package io.ebean.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

An annotation for declaring an index.
Author:
rvbiljouw/**
 * An annotation for declaring an index.
 *
 * @author rvbiljouw
 */
@Target({ElementType.TYPE, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Repeatable(Indices.class)
public @interface Index {

  
Name of the index. If left blank a name is derived using the built in naming convention.
/**
   * Name of the index. If left blank a name is derived using the built in naming convention.
   */
  String name() default "";

  
If set true indicates this is a unique index.
/**
   * If set true indicates this is a unique index.
   */
  boolean unique() default false;

  
If set true with Postgres this index should be created concurrently.

This attribute currently only applies to Postgres applying to both the
create index and drop index generated DDL.
/**
   * If set true with Postgres this index should be created concurrently.
   * <p>
   * This attribute currently only applies to Postgres applying to both the
   * <code>create index</code> and <code>drop index</code> generated DDL.
   */
  boolean concurrent() default false;

  
When placed on the class (rather than field) you can specify the columns
to include in the index in order.

When placed on a field, and columnNames are specified, the field-column has to be included.
You can use "${fa}" for alias.
/**
   * When placed on the class (rather than field) you can specify the columns
   * to include in the index in order.
   * <p>
   * When placed on a field, and columnNames are specified, the field-column has to be included.
   * You can use "${fa}" for alias.
   */
  String[] columnNames() default {};

  
Platforms this index applies to - default is all platforms.

This provides an alternative to using extra-dll.xml to specify
platform specific index ddl.

Changing platforms is NOT detected as part of DB migration
generation (no platform specific DIFF) so using extra-ddl.xml
may be preferred.
/**
   * Platforms this index applies to - default is all platforms.
   * <p>
   * This provides an alternative to using extra-dll.xml to specify
   * platform specific index ddl.
   * <p>
   * Changing platforms is NOT detected as part of DB migration
   * generation (no platform specific DIFF) so using extra-ddl.xml
   * may be preferred.
   */
  Platform[] platforms() default {};

  
The full raw SQL definition to create the index.

The indexName should be provided such that the drop index statement can
be generated as needed.

This allows for platform specific index creation features as an alternative to using
ebean extra-dll.xml to define extra potentially platform specific DDL.

  @Index(name = "ix_t_detail_defn",
    definition = "create index ix_t_detail_defn on t_detail using hash (lower(name)) where lower(name) like 'r%'",
    platforms = Platform.POSTGRES)

/**
   * The full raw SQL definition to create the index.
   * <p>
   * The indexName should be provided such that the drop index statement can
   * be generated as needed.
   * <p>
   * This allows for platform specific index creation features as an alternative to using
   * ebean extra-dll.xml to define extra potentially platform specific DDL.
   *
   * <pre>{@code
   *
   *   @Index(name = "ix_t_detail_defn",
   *     definition = "create index ix_t_detail_defn on t_detail using hash (lower(name)) where lower(name) like 'r%'",
   *     platforms = Platform.POSTGRES)
   *
   * }</pre>
   */
  String definition() default "";

}