1. A method implemented at least in part by a computer, the method comprising: accessing metadata of pages of a database buffer pool, the database buffer pool potentially including pages that are stored in main memory, pages that are stored in solid state memory, and pages that are stored in both main memory and solid state memory; determining, from the metadata, a cold threshold usable to determine whether a page is cold, wherein the page is cold if applying a function to access data represented by the metadata of the page returns a value less than or equal to the cold threshold; determining, from the metadata, a warm threshold usable to determine whether the page is warm, wherein a page is warm if applying the function to the access data of the metadata of the page returns a value greater than the cold threshold and less than or equal to the warm threshold; and evicting a page from the main memory or the solid state memory to free space for one or more other pages.