# QuestDB 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 QuestDB first on the direct prompt; zero named PostgreSQL. Page: https://it-ai-index.com/it-data/time-series-databases/questdb-vs-postgresql/

| | First-choice share | Rank | Negative rate | Labels | Models naming it |
|---|---|---|---|---|---|
| QuestDB | 4% | #4 of 9 | 4% | 57 | 14 of 14 |
| PostgreSQL | 2% | #6 of 9 | 58% | 12 | 10 of 14 |

## The direct prompt, model by model

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

## What the models said about QuestDB

- "QuestDB is strong for time-centric analytics, but it is not the best choice if most of your queries do not filter by time" (Perplexity Sonar, negative prompt, soft negative)
- "QuestDB (SQLi)" (GLM 4.7 FlashX, negative prompt, soft negative)
- "1. QuestDB: A time series database that is designed to handle large amounts of data and provide fast query performance." (Llama 4 Maverick, paraphrase prompt, first choice)
- "specialized TSDBs like InfluxDB, TimescaleDB, or QuestDB are generally safer choices" (Mistral Small, negative prompt, first choice)
- "For new projects in 2026, I'd strongly lean toward QuestDB" (DeepSeek V4 Flash, negative 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.