Lesson 5 Indexes (FLASH CARDS) - C170 - Database Management Applications (WGU)

Lesson 5 Indexes (FLASH CARDS) - C170 - 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. DBMS performance tuning