Define a Subgraph
A subgraph defines which data The Graph will index from a blockchain, and how it will store it. Once deployed, it will form a part of a global graph of blockchain data which you can retrieve using GraphQL.
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Define a Subgraph
The subgraph definition consists of a few files:
  • subgraph.yaml: a YAML file containing the subgraph manifest
  • schema.graphql: a GraphQL schema that defines what data is stored for your subgraph, and how to query it via GraphQL
  • AssemblyScript Mappings: AssemblyScript code that translates from the event data to the entities defined in your schema (e.g. mapping.ts in this tutorial)
Before you go into detail about the contents of the manifest file, you need to install the Graph CLI which you will need to build and deploy a subgraph.

The Graph CLI is written in JavaScript, and you will need to install either yarn or npm to use it; it is assumed that you have yarn in what follows.
Once you have yarn, install the Graph CLI by running
Install with yarn:
yarn global add @graphprotocol/graph-cli
Install with npm:
npm install -g @graphprotocol/graph-cli
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