[jira] [Commented] (S2GRAPH-204) Avoid N + 1 queries in GraphQL

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/S2GRAPH-204?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16440530#comment-16440530 ] 

ASF GitHub Bot commented on S2GRAPH-204:
----------------------------------------

GitHub user daewon opened a pull request:

    https://github.com/apache/incubator-s2graph/pull/157

    [S2GRAPH-204] Avoid N + 1 queries in GraphQL

    I removed the part where 'N + 1' queries occur in queries that fetch Vertices and Edges using 'DeferredResolver' provided by sangria framework.
    
    http://sangria-graphql.org/learn/#deferred-value-resolution
    


You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/daewon/incubator-s2graph S2GRAPH-204

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/incubator-s2graph/pull/157.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #157
    
----
commit 69ca2787fb2f863a1c383b55e62798e0cd62b305
Author: daewon <da...@...>
Date:   2018-04-10T10:25:14Z

    resolve n+1 query

----


> Avoid N + 1 queries in GraphQL 
> -------------------------------
>
>                 Key: S2GRAPH-204
>                 URL: https://issues.apache.org/jira/browse/S2GRAPH-204
>             Project: S2Graph
>          Issue Type: Improvement
>          Components: s2graphql
>            Reporter: Daewon Jeong
>            Assignee: Daewon Jeong
>            Priority: Minor
>
> h1. Avoid N + 1 queries in GraphQL
> Let's look at the query below.
> {noformat}
> query {
>   User(id: 1) {
>     name
>     Like(limit: 5) { # fetch edge (has sourceVertex id == 1)      
>       Movie { # fetch vertex every edges, N + 1 query  for fetch vertex info        
>         title        
>       }
>     }
>   }
> }
> {noformat}
> The query retrieves the User(id: 1)'s name and 10 movie titles the user likes.
>  In this case, the query that occurs internally in S2Graph is as follows
>  # Fetch a vertex to resolving the 'name' field (1 IO)
>  # fetch 5 edges to resolving the 'Like' field (1 IO)
>  # fetch 5 vertices for each Edge to resolving the movie 'title' (10 IO)
> Assuming that the Movie ID of the edge returned in step.2 is [e1..e5], the query executed to get Movie title is as follows.
> {noformat}
>   getVertices(e1)
>   getVertices(e2) 
>   getVertices(e3) 
>   getVertices(e4)
>   getVertices(e5)
> {noformat}
> Retrieving every vertices one-by-one would be very inefficient
>  In this case, you can query the Movie Vertex of the edge by collecting 5 IDs without querying each one.
> {noformat}
> ex) getVertices([e1, e2, e3, e4, e5])
> {noformat}
> Which of these two approaches Whether it is more efficient depends on the internal implementation of S2Graph.
> But here we are considering the GraphQL implementation.
> Follow the instructions below to resolve the issue.
> Reference:
>  [http://sangria-graphql.org/learn/#deferred-value-resolution]
>  [https://github.com/sangria-graphql/sangria/issues/63]



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