Data Management - Applications 4 Flashcards
An ordered data structure organized as an upside-down tree.
An index that uses a bit array (0s and 1s) to represent the existence of a value or condition.
A shared, reserved memory area that stores the most recently accessed data blocks in RAM. Also called buffer cache.
B-tree index / bitmap index / data cache
A named physical storage space that stores a database’s data. It can reside in a different directory on a hard disk or on one or more hard disks. All data in a database is stored in data files. A typical enterprise database is normally composed of several data files. A ??? ??? can contain rows from one or more tables.
data files
A column distribution of values or the number of different values a column can have.
A set of activities and procedures designed to reduce the response time of a database system—that is, to ensure that an end-user query is processed by the DBMS in the minimum amount of time.
data sparsity / database performance tuning
In query optimization, measurements about database objects, such as the number of rows in a table, number of disk blocks used, maximum and average row length, number of columns in each row, and number of distinct values in each column. Such statistics provide a snapshot of database characteristics.
database statistics
Activities to ensure that clients’ requests are addressed as quickly as possible while making optimum use of existing resources.
The process of determining the SQL access strategy at run time, using the most up-to-date information about the database.
DBMS performance tuning / dynamic query optimization
In a DBMS, the capability to automatically evaluate and update the database access statistics after each data access operation.
In a DBMS environment, refers to the ability of data files to expand in size automatically using predefined increments.
dynamic statistical generation mode / extents
A mode of generating statistical data access information for query optimization. In this mode, the DBA must periodically run a routine to generate the data access statistics—for example, running the RUNSTAT command in an IBM DB2 database.
manual statistical generation mode
A DBMS process that analyzes SQL queries and finds the most efficient way to access the data. The ??? ??? generates the access or execution plan for the query.
A query optimization technique that uses preset rules and points to determine the best approach to executing a query.
query optimizer / rule-based query optimization algorithm
A query optimization mode in which the access path to a database is predetermined at compilation time.
A query optimization technique that uses statistical information about a database. The DBMS then uses these statistics to determine the best access strategy.
static query optimization / statistically based query optimization algorithm
In a DBMS, a logical storage space used to group related data. Also known as a file group.
table space
