User guide3 min read

Embedded SQLite, FTS5 Search & OPFS SAHPool VFS Architecture

Technical specification for embedded SQLite WASM, FTS5 sub-millisecond search across 100,000+ songs, and OPFS SAHPool VFS (Synchronous Access Handle Pool) for zero-latency disk persistence.

1. SQLite WASM & FTS5 Search Engine

SQLite WASM is the world’s most trusted relational database engine compiled into WebAssembly for web browser execution. Combined with FTS5 (Full-Text Search), it enables sub-millisecond keyword searching across massive karaoke song databases (100,000+ tracks) by song code, title, artist, or lyric lines as you type each letter.

OPFS SAHPool VFS (Origin Private File System Synchronous Access Handle Pool)

In Next Karaoke, OPFS (Origin Private File System) is used exclusively as SQLite's virtual file system backend through OPFS SAHPool VFS. The SAHPool architecture pre-allocates synchronous access handles (FileSystemSyncAccessHandle) inside a Dedicated Web Worker. This allows SQLite WASM to read and write database pages and transaction logs directly to physical disk with zero-latency synchronous I/O, preventing database corruption and delivering native C-like database file performance directly inside the browser!

Key Benefits of SQLite WASM + OPFS SAHPool VFS

Search Speed

FTS5 Full-Text Indexing

Instantly searches through 100,000+ karaoke songs in under 1 millisecond. Replaces sluggish in-memory JavaScript array filtering.

Disk Persistence

OPFS SAHPool Synchronous I/O

Uses OPFS SAHPool VFS to provide unbuffered, zero-latency synchronous disk writes for database pages, guaranteeing ACID transaction safety.