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• CountsRead.java

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org.neo4j.kernel.api.CountsRead Maven / Gradle / Ivy

/*
 * Copyright (c) 2002-2015 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.kernel.api;

public interface CountsRead
{
    int ANY_LABEL = -1;
    int ANY_RELATIONSHIP_TYPE = -1;

    /**
     * The number of nodes in the graph.
     *
     * If the label parameter is {@link #ANY_LABEL}, this method returns the total number of nodes in the graph, i.e.
     * {@code MATCH (n) RETURN count(n)}.
     *
     * If the label parameter is set to any other value, this method returns the number of nodes that has that label,
     * i.e. {@code MATCH (n:LBL) RETURN count(n)}.
     *
     * @param labelId the label to get the count for, or {@link #ANY_LABEL} to get the total number of nodes.
     * @return the number of matching nodes in the graph.
     */
    long countsForNode( int labelId );

    /**
     * The number of relationships in the graph.
     *
     * Returns the number of relationships in the graph that matches the specified pattern,
     * {@code (:startLabelId)-[:typeId]->(:endLabelId)}, like so:
     *
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
     * 
{@code startLabelId}
{@code typeId}
                  
{@code endLabelId}
                 
Pattern
                       
{@link #ANY_LABEL}
      
{@link #ANY_RELATIONSHIP_TYPE}
  
{@link #ANY_LABEL}
{@code MATCH}
    
{@code ()-[r]->()}
            
{@code RETURN count(r)}
{@link #ANY_LABEL}
      
{@code REL}
                     
{@link #ANY_LABEL}
{@code MATCH}
    
{@code ()-[r:REL]->()}
        
{@code RETURN count(r)}
{@code LHS}
             
{@link #ANY_RELATIONSHIP_TYPE}
  
{@link #ANY_LABEL}
{@code MATCH}
    
{@code (:LHS)-[r]->()}
        
{@code RETURN count(r)}
{@link #ANY_LABEL}
      
{@link #ANY_RELATIONSHIP_TYPE}
  
{@code RHS}
{@code MATCH}
    
{@code ()-[r]->(:RHS)}
        
{@code RETURN count(r)}
{@code LHS}
             
{@code REL}
                     
{@link #ANY_LABEL}
{@code MATCH}
    
{@code (:LHS)-[r:REL]->()}
    
{@code RETURN count(r)}
{@link #ANY_LABEL}
      
{@code REL}
                     
{@code RHS}
{@code MATCH}
    
{@code ()-[r:REL]->(:RHS)}
    
{@code RETURN count(r)}
{@code LHS}
             
{@link #ANY_RELATIONSHIP_TYPE}
  
{@code RHS}
{@code MATCH}
    
{@code (:LHS)-[r]->(:RHS)}
    
{@code RETURN count(r)}
{@code LHS}
             
{@code REL}
                     
{@code RHS}
{@code MATCH}
    
{@code (:LHS)-[r:REL]->(:RHS)}
{@code RETURN count(r)}
     *
     * @param startLabelId the label of the start node of relationships to get the count for, or {@link #ANY_LABEL}.
     * @param typeId       the type of relationships to get a count for, or {@link #ANY_RELATIONSHIP_TYPE}.
     * @param endLabelId   the label of the end node of relationships to get the count for, or {@link #ANY_LABEL}.
     * @return the number of matching relationships in the graph.
     */
    long countsForRelationship( int startLabelId, int typeId, int endLabelId );
}