Database Scanning Methods

SQL-compliant databases provide a number of different methods for scanning, searching, and selecting data. The right scan method to use is very much dependent on the use case and the state of the database at the time of scanning. How many records are in the database? Which fields are we interested in? How many records do we expect to be returned? How often do we need to execute the query? These are just some of the questions that we may want to ask when selecting the most appropriate scanning method.

Throughout this section, we will describe some of the search methods available, how they are used within SQL to execute scans, and a number of scenarios where they should/should not be used.

Query Planning

Before investigating the different methods of executing queries or scanning a database for information, it is useful to understand how the SQL server makes various decisions about the types of queries to be used. SQL-compliant databases possess a powerful...