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💪 Introduction

The core declarative_sqlite library is the powerhouse of the ecosystem. It contains all the essential tools for defining your schema, managing migrations, querying data, and handling Last-Writer-Wins conflict resolution.

This section provides a deep dive into the advanced features of the core library.

🎯 Key Feature Areas​

🔍 Querying​

  • Query Builder: A fluent, type-safe API for constructing complex SQL queries. It supports SELECT, JOIN, WHERE, GROUP BY, ORDER BY, and more, reducing the risk of syntax errors.
  • Streaming Queries: The foundation for building reactive applications. These queries return a StreamingQuery that automatically emits a new list of results whenever the underlying data changes. The library performs sophisticated dependency analysis to ensure that streams are only updated when relevant data is modified.

📊 Data Modeling​

  • DbRecord and Code Generation: A pattern for creating typed data models that map directly to your database tables. The declarative_sqlite_generator package can be used to automatically generate typed getters for all columns and setters for LWW columns, eliminating boilerplate and improving code safety.
  • File Management: A robust system for associating files with your database records. The fileset column type allows you to manage collections of files, with built-in support for adding, retrieving, deleting, and garbage-collecting file assets.

🔄 LWW Conflict Resolution​

  • Hybrid Logical Clock (HLC): Used for Last-Writer-Wins (LWW) columns, the HLC is a timestamping mechanism that combines physical time with a logical counter. This ensures consistent conflict resolution when the same data is modified from multiple sources.
  • LWW Columns: Special column type that automatically tracks the last modification time using HLC timestamps, enabling conflict-free data merging in distributed scenarios.

📖 What You'll Learn​

In this section, you will learn how to:

  • Build complex, multi-table queries with the Query Builder.
  • Create reactive user interfaces with Streaming Queries.
  • Model your data effectively using DbRecord and Code Generation.
  • Attach and manage files with the File Management system.
  • Use LWW Columns for conflict resolution.