FIX: SQL Server 2000 May Be More Aggressive with Read-Ahead Than SQL Server 7.0 (305377)

SYMPTOMS

SQL Server 2000 may be more aggressive in using the read-ahead features to issue asynchronous I/O for a query than SQL Server 7.0. Some types of queries, such as those that use a TOP N clause, may issue unnecessary I/O to the disk for database pages that the query does not need.

RESOLUTION

To resolve this problem, obtain the latest service pack for Microsoft SQL Server 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

290211 INF: How to Obtain the Latest SQL Server 2000 Service Pack

Hotfix

NOTE: The following hotfix was created prior to Microsoft SQL Server 2000 Service Pack 2.

The English version of this fix should have the following file attributes or later:

   Version     File name       Platform
   -------------------------------------
   8.00.428    Sqlservr.exe    i386

NOTE: Due to file dependencies, the most recent hotfix or feature that contains the preceding files may also contain additional files.

MORE INFORMATION

With the change provided by the hotfix, SQL Server 2000 issues read-ahead in a similar fashion as before, but in a more steady, "scale-up" approach. This behavior allows queries that truly benefit from read-ahead to achieve the same performance as before, while queries that may not need read-ahead as much may not cause any performance degradation because of unnecessary I/O.