what’s buffer pool in dbms

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it’s a part of DBMS that’s responsible for disk I/O
- i.e., moving data to and from memory and disk
- it decides the content in memory
- it gets pages from disk to memory, and passes a pointer to the data back to high level of dbms (execution engine)
  - it maps page id to RAM address
it also acts as a cache
- frequently accessed data are cached in memory
two things DBMS is optimizing
- spatial control: pages that are often accessed together should be physically stored closer to each other on disks
- temporal control: when to read from disk and when to write back to disks
by implementing its own buffer pool and not relying on OS to manage pages, DBMS gets to decide its own page replacement policy
- i.e., DBMS decides when to evict or flush what pages
- DBMS operates on the concept of transactions, and OS doesn’t know anything about transactions