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docs/guides/query-batching.md

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+---
+title: Query Batching
+---
+
+# Query Batching
+
+Query batching is a feature in Strawberry GraphQL that allows clients to send
+multiple queries, mutations, or a combination of both in a single HTTP request.
+This can help optimize network usage and improve performance for applications
+that make frequent GraphQL requests.
+
+This document explains how to enable query batching, its configuration options,
+and how to integrate it into your application with an example using FastAPI.
+
+---
+
+## Enabling Query Batching
+
+To enable query batching in Strawberry, you need to configure the
+`StrawberryConfig` when defining your GraphQL schema. The batching configuration
+is provided as a dictionary with the key `enabled`:
+
+```python
+from strawberry.schema.config import StrawberryConfig
+
+config = StrawberryConfig(batching_config={"enabled": True})
+```
+
+When batching is enabled, the server can handle a list of operations
+(queries/mutations) in a single request and return a list of responses.
+
+## Example Integration with FastAPI
+
+Query Batching is supported on all Strawberry GraphQL framework integrations.
+Below is an example of how to enable query batching in a FastAPI application:
+
+```python
+import strawberry
+from fastapi import FastAPI
+from strawberry.fastapi import GraphQLRouter
+from strawberry.schema.config import StrawberryConfig
+
+
+@strawberry.type
+class Query:
+    @strawberry.field
+    def hello(self) -> str:
+        return "Hello World"
+
+
+schema = strawberry.Schema(
+    Query, config=StrawberryConfig(batching_config={"enabled": True})
+)
+
+graphql_app = GraphQLRouter(schema)
+
+app = FastAPI()
+app.include_router(graphql_app, prefix="/graphql")
+```
+
+### Running the Application
+
+1.Save the code in a file (e.g., app.py). 2. Start the FastAPI server:
+`bash     uvicorn app:app --reload     ` 3.The GraphQL endpoint will be
+available at http://127.0.0.1:8000/graphql.
+
+### Testing Query Batching
+
+You can test query batching by sending a single HTTP request with multiple
+GraphQL operations. For example:
+
+#### Request
+
+```bash
+curl -X POST -H "Content-Type: application/json" \
+-d '[{"query": "{ hello }"}, {"query": "{ hello }"}]' \
+http://127.0.0.1:8000/graphql
+```
+
+#### Response
+
+```json
+[{ "data": { "hello": "Hello World" } }, { "data": { "hello": "Hello World" } }]
+```
+
+### Error Handling
+
+#### Batching Disabled
+
+If batching is not enabled in the server configuration and a batch request is
+sent, the server will respond with a 400 status code and an error message:
+
+```json
+{
+  "error": "Batching is not enabled"
+}
+```
+
+#### Too Many Operations
+
+If the number of operations in a batch exceeds the max_operations limit, the
+server will return a 400 status code and an error message:
+
+```json
+{
+  "error": "Too many operations"
+}
+```
+
+### Limitations
+
+#### Multipart Subscriptions:
+
+Query batching does not support multipart subscriptions. Attempting to batch
+such operations will result in a 400 error with a relevant message.
+
+### Additional Notes
+
+Query batching is particularly useful for clients that need to perform multiple
+operations simultaneously, reducing the overhead of multiple HTTP requests.
+Ensure your client library supports query batching before enabling it on the
+server.