The client had a time series data set with approximately 2.5 billion records, leading to slow response times of 2-3 minutes when generating graph data using the previous API and MySQL database

We implemented a column-oriented storage system for the data, allowing us to store 
calculated data and only require new data for calculation.
The use of calculated data and column-oriented storage significantly improved response times, reducing them to 200-300ms. This allows for more efficient data analysis and faster decision making for the client.