In general, how much RAM does an in-memory database require? I would assume it requires enough RAM for:
- Operating system and general system services, plus
- DBMS, plus
- the entire database (same amount as stored on disk), plus
- temporary database tables
- some slack
Considering that the largest component of this would normally be the size of the entire database, then it would require the normal size of RAM required to run a regular on-disk database (e.g. 16 GB) plus the on-disk size of the database (let's say 50 GB for a fairly large DB); in this example it would be at least 76 GB plus room for gradual growth of the database.
I know that the answer would be different for different DBMSs (e.g. SAP Hana or Oracle TimesTen), but I am asking about the general components of the calculation.
Is this analysis accurate, or am I missing some important components of the calculation?