DATACASS-213 - Create secondary indexes for annotated properties.

We now create secondary indexes for annotated properties via @Indexed. Index creation is part of schema creation that is executed after Session initialization and table creation.

We support plain secondary indexes and key/value/entry indexes for map columns. Index creation is useful for rapid development but should not be used in large setups or at least with care to not impact performance in a negative way.

@Table
public class Person {

  @Id
  private String key;

  @Indexed("name_index")
  private String name;

  private Map<@Indexed String, String> keys;
}

src/main/asciidoc/new-features.adoc

@@ -7,6 +7,7 @@
 * CRUD repository interface renaming: `CassandraRepository` using `MapId` is now renamed to `MapIdCassandraRepository`. `TypedIdCassandraRepository` is renamed to `CassandraRepository`.
 * Lightweight transactions via `InsertOptions` and `UpdateOptions` using the Template API.
 * Merge of Spring CQL into Spring Data Cassandra.
+* Index creation on application startup via `@Indexed`.
 
 [[new-features.1-5-0]]
 == What's new in Spring Data for Apache Cassandra 1.5

src/main/asciidoc/reference/cassandra.adoc

@@ -672,7 +672,7 @@ These entity classes can be used to create Cassandra table specifications and us
 Schema creation is tied to `Session` initialization with `SchemaAction`. Following actions are supported:
 
 * `SchemaAction.NONE`: No tables/types will be created or dropped. This is the default setting.
-* `SchemaAction.CREATE`: Create tables and user-defined types from entities annotated with `@Table` and types annotated with `@UserDefinedType`. Existing tables/types will cause an error if the type is attempted to be created.
+* `SchemaAction.CREATE`: Create tables, indexesm and user-defined types from entities annotated with `@Table` and types annotated with `@UserDefinedType`. Existing tables/types will cause an error if the type is attempted to be created.
 * `SchemaAction.CREATE_IF_NOT_EXISTS`: Like `SchemaAction.CREATE` but with `IF NOT EXISTS` applied. Existing tables/types won't cause any errors but may remain stale.
 * `SchemaAction.RECREATE`: Drops and recreate existing tables and types that are known to be used. Tables and types that are not configured in the application are not dropped.
 * `SchemaAction.RECREATE_DROP_UNUSED`: Drop all tables and types and recreate only known tables and types.

src/main/asciidoc/reference/mapping.adoc

@@ -245,6 +245,7 @@ be referenced with `@PrimaryKey`.
 where it is applied from being stored in the database.
 * `@Column` - applied at the field level. Describes the column name as it will be represented in the Cassandra table
 thus allowing the name to be different than the field name of the class.
+* `@Indexed` - applied at the field level. Describes the index to be created at session initialization.
 * `@CassandraType` - applied at the field level to specify a Cassandra data type. Types are derived from
 the declaration by default.
 * `@UserDefinedType` - applied at the type level to specify a Cassandra user-defined data type (UDT). Types are derived
@@ -286,6 +287,7 @@ public class Person {
   private String firstName;
 
   @Column(forceQuote = true)
+  @Indexed
   private String lastName;
 
   private Address address;
@@ -299,7 +301,7 @@ public class Person {
   @CassandraType(type = Name.SET, typeArguments = Name.BIGINT)
   private Set<Long> timestamps;
 
-  private Map<String, InetAddress> sessions;
+  private Map<@Indexed String, InetAddress> sessions;
 
   public Person(Integer ssn) {
     this.ssn = ssn;
@@ -346,6 +348,37 @@ public class Address {
 NOTE: Working with User-Defined Types requires a `UserTypeResolver` configured with the mapping context.
 See the <<cassandra.connectors,configuration chapter>> for how to configure a `UserTypeResolver`.
 
+==== Index creation
+
+You can annotate particular entity properties with `@Indexed` if you whish to create secondary indexes on application
+startup. Index creation will create simple secondary indexes for scalar types, user-defined, and collection types.
+
+Map types distinguish between `ENTRY`, `KEYS` and `VALUES` indexes. Index creation derives the index type from the
+annotated element:
+
+.Variants of map indexing
+====
+[source,java]
+----
+@Table
+public class Person {
+
+  @Id
+  private String key;
+
+  @Indexed("indexed_map")
+  private Map<String, String> entries;
+
+  private Map<@Indexed String, String> keys;
+
+  private Map<String, @Indexed String> values;
+
+  // …
+}
+----
+====
+
+WARNING: Index creation on session initialization may have a severe performance impact on application startup.
 
 [[cassandra.mapping.explicit-converters]]
 === Overriding Mapping with explicit Converters