Ultimate Database Engineering

Engine-agnostic principles first. For engine-specific patterns, indexes, and operational details see the reference/ files.

Reference files

Engine	File	When to read
PostgreSQL	reference/postgresql.md	SQL, MVCC, JSONB, FTS, RLS, replication, pooling, extensions
MySQL	reference/mysql.md	InnoDB, charset, fulltext, replication
MongoDB	reference/mongodb.md	Document modeling, aggregation, Atlas
ClickHouse	reference/clickhouse.md	OLAP, MergeTree engines, insert strategy
Redis	reference/redis.md	Caching, pub/sub, streams, data structures
SQLite	reference/sqlite.md	Embedded, WAL, local-first applications
DuckDB	reference/duckdb.md	In-process OLAP, Parquet, analytics

Read the relevant reference file before making engine-specific decisions. Always check docs for the exact version in use.