Database Load Testing: Realistic Patterns

Load tests that don’t match production traffic are theatre. Realistic test design matters more than the tool.

Why synthetic tests miss

Synthetic loops do uniform queries; production has skew, multiple shapes, transactions, lock contention.

Without realistic shape, tests pass; production fails.

Four-component realistic test

• 1. Mixed query shapes (read/write ratio).
• 2. Realistic data distribution (skew matches production).
• 3. Concurrent transactions (with retries).
• 4. Failure injection (network blips; one node down).

Production-like data shape

Anonymized production dump as test data.

Synthetic data: must reproduce skew patterns; not just volume.

Test cadence

Quarterly: full load test against next-major release.

Pre-deploy: smoke load test for major changes.

Antipatterns

• Uniform synthetic data. Misses hot-key issues.
• Read-only tests. Misses contention.
• Test in dev DB. Wrong scale; wrong data.

What to do this week

Three moves. (1) Apply this pattern to your most-loaded table. (2) Measure query latency / write throughput before/after. (3) Document the win and the constraint so the next refactor inherits the knowledge.