Data aggregation

[arif-hanif]

@PascalSenn started the proposal, we can discuss spec here.
#924

Who all is interested in data aggregation for different data sources?
Entity Framework
MongoDb
Neo4j

Aggregations

This proposal is very Work In Progress

Introduction

Aggregations are very useful for querying big data sources. To count items or sum a value, it's not necessary to load all the data. Querying already aggregated data in the backend has less overhead.

Proposal

A new API Endpoint is generated for a collection. The type of this endpoint has different aggregation fields on them.

It will not be possible to cover all aggregation cases. We simply cannot create types for all possible scenarios.

Proposed are the following:

Example Objects

All examples will take place in the following domain:

public class Foo {
     public string role {get;set;}
     public int num {get;set;}
     public Bar bars {get;set;}
}

public class Bar {
     public string baz {get;set;}
     public int blub {get;set;}
}

count

{
  foosMeta {
    count
}

returns the amount of foo's in foos.

sum

{
  foosMeta {
    sum_num
}

returns the sum of all nums.

average

{
  foosMeta {
    sum_average
}

returns the average of all nums.

group_by

Example

{
  foosMeta {
    group_by {
      role {
        key
        value {
          bar {
            baz
          }
        }
      }
    }
  }
}

How others did it

Prisma (Issue prisma/prisma#1312)

# Count all posts with a title containing 'GraphQL'
query {
  postsConnection(where: {
    title_contains: "GraphQL"
  }) {
    aggregate {
      count
    }
  }
}
{
  allUsersConnection(where: {city: "Aarhus"}) {
    aggregate {
      avg {
        age
      }
      max {
        age
      }
    }
    edges {
      node { name, age }
    }
  }
}
{
  allUsersConnection(where: {city: "Aarhus"}) {
    aggregate {
      avg {
        age
      }
      max {
        age
      }
    }
    edges {
      node { name, age }
    }
  }
}

Horsura

query {
  article_aggregate {
    aggregate {
      count
      sum {
        rating
      }
      avg {
        rating
      }
      max {
        rating
      }
    }
    nodes {
      id
      title
      rating
    }
  }
}
query {
  author (where: {id: {_eq: 1}}) {
    id
    name
    articles_aggregate {
      aggregate {
        count
        avg {
          rating
        }
        max {
          rating
        }
      }
      nodes {
        id
        title
        rating
      }
    }
  }
}

Gatsby

### no example found

GraphCMS

### no example found

[michaelstaib]

I think we should follow Prisma and aggregate on the connection.

[michaelstaib]

This essentially would work with both the offset paging and the cursor paging.

[twilly86]

I want the aggregate to sum on all records outside paging. Would this be possible? So if I have page limit 10 and 1000 records the count would be 1000

[a5ter0id]

@michaelstaib

1. Could you tell us the upcoming plan or maybe the release date of the aggregation/grouping functionality?
2. Do you have a source code (alpha version) that implements this functionality. Maybe we can cooperate/collaborate and develop it together?

[MaheshB0ngani]

This is all I am waiting for. Do you have any roadmap for this. If there is any initial work done on this please share the branch details so that we can understand the details and complexity, thus we can also contribute parallelly.

This is what I am looking for link

[mu-dawood]

any update on that

[a5ter0id]

I see that the plan is 2022
https://github.com/ChilliCream/hotchocolate/projects/28#card-55772065

but I am not sure that something will happen this year
because this date is updated several times and no progress yet

[michaelstaib]

It's in the 2022 backlog, which does not mean it will be pulled. At the moment we are focusing on papercuts and schema-stitching.

[aaron-manning]

This feature is pretty vital to bridge the feature gap between HC and hasura / postgraphile.

[M2xAy]

Hi Community
When will you release aggregation on nodes?
Best regards

[ramagott]

Hi @michaelstaib

We are also planning to use this data aggregation feature in our service. Is there any update on the timeline?

[andreamorello93]

hi @michaelstaib any update on this?