- The data in SQL Server is stored in the form of data pages.
- The size of each data page is 8kb.
- The data page contains the page header which is 96 bytes.
- The header will have previous pointer (PP), object id, next pointer (NP).
- The previous pointer pointing to the previous page, this value is NULL for first page.
- The next pointer pointing to the next page, it’s value is NULL for the last page.
In SQL Server Data will be accessed in two ways.
Table Scan : It starts from beginning of the table and scan each and every page for required data, it extracts the rows to meet the query criteria.
Using Index: When index is created for a table, it travels through index tree structure to determine the required rows and extracts the rows which will meets the query criteria.