org.apache.ignite.cache.query.annotations

注釈型 QuerySqlField

@Documented
 @Retention(value=RUNTIME)
 @Target(value={METHOD,FIELD})
public @interface QuerySqlField

Annotates fields for SQL queries. All fields that will be involved in SQL clauses must have this annotation. For more information about cache queries see CacheQuery documentation.

関連項目:

CacheQuery

任意要素のサマリー

任意要素

修飾子とタイプ	任意要素と説明
boolean	descending Specifies whether index should be in descending order or not.
java.lang.String[]	groups Array of index groups this field belongs to.
boolean	index Specifies whether cache should maintain an index for this field or not.
java.lang.String	name Property name.
QuerySqlField.Group[]	orderedGroups Array of ordered index groups this field belongs to.

要素の詳細

index

public abstract boolean index

Specifies whether cache should maintain an index for this field or not. Just like with databases, field indexing may require additional overhead during updates, but makes select operations faster.

When indexing SPI and indexed field is of type com.vividsolutions.jts.geom.Geometry (or any subclass of this class) then Ignite will consider this index as spatial providing performance boost for spatial queries.

戻り値:

True if index must be created for this field in database.

デフォルト:

false

descending

public abstract boolean descending

Specifies whether index should be in descending order or not. This property only makes sense if index() property is set to true.

戻り値:

True if field index should be in descending order.

デフォルト:

false

groups

public abstract java.lang.String[] groups

Array of index groups this field belongs to. Groups are used for compound indexes, whenever index should be created on more than one field. All fields within the same group will belong to the same index.

Group indexes are needed because SQL engine can utilize only one index per table occurrence in a query. For example if we have two separate indexes on fields a and b of type X then query select * from X where a = ? and b = ? will use for filtering either index on field a or b but not both. For more effective query execution here it is preferable to have a single group index on both fields.

For more complex scenarios please refer to QuerySqlField.Group documentation.

戻り値:

Array of group names.

デフォルト:

{}

orderedGroups

public abstract QuerySqlField.Group[] orderedGroups

Array of ordered index groups this field belongs to. For more information please refer to QuerySqlField.Group documentation.

戻り値:

Array of ordered group indexes.

関連項目:

groups()

デフォルト:

{}

name

public abstract java.lang.String name

Property name. If not provided then field name will be used.

戻り値:

Name of property.

デフォルト:

""