Managing Data Freshness and Performance in React Query with CacheTime

React Query's cache time setting is a powerful feature that controls how long unused data remains in the cache before being garbage collected. This optimizes app performance by reducing the number of requests to the server, while also ensuring that the data displayed to the user is as fresh as possible.

What is cache time?

The cacheTime option in React Query specifies the duration (in milliseconds) that cached data should remain in memory after all of the instances of useQuery that are using it have been unmounted. The default value is 5 minutes (300000 milliseconds). This means that if the data is not used (i.e., not displayed on the UI) for this duration, React Query will remove it from the cache.

import { useQuery } from 'react-query';

const fetchData = async () => {
  const response = await fetch('<https://api.example.com/data>');
  if (!response.ok) {
    throw new Error('Network response was not ok');
  }
  return response.json();
};

function App() {
  const { data, isError, isLoading } = useQuery('dataKey', fetchData, {
    cacheTime: 1000 * 60 * 5, // 5 minutes
  });

  if (isLoading) return <div>Loading...</div>;
  if (isError) return <div>Error fetching data</div>;

  return (
    <div>
      {/* Render your data here */}
    </div>
  );
}

How to adjust cache time for better performance?

Adjusting the cacheTime can significantly impact your application's performance and the freshness of the data that’s being presented. A shorter cacheTime means that data will be fetched more frequently, ensuring that the data is up-to-date but potentially increasing the load on your server. A longer cacheTime reduces the number of requests to the server but might result in stale data being shown to the user.

When to adjust cache time

• Increase cache time for data that changes infrequently. This reduces the number of network requests, which can improve performance for both the client and the server.
• Decrease cache time for data that changes frequently or for data that is critical to be as up-to-date as possible. This ensures that the user always sees the most current data at the expense of more frequent network requests.

React Query's flexible cache control mechanisms, including cacheTime, offer developers fine-grained control over how data is cached and managed within their applications. By tuning these settings, developers can strike the right balance between minimizing server load and providing a responsive, up-to-date user experience.