Database Management Applications (WGU)
access plan
A set of instructions generated at application compilation time that is created and managed by a
DBMS. The access plan predetermines how an application's query will access the database at run
time.
algorithms
A process or set of operations in a calculation.
automatic query optimization
A method by which a DBMS finds the most efficient access path for the execution of a query.
B-tree index
An ordered data structure organized as an upside-down tree.
bitmap index
An index that uses a bit array (0s and 1s) to represent the existence of a value or condition.
buffer cache
See data cache.
data cache
A shared, reserved memory area that stores the most recently accessed data blocks in RAM. Also
called buffer cache.
data files
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 data file can contain rows from one
or more tables.
data sparsity
A column distribution of values or the number of different values a column can have.
database performance tuning
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.
database statistics
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.