# Ternoa indexer

### Overview⛓️ <a href="#overview" id="overview"></a>

The indexer is an open, flexible, and fast tool based on the [**SubQuery Framework**](https://doc.subquery.network/)**.** It is used to transform blockchain data into a **graphql queryable database**.

#### How it works:

The indexer scans through each block and their events to see what happened on the Ternoa Blockchain. It then parses all that data into entities and inserts it in a Postgres DB. Ternoa deploys its indexer, and anybody can run his own.

> You can get more information on the [**SubQuery official documentation**](https://doc.subquery.network/faqs/faqs.html)

> You can also check out [**our repository**](https://github.com/capsule-corp-ternoa/ternoa-subql) to see how we set up the subquery project to connect to the ternoa blockchain.

#### The most important files are:

* Project.yaml: set up the endpoint, the genesis hash, the types file, and the different filters to get only the specific events / extrinsics needed. We can also filter on the success status of the event / extrinsic.
* Schema.graphql: specifies the custom data we need to record in our Postgres db.
* The Mappings folder: Your mappingHandlers will handle the functions to transform the blockchain data into the needed GraphQL entities contained in the Schema.graphql. More info [here](https://academy.subquery.network/build/mapping/polkadot.html)


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