Class BranchRow


  • public class BranchRow
    extends java.lang.Object
    Implements row which is stored in the branch pages of a btree. A non-suffix compressed branch row contains all of the columns of the leaf rows of a btree and contains an additional field at the end. The extra field of a branch row in a branch page at level N, is the child page field pointing the page at level N-1 which has keys which follow or equal the branch row entry. There are 3 ways to use this class to produce a branch row: createEmptyTemplate() creates a empty row template createBranchRowFromOldBranchRow() creates a new row with reference to an old branch row. createBranchRowFromOldLeafRow() creates a new row with reference to an old leaf row.
    • Constructor Detail

      • BranchRow

        private BranchRow()
        Constuctor for creating an "empty" BranchRow template, suitable for reading in a branchRow from disk.
    • Method Detail

      • getChildPage

        private SQLLongint getChildPage()
        Accessor for the child page field of the branch row.
        Returns:
        The child page object.
      • createEmptyTemplate

        public static BranchRow createEmptyTemplate​(Transaction rawtran,
                                                    BTree btree)
                                             throws StandardException
        Create an empty branch row template suitable for reading branch rows in from disk. This routine will create newly allocated "empty" objects for every column in the template row.
        Throws:
        StandardException - Standard exception policy.
      • createBranchRowFromOldBranchRow

        public BranchRow createBranchRowFromOldBranchRow​(long childpageno)
        Create a new branch row, given a old branch row and a new child page. Used by BranchControlRow to manufacture new branch rows when splitting or growing the tree. There is no way to "copy" values of a template row, so this class just stores a reference to each of the columns of the Indexable row passed in. This is ok as all usages of this class when instantiated this way, have an old branch row from which they are creating a new branch row with the same key values, and a different child page number. WARNING - this branch row is only valid while the old branch row is valid, as it contains references to the columns of the old branch row. So use of the row should only provide read-only access to the objects of the old branch row which are referenced.
      • createBranchRowFromOldLeafRow

        public static BranchRow createBranchRowFromOldLeafRow​(DataValueDescriptor[] leafrow,
                                                              long childpageno)
        Create a new branch row, given a old leaf row and a new child page. Used by LeafControlRow to manufacture new branch rows when splitting or growing the tree. There is no way to "copy" values of a template row, so this class just stores a referece to the Indexable row passed in. This is ok as all usages of this class when instantiated this way, have an old leaf row from which they are creating a new branch row with the same key values, and a different child page number. WARNING - this branch row is only valid while the old leaf row is valid, as it contains references to the columns of the old leaf row. So use of the row should only provide read-only access to the objects of the old leaf row which are referenced.
      • getRow

        protected DataValueDescriptor[] getRow()
        Return the branch row.

        Return the DataValueDescriptor array that represents the branch row, for use in raw store calls to fetch, insert, and update.

        Returns:
        The branch row object array.
      • setPageNumber

        protected void setPageNumber​(long page_number)
        Set the page number field of the branch row to a new value.
        Parameters:
        page_number - the new page number.
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object