SQLite vs PostgreSQL (LLM Mock Stress Comparison)

This page summarizes the LLM mock stress test comparison for EchoCenter.

The stress tooling itself is maintained in branch:

• chore/mock-llm-loadtest

Run command:

git checkout chore/mock-llm-loadtest
make stress-llm

Test Profile

• STRESS_REQUESTS=1000
• STRESS_CONCURRENCY=20
• STRESS_TIMEOUT=20s
• MOCK_MODE LLM delay: 800ms

Summary

SQLite

• throughput=24.31 req/s
• p50=811.6ms, p95=869.4ms, p99=876.7ms
• Under concurrent writes, logs showed many SQLITE_BUSY and persist-failure signals.

Local PostgreSQL

• throughput=24.34 req/s
• p50=815.6ms, p95=858.2ms, p99=872.2ms
• No corresponding DB lock/persist-failure signals in this run.

Conclusion

• In this mock setup, latency/throughput are both dominated by the 800ms LLM delay, so raw performance is close.
• Reliability under concurrent writes is better with PostgreSQL.
• Recommendation: prefer PostgreSQL for stress/production paths, use SQLite mainly for lightweight local development.