When using memory optimized tables, should the database size not exceed RAM size?

Question

In SQL Server 2016, if we create a database in RAM (i.e using memory optimized tables), the database size should not exceed RAM size, am I right in saying that?

Answer 1

SQL Server 2016 memory-optimized tables require that sufficient memory exist to keep all of the rows and indexes in memory.

• Requirements for Using Memory-Optimized Tables

• Estimate Memory Requirements for Memory-Optimized Tables

The size of a memory-optimized table corresponds to the size of data plus some overhead for row headers. When migrating a disk-based table to memory-optimized, the size of the memory-optimized table will roughly correspond to the size of the clustered index or heap of the original disk-based table.

You wouldn't normally create all your database tables as memory-optimised tables, only those with high throughput/insertion OLTP workloads.

So before you go converting all your tables to memory-optimised tables, first identify those with high activity, convert and then measure any performance increase (and monitor RAM usage).