Parallel Queries

"Parallel" queries are queries that are executed in parallel, or at the same time so as to maximize fetching concurrency.

Manual Parallel Queries

When the number of parallel queries does not change, there is no extra effort to use parallel queries. Just use any number of React Query's useQuery and useInfiniteQuery hooks side-by-side!

1 function App () {
2   // The following queries will execute in parallel
3   const usersQuery = useQuery(['users'], fetchUsers)
4   const teamsQuery = useQuery(['teams'], fetchTeams)
5   const projectsQuery = useQuery(['projects'], fetchProjects)
6   ...
7 }

When using React Query in suspense mode, this pattern of parallelism does not work, since the first query would throw a promise internally and would suspend the component before the other queries run. To get around this, you'll either need to use the useQueries hook (which is suggested) or orchestrate your own parallelism with separate components for each useQuery instance (which is lame).

Dynamic Parallel Queries with useQueries

If the number of queries you need to execute is changing from render to render, you cannot use manual querying since that would violate the rules of hooks. Instead, React Query provides a useQueries hook, which you can use to dynamically execute as many queries in parallel as you'd like.

useQueries accepts an options object with a queries key whose value is an array of query objects. It returns an array of query results:

1 function App({ users }) {
2   const userQueries = useQueries({
3     queries: users.map(user => {
4       return {
5         queryKey: ['user', user.id],
6         queryFn: () => fetchUserById(user.id),
7       }
8     })
9   })
10 }