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Difference between revisions of "EclipseLink/UserGuide/JPA/Advanced JPA Development/Data Partitioning"

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=Data Partitioning=
 
=Data Partitioning=
  
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This section is in progress...
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The PartitioningPolicy field in ClassDescriptor, AbstractSession, and DatabaseQuery is used to define a partition policy.
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A partition policy is settable on a mapping, which sets it on each of the mapping's queries.
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The different kinds of policies are:
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* RoundRobinPolicy - Cycles through a list of connection pools to distribute the load evenly. There is an option to load balance read queries only and an option to replicate write queries.
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* RangePartitionPolicy - Maps a query parameter name to a node, based on its value and a set of ranges. If the query does not define the parameter, the policy either uses the session default behavior or, based on the XXXXXXX option setting, sends the query to all pools and unions the result.
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* ValuePartitionPolicy - Behaves the same as the range policy, but maps value to a pool instead of a range. It also defines a default pool to use for any unmapped values.
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* HashPartitionPolicy - Hashes the parameter value into a list of connection pools.
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* ReplicationPolicy - Sends write queries to a set of connection pools.
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* UnionPartitionPolicy - Sends read queries to a set of connection pools and has an option to replicate wrties.
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== Configuration Files ==
 
== Configuration Files ==
  

Revision as of 15:50, 20 January 2011

EclipseLink JPA


Data Partitioning

This section is in progress...

The PartitioningPolicy field in ClassDescriptor, AbstractSession, and DatabaseQuery is used to define a partition policy.


A partition policy is settable on a mapping, which sets it on each of the mapping's queries.

The different kinds of policies are:

  • RoundRobinPolicy - Cycles through a list of connection pools to distribute the load evenly. There is an option to load balance read queries only and an option to replicate write queries.
  • RangePartitionPolicy - Maps a query parameter name to a node, based on its value and a set of ranges. If the query does not define the parameter, the policy either uses the session default behavior or, based on the XXXXXXX option setting, sends the query to all pools and unions the result.
  • ValuePartitionPolicy - Behaves the same as the range policy, but maps value to a pool instead of a range. It also defines a default pool to use for any unmapped values.
  • HashPartitionPolicy - Hashes the parameter value into a list of connection pools.
  • ReplicationPolicy - Sends write queries to a set of connection pools.
  • UnionPartitionPolicy - Sends read queries to a set of connection pools and has an option to replicate wrties.


Configuration Files

orm.xml

<partitioning-policy class="org.acme.MyPolicy"/>
<round-robin-policy replicate-writes="true">
  <connection-pool>node1</connection-pool>
  <connection-pool>node2</connection-pool>
</round-robin-policy>
<random-policy replicate-writes="true">
  <connection-pool>node1</connection-pool>
  <connection-pool>node2</connection-pool>
</random-policy>
<replication-policy>
  <connection-pool>node1</connection-pool>
  <connection-pool>node2</connection-pool>
</replication-policy>
<range-partitioning-policy parameter-name="id" exclusive-connection="true" union-unpartitionable-queries="true">
  <range-partition connection-pool="node1" start-value="0" end-value="100000" value-type="java.lang.Integer"/>
  <range-partition connection-pool="node2" start-value="100001" end-value="200000" value-type="java.lang.Integer"/>
  <range-partition connection-pool="node3" start-value="200001" value-type="java.lang.Integer"/>
</range-partitioning-policy>

persistence.xml

 

Examples

@Entity
@IdClass(EmployeePK.class)
@UnionPartitioning(
        name="UnionPartitioningAllNodes",
        replicateWrites=true)
@ValuePartitioning(
        name="ValuePartitioningByLOCATION",
        partitionColumn=@Column(name="LOCATION"),
        unionUnpartitionableQueries=true,
        defaultConnectionPool="default",
        partitions={
            @ValuePartition(connectionPool="node2", value="Ottawa"),
            @ValuePartition(connectionPool="node3", value="Toronto")
        })
@Partitioned("ValuePartitioningByLOCATION")
public class Employee {
    @Id
    @Column(name = "EMP_ID")
    private Integer id;
 
    @Id
    private String location;
    ...
 
    @ManyToMany(cascade = { PERSIST, MERGE })
    @Partitioned("UnionPartitioningAllNodes")
    private Collection<Project> projects;
    ...
}
@Entity
@RangePartitioning(
        name="RangePartitioningByPROJ_ID",
        partitionColumn=@Column(name="PROJ_ID"),
        partitionValueType=Integer.class,
        unionUnpartitionableQueries=true,
        partitions={
            @RangePartition(connectionPool="default", startValue="0", endValue="1000"),
            @RangePartition(connectionPool="node2", startValue="1000", endValue="2000"),
            @RangePartition(connectionPool="node3", startValue="2000")
        })
@Partitioned("RangePartitioningByPROJ_ID")
public class Project {
    @Id
    @Column(name="PROJ_ID")
    private Integer id;
    ...
}

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