A disk system that comprises multiple disk drives (an array) to provide higher performance, reliability, storage capacity, and lower cost. Fault-tolerant arrays are categorized in six RAID levels: 0 through 5. Each level uses a different algorithm to implement fault tolerance.
rebuilding indexes
Helps in collecting the defragmented pages of information and bringing index data back to its original form. This increases the overall performance by making it easier for SQL Server to read pages to get data.
recompile
The queries used by stored procedures and triggers are optimized only when they are compiled. As indexes or other changes that affect statistics are made to the database, compiled stored procedures and triggers may lose efficiency. By recompiling stored procedures and triggers that act on a table, you can reoptimize the queries.
reconfigure
Command used to update the currently configured value of a configuration option changed with the sp_configure system stored procedure.
recursive trigger
A recursive trigger is a trigger that updates, deletes, or inserts data into its own table or another table, which houses a trigger, and then fires another trigger.
relational database
A collection of information organized in tables. Each table models a class of objects of interest to the organization (for example, Customers, Parts, Suppliers). Each column in a table models an attribute of the object (for example, LastName, Price, Color). Each row in a table represents one entity in the class of objects modeled by the table (for example, the customer name John Smith or the part number 1346). Queries can use data from one table to find related data in other tables.
Relational Database Management System
The controlling software for databases in which data is organized into related objects within a database rather than tied to a file. Each of these objects is related to another in some way.
relationship
A connection between entities ties a parent entity to a child entity through the Primary Key in one entity to a Foreign Key in another.
replication
A process that copies and distributes data and database objects from one database to another and then synchronizes information between databases for consistency.
Replication agent
Tool that enables SQL Server to perform the different types of replication processes when distributing data.
replication configurations
Different physical scenarios in which replication is set up; these provide specific benefits and uses that are relevant to the configuration you use. Replication models, which include Single Publisher/Multiple Subscriber, Single Subscriber/Multiple Publishers, and Multiple Publishers/Multiple Subscribers, are the physical implementation. Each of the replication types may be implemented using any of the these models.
roles
A SQL Server security account is a collection of other security accounts that can be treated as a single unit when managing permissions. A role can contain SQL Server logins, other roles, and Windows logins or groups.
row lock
The finest granularity of locking available on SQL Server allowing for a single data record to be locked.
rules
A database object that is bound to columns or user-defined data types, and specifies what data values are acceptable in a column. CHECK constraints provide the same functionality and are preferred because they are in the SQL-92 standard.
