cache aging
The mechanism of caching that determines when a cache row is outdated and when it must be refreshed.
cached execution plan
A query execution plan that has been inserted into the execution plan, cached, and is available for reuse on the next execution of the query. Cached execution plans are one of the major performance features of SQL Server and allow the optimization step of query execution, which can be time-consuming, to be avoided on subsequent query executions. Execution plans are aged out of cache when they have not been accessed for a certain amount of time and each time the server is rebooted.
calculated column
A column in a table that displays the result of an expression rather than stored data (for example, CalculatedCostColumn = Price * Quantity).
calculated field
A field defined in a query that displays the result of an expression, rather than stored data.
A member of a dimension whose value is calculated at run time by using an expression. Calculated member values can be derived from other members' values. A calculated member is any member that is not an input member. For example, a calculated member Profit can be determined by subtracting the value of the member Costs from the value of the member Sales. See also input member.
A multidimensional expressions (MDX) logical expression used to determine whether a calculation formula will be applied against a cell in a calculation subcube. See also solve order.
A multidimensional expression (MDX) used to supply a value for cells in a calculation subcube (subject to the application of a calculation condition). See also solve order.
A stage of calculation in a multidimensional cube in which applicable calculations are evaluated. Multiple passes might be required to complete all calculations. See also solve order.
The set of multidimensional cube cells used to create a calculated cells definition. The set of cells is defined by a combination of multidimensional expressions (MDX) set expressions. See also solve order.
The interface supported by ODBC for use by an application.
candidate key
A column (or set of columns) that has a unique value for each row in a table. Each candidate key value uniquely identifies a single row in the table. Tables can have multiple candidate keys. One candidate key in a table is specified by the database designer to be the primary key for the table, and any other candidate key is called an alternate key.
A ratio that describes the number of relationship instances (for example, one-to-many).
cascading delete
An operation that deletes a row containing a primary key value that is referenced by foreign key columns in existing rows in other tables. On a cascade delete, all of the rows whose foreign key values reference the deleted primary key value are also deleted.
cascading update
An operation that updates a primary key value that is referenced by foreign key columns in existing rows in other tables. On a cascade update, all of the foreign key values are updated to match the new primary key value.
In data mining, an abstract view of data characterized by attributes and relations to other cases. A case is a distinct member of a case set and can be a member of multiple case sets. See also attribute, case key, case set.
In data mining, the element of a case by which the case is referenced within a case set. See also case.
In data mining, a set of cases. See also case.
cell
In a cube, the set of properties, including a value, specified by the intersection when one member is selected from each dimension.
certificate
A collection of data used for authentication and the secure exchange of information on non-secure networks, such as the Internet. A certificate securely binds a public encryption key to the entity that holds the corresponding private encryption key. Certificates are digitally signed by the issuing certification authority and can be managed for a user, computer, or service.
change script
A text file that contains SQL statements for all changes made to a database, in the order in which they were made, during an editing session. Each change script is saved in a separate text file with a .SQL extension. Change scripts can be applied back to the database later by using a tool such as osql.
changing dimension
A dimension that has a flexible member structure. A changing dimension is designed to support frequent changes to structure and data.
char data type
A character data type that holds a maximum of 8000 characters.
Data stored in a bulk-copy data file by using text characters. See also native format.
character set
A character set determines the types of characters that SQL Server recognizes in the char, varchar, and text data types. Each character set is a set of 256 letters, digits, and symbols specific to a country or language. The printable characters of the first 128 values are the same for all character sets. The last 128 characters, sometimes referred to as extended characters, are unique to each character set. A character set is related to, but separate from, Unicode characters.
CHECK constraint
Defines which data values are acceptable in a column. You can apply CHECK constraints to multiple columns, and you can apply multiple CHECK constraints to a single column. When a table is dropped, CHECK constraints are also dropped.
An event in which the database engine writes dirty buffer pages to disk. Dirty pages are pages that have been modified, but the modifications have not yet been written to disk. Each checkpoint writes to disk all pages that were dirty at the last checkpoint and that still have not been written to disk. Checkpoints occur periodically based on the number of log records generated by data modifications or when requested by a user or a system shutdown.
child
A member in the next lower level in a hierarchy that is directly related to the current member. For example, in a Time dimension containing the levels Quarter, Month, and Day, January is a child of Qtr1.
classification
See prediction.
clause
In English Query, a sequence of related words within a sentence that have both a subject and a predicate and that function as either an independent or a dependent unit. In Transact-SQL, a clause is a subunit of a SQL statement. A clause begins with a keyword.
See call-level interface (CLI).
client application
An application that retrieves data from an Analysis server and that performs local analysis and presentation of data from relational or multidimensional databases. Client applications connect to the Analysis server through the PivotTable Service component.
client cursor
A cursor implemented on the client. The entire result set is first transferred to the client, and the client application programming interface (API) software implements the cursor functionality from this cached result set.
An index in which the logical order of the key values determines the physical order of the corresponding rows in a table.
A data mining technique that analyzes data in order to group records together according to their location within the multidimensional attribute space. Clustering is an unsupervised learning technique. See also segmentation.
code page
For character and Unicode data, a definition of the bit patterns that represent specific letters, numbers, or symbols (such as 0x20 representing a blank space and 0x74 representing the character 't'). Some data types use one byte per character, and each byte can have one out of 256 different bit patterns.
