How to setup a default database?

DefaultDatabase property allows you to setup a default database for a DocumentStore. Implication of setting up a default database is that each time you access Commands or create a Session without explicitly passing database on which they should operate on then default database is assumed.

Example I

using (IDocumentStore store = new DocumentStore
{
  Urls = new[] { "http://your_RavenDB_server_URL" }
  // Default database is not set
}.Initialize())
{
  // Specify the 'Northwind' database when opening a Session
  using (IDocumentSession session = store.OpenSession(database: "NorthWind"))
  {
      // Session will operate on the 'Northwind' database
  }

  // Specify the 'Northwind' database when sending an Operation
  store.Maintenance.ForDatabase("Northwind").Send(new DeleteIndexOperation("NorthWindIndex"));
}

Example II

using (IDocumentStore store = new DocumentStore
{
  Urls = new[] { "http://your_RavenDB_server_URL" },
  // Default database is set to 'Northwind'
  Database = "Northwind"
}.Initialize())
{
  // Using the default database
  using (IDocumentSession northwindSession = store.OpenSession())
  {
      // Session will operate on the default 'Northwind' database
  }

  // Operation for default database
  store.Maintenance.Send(new DeleteIndexOperation("NorthWindIndex"));

  // Specify the 'AdventureWorks' database when opening a Session
  using (IDocumentSession adventureWorksSession = store.OpenSession(database: "AdventureWorks"))
  {
      // Session will operate on the specifed 'AdventureWorks' database
  }

  // Specify the 'AdventureWorks' database when sending an Operation
  store.Maintenance.ForDatabase("AdventureWorks").Send(new DeleteIndexOperation("AdventureWorksIndex"));
}

Remarks

By default value of DefaultDatabase property in DocumentStore is null which means that actions will be executed on <system> database.