Table Organization

The data for each table now is stored in a collection of 8-KB data pages. Each data page has a 96-byte header containing system information, such as the ID of the table that owns the page and pointers to the next and previous pages for pages linked in a list. A row-offset table is at the end of the page; data rows fill the rest of the page.

SQL Server 7.0 tables use one of two methods to organize data pages:

• Clustered tables, which are tables that have a clustered index. The data rows are stored in order based on the clustered index key. The data pages are linked in a doubly linked list, and the index is implemented as a B-tree index structure that supports fast retrieval of the rows based on their clustered index key values.
• Heaps, which are tables that have nonclustered indexes. The data rows are not stored in any particular order, and there is no particular order to the sequence of the data pages. The data pages are not linked in a linked list.