how to avoid n + 1 query

[wangfeipeng]

my data struct like this：
{
"data": {
"customers": [{
"customerProfile": {
"nickName": "1"
},
"id": 1,
"sex": 0,
"status": 1,
"type": 1
}, {
"customerProfile": {
"nickName": "12"
},
"id": 12,
"sex": 0,
"status": 1,
"type": 0
}]
}
}
it's a list of customer , but I need to query N times to get the customerProfile like this:

it will be bad when N is a big num , how to avoid this problem

[sfriedel]

Hi @wangfeipeng,

in the JS world you'd probably use Facebook's dataloader library. Although there are at least 2 implementations of a similar library in Golang, it would not be of much use since in graphql-go all fields are resolved sequentially.

There is a PR for parallel field resolution but the current state of it is somewhat unclear. See #213

[gburt]

I believe this issue is a duplicate of #106

[danielspk]

Parallel queries to the database does not solve the problem n + 1.
It is necessary to defer resolvers in order execute SQL queries with IN operator. Example: SELECT * FROM posts WHERE user_id IN (?).

Any suggestions?

[chris-ramon]

Parallel queries to the database does not solve the problem n + 1.
It is necessary to defer resolvers in order execute SQL queries with IN operator. Example: SELECT * FROM posts WHERE user_id IN (?).

Any suggestions?

Hi @danielspk, thanks for reaching us for a question, that's correct parallel/concurrent queries doesn't solve the n + 1 problem, but parallel/concurrent resolvers + a batching library like dataloader does, you might want to take a look to this two working examples that solves the n + 1 query problem:

• https://gist.github.com/chris-ramon/e90e245ae79d664ec2f22e4c5682ea3b
• https://github.com/graphql-go/graphql-dataloader-example

[chris-ramon]

closing this one since was addressed via: #389

[limianwang]

@chris-ramon Thanks for you example. I am wondering (not sure if this is the right place) how would we pass the graphQLArgs to the dataloader? For example, if i wanted to get a list of customers with a limit.

query search() {
   users {
      customers(limit: 10) {
           name
      }
   }
}