com.bigdata.bop

Class BOpContextBase

java.lang.Object

com.bigdata.bop.BOpContextBase

Direct Known Subclasses:

BOpContext

public class BOpContextBase
extends Object

Base class for the bigdata operation evaluation context (NOT serializable).

Constructor Summary

Constructors

Constructor and Description
BOpContextBase(IBigdataFederation<?> fed, IIndexManager localIndexManager) Core constructor.
BOpContextBase(QueryEngine queryEngine)

Method Summary

Methods

Modifier and Type	Method and Description
<E> IAccessPath<E>	getAccessPath(IRelation<E> relation, IPredicate<E> predicate) Obtain an access path reading from the identified IRelation using the specified IPredicate.
Executor	getExecutorService() Return the Executor on to which the operator may submit tasks.
IBigdataFederation<?>	getFederation() The IBigdataFederation IFF the operator is being evaluated on an IBigdataFederation and otherwise null.
IIndexManager	getIndexManager() The local IIndexManager.
<E> IRelation<E>	getRelation(IPredicate<E> pred) Locate and return the view of the relation identified by the IPredicate.
ILocatableResource<?>	getResource(String namespace, long timestamp) Locate and return the view of the identified relation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BOpContextBase

public BOpContextBase(QueryEngine queryEngine)

BOpContextBase

public BOpContextBase(IBigdataFederation<?> fed,
              IIndexManager localIndexManager)

Core constructor.

Parameters:

fed - The federation iff running in scale-out.

localIndexManager - The local index manager.

Method Detail

getIndexManager

public final IIndexManager getIndexManager()

The local IIndexManager. Query evaluation occurs against the local indices. In scale-out, query evaluation proceeds shard-wise and this IIndexManager MUST be able to read on the ILocalBTreeView.

getFederation

public final IBigdataFederation<?> getFederation()

The IBigdataFederation IFF the operator is being evaluated on an IBigdataFederation and otherwise null. When evaluating operations against an IBigdataFederation, this reference provides access to the scale-out view of the indices and to other bigdata services.

getExecutorService

public final Executor getExecutorService()

Return the Executor on to which the operator may submit tasks.

Note: The is the ExecutorService associated with the local index manager.

getRelation

public <E> IRelation<E> getRelation(IPredicate<E> pred)

Locate and return the view of the relation identified by the IPredicate.

Parameters:

pred - The IPredicate, which MUST be a tail from some IRule.

Returns:

The IRelation -or- null if the relation did not exist for that timestamp.

getResource

public ILocatableResource<?> getResource(String namespace,
                                long timestamp)

Locate and return the view of the identified relation.

Parameters:

namespace - The namespace of the relation.

timestamp - The timestamp of the view of that relation.

Returns:

The ILocatableResource -or- null if the relation did not exist for that timestamp.

getAccessPath

public <E> IAccessPath<E> getAccessPath(IRelation<E> relation,
                               IPredicate<E> predicate)

Obtain an access path reading from the identified IRelation using the specified IPredicate.

Note: Passing in the IRelation is important since it otherwise must be discovered using the IResourceLocator. By requiring the caller to resolve it before hand and pass it into this method the contention and demand on the IResourceLocator cache is reduced.

Scale-Out

Note: You MUST be extremely careful when using expanders with a local access path for a shared-partitioned or hash-partitioned index. Only expanders whose semantics remain valid with a partial view of the index will behave as expected. Here are some examples that DO NOT work:

• "DISTINCT" on a partitioned local access path is not coherent
• Expanders which generate reads against keys not found on that shard are not coherent.

If you have requirements such as these, then either use a remote access path or change your query plan design more radically to take advantage of efficient shard-wise scans in scale-out.

Parameters:

relation - The relation.

pred - The predicate. When IPredicate.getPartitionId() is set, the returned IAccessPath MUST read on the identified local index partition (directly, not via RMI).

Returns:

The access path.