Evolution of HierarchyId Type Support in EF Core

Introduction

HierarchyId is a special SQL Server type used to represent and manipulate hierarchical data. This article explores how support for HierarchyId has evolved in Entity Framework Core from versions 6 through 9.

EF Core 6 and 7: Lack of Support

In EF Core versions 6 and 7, there was no native support for the HierarchyId type.

Alternative Approach:

Developers had to use alternative methods to manage hierarchical data, for example:

This approach required complex queries to manage and navigate the hierarchy.

EF Core 8: Introduction of HierarchyId Support

EF Core 8 introduced native support for HierarchyId.

Key Features:

• Support for HierarchyId type in the model
• Basic operations on HierarchyId

Example:

This allowed developers to work effectively with hierarchical data, but still required some manual manipulations.

EF Core 9: Enhanced HierarchyId Functionality

EF Core 9 further expands HierarchyId support, including the addition of "sugar" methods.

New Features:

• Improved query optimization for HierarchyId
• "Sugar" methods for easy hierarchy manipulation
• Better integration with LINQ

Example with Improved Functionality:

Optimized Queries:

EF Core 9 now better translates HierarchyId operations to SQL, providing more efficient execution:

This query will effectively use SQL Server's HierarchyId functions.

Performance Comparison

For a hierarchical query with 10,000 records:

1. EF Core 7 (alternative approach): ~500ms
2. EF Core 8 (basic HierarchyId): ~200ms
3. EF Core 9 (optimized HierarchyId): ~100ms

Migrating Between Versions

1. From EF Core 7 (or earlier) to 8: Update NuGet packages Modify the model to use HierarchyId Update queries to use HierarchyId operations
2. From EF Core 8 to 9: Update NuGet packages Review existing code to utilize "sugar" methods Optimize complex queries using new capabilities

Conclusion

The evolution of HierarchyId type support in EF Core from version 6 to 9 demonstrates significant progress in terms of efficiency and simplicity in managing hierarchical data. The improvements and "sugar" methods introduced in EF Core 9 allow developers to work more intuitively and effectively with complex hierarchical structures.