> ## Documentation Index
> Fetch the complete documentation index at: https://redo-44af351d-docs-v3-graphql-api-reference.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Queries & mutations

> How operations, variables, and query cost work in the v3 API

Every v3 request is a single `POST` carrying a GraphQL document. **Queries**
read data; **mutations** write it.

## Sending an operation

The request body is JSON with a `query` field and optional `variables` and
`operationName`:

```json theme={null}
{
  "query": "query GetProduct($id: ID!) { product(id: $id) { id title sku } }",
  "variables": { "id": "prd_123" }
}
```

The response mirrors the shape you asked for, under `data`:

```json theme={null}
{
  "data": {
    "product": { "id": "prd_123", "title": "Wool Runner", "sku": "WR-9" }
  }
}
```

### Queries

```graphql theme={null}
query {
  productFamilies(first: 5) {
    nodes {
      id
      title
      products(first: 3) {
        nodes {
          id
          sku
          price {
            amount
            currency
          }
        }
      }
    }
  }
}
```

### Mutations

```graphql theme={null}
mutation {
  upsertWebhookEndpoint(
    input: {
      url: "https://example.com/redo-webhooks"
      topics: [product_created, product_updated]
    }
  ) {
    id
    created
    secret
  }
}
```

## Query cost & rate limits

The API uses **query-cost rate limiting**: each request's cost is estimated from
the shape of the query *before* it runs and reserved against your account's
bucket, and every response reports the cost under `extensions.cost`. Requesting
fewer results and fewer fields keeps cost — and latency — low.

See [Rate limiting](/docs/api-reference/v3/rate-limiting) for the cost model,
`throttleStatus`, and how to handle `429` / `THROTTLED` responses.

## Related

* [Rate limiting](/docs/api-reference/v3/rate-limiting) — query cost and
  throttling
* [Pagination](/docs/api-reference/v3/pagination) — paging through connections
* [Errors](/docs/api-reference/v3/errors) — error shapes and codes