Data architecture planning is a key step in custom web app development.. It involves understanding the data requirements of the application, evaluating existing data structures and designing an architecture that is secure, efficient, and effective. When it comes to data architecture planning, we first evaluate the data requirements of the custom web application. This includes understanding the types of data that will be used, the structure of the data, and the relationships between different data elements. We then evaluate existing data structures and determine if they are suitable for the application. If they are not suitable, we then design an architecture that meets the requirements of the application. When designing an architecture, we consider different factors such as scalability, security, maintainability, and performance. We use proven design patterns and best practices to ensure that the architecture is secure and efficient. We also take into account the specific needs of the custom web application and use appropriate data technologies to ensure that the application performs optimally. We also consider the different ways that data can be stored, retrieved, and managed. This includes determining when data should be fetched from a database, when it should be cached, and when it should be stored in a file system. We then design the data architecture to ensure that data is stored and accessed by the custom web application in the most efficient way.