Read-Write Splitting

FreeSql supports database read-write splitting. This feature pertains to client-side read-write splitting behavior; how the database server itself is configured remains unchanged and unaffected by this feature. For convenience, when referring to read-write splitting below, it will mean the client-side functionality support.

The methods for read-write splitting vary among different databases. Once the read-write splitting feature is enabled on the database server, the implementation generally falls into the following categories:

1. Nginx proxy, which is complex to configure and prone to errors;
2. Middleware, such as MyCat;
3. Client-side support;

FreeSql implements the third option, supporting one master database and multiple slave databases, with the query strategy for slave databases being random.

If a slave database fails, it will switch to other available slave databases. If all slave databases are unavailable, it will fall back to querying the master database.

Failed slave databases are isolated and periodically checked for availability until they recover.

var connstr = "Data Source=127.0.0.1;Port=3306;User ID=root;Password=root;" +
    "Initial Catalog=cccddd;Charset=utf8;SslMode=none;Max pool size=10";

static IFreeSql fsql = new FreeSql.FreeSqlBuilder()
    .UseConnectionString(FreeSql.DataType.MySql, connstr)
    .UseSlave("connectionString1", "connectionString2") // Use slave databases, multiple supported
    .Build(); // Be sure to define as Singleton

fsql.Select<T>().Where(a => a.Id == 1).ToOne(); // Read from **slave database** (default)

fsql.Select<T>().Master().WhereId(a => a.Id == 1).ToOne(); // Force read from **master database**

fsql.Ado.Query<T>("/*master*/ select * from t where ..."); // Force read from **master database**