ipld-eth-server/documentation/postgraphile.md

Postgraphile

You can expose VulcanizeDB data via Postgraphile. Check out their documentation for the most up-to-date instructions on installing, running, and customizing Postgraphile.

Simple Setup

As of April 30, 2019, you can run Postgraphile pointed at the default vulcanize_public database with the following commands:

npm install -g postgraphile
postgraphile --connection postgres://localhost/vulcanize_public --schema=public,custom --disable-default-mutations

Arguments:

• --connection specifies the database. The above command connects to the default vulcanize_public database defined in the example config.
• --schema defines what schema(s) to expose. The above exposes the public schema (for core VulcanizeDB data) as well as a custom schema (where custom is the name of a schema defined in executed transformers).
• --disable-default-mutations prevents Postgraphile from exposing create, update, and delete operations on your data, which are otherwise enabled by default.

Customizing Postgraphile

By default, Postgraphile will expose queries for all tables defined in your chosen database/schema(s), including filtering and auto-discovered relations.

If you'd like to expose more customized windows into your data, there are some techniques you can apply when writing migrations:

• Computed columns enable you to derive additional fields from types defined in your database. For example, you could write a function to expose a block header's state root over Postgraphile with a computed column - without modifying the public.headers table.
• Custom queries enable you to provide on-demand access to more complex data (e.g. the product of joining and filtering several tables' data based on a passed argument). For example, you could write a custom query to get the block timestamp for every transaction originating from a given address.
• Subscriptions enable you to publish data as it is coming into your database.

The above list is not exhaustive - please see the Postgraphile documentation for a more comprehensive and up-to-date description of available features.