generate-guids

name	generate-guids
description	ABP IGuidGenerator entity IDs and sequential GUID layout for the active database provider. USE FOR: IGuidGenerator.Create; SequentialGuidGenerator; SimpleGuidGenerator; AbpSequentialGuidGeneratorOptions.DefaultSequentialGuidType; SequentialAtEnd / SequentialAsString / SequentialAsBinary. DO NOT USE FOR: cache keys and invalidation (cache-entities); cryptographic tokens or secrets (encrypt-strings); schema and repository design.
license	MIT

Generate GUIDs in ABP

Use IGuidGenerator.Create() for entity IDs instead of Guid.NewGuid(). ABP's default SequentialGuidGenerator preserves GUID uniqueness while placing a timestamp component where the target database can order it efficiently.

When to Use

• Create a Guid before constructing a new entity or aggregate root.
• Keep entity creation independent of the database provider.
• Select the sequential byte layout for SQL Server, MySQL, PostgreSQL, or Oracle.
• Use the pre-injected GuidGenerator property on ABP application/domain service base classes.

When Not to Use

• Create cache keys or coordinate cache invalidation — use cache-entities.
• Create password reset tokens, API secrets, or cryptographic nonces — GUID generation is not a token-protection workflow.
• Choose entity key types or model database indexes generally — this skill only covers ABP GUID generation.

How it works

Generate IDs at the creation boundary

IGuidGenerator exposes only Guid Create():

public class ProductAppService : ApplicationService
{
    private readonly IRepository<Product, Guid> _productRepository;

    public ProductAppService(IRepository<Product, Guid> productRepository)
    {
        _productRepository = productRepository;
    }

    public async Task CreateAsync(string name)
    {
        var product = new Product(GuidGenerator.Create(), name);
        await _productRepository.InsertAsync(product);
    }
}

Outside an ABP base class, inject IGuidGenerator. Pass the generated ID into the entity constructor; do not make entity constructors call a service locator or Guid.NewGuid().

Understand the two implementations

• SequentialGuidGenerator implements IGuidGenerator and ITransientDependency; it is the default DI implementation. It uses 10 cryptographically random bytes plus a six-byte UTC millisecond timestamp.
• SimpleGuidGenerator.Instance implements IGuidGenerator by returning Guid.NewGuid(). ABP base classes use it as a fallback only when no IGuidGenerator service can be resolved.

Sequential GUIDs address the insert cost of random GUID clustered keys: inserting unrelated random values can require database index page reordering. They do not make insertion order a business-level ordering contract; store an explicit timestamp or sequence when ordering matters.

Choose the database-specific layout

AbpSequentialGuidGeneratorOptions.DefaultSequentialGuidType is nullable and defaults to null. GetDefaultSequentialGuidType() falls back to SequentialAtEnd.

Value	Sequential representation	Database mapping
SequentialAtEnd	Timestamp at the end of the GUID data	SQL Server; fallback default
SequentialAsString	Sequential when formatted with Guid.ToString()	MySQL and PostgreSQL
SequentialAsBinary	Sequential when formatted with Guid.ToByteArray()	Oracle

The matching ABP EF Core provider modules set the value only when it is still null. Manual configuration is normally unnecessary when using those packages:

using Volo.Abp.Guids;

Configure<AbpSequentialGuidGeneratorOptions>(options =>
{
    options.DefaultSequentialGuidType = SequentialGuidType.SequentialAsString;
});

Configure it manually only when the actual database storage and comparison behavior requires an override.

Validation

• Resolve IGuidGenerator and confirm the concrete implementation is SequentialGuidGenerator in the application.
• Generate a large sample and assert uniqueness.
• Verify the configured SequentialGuidType matches the real database provider and GUID column representation.
• Insert representative rows and inspect index behavior with the production database engine when performance is the reason for the change.
• Confirm entity creation paths use IGuidGenerator, including data seeders and imports.

Common Pitfalls

• Using Guid.NewGuid() for entity IDs — it bypasses ABP's sequential strategy.
• Choosing a layout by intuition — string, binary, and SQL Server GUID ordering differ.
• Overriding an EF Core provider's correct default unnecessarily — provider modules configure the matching type when the option is null.
• Using SimpleGuidGenerator as the normal application service — it intentionally delegates to Guid.NewGuid().
• Sorting by generated GUID as business chronology — the generator contains a timestamp component but does not define a domain ordering contract.