A single SQL database has a limit to the volume of data that it can contain. Throughput is constrained by architectural factors and the number of concurrent connections that it supports.
Elastic pools support horizontal scaling for a SQL database. Using elastic pools, you can partition your data into shards that are spread across multiple SQL databases. You can also add or remove shards as the volume of data that you need to handle grows and shrinks. Elastic pools can also help reduce contention by distributing the load across databases.
https://learn.microsoft.com/en-us/azure/architecture/best-practices/data-partitioning-strategies
