# MongoDB vs PostgreSQL: which do AI models recommend for nosql, October 2026

IT AI Recommendation Index, October 2026 Edition, NoSQL databases. Fourteen of fourteen models named MongoDB first on the direct prompt; zero named PostgreSQL. Page: https://it-ai-index.com/it-data/nosql-databases/mongodb-vs-postgresql/

| | First-choice share | Rank | Negative rate | Labels | Models naming it |
|---|---|---|---|---|---|
| MongoDB | 74% | #1 of 13 | 13% | 82 | 14 of 14 |
| PostgreSQL | 2% | #6 of 13 | 0% | 11 | 9 of 14 |

## The direct prompt, model by model

- Claude Haiku 4.5: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, Google Cloud Firestore, PostgreSQL with JSON)
- GPT-5.4 mini: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, Apache Cassandra)
- Gemini 3.5 Flash: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, Couchbase)
- Perplexity Sonar: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, Azure Cosmos DB)
- Grok 4.1 Fast: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, Apache Cassandra)
- Mistral Small: mongodb first (first choices: Amazon DynamoDB, MongoDB) (alternatives: Azure Cosmos DB, Redis)
- DeepSeek V4 Flash: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, PostgreSQL)
- Llama 4 Maverick: mongodb first (first choices: MongoDB)
- Qwen 3.7 Flash: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, Neo4j, PostgreSQL)
- Kimi K2: mongodb first (first choices: MongoDB) (alternatives: Couchbase)
- GLM 4.7 FlashX: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, Apache Cassandra, Couchbase)
- MiniMax M2.5: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, Couchbase)
- GPT-6 Luna: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB, PostgreSQL)
- Muse Glimmer 30B: mongodb first (first choices: MongoDB) (alternatives: Amazon DynamoDB)

## What the models said about MongoDB

- "MongoDB's own docs warn that sharded clusters require careful planning and that poor shard-key choice can hurt scalability and performance." (GPT-5.4 mini, negative prompt, soft negative)
- "The most popular document database and production-ready, but with a long history of internet-exposed instances and NoSQL injection risk." (Muse Glimmer 30B, negative prompt, soft negative)
- "If you need a quick start with flexible JSON documents and strong consistency: MongoDB Community Edition self-hosted, or Atlas Free/Flex for a managed free tier." (Muse Glimmer 30B, budget prompt, first choice)
- "Often the default choice for B2B applications... For most mid-market B2B companies without extreme scale requirements, MongoDB ... are safe bets." (Claude Haiku 4.5, direct prompt, first choice)
- "MongoDB Community Edition is often considered the most popular choice for budget-conscious companies due to its balance of features and ease of use." (Claude Haiku 4.5, budget prompt, first choice)

## What the models said about PostgreSQL

- "Before choosing any NoSQL database, ask yourself: "Why can't I use PostgreSQL?"" (Gemini 3.5 Flash, negative prompt, first choice)
- "If your data is highly normalized and relational ... stick to Postgres." (Qwen 3.7 Flash, scale prompt, first choice)
- "modern trends suggest looking at PostgreSQL (specifically with JSONB) as the ultimate hybrid solution" (Qwen 3.7 Flash, direct prompt, alternative)

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.