What is GraphQL
Tech Talk

What is GraphQL?

GraphQL is an open-source query language which is developed by Facebook. It provides us with a more efficient way of executing queries with existing data. GraphQL can optimize RESTful API calls. Basically, it is a replacement for REST. It provides a single endpoint that helps programmers to choose the types of requests they like to make without any versions of the same API.

Why use GraphQL?

The following reasons for using GraphQL:

  • It provides a human-readable query.
  • In GraphQL, it is effortless to deal with many databases.
  • It is suited for microservices and complex systems.
  • Over, and under-fetching problems can be solved using GraphQL.
  • Tailoring requests to your needs.
  • It allows you to discover the schema in the appropriate format.
  • API evolution is possible without versioning.
  • GraphQL fields are used in multiple queries that can be shared to a higher component level for reuse.
  • It can be useful for rapid application prototyping.

Applications of GraphQL

Here are the critical applications of GraphQL:

  • It provides Relay and other client frameworks.
  • GraphQL helps you to enhance the performance of the mobile app.
  • It can reduce the over-fetching problem to lower server-side cloud service and decrease client-side, network usage.
  • We can specify which fields are needed in a long query format in client applications.
  • It can be utilized completely when you have to include functionality to your old or existing API.
  • Using GraphQL, we can simplify a complex API.
  • When you aggregate data from more than one place into one convenient API.
  • You can use it as an abstraction on an existing API to specify the response structure based on user needs.

GraphQL Key Components

graphQL key components

The following are three key components of GraphQL:

 1) Query,

 2) Resolver

3) Schema.


The Query is a request made from the client side. It supports augments and points to arrays. The query is useful for read or fetch values.

Parts of Query:

Following are the important parts of Query


A field is a particular information that we are asking the server.


In GraphQL Every field and nested object can have its own set of arguments, so we can avoid making multiple APIs



Resolvers are a collection of functions that provide directions for converting GraphQL operations into data. It contains the process and s the location to fetch data according to a specific field.


Schemas describe the functionality available to the clients who are connecting to it. GraphQLSchemas can be written in any programming language and build an interface around it

What is Mutation?

A mutation is a way to change the dataset in GraphQL. It alters data in the data store and returns a value. Mutations enable you to insert, update, or remove data. Usually, mutations are defined as a schema part.

Upsert Mutation?

  • Upsert means the combination of Updates and inserts
  • Upsert mutations enable you to perform add or update operations depending on whether a specific ID exists in the database.

mutation upsert

Difference between GraphQL and REST

The following table shows the important difference between GraphQL and REST.

It follows client-driven architecture. It follows server-driven architecture.
Based on schema we can organize GraphQL REST can be formulated in terms of endpoints.
It is a growing community. REST is a very large community.
The development speed  is fast. The development speed in REST is Slow.
The learning curve is difficult. The learning curve in REST is moderate.
The server determines available resources. REST server determines the shape and size of the resources
It provides high consistency across all platforms. It is hard to get stability across all platforms.

Disadvantages of GraphQL

Here are the GraphQL disadvantages:

  • Young ecosystem
  • Lack of resources on the backend part.
  • Missing design pattern for a complex app.
  • Performance issues with complex queries.
  • Overkill for small applications
  • It doesn’t depend on the HTTP caching methods, which enable storing request content.
  • It does not understand files. So no file-uploading feature is also in it.
  • Learning GraphQL is time-consuming. It has a lot of pre-development education like learning the Schema Definition Language.

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