# Prometheus vs PostgreSQL: which do AI models recommend for time series dbs, October 2026

IT AI Recommendation Index, October 2026 Edition, Time series databases. Zero of fourteen models named Prometheus first on the direct prompt; zero named PostgreSQL. Page: https://it-ai-index.com/it-data/time-series-databases/prometheus-vs-postgresql/

| | First-choice share | Rank | Negative rate | Labels | Models naming it |
|---|---|---|---|---|---|
| Prometheus | 2% | #5 of 9 | 19% | 43 | 14 of 14 |
| PostgreSQL | 2% | #6 of 9 | 58% | 12 | 10 of 14 |

## The direct prompt, model by model

- Claude Haiku 4.5: neither first, one named (first choices: InfluxDB, TimescaleDB) (alternatives: Prometheus)
- GPT-6 Luna: neither first, one named (first choices: TimescaleDB) (alternatives: ClickHouse Cloud, InfluxDB, Prometheus)
- GPT-5.4 mini: neither named (first choices: TimescaleDB) (alternatives: ClickHouse Cloud, InfluxDB, QuestDB)
- Gemini 3.5 Flash: neither named (first choices: TimescaleDB) (alternatives: ClickHouse Cloud, InfluxDB)
- Perplexity Sonar: neither named (first choices: TimescaleDB) (alternatives: Amazon Timestream, InfluxDB, QuestDB)
- Grok 4.1 Fast: neither named (first choices: InfluxDB) (alternatives: ClickHouse Cloud, TimescaleDB)
- Mistral Small: neither named (first choices: TimescaleDB) (alternatives: InfluxDB, QuestDB)
- DeepSeek V4 Flash: neither named (first choices: TimescaleDB) (alternatives: ClickHouse Cloud, InfluxDB, QuestDB)
- Llama 4 Maverick: neither named
- Qwen 3.7 Flash: neither named (first choices: TimescaleDB) (alternatives: InfluxDB, QuestDB)
- Kimi K2: neither named (first choices: TimescaleDB) (alternatives: InfluxDB, QuestDB)
- GLM 4.7 FlashX: neither named (first choices: TimescaleDB) (alternatives: ClickHouse Cloud, QuestDB)
- MiniMax M2.5: neither named (first choices: InfluxDB, TimescaleDB) (alternatives: Amazon Timestream, QuestDB)
- Muse Glimmer 30B: neither named (first choices: TimescaleDB) (alternatives: InfluxDB, QuestDB)

## What the models said about Prometheus

- "Prometheus local storage as your only durable, highly available store. ... its local TSDB isn't clustered or replicated." (GPT-6 Luna, negative prompt, soft negative)
- "Prometheus is by default free to use... Prometheus is an excellent choice as a powerful open-source monitoring and alerting toolkit." (Claude Haiku 4.5, budget prompt, first choice)

## What the models said about PostgreSQL

- "they are not optimized for large volumes... making them poor choices for serious time series workloads" (Mistral Small, negative prompt, hard negative)
- "PostgreSQL, MySQL, and SQL Server are fine for *small-scale* time-series workloads, but ... they become a poor fit as ingest volume, retention, and query complexity grow." (Perplexity Sonar, negative prompt, soft negative)
- "General-purpose databases like PostgreSQL or MySQL can handle time-series workloads at small scale, but performance degrades" (Claude Haiku 4.5, negative prompt, soft negative)
- "Start with PostgreSQL + TimescaleDB if your scale is modest. It minimizes new tooling and hiring complexity." (GPT-5.4 mini, budget prompt, first choice)

Share is the count of first choices across the direct, paraphrase, budget and scale prompts over all fourteen models, for a mid-market B2B company; rank is within the category. Comparisons are drawn for the top eight products in each category. Published under CC BY 4.0; the output is the models' output, and nothing here is a recommendation by the index.