Using variables destroys performance

[wooque]

Query without variables:

{
  user_news(where: {user_id: {_eq: 1}, status: {_eq: 0}}, limit: 10, order_by: {id: desc}) {
    id
  }
}

Throughput: 3800 req/s

Query with variables:

query($user:Int, $status: Int){
  user_news(where: {user_id: {_eq: $user}, status: {_eq: $status}}, limit: 10, order_by: {id: desc}) {
    id
  }
}

Variables:

{
  "user":1,
  "status":0
}

Throughput: 980 req/s

In more complex example where I first noticed this performance drop it went from ~1500req/s to ~250req/s.

[0x777]

Use non nullable variables. The query plan caching kicks in when all the variables are non-nullable scalars.

query($user:Int!, $status: Int!){
  user_news(where: {user_id: {_eq: $user}, status: {_eq: $status}}, limit: 10, order_by: {id: desc}) {
    id
  }
}

[0x777]

Also, if you can spare more than one core to graphql-engine, you can set GHCRTS environment variable to -N (uses all available cores, you can restrict it by -N<n>, like -N2).

[wooque]

Yep, non nullable variables brought it to 90+% of non variable query performance.
This should really be in documentation because it will byte a lot of people, I didn't even know that variables could be nullable, let alone that there is big difference in performance.

The trick with with GHCRTS also improved performance for quite a bit, I'm surprised it's not default

[0x777]

This should really be in documentation because it will byte a lot of people, I didn't even know that variables could be nullable, let alone that there is big difference in performance.

We'll add this to documentation.

The trick with GHCRTS also improved performance for quite a bit, I'm surprised it's not default

Historical reasons. We'll set it as the default in the next release.

[wooque]

Thanks. I would leave this open as reminder