Exemplo n.º 1
0
        public static void Sort(Table Element, RecordMatcher Comparer)
        {
            // Check that this is a heap table //
            if (!(Element is HeapTable))
            {
                throw new Exception("Can only sort heap tables");
            }
            if (Element.Header.IndexHeaders.Count != 0)
            {
                throw new Exception("Cannot sort a table with indexes");
            }

            // Sort each element //
            SortEach(Element, Comparer);

            // Merge sort //
            Table.PageWalker x = new Table.PageWalker(Element);
            Table.PageWalker y = new Table.PageWalker(Element);

            while (x.CanAdvance)
            {
                // Get x's page //
                Page A = x.SelectNext();

                // Break if we on the last page //
                if (A.NextPageID == -1)
                {
                    break;
                }

                // Open a new page walker that starts at the next page //
                y.ToPage(A.NextPageID);

                // Loop through y //
                while (y.CanAdvance)
                {
                    // Get the second page //
                    Page B = y.SelectNext();

                    // Merge //
                    Merge(A, B, Comparer);

                    // Set B //
                    Element.SetPage(B);
                }

                // A is final at this point //
                Element.SetPage(A);
            }
        }
Exemplo n.º 2
0
        private static void SortEach(Table Element, RecordMatcher Comparer)
        {
            if (Element.Header.ClusterKey.Count != 0)
            {
                throw new Exception("Can only sort a heap table");
            }

            if (Element.RecordCount == 0)
            {
                return;
            }

            Table.PageWalker walker = new Table.PageWalker(Element);

            while (walker.CanAdvance)
            {
                Page p = walker.SelectNext();
                Sort(p, Comparer);
                Element.SetPage(p);
            }
        }