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Microsoft SQL Server 2008 R2 Unleashed- P117

Microsoft SQL Server 2008 R2 Unleashed- P117:SQL Server 2005 provided a number of significant new features and enhancements over what was available in SQL Server 2000. This is not too surprising considering there was a five-year gap between these major releases.Microsoft SQL Server 2008 is not as much of a quantum leap forward from SQL Server 2005 | 1104 CHAPTER 34 Data Structures Indexes and Performance TABLE 34.4 Information Contained in the Page Header Page Header Fields Description PageID Unique identifier for the page. It consists of two parts the file ID number and page number. NextPage File number and page number of the next page in the chain 0 i f the page is the last or only page in the chain or if the page belongs to a heap table . PrevPage File number and page number of the previous page in the chain 0 i f the page is the first or only page in the chain or if the page belongs to a heap table . ObjectID ID of the object to which this page belongs. PartitionID ID of the partition of which this page is a part. AllocUnitID ID of the allocation unit that contains this page. LSN Log sequence number LSN value used for changes and updates to this page. SlotCnt Total number of rows slots used on the page. Level Level at which this page resides in an index tree 0 indicates a leaf page or data page . IndexID ID of the index this page belongs to 0 indicates that it is a data page . freedata Byte offset where the available free space starts on the page. Pminlen Minimum size of a data row. Essentially this is the number of bytes in the fixed-length portion of the data rows. FreeCnt Number of free bytes available on the page. reservedCnt Number of bytes reserved by all transactions. Xactreserved Number of bytes reserved by the most recently started transaction. tornBits Bit string containing 1 bit per sector for detecting torn page writes or checksum information if torn_page_detection i s not on . flagBits Two-byte bitmap that contains additional information about the page. The Data Rows Following the page header starting at byte 96 on the page are the actual data rows. Each data row has a unique row number within the page. Data rows in SQL Server cannot cross page boundaries. The maximum available space in a SQL Server page is 8 060 bytes of in-row data. When a data row is logged in the transaction log for an .