com.bigdata.mdi

Interface IPartitionMetadata

All Superinterfaces:

ISeparatorKeys

All Known Implementing Classes:

LocalPartitionMetadata, PartitionLocator

public interface IPartitionMetadata
extends ISeparatorKeys

A description of the metadata state for a partition of a scale-out index.

Each index partition has a distinct partitionId. This partitionId is assigned by a centralized service - the IMetadataService for the scale-out index for that index partition. A centralized service is required in order to obtain distinct int32 partition identifiers because those partition identifiers are used in turn to support scale-out partition local ICounters - the partitionId forms the upper word of the int64 counter value.

The scale-out index name and the left and right separator keys are a complete identifier for an index partition - any two index partitions which share those three properties MUST be the same index partition. However, access to index partitions is generally in terms of the name of the scale-out index and the partitionId. See DataService.getIndexPartitionName(String, int) which returns the name under which an index partition will be registered and the name that must be used when requesting operations on that index partition using an IDataService.

An index partition has additional state, including:

• the IDataService on which it resides.
• the IResourceMetadata[] describing the resources required to materialize a view of the index partition.
• those resources themselves, which contain the index partition data.

The left and right separator keys define the half-open key range of the index partition. The separator keys are available directly as the keys of the MetadataIndex, therefore they are not stored in the index partition records within the metadata index. However, the separator keys are stored in the index partition description within the IndexMetadata records so that they are available locally with the index partition data.

If the client knows a key or key range of interest for a scale-out index then they can obtain the relevant index partition descriptions and a data service locator either either by flooding the query to the IDataServices or from the MetadataIndex.

Version:

$Id$

Author:

Bryan Thompson

Method Summary

Methods

Modifier and Type	Method and Description
int	getPartitionId() The unique partition identifier.
int	hashCode() Return getPartitionId()

Methods inherited from interface com.bigdata.mdi.ISeparatorKeys

getLeftSeparatorKey, getRightSeparatorKey

Method Detail

getPartitionId

int getPartitionId()

The unique partition identifier.

hashCode

int hashCode()

Return getPartitionId()

Overrides:

hashCode in class Object