Dual-Database Design

TrustRAG supports two database backends via Rust feature flags.

PostgreSQL Mode (--features postgres)

Used in server deployments. Provides:

• pgvector for vector similarity search
• pg_trgm for trigram-based text similarity
• Full SQL feature set
• Multi-user concurrent access

SQLite Mode (--features desktop)

Used in desktop self-contained apps. Provides:

• FTS5 for full-text search
• Zero-configuration embedded database
• Single-file storage
• No external dependencies

Compatibility Layer

The db::compat module handles cross-database differences:

Concern	PostgreSQL	SQLite
UUIDs	Native UUID type	TEXT with string parsing
Booleans	true/false	1/0
Timestamps	NOW()	datetime('now')
OFFSET	Standard	Requires explicit syntax
RETURNING	Full support	Limited support

Migration Files

• backend/migrations/ — PostgreSQL migrations (SQLx)
• backend/migrations_sqlite/init.sql — SQLite schema initialization