Class JoinType


  • public abstract class JoinType
    extends java.lang.Object
    Defines how a set of matched rows from input tables (RowLink objects) are used to select rows for inclusion in an output table which represents the result of the matching operation. This corresponds to the type of the join in database terminology, though the naming of the instances of this class do not follow that terminology (left outer join etc), and the options here present a more complete set.

    Instances of this class are available as public static members of it. Currently, these instances should only be used with the results of pair matches (ones involving exactly two tables).

    Since:
    5 Sep 2005
    Author:
    Mark Taylor
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static JoinType _1AND2
      Selects only rows with input from both input tables.
      static JoinType _1NOT2
      Selects only rows in the first input table which are not matched by any row in the second input table.
      static JoinType _1OR2
      Selects rows with input from either or both input tables.
      static JoinType _1XOR2
      Selects only rows with input from exactly one of the two input tables.
      static JoinType _2NOT1
      Selects only rows in the second input table which are not matched by any row in the first input table.
      static JoinType _ALL1
      Selects all output rows with input from the first input table.
      static JoinType _ALL2
      Selects all output rows with input from the second input table.
    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      abstract java.lang.String getDescription()
      Returns a short textual description of this type.
      java.lang.String getName()
      Returns the name of this type.
      static JoinType[] getPairTypes()
      Returns a list of all the known types which apply to two-table matches.
      abstract boolean getUsedMatchFlag()
      Returns a value which indicates whether the matchScore is ever non-empty in the output table.
      abstract boolean[] getUsedTableFlags()
      Returns an array of flags indicating whether each of the tables in the input will ever have non-empty rows in the output.
      abstract LinkSet processLinks​(LinkSet links, int[] rowCounts)
      Turns a set of links which represent matches from the matching operation into a set of links which represent the rows to output.
      java.lang.String toString()
      Returns the name of this type.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Field Detail

      • _1AND2

        public static final JoinType _1AND2
        Selects only rows with input from both input tables.
      • _1OR2

        public static final JoinType _1OR2
        Selects rows with input from either or both input tables.
      • _ALL1

        public static final JoinType _ALL1
        Selects all output rows with input from the first input table.
      • _ALL2

        public static final JoinType _ALL2
        Selects all output rows with input from the second input table.
      • _2NOT1

        public static final JoinType _2NOT1
        Selects only rows in the second input table which are not matched by any row in the first input table.
      • _1NOT2

        public static final JoinType _1NOT2
        Selects only rows in the first input table which are not matched by any row in the second input table.
      • _1XOR2

        public static final JoinType _1XOR2
        Selects only rows with input from exactly one of the two input tables.
    • Method Detail

      • processLinks

        public abstract LinkSet processLinks​(LinkSet links,
                                             int[] rowCounts)
        Turns a set of links which represent matches from the matching operation into a set of links which represent the rows to output. links is a set of RowLink objects; if the matching operation was between two tables, each element will represent a pair match (have two RowRefs, with table indices of 0 and 1 respectively). The ordering of links may influence the order of the returned collection. links may be modified by this method, and the returned value may or may not be the same object as the input links itself.
        Parameters:
        links - set of RowLinks representing actual matches
        rowCounts - numbers of rows in the tables on which the match was performed
        Returns:
        set of RowLinks representing rows for the output table
      • getUsedTableFlags

        public abstract boolean[] getUsedTableFlags()
        Returns an array of flags indicating whether each of the tables in the input will ever have non-empty rows in the output.
        Returns:
        2-element boolean array indicating whether first and second input tables appear in output
      • getUsedMatchFlag

        public abstract boolean getUsedMatchFlag()
        Returns a value which indicates whether the matchScore is ever non-empty in the output table.
        Returns:
        true iff the matchScore may be used in the output
      • getName

        public java.lang.String getName()
        Returns the name of this type.
        Returns:
        name
      • getDescription

        public abstract java.lang.String getDescription()
        Returns a short textual description of this type.
        Returns:
        description
      • toString

        public java.lang.String toString()
        Returns the name of this type.
        Overrides:
        toString in class java.lang.Object
      • getPairTypes

        public static JoinType[] getPairTypes()
        Returns a list of all the known types which apply to two-table matches.
        Returns:
        array of the 7 known types