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Dgraph DQL Tour

Schema

Adding schema - mutating schema

As we saw in an earlier lesson, Dgraph stores a schema describing the types of predicates.

When we want to add new data to an existing schema, we can just add it. But if we want to add new data in a new schema we have two choices

  • Add the data and let Dgraph work out the schema, or
  • Specify a schema and then add the data

Dgraph can work out the schema just fine. Functions at query root can only be applied to indexed predicates and for that we need to specify the schema. Comparison functions at the query root level (aka func:) can only be applied on indexed predicates, which are added by annotating the predicate definition on the schema. Since v1.2, comparison functions can now be used on @filter directives even on predicates that have not been indexed.

Alter schema to define data types and to add indexes.

Run to alter schema. The index allows applying filter functions, such as searching for all companies that participate in a particular industry.

Dgraph DQL Tour

An interactive tutorial with real queries and real results, designed to run on Chrome on your machine.

Modules

. GraphQL Introduction . GraphQL Basic Features . GraphQL Schema . GraphQL Search . GraphQL Data and More Data . DQL Introduction . DQL Basic Features . DQL Schema . DQL Data and More Data . DQL Query Blocks and Variables . DQL Search

DQL Schema

This module shows you how schemas work inside Dgraph; and how to add, update, and delete data.

Module Breakdown

3.1. Adding schema - mutating schema 3.2. Adding Data - mutating data 3.3. External Identifiers 3.4. Language Support 3.5. Reverse edges 3.6. Reverse edges Query 3.7. Exercise : Integrating existing data 3.8. Deleting Data 3.9. Expand Predicate 3.10. Congratulations
Endpoint: /alter
Dgraph: http://localhost:8080
Reset Run
Response

3.1 Adding schema - mutating schema