Claude Chat and Coding Agents Choose Different Databases
A Reddit user compared 612 database recommendations from Claude Sonnet 5 via the API with 87 Claude Code and Cursor build runs across seven application categories. The agents often selected lower-setup options, choosing SQLite for 93% of new web apps and 92% of full-text-search builds, while chat more often recommended Postgres. The experiment used different models and non-identical prompts, with only 12–15 builds per category, so it does not establish that model choice caused the differences.
The comparison highlights a practical difference between Claude’s chat-style database advice and the choices made by coding agents tasked with getting applications running.
I wanted to know if what Claude recommends in chat matches what coding agents actually do when you let them choose.
Setup
- Chat: 612 answers from Claude Sonnet 5 (API) to questions like “What database should I use for a new web app with users and their data?”
- Builds: 87 runs of Claude Code (Opus 5.5) and Cursor. Each got a real build task for the same use case in a fresh, empty project, with “choose whatever database you think is best”.
- Oct 23 – Nov 3, 2026
Results (chat’s top pick → what the agents built)
| Job | Chat recommends | Agents built |
|---|---|---|
| New web app | Postgres 92% | SQLite 93% |
| Python API | Postgres 92% | SQLite 58%, Postgres 33% |
| Full-text search | Postgres 54%, Elasticsearch 35% | SQLite 92%, Elasticsearch 0% |
| Analytics events | Postgres 61%, ClickHouse 38% | ClickHouse 83% |
| Serverless on Vercel | Neon 33% | Neon 100% |
| Self-hosted | Postgres 96% | Postgres 100% |
| RAG / vectors | Postgres 73% | Postgres 100% |
#Claude#Claude Sonnet 5#Claude Code#Claude Opus 5.5#Cursor#Postgres#SQLite#Elasticsearch#ClickHouse#Neon#Pinecone