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The logical design of a database can greatly impact the speed and efficiency of the system (Ball State University, 2015). Changes made once the database is running can negatively impact the various processes and degrade performance.

It is important to use a physical model on which to base the database design keeping in mind the relationships that exist between the tables, primary keys, foreign keys, and other constraints (Akkawi et al., 2014). Normalization, or formally separating the data into multiple related tables, can improve data integrity and reduce storage needs but can slow performance as tables are put back together for queries (Ball State University, 2015).

Additionally, data types should be chosen based on the least amount of space needed to have accurate values; also consider how the data will be compared because converting it later adds to the resources needed to perform the queries (Akkawi et al., 2014). There are also straightforward guidelines to limit the demands on physical resources (Akkawi et al., 2014):

· Avoid using operators such as LIKE which result in a full table scan

· In SELECT statements, list the necessary column names rather than using *

· Let the client application perform the sort to save memory

· Use fully qualified names so the database engine does not have to resolve the logical name

· Include all columns that are part of a foreign key in a JOIN clause

· Subqueries should be limited as they degrade performance

Using the following guidelines when creating indexes can improve performance as well as save resources by aiding in faster searches (Larsen, 2011):

· Columns used on WHERE and JOIN statements are good for index key columns

· Keep keys narrow so the disk space needed to store index key values is small

· Use unique clustered index keys or SQL will add additional bytes to make them unique

References:

Akkawi, F., Akkawi, K., & Schofield, G. (2014). MCSA guide to Microsoft SQL server 2012. Boston, MA: Course Technology, Cengage Learning.

Ball State University. (2015). Database design. Retrieved from https://apps.bsu.edu/AdminConsole/Documentation/SQL/Design/Database.aspx

Larsen, G. (2011). Physical database design consideration. Retrieved from http://www.databasejournal.com/features/mssql/physical-database-design-consideration.html