 GB 1600 MHz
Storage	- Dell PERC H800 SAS HBA - Dell MD1220 drive enclosure - 24x 15k RPM SAS drives configured in RAID 10	- QLogic QLE2562 dual-port 8 Gbit FC HBA - PureStorage SSD-based SAN
OS	CentOS 5.6 x86_64	CentOS 6.3 x86_64
Kernel	2.6.18-238.9.1.el5	2.6.32-279.2.1.el6.x86_64

As you can probably guess, moving from spinning disk onto SSD was the centerpiece of the upgrade. We’d tested the PureStorage system pretty extensively and used it in some secondary databases and seen some amazing improvements. We were excited to see how it would handle our production workload.

Using WAL archiving & Compellent snapshots for PostgreSQL backups

Wed, 13 Jul 2011 13:46:40 +0000

Changing my Postgres DB backup strategy from nightly pg_dumps to WAL archiving with SAN snapshots.

Migrating a PostgreSQL DB to a new machine without doing a dump & restore

Mon, 11 Jul 2011 14:39:16 +0000

rsync over NFS can be so fast.