A set of rules that determines how data is compared, ordered, and presented. Character data is sorted by using collation information, including locale, sort order, and case-sensitivity. See also locale, SQL collation.
In a SQL table, the area in each row that stores the data value for some attribute of the object modeled by the table. For example, the Employees table in the Northwind sample database models the employees of the Northwind Traders company. The LastName column in each row of the Employees table stores the last name of the employee represented by that row in the same way that a Last Name field in a window or form would contain a last name. See also row.
column filter
Column filters restrict the columns to be included as part of a snapshot or transactional or merge publication.
column-level collation
The capability of SQL Server 2000 to support multiple collations in a single instance. Databases can have default collations different from the default collation of the instance. Individual columns and variables can be assigned collations different from the default collation for the instance or database. Each column in a table can have a different collation.
A constraint definition that is specified within a column definition when a table is created or altered. The constraint applies only to the associated column. See also constraint.
COM
See Component Object Model (COM).
A Component Object Model (COM) compound file used by Data Transformation Services (DTS) to store the version history of a saved DTS package.
command relationship
Provides instructions to hardware based on natural-language questions or commands (for example, 'Play the album with song XXX on it').
An operation that saves all changes to databases, cubes, or dimensions made since the start of a transaction. A commit guarantees that all of the transaction's modifications are made a permanent part of the database, cube, or dimension. A commit also frees resources, such as locks, that are used by the transaction. See also rollback.
A Microsoft specification for developing component software. Several SQL Server and database application programming interfaces (APIs) such as SQL-DMO, OLE DB, and ADO are based on COM. Some SQL Server components, such as Analysis Services and English Query, store objects as COM objects. See also method.
composite index
An index that uses more than one column in a table to index data.
composite key
A key composed of two or more columns.
computed column
A virtual column in a table whose value is computed at run time. The values in the column are not stored in the table but are computed based on the expression that defines the column.
concatenation
To combine two or more character strings or expressions into a single character string or expression or to combine two or more binary strings or expressions into a single binary string or expression.
concurrency
A process that allows multiple users to access and change shared data at the same time. SQL Server uses locking to allow multiple users to access and change shared data at the same time without a conflict.
connection
An interprocess communication (IPC) linkage established between a SQL Server 2000 application and an instance of SQL Server 2000. The connection is a network link if the application is on a computer different from the SQL Server 2000 instance. If the application and the SQL Server 2000 instance are on the same computer, the linkage is formed through a local IPC mechanism, such as shared memory. The application uses the IPC linkage to send Transact-SQL statements to SQL Server and to receive result sets, errors, and messages from SQL Server.
At the end of a transaction, all of the data must be consistent, with data integrity intact. Consistency is one of the four characteristics required for a unit of work to be considered a transaction.
constant
A group of symbols that represent a specific data value. The format of a constant depends on the data type of the value that it represents. For example, 'abc' is a character string constant, '123' is an integer constant, 'December_16,_1999' is a datetime constant, and '0x02FA' is a binary constant.
A property assigned to a table column that prevents certain types of invalid data values from being placed in the column. For example, a UNIQUE or PRIMARY_KEY constraint prevents you from inserting a value that is a duplicate of an existing value; a CHECK constraint prevents you from inserting a value that does not match a search condition; and NOT_NULL prevents you from inserting a NULL value. See also column-level constraint.
continuation media
The backup media used when the initial medium becomes full, allowing continuation of the backup operation.
control-break report
A report that summarizes data in user-defined groups or breaks. A new group is triggered when different data is encountered.
control-of-flow language
Transact-SQL keywords that control the flow of execution of SQL statements and statement blocks in triggers, stored procedures, and batches.
correlated subquery
A subquery that references a column in the outer statement. The inner query is executed for each candidate row in the outer statement.
CPU busy
A SQL Server statistic that reports the time (in milliseconds) that the central processing unit (CPU) spent on SQL Server work.
crosstab query
Displays data for summarized values from a field or a table and then groups them by two sets of facts: one down the left side and the other across the top of the data sheet.
An aggregate function to return the number of items in a group.
A set of data that is organized and summarized into a multidimensional structure defined by a set of dimensions and measures. See also multidimensional structure.
cube file
See local cube.
A collection of users and groups that have the same access to a cube. A cube role is created when you assign a database role to a cube, and it applies only to that cube. See also database role.
An entity that maps over a result set and establishes a position on a single row within the result set. After the cursor is positioned on a row, operations can be performed on that row or on a block of rows starting at that position. The most common operation is to fetch (retrieve) the current row (or block of rows).
cursor data type
A special data type used to reference a cursor.
cursor library
A part of the ODBC and DB- Library application programming interfaces (APIs) that implements client cursors. A cursor library is not commonly used in current systems; rather, server cursors are used instead.
custom rollup
An aggregation calculation that is customized for a dimension level or member and that overrides the aggregate functions of a cube's measures.
In a role, a specification that limits the dimension members or cube cells that users in the role are permitted to access. See also database role.