Every major database will load the hottest data into RAM, where the scope of "hottest" broadens to whatever amount will fit in RAM. A small percentage of them r

Every major database will load the hottest data into RAM, where the scope of "hottest" broadens to whatever amount will fit in RAM. A small percentage of them require you to confirm how much RAM it can use for this cache. Putting the data on a ramdisk just becomes entirely redundant because it's still going to create a second memory cache that it uses. Many operations do a local cache warming by running the common queries over the database before they it is brought online for processing. As a secondary note, people often under-estimate the size of their data because they don't account for all of the keys, indexes and relationships that also would be memory cached in an ideal situation.