Class VirtualTable

  • All Implemented Interfaces:
    TableDataSource

    public class VirtualTable
    extends JoinedTable
    A VirtualTable is a representation of a table whose rows are actually physically stored in another table. In other words, this table just stores pointers to rows in other tables.

    We use the VirtualTable to represent temporary tables created from select, join, etc operations.

    An important note about VirtualTables: When we perform a 'select' operation on a virtual table, unlike a DataTable that permanently stores information about column cell relations, we must resolve column relations between the sub-set at select time. This involves asking the tables parent(s) for a scheme to describe relations in a sub-set.

    Author:
    Tobias Downer
    • Field Detail

      • row_list

        protected IntegerVector[] row_list
        Array of IntegerVectors that represent the rows taken from the given parents.
    • Constructor Detail

      • VirtualTable

        protected VirtualTable()
    • Method Detail

      • init

        protected void init​(Table[] tables)
        Helper function for the constructor.
        Overrides:
        init in class JoinedTable
      • getReferenceRows

        protected IntegerVector[] getReferenceRows()
        Returns the list of IntegerVector that represents the rows that this VirtualTable references.
      • resolveRowForTableAt

        protected int resolveRowForTableAt​(int row_number,
                                           int table_num)
        Description copied from class: JoinedTable
        Given a row and a table index (to a parent reference table), this will return the row index in the given parent table for the given row.
        Specified by:
        resolveRowForTableAt in class JoinedTable
      • resolveAllRowsForTableAt

        protected void resolveAllRowsForTableAt​(IntegerVector row_set,
                                                int table_num)
        Description copied from class: JoinedTable
        Given an IntegerVector that represents a list of pointers to rows in this table, this resolves the rows to row indexes in the given parent table. This method changes the 'row_set' IntegerVector object.
        Specified by:
        resolveAllRowsForTableAt in class JoinedTable