SEEK

SQL Server

Example

SET STATISTICS IO ON;
SELECT * FROM Employees
WHERE EmployeeID = 5;
SET STATISTICS IO OFF;

Output

Table 'Employees'. Scan count 0, logical reads 3

Explanation

In the example above, the SEEK operation was used during the execution of the SELECT statement. Sql Server had to look for the particular Employee whose EmployeeID is 5, hence it executed an Index Seek operation. ‘Scan count 0, logical reads 3’ implies that it had to perform 3 logical reads to retrieve the Employee information but it did not have to perform a full scan. This number represents the number of pages read from disk, which makes seek operations far more efficient than scan operations when retrieving a small subset of a large dataset.