PostgreSQL is a pretty good database, and I enjoy working with it. However, there is an implementation detail that not everyone knows about, which can drastically affect table performance. What is this mysterious feature? I am, of course, referring to foreign keys.
Foreign keys are normally a part of good database design, and for good reason. They inform about entity relationships, and they verify, enforce, and maintain those relationships. Yet all of this comes at a cost that might surprise you.
With the release of PostgreSQL 8.4, the community gained the ability to use CTE syntax. As such, this is a fairly old feature, yet it’s still misunderstood in a lot of ways. At the same time, the query planner has been advancing incrementally since that time. Most recently, PostgreSQL has gained the ability to perform index-only scans, making it possible to fetch results straight from the index, without confirming rows with the table data.
I’ve managed to convince my employer to open source one of the tools I recently wrote. That tool goes by the name of walctl, and I believe the importance of this kind of tool can not be overstated.
The PostgreSQL Write Ahead Log (WAL) files are key to crash recovery, point in time recovery, and all standby use not derived from streaming replication. WAL files are extremely critical to proper database operation.
Another free book giveaway? What, am I running a library here? Well, it turns out Packt liked my review of Instant PostgreSQL Starter so much, they want me host a short period where you can obtain your very own copy for the low, low price of $0.
To those ends, I have a few brand new digital copies comprised of shiny premium electrons ready to dispense to three lucky commenters. Does that sound good?
It occurs to me I forgot to congratulate the winners of the free ebooks. So without further ado:
SAB, who seems to host a nice blog geared toward server administration. Stephan, who’s looking to improve existing strategies. Jeff and his growing PostgreSQL cluster. Pierre, who apparently has an experimental PostgreSQL backend for MySQL. Interesting. Congrats to the winners. But more, I call upon them to pay it forward by contributing to the community, either by corresponding with the excellent PostgreSQL mailing lists, or maybe submitting a patch or two to the code.
