Sharding explained

AuthP's multi-tenant uses the enum TenantTypes to define what type of multi-tenant you want to use. By default all the tenant's data is stored in one database, with a DataKey to select each tenant's data. See Multi-tenant explained documentation for an overview of the multi-tenant options.

But if you add the SetupMultiTenantSharding method to your registering of the AuthP code, then an extra TenantTypes called AddSharding is added, which adds the extra ability for a tenant to store its data in its own database. This means that you have two approaches to build your multi-tenant app: either Hybrid or Sharding-only (see diagram below to explain these to approaches).

This means that when the AddSharding enum is added, then for each HTTP request from a tenant user (i.e. a user that is linked to a specific tenant) the multi-tenant code must select a database so that they can access the tenant's data. The AuthP does this via two parts

1. Getting the database server from the connection strings

Anyone that uses ASP.NET Core will know that the appsettings.json file contains a ConnectionStrings section that holds connection strings. These connection strings usually everything you about a database (database name, server name, authentication, etc.) you want to use. But for AuthP sharding code uses the connection strings to access the server name, authentication, etc. but it will add the database name.

If you look at Example6's appsettings.json you will see that the first connection string (called "DefaultConnection") has the normal format, i.e with the database name included, but the other connection string don't have a database part, which means only defines the server.

So, how do we get the database name? See below.

2. Getting the database name from the sharding entries.

AuthP holds a list of the entries (known as sharding entries) that provides the data needed to create a complete connection string. Each sharding entry contains

Name	What is contains
DatabaseName	The name of the database
ConnectionName	The name of the connection string defining the server
DatabaseType	The EF Core's short name (e.g. SqlServer) of the database type to use
Name	This is the unique key to this entry

See ???? document to see the actual steps provide the created connection string is built and then used to allow a tenant user can access the tenant's data.

The choosing between the Hybrid or Sharding-Only approach

The Hybrid and Sharding-Only approaches have pros and cons which I show in the table below

What	Hybrid	Sharding-Only
Summary	Good for a large range of small and large tenant data	Best performance and easy to use, but costly if you have lots of cloud databases
Easy of coding	Some features are more difficult, e.g. "Sign up now"	Extra Sharding-Only services makes coding easier
Easy for admin	It takes two steps to add a new Tenant (and fiddly)	It takes one step to add a new Tenant
Easy for tenant	Good	Good
Performance	Tenants sharing one database is slower	Best performance
Backups	Tenants sharing one database is difficult	Good: each database can be backed up

In AuthP version 6 and above allows you select whether you want to use Hybrid or Sharding-Only approach. Here are the changes between the Hybrid or Sharding-Only approach.

Hybrid selected

• The "DefaultConnection" connection string, which provides the database use by AuthP's to hold its data, is available to add sharing tenant

/?????????????????????????????? By default the SetupMultiTenantSharding method will

Because the sharding-only approach is a popular choice, the AuthP version 6 provides various features / services to help developers who want to build a sharding-only