XAP

XAP Skyline

Smart DIH

Space Index

Index Types

The index type is determined by the SpaceIndexType enumeration. The index types are:

NONE - No indexing is used.

EQUAL - performs equality matching (equal to/not equal to).

ORDERED - performs ordered matching (bigger than/less than).

EQUAL_AND_ORDERED - performs both equality and ordered matching, and uses a larger memory footprint than the other indexing types.

The BASIC and EXTENDED index types have been deprecated as of version 12.3.

Indexing at Design Time

Specifying which properties of a class are indexed is done using annotations or gs.xml.

@SpaceClass
public class Person
{
    private String lastName;
    private String firstName;
    private Integer age;

    ...
    @SpaceIndex(type=SpaceIndexType.EQUAL)
    public String getFirstName() {return firstName;}
    public void setFirstName(String firstName) {this.firstName = firstName;}

    @SpaceIndex(type=SpaceIndexType.EQUAL)
    public String getLastName() {return lastName;}
    public void setLastName(String name) {this.lastName = name;}

    @SpaceIndex(type=SpaceIndexType.ORDERED)
    public Integer getAge() {return age;}
    public void setAge(Integer age) {this.age = age;}
}

<gigaspaces-mapping>
    <class name="com.gigaspaces.examples.Person" persist="false" replicate="false" fifo="false" >
        <property name="lastName">
            <index type="EQUAL"/>
        </property>
        <property name="firstName">
            <index type="EQUAL"/>
        </property>
        <property name="age">
             <index type="ORDERED"/>
        </property>
    </class>
</gigaspaces-mapping>

Inheritance

By default, a property's index is inherited in sub-classes (i.e. if a property is indexed in a superclass, it is also indexed in a sub-class). If you need to change the index type of a property in a sub-class, you can override the property and annotate it with @SpaceIndex using the requested index type (to disable indexing, use NONE).

Query Protective Mode

Query protection mode provides protection against executing queries that perform a full scan if the table size is above a limit.

Parameters:

  • com.gs.protectiveMode.queryWithoutIndex

  • com.gs.protectiveMode.queryWithoutIndex.queryWithoutIndexLimitValue - default value is 10000.

By default, this protective mode is disabled. If enabled, an exception will be thrown when a query as ” select * from the table” is performed and the table size is larger than the specified limit. The same will happen if the query includes a condition, but no index can be used.

Doing readMultiple and limiting the results with max entries less than the limit will pass successfully.

Also, “select count(*) from table” or using an aggregation that uses the index will pass the protective mode, as no full scan is performed.

If the protective mode is disabled, a warning message will be logged if the query meets the protective mode conditions. It is recommended to enable this property in QA and stage environments.