SQLite At The Edge: Single-File SQL Without A Server Process

**SQLite** is a self-contained, serverless SQL engine in a library. The database is a file (or memory image). Documentation on `sqlite.org` is exceptionally thorough, including query planner internals.

**WAL** (write-ahead logging) mode improves concurrent readers during writes. Still, SQLite suits **read-heavy** or **single-writer** patterns; many concurrent writers need a client/server RDBMS.

Valid uses: mobile app local store, browser WASM builds (sql.js), edge workers with embedded replicas, test fixtures. Invalid use: high-write multi-tenant SaaS primary database at large scale without careful sharding.

Enable foreign keys (`PRAGMA foreign_keys=ON`), run migrations explicitly, and backup files atomically. SQLite is public domain software.