Expert Oracle Exadata - Parent Directory

CHAPTER 3 HYBRID COLUMNAR COMPRESSIONCommon andVariable HeaderTable DirectoryRow DirectoryFree SpaceDatabaseBlockRow DataFigure 3-1. The standard Oracle block format (row-major storage)Rows are stored in no specific order, but columns are generally stored in the order in which theywere defined in the table. For each row in a block there will be a row header, followed by the columndata for each column. Figure 3.2 shows how the pieces of a row are stored in a standard Oracle block.Note that we called it a row piece, because occasionally a row’s data may be stored in more than onechunk. In this case, there will be a pointer to the next piece.Common andVariable HeaderTable DirectoryRow DirectoryFree SpaceRow HeaderColumn DataDatabaseBlockRow DataColumn LengthColumn ValueColumn LengthColumn ValueFigure 3-2. The standard Oracle row format (row-major storage)66