PostgreSQL 8.4 vs MySQL 5.1: The Battle for Your Data Integrity

It is January 2010. The tech world is holding its breath. Oracle is about to finalize its acquisition of Sun Microsystems, and every sysadmin I know in Oslo is asking the same question: "Is MySQL still safe?"

Ignore the FUD (Fear, Uncertainty, and Doubt) for a moment. Whether you are running a high-traffic forum on vBulletin or a mission-critical billing system for a Norwegian telecom, the choice between MySQL and PostgreSQL isn't about politics. It's about architecture. It is about whether you need raw read speed or absolute data consistency when the power grid flickers.

I have spent the last week migrating a client from a crashed MyISAM table to a transactional PostgreSQL setup. Here is the reality: Most VPS providers sell you "burst" RAM that vanishes when you need it most. That kills databases. At CoolVDS, we use strict KVM isolation, but software choice is just as critical. Let's dig into the config files.

The MySQL 5.1 Reality: Speed vs. Safety

MySQL is the engine of the web. It is the 'M' in LAMP. But out of the box, the default configuration in 2010 is frankly dangerous for serious businesses. By default, MySQL still leans heavily on the MyISAM storage engine. MyISAM is fast for reads, but it lacks full transaction support (ACID). If your server crashes during a write, say goodbye to your data integrity.

If you are sticking with MySQL, you must switch to InnoDB. It provides row-level locking and crash recovery. However, the default my.cnf usually ships with a tiny buffer pool.

Crucial MySQL Optimization

Do not leave your innodb_buffer_pool_size at the default 8MB. On a 4GB RAM node from CoolVDS, you should be allocating up to 70% of memory to this if it is a dedicated DB server.

[mysqld]
# The default storage engine should be InnoDB for data safety
default-storage-engine = InnoDB

# Main memory allocation
# CAUTION: Ensure your VPS has enough dedicated RAM. 
# On OpenVZ, this can trigger OOM killers if the host is oversold.
innodb_buffer_pool_size = 2G
innodb_additional_mem_pool_size = 20M

# Log file size - critical for write-heavy loads
innodb_log_file_size = 256M
innodb_log_buffer_size = 8M

# Flush method for Linux
innodb_flush_method = O_DIRECT

Pro Tip: If you are hosting in Norway, remember that latency to the NIX (Norwegian Internet Exchange) is low, but disk I/O is the bottleneck. Using O_DIRECT bypasses the OS cache, sending data straight to the disk controller. This reduces double-buffering but requires high-performance storage subsystems like the RAID-10 SAS arrays we use.

PostgreSQL 8.4: The Strict Professor

While MySQL is loose and fast, PostgreSQL is strict and robust. Version 8.4, released last year, brought massive improvements like Window Functions and Common Table Expressions (CTEs). If you are doing complex analytics or financial calculations compliant with the Norwegian Accounting Act (Bokføringsloven), PostgreSQL is the superior choice.

PostgreSQL does not corrupt data. It just refuses to accept bad data. However, it handles memory differently. It relies heavily on the operating system's file system cache.

Tuning postgresql.conf

The default PostgreSQL config assumes you are running on a machine from 1995. Here is how to wake it up:

# /etc/postgresql/8.4/main/postgresql.conf

# 1/4 of total RAM is a good rule of thumb for shared_buffers
shared_buffers = 1024MB

# This tells the query planner how much RAM is actually available for caching
# Set this to total RAM minus shared_buffers and OS overhead
effective_cache_size = 3GB

# Checkpoints: increasing these reduces I/O spikes
checkpoint_segments = 32
checkpoint_completion_target = 0.9

Feature Comparison: The 2010 Landscape

The Hardware Factor: Why "Cloud" Marketing is Dangerous

You will hear a lot of buzzwords this year about "Cloud Computing." Be careful. Many budget hosts use container-based virtualization (like standard OpenVZ) where all customers share the same kernel. If your neighbor's MySQL process goes rogue, your PostgreSQL latency spikes.

For databases, you need predictable I/O. When a database writes to the Write Ahead Log (WAL), it needs to know that the data hit the platter.

At CoolVDS, we prioritize KVM (Kernel-based Virtual Machine) technology. This gives you a true dedicated kernel. We also deploy on Enterprise 15k RPM SAS drives in RAID-10. While SSDs (Solid State Drives) like the Intel X25-E are starting to enter the enterprise market, they are still prohibitively expensive for mass storage. A tuned RAID-10 SAS array offers the best balance of reliability and speed for 2010 workloads.

Legal Compliance in Norway

We take Datatilsynet (The Norwegian Data Protection Authority) seriously. Under the Personal Data Act, you are responsible for securing user data. Using a database that silently truncates data (looking at you, default MySQL strict mode is off) can lead to data loss incidents.

If you choose MySQL, enable strict mode immediately to ensure you aren't storing partial data strings:

# Add this to my.cnf
sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"

Final Verdict

• Choose MySQL 5.1 if you are running a standard CMS like WordPress or Joomla, need simple replication, and your workload is 90% reads.
• Choose PostgreSQL 8.4 if you are building a custom application, need complex joins, GIS data (PostGIS), or cannot afford to lose a single transaction.

Whichever engine you choose, the platform underneath dictates your uptime. Don't let shared kernel resource contention kill your queries. Deploy your database on a KVM-backed VPS where resources are guaranteed.

Need a test environment? Spin up a CoolVDS instance in Oslo today and benchmark your queries on true dedicated resources.