MySQL vs PostgreSQL: The Database War for Your VPS

It is the classic dilemma for any System Administrator in 2010: do you go with the ubiquitous speed of the LAMP stack's default database, or do you opt for the strict, academic rigor of the object-relational contender? I see too many developers blindly running apt-get install mysql-server without understanding the architectural debt they are incurring.

When you are scaling an application targeting the Norwegian market, latency and data integrity are the only metrics that matter. A 500ms delay in database query time can ruin the user experience faster than you can say "Request Timed Out." Let’s break down the reality of running MySQL 5.1 versus PostgreSQL 8.4 on a virtualized environment.

The MySQL 5.1 Reality: Speed vs. Locking

MySQL is everywhere. It is the engine behind Facebook and Wikipedia. But out of the box, standard MySQL installations default to the MyISAM storage engine. For read-heavy websites—think blogs or news portals—MyISAM is incredibly fast. It is simple, and it has a small memory footprint.

The Trap: MyISAM uses table-level locking. If you have a long-running write operation (like a user updating their profile or a nightly backup script), MyISAM locks the entire table. No one else can read from it until that write is finished. On a busy e-commerce site, this creates a bottleneck that looks like server lag, but is actually database contention.

If you stick with MySQL, you must look into InnoDB. It supports row-level locking and transactions (ACID compliance). It is heavier on RAM, but essential for concurrency.

# /etc/mysql/my.cnf optimization for 2010 hardware
[mysqld]
# Stop using MyISAM for serious apps
default-storage-engine = InnoDB
# Allocate 70-80% of RAM to this if it's a dedicated DB server
innodb_buffer_pool_size = 512M 
innodb_flush_log_at_trx_commit = 2 # Trade tiny ACID risk for speed

PostgreSQL 8.4: The Tank

PostgreSQL has always been the "serious" choice. With the release of version 8.4 last year, it has become a viable performance competitor too. Postgres uses MVCC (Multi-Version Concurrency Control), which essentially means readers do not block writers, and writers do not block readers.

If your application handles complex data—financial transactions, geospatial data (PostGIS is brilliant), or strictly enforces foreign keys—Postgres is the superior choice. The new Window Functions in 8.4 allow for complex analytics directly in SQL, saving your PHP or Python code from doing heavy lifting.

Pro Tip: Linux handles memory caching differently for Postgres. While MySQL manages its own memory pool, Postgres relies heavily on the OS kernel's file cache. Do not set shared_buffers too high; let the kernel do its job.

The War Story: The "OOM Killer"

I recently audited a client's server hosting a busy forum. They were on a cheap budget VPS from a generic provider. Every day at 3:00 PM, their database crashed.

The culprit wasn't bad code—it was virtualization. They were on an OpenVZ container with "burstable" RAM. When MySQL tried to grab memory during a traffic spike, the host node denied the allocation because the neighbors were noisy. The Linux kernel invoked the OOM (Out of Memory) Killer and terminated the mysqld process to save the system.

This is why at CoolVDS, we strictly use KVM (Kernel-based Virtual Machine) and Xen. When you buy 1GB of RAM on our nodes, that memory is hard-allocated to your kernel. No over-selling, no OOM surprises. For a database, resource isolation isn't a luxury; it's a requirement.

Hardware & I/O: The Bottleneck

Whether you choose MySQL or Postgres, your database is only as fast as your disk I/O. In 2010, the biggest bottleneck is the mechanical latency of spinning hard drives. Seeking data on a fragmented 7.2k RPM drive will kill your "Wait Time."

We configure our storage arrays with high-performance RAID-10 SAS setups. This gives you the redundancy of RAID-1 (mirroring) with the speed of RAID-0 (striping). We are also testing early enterprise SSDs for caching layers, which drastically reduces I/O wait times compared to standard SATA hosting.

Comparison: When to Choose What

Data Sovereignty in Norway

Finally, consider the legal aspect. If you are storing customer data, you are subject to the Personopplysningsloven (Personal Data Act). Hosting your database outside the EEA or in unstable jurisdictions can lead to compliance headaches with Datatilsynet.

CoolVDS servers are located physically in Oslo. This ensures your data stays within Norwegian jurisdiction and, perhaps more importantly, ensures single-digit millisecond latency to the NIX (Norwegian Internet Exchange). If your users are in Norway, your database should be too.

The Verdict

If you are running a standard LAMP stack CMS, tune MySQL 5.1 with InnoDB. If you are building a custom application requiring complex logic and data safety, learn PostgreSQL 8.4.

But regardless of the software, ensure your foundation is solid. Don't let disk I/O or stolen RAM allow your queries to hang. Deploy a KVM-based instance on CoolVDS today and see what dedicated resources do for your query execution times.