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Version: v2.x

Postgres: Live Query Subscriptions

Introduction

A Live query subscription will return the latest result of the query being made and not necessarily all the individual events leading up to the result, such as with a streaming subscription.

By default, updates are delivered to clients every 1 sec.

A live query is a query that is continuously monitored for changes in the database and automatically updates the query result whenever the underlying data changes. Live queries are a PostgreSQL-specific implementation that allow real-time updates to clients without the need for manual polling or refreshing.

Convert a query to a subscription

You can turn any query into a subscription by simply replacing query with subscription as the operation type.

Single subscription in each query caveat

Hasura follows the GraphQL spec which allows for only one root field in a subscription. You also cannot execute multiple separate subscriptions in one query. To have multiple subscriptions running at the same time they must be in separate queries.

Use cases