LumenLearn

Database Systems · intro

Disk-Oriented DBMS Architecture

How a disk-oriented database stores files as pages, maps table rows into slotted pages, and caches pages in a buffer pool.

Data Structures · intro

Array vs Linked List

See contiguous array cells beside pointer-linked nodes — and why random access cost differs.

Database Systems · intro

Pages vs Frames

Map students pages (P1–P4 from the disk lesson) into fixed RAM frames with a page table, pins, and dirty flags — foundation for replacement policies.

Database Systems · intermediate

Tables, Catalog & datadb.db

Click Create users / orders, watch the RAM catalog store first_page_id, inspect the raw datadb.db hex, then Insert through the catalog into the right page.

Database Systems · intermediate

PageGuard, pin & two latches

Vertical 8 KB pages: UPDATE Ava then INSERT Ivy. BPM lock → pin the frame → page lock → mutate slots/tuples → SAVE back to disk.

Database Systems · intermediate

LRU Cache Replacement

Least-recently-used eviction on the students table: recency list, hit→MRU, miss→evict the cold end.

Database Systems · intermediate

MRU Cache Replacement

Most-recently-used eviction: drop the page you just finished. Same students trace, opposite victim of LRU.

Database Systems · advanced

LRU-K Cache Replacement

Track the last K=2 access times. Correlated re-reads of P1 outrank a single scan touch on P5.

Database Systems · intermediate

Clock Cache Replacement

Second-chance CLOCK: a circular hand and one reference bit per frame approximate LRU without sorting.

Database Systems · advanced

2Q Cache Replacement

Two queues: first touch lands in A1in (FIFO); a re-hit promotes to Am (LRU). Scan junk dies in A1in.

Database Systems · advanced

ARC Cache Replacement

Adaptive Replacement Cache: T1 recency, T2 frequency, ghost lists B1/B2, and a moving target p. BusTub P1 family.