Global query client with SSR

[amuttsch]

Hi,

when using next.js SSR with react-query a global queryClient is created. This client get hydrated during server side rendering with the data provided from getInitialProps or getServerSideProps. If we have a secured endpoint (e.g. account information) that is indistinguishable between users from a query key perspective (users are separated by a session cookie) and two users now simultaneously access the account page. The SSR fetches the correct data and then hydrates the global query client. Could it be that then the client has only one of the account data in the cache and the SSR renders the same data for both users?

Would setting the cacheTime to 0 make a difference? (Once #1442 got released)

Or is this a bad practice and we should add a unique user identifier to the query key?

According to the docs it's ok to use a global client: https://react-query.tanstack.com/guides/ssr#using-hydration

Thanks!