Package 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 Object implements QueryIndex.AdvanceFulltextQueryIndex
A virtual full-text that can aggregate nodes based on aggregate definitions. Internally, it uses another full-text index.

  • Constructor Details

  • Method Details

    • 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 List<QueryIndex.IndexPlan> getPlans(Filter filter, 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 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 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 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