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Indexes : Creating and Deploying Indexes

Indexes are used by the server to satisfy queries. Whenever a user issues a query, RavenDB will use an existing index if it matches the query. If it doesn't, RavenDB will create a new one.

Remember

Indexes are created by issuing a query are called dynamic or Auto indexes. They can be easily identified. Their name starts with Auto/ prefix.

Indexes created explicitly by the user are called static.

Static indexes

There are a couple of ways to create a static index and send it to the server. We can use maintenance operations or create a custom class. You can also scan an assembly and deploy all found indexes.


Using AbstractIndexCreationTask

If you are interested in having a strongly-typed syntax during index creation, or have an ability to deploy indexes using assembly scanner, avoid hard-coding index names in every query, then AbstractIndexCreationTask should be your choice.

Note

We recommend creating and using indexes in this form due to its simplicity. There are many benefits and few disadvantages.

Naming Convention

There is only one naming convention: each _ in the class name will be translated to / in the index name.

e.g.

In the Northwind samples, there is a index called Orders/Totals. To get such a index name, we need to create a class called Orders_Totals.

public class Orders_Totals : AbstractIndexCreationTask<Order>
{
    // ...
}

Sending to Server

There is not much use from an index if it is not deployed to the server. To do so, we need to create an instance of our class that inherits from AbstractIndexCreationTask and use one of the deployment methods: Execute or ExecuteAsync for an asynchronous call.

// deploy index to database defined in `DocumentStore.Database` property
// using default DocumentStore `Conventions`
new Orders_Totals().Execute(store);

// deploy asynchronously index to database defined in `DocumentStore.Database` property
// using default DocumentStore `Conventions`
await new Orders_Totals().ExecuteAsync(store, store.Conventions);

// deploy index to `Northwind` database
// using default DocumentStore `Conventions`
new Orders_Totals().Execute(store, store.Conventions, "Northwind");

Safe By Default

If an index exists on the server and the stored definition is the same as the one that was sent, it will not be overwritten. The indexed data will not be deleted and indexation will not start from scratch.

Using Assembly Scanner

All classes that inherit from AbstractIndexCreationTask can be deployed at once using one of IndexCreation.CreateIndexes method overloads.

// deploy all indexes 
// from assembly where `Orders_Totals` is found
// to database defined in `DocumentStore.Database` property
IndexCreation.CreateIndexes(typeof(Orders_Totals).Assembly, store);

Underneath, the IndexCreation will attempt to create all indexes in a single request. If it fails, then it will repeat the execution by calling the Execute method one-by-one for each of the found indexes in separate requests.

Example

public class Orders_Totals : AbstractIndexCreationTask<Order>
{
    public class Result
    {
        public string Employee { get; set; }

        public string Company { get; set; }

        public decimal Total { get; set; }
    }

    public Orders_Totals()
    {
        Map = orders => from order in orders
                        select new
                        {
                            order.Employee,
                            order.Company,
                            Total = order.Lines.Sum(l => (l.Quantity * l.PricePerUnit) * (1 - l.Discount))
                        };
    }
}

public static void Main(string[] args)
{
    using (DocumentStore store = new DocumentStore
    {
        Urls = new[] { "http://localhost:8080" },
        Database = "Northwind"
    })
    {
        store.Initialize();

        new Orders_Totals().Execute(store);

        using (IDocumentSession session = store.OpenSession())
        {
            IList<Order> orders = session
                .Query<Orders_Totals.Result, Orders_Totals>()
                .Where(x => x.Total > 100)
                .OfType<Order>()
                .ToList();
        }
    }
}


Using Maintenance Operations

The PutIndexesOperation maintenance operation (which API references can be found here) can be used also to send index(es) to the server.

The benefit of this approach is that you can choose the name as you feel fit, and change various settings available in IndexDefinition. But you lose the ability to deploy using the assembly scanner. You will also have to use string-based names of indexes when querying.

store
    .Maintenance
    .Send(new PutIndexesOperation(new IndexDefinition
    {
        Name = "Orders/Totals",
        Maps =
        {
            @"from order in docs.Orders	
              select new 
              { 
                  order.Employee, 
                  order.Company,
                  Total = order.Lines.Sum(l => (l.Quantity * l.PricePerUnit) * (1 - l.Discount))
              }"
        }
    }));

IndexDefinitionBuilder

IndexDefinitionBuilder is a very useful class that enables you to create IndexDefinitions using strongly-typed syntax with access to low-level settings not available when the AbstractIndexCreationTask approach is used.

IndexDefinitionBuilder<Order> builder = new IndexDefinitionBuilder<Order>();
builder.Map = orders => from order in orders
                        select new
                        {
                            order.Employee,
                            order.Company,
                            Total = order.Lines.Sum(l => (l.Quantity * l.PricePerUnit) * (1 - l.Discount))
                        };

store
    .Maintenance
    .Send(new PutIndexesOperation(builder.ToIndexDefinition(store.Conventions)));

Remarks

Information

Maintenance Operations or IndexDefinitionBuilder approaches are not recommended and should be used only if you can't do it by inheriting from AbstractIndexCreationTask.

Side-by-Side

Since RavenDB 4.0, all index updates are side-by-side by default. The new index will replace the existing one once it becomes non-stale. If you want to force an index to swap immediately, you can use the Studio for that.

Auto indexes

Auto-indexes are created when queries that do not specify an index name are executed and, after in-depth query analysis, no matching AUTO index is found on the server-side.

Naming Convention

Auto-indexes can be recognized by the Auto/ prefix in their name. Their name also contains the name of a collection that was queried, and list of fields that were required to find valid query results.

For instance, issuing a query like this

List<Employee> employees = session
    .Query<Employee>()
    .Where(x => x.FirstName == "Robert" && x.LastName == "King")
    .ToList();
from Employees
where FirstName = 'Robert' and LastName = 'King'

will result in a creation of a index named Auto/Employees/ByFirstNameAndLastName.

Auto Indexes and Indexing State

To reduce the server load, if auto-indexes are not queried for a certain amount of time defined in Indexing.TimeToWaitBeforeMarkingAutoIndexAsIdleInMin setting (30 minutes by default), then they will be marked as Idle. You can read more about the implications of marking index as Idle here.

Setting this configuration option to a high value may result in performance degradation due to the possibility of having a high amount of unnecessary work that is all redundant and not needed by indexes to perform. This is not a recommended configuration.