grdb

Direct SQLite access using GRDB.swift - type-safe Swift wrapper with full SQLite power when you need it.

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Install skill "grdb" with this command: npx skills add johnrogers/claude-swift-engineering/johnrogers-claude-swift-engineering-grdb

GRDB

Direct SQLite access using GRDB.swift - type-safe Swift wrapper with full SQLite power when you need it.

Reference Loading Guide

ALWAYS load reference files if there is even a small chance the content may be required. It's better to have the context than to miss a pattern or make a mistake.

Reference Load When

Getting Started Setting up DatabaseQueue or DatabasePool

Queries Writing raw SQL, Record types, type-safe queries

Value Observation Reactive queries, SwiftUI integration

Migrations DatabaseMigrator, schema evolution

Performance EXPLAIN QUERY PLAN, indexing, profiling

When to Use GRDB vs SQLiteData

Scenario Use

Type-safe @Table models SQLiteData

CloudKit sync needed SQLiteData

Complex joins (4+ tables) GRDB

Window functions (ROW_NUMBER, RANK) GRDB

Performance-critical raw SQL GRDB

Reactive queries (ValueObservation) GRDB

Core Workflow

  • Choose DatabaseQueue (single connection) or DatabasePool (concurrent reads)

  • Define migrations with DatabaseMigrator

  • Create Record types (Codable, FetchableRecord, PersistableRecord)

  • Write queries with raw SQL or QueryInterface

  • Use ValueObservation for reactive updates

Requirements

  • iOS 13+, macOS 10.15+

  • Swift 5.7+

  • GRDB.swift 6.0+

Common Mistakes

Performance assumptions without EXPLAIN PLAN — Assuming your query is fast or slow without checking EXPLAIN QUERY PLAN is guessing. Always profile queries with EXPLAIN before optimizing.

Missing indexes on WHERE clauses — Queries filtering on non-indexed columns scan the entire table. Index any column used in WHERE, JOIN, or ORDER BY clauses for large tables.

Improper migration ordering — Running migrations out of order or skipping intermediate versions breaks schema consistency. Always apply migrations sequentially; never jump versions.

Record conformance shortcuts — Not conforming Record types to PersistableRecord or FetchableRecord correctly leads to silent data loss or deserialization failures. Always implement all required protocols correctly.

ValueObservation without proper cleanup — Forgetting to cancel ValueObservation when views disappear causes memory leaks and stale data subscriptions. Store the cancellable and clean up in deinit.

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