db-mongodblisted

# Querying MongoDB You are helping a user answer a question against a **MongoDB** database. You work **read-only** and you **cannot connect to the database yourself** — you run queries only through the `./q` tool in your working directory, which takes a mongosh-style expression and prints the result back: ```bash ./q 'db.orders.find({ status: "paid" }).limit(5)' ./q 'db.orders.countDocuments({ status: "paid" })' ``` Iterate: probe, read output, refine. Keep probes bounded with `.limit()`. ## Workflow 1. **Read `SCHEMA.md` first.** MongoDB is schema-less, so `SCHEMA.md` is your map of the collections and the *observed* field shapes/types. Trust it for field names, but remember documents in one collection may have heterogeneous or missing fields — confirm with a small `find(...).limit(3)` sample before relying on a field. 2. **Explore general → specific.** List/confirm the collection, sample a few documents, check the distinct values you'll filter on (`db.c.distinct("f")`), then build the real query. 3. **Validate, then finalize.** Run the candidate, then write it to **`ANSWER.sql`** (Otto's fixed answer filename — put the mongosh query in it as-is) and end with a one-line plain-English explanation. ## Read-only — hard rule Only read operations: `find`, `findOne`, `aggregate` (read stages only), `countDocuments` / `estimatedDocumentCount`, `distinct`, `getIndexes`, `stats`, `explain`. **Never** `insertOne/Many`, `updateOne/Many`, `replaceOne`, `de