DB Internals

Storage engines, B-trees, WAL, MVCC

01 Storage Engines How databases actually store data on disk — pages, heaps, and the tradeoffs between read and write optimization. beginner 14 min →
02 B-Trees & Indexes The data structure behind every relational database index — how B-trees keep data sorted and queries fast. beginner 16 min →
03 Write-Ahead Logging (WAL) How databases survive crashes without losing data — the log-first strategy that makes ACID possible. beginner 13 min →
04 MVCC — Multi-Version Concurrency Control How databases let readers and writers work simultaneously without blocking — snapshots, visibility rules, and isolation levels. intermediate 17 min →
05 Query Planning & Execution How the database turns your SQL into an execution plan — parsing, optimization, and why EXPLAIN is your best friend. intermediate 15 min →
06 LSM Trees The write-optimized alternative to B-trees — how RocksDB, Cassandra, and LevelDB handle massive write throughput. intermediate 14 min →
07 Transactions & ACID Atomicity, Consistency, Isolation, Durability — the guarantees that make databases reliable and how they're implemented. intermediate 14 min →
08 Replication & Sharding Scaling databases beyond a single machine — leader-follower replication, consensus, and horizontal partitioning. advanced 18 min →