org.apache.jackrabbit.oak.plugins.index.aggregate

Class AggregateIndex

java.lang.Object

org.apache.jackrabbit.oak.plugins.index.aggregate.AggregateIndex

All Implemented Interfaces:

QueryIndex, QueryIndex.AdvancedQueryIndex, QueryIndex.AdvanceFulltextQueryIndex, QueryIndex.FulltextQueryIndex, QueryIndex.NativeQueryIndex

public class AggregateIndex
extends java.lang.Object
implements QueryIndex.AdvanceFulltextQueryIndex

A virtual full-text that can aggregate nodes based on aggregate definitions. Internally, it uses another full-text index.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.jackrabbit.oak.spi.query.QueryIndex

QueryIndex.AdvancedQueryIndex, QueryIndex.AdvanceFulltextQueryIndex, QueryIndex.FulltextQueryIndex, QueryIndex.IndexPlan, QueryIndex.NativeQueryIndex, QueryIndex.NodeAggregator, QueryIndex.OrderEntry

Constructor Summary

Constructors

Constructor and Description
AggregateIndex(QueryIndex.AdvanceFulltextQueryIndex baseIndex)

Method Summary

Modifier and Type	Method and Description
double	getCost(Filter filter, NodeState rootState) Estimate the worst-case cost to query with the given filter.
java.lang.String	getIndexName() Get the generic index name (normally the index type).
double	getMinimumCost() Returns the minimum cost which QueryIndex.getCost(Filter, NodeState) would return in the best possible case.
QueryIndex.NodeAggregator	getNodeAggregator() Returns the NodeAggregator responsible for providing the aggregation settings or null if aggregation is not available/desired.
java.lang.String	getPlan(Filter filter, NodeState rootState) Get the query plan for the given filter.
java.lang.String	getPlanDescription(QueryIndex.IndexPlan plan, NodeState root) Get the query plan description (for logging purposes).
java.util.List<QueryIndex.IndexPlan>	getPlans(Filter filter, java.util.List<QueryIndex.OrderEntry> sortOrder, NodeState rootState) Return the possible index plans for the given filter and sort order.
Cursor	query(Filter filter, NodeState rootState) Query the index.
Cursor	query(QueryIndex.IndexPlan plan, NodeState rootState) Start a query.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.jackrabbit.oak.spi.query.QueryIndex

getIndexName

Constructor Detail

AggregateIndex

public AggregateIndex(QueryIndex.AdvanceFulltextQueryIndex baseIndex)

Method Detail

getMinimumCost

public double getMinimumCost()

Description copied from interface: QueryIndex

Returns the minimum cost which QueryIndex.getCost(Filter, NodeState) would return in the best possible case.

The implementation should return a static/cached value because it is called very often.

Specified by:

getMinimumCost in interface QueryIndex

Returns:

the minimum cost for the index

getCost

public double getCost(Filter filter,
                      NodeState rootState)

Description copied from interface: QueryIndex

Estimate the worst-case cost to query with the given filter. The returned cost is a value between 1 (very fast; lookup of a unique node) and the estimated number of entries to traverse, if the cursor would be fully read, and if there could in theory be one network roundtrip or disk read operation per node (this method may return a lower number if the data is known to be fully in memory).

The returned value is supposed to be an estimate and doesn't have to be very accurate. Please note this method is called on each index whenever a query is run, so the method should be reasonably fast (not read any data itself, or at least not read too much data).

If an index implementation can not query the data, it has to return Double.MAX_VALUE.

Specified by:

getCost in interface QueryIndex

Parameters:

filter - the filter

rootState - root state of the current repository snapshot

Returns:

the estimated cost in number of read nodes

query

public Cursor query(Filter filter,
                    NodeState rootState)

Description copied from interface: QueryIndex

Query the index. The returned cursor is supposed to return as few nodes as possible, but may return more nodes than necessary.

An implementation should only filter the result if it can do so easily and efficiently; the query engine will verify the data again (in memory) and check for access rights.

The method is only called if this index is used for the given query and selector, which is only the case if the given index implementation returned the lowest cost for the given filter. If the implementation returned Double.MAX_VALUE in the getCost method for the given filter, then this method is not called. If it is still called, then it is supposed to throw an exception (as it would be an internal error of the query engine).

Specified by:

query in interface QueryIndex

Parameters:

filter - the filter

rootState - root state of the current repository snapshot

Returns:

a cursor to iterate over the result

getPlans

public java.util.List<QueryIndex.IndexPlan> getPlans(Filter filter,
                                                     java.util.List<QueryIndex.OrderEntry> sortOrder,
                                                     NodeState rootState)

Description copied from interface: QueryIndex.AdvancedQueryIndex

Return the possible index plans for the given filter and sort order. Please note this method is supposed to run quickly. That means it should usually not read any data from the storage.

Specified by:

getPlans in interface QueryIndex.AdvancedQueryIndex

Parameters:

filter - the filter

sortOrder - the sort order or null if no sorting is required

rootState - root state of the current repository snapshot

Returns:

the list of index plans (null if none)

query

public Cursor query(QueryIndex.IndexPlan plan,
                    NodeState rootState)

Description copied from interface: QueryIndex.AdvancedQueryIndex

Start a query. The filter and sort order of the index plan is to be used.

The index plan is one of the plans that the index returned in the getPlans call.

Specified by:

query in interface QueryIndex.AdvancedQueryIndex

Parameters:

plan - the index plan to use

rootState - root state of the current repository snapshot

Returns:

a cursor to iterate over the result

getPlan

public java.lang.String getPlan(Filter filter,
                                NodeState rootState)

Description copied from interface: QueryIndex

Get the query plan for the given filter. This method is called when running an EXPLAIN SELECT query, or for logging purposes. The result should be human readable.

Specified by:

getPlan in interface QueryIndex

Parameters:

filter - the filter

rootState - root state of the current repository snapshot

Returns:

the query plan

getPlanDescription

public java.lang.String getPlanDescription(QueryIndex.IndexPlan plan,
                                           NodeState root)

Description copied from interface: QueryIndex.AdvancedQueryIndex

Get the query plan description (for logging purposes).

The index plan is one of the plans that the index returned in the getPlans call.

Specified by:

getPlanDescription in interface QueryIndex.AdvancedQueryIndex

Parameters:

plan - the index plan

root - root state of the current repository snapshot

Returns:

the query plan description

getIndexName

public java.lang.String getIndexName()

Description copied from interface: QueryIndex

Get the generic index name (normally the index type).

Specified by:

getIndexName in interface QueryIndex

Returns:

the index name

getNodeAggregator

public QueryIndex.NodeAggregator getNodeAggregator()

Description copied from interface: QueryIndex.FulltextQueryIndex

Returns the NodeAggregator responsible for providing the aggregation settings or null if aggregation is not available/desired.

Specified by:

getNodeAggregator in interface QueryIndex.FulltextQueryIndex

Returns:

the node aggregator or null