Modern Database Management - Chapter 6
Extent
A contiguous section of disk storage space
Data type
A detailed coding scheme recognized by system software, such as a DBMS, for representing organizational data.
Pointer
A field of data that can be used to locate a related field or record of data.
Hashed index table
A file organization that uses hashing to the map a key into a location in a index, where there is a pointer to the actual data record matching the hashing key.
Physical record
A group of fields stored in adjacent memory locations and retrieved and written. together as a unit by a DBMS.
Physical file
A named portion of secondary memory (a magnetic tape pr hand disk.) allocated for the purpose of storing physical records
Tablespace
A named set of disk storage elements in which physical files for database tables may be stored.
Hashing algorithm
A routine that converts a primary key value into a relative record number ( or relative file address).
Redundant Array of Inexpensive Disks (RAID)
A set, or array of physical disk drives that appears to the database user (and programs) as if they form one large logical storage unit.
Hashed file organization
A storage system in which the address for each record is determined using a hashing algorithm.
Bitmap index
A table of bits in which each row represents the distinct values of a key and each column is a bit, which when on indicates that the record for that bit column position has the associated field value
Index
A table or data structure used to determine the location of rows in a file that satisfy some condition.
File organization
A technique for physically arranging the records of a file on secondary storage devices.
Join index
An index on columns from two or more tables that come from the same domain of values
Vertical partitioning
Distributing the columns of a table into several separate physical records
Horizontal partitioning
Distributing the rows of a table into several separate files
Secondary key
One field or a combination of fields for which more then one record may have the same combination of values. Also called a nonunique key.
Field
The Smallest unit of named application data recognized by system software.
Page
The amount of data read or written by an operating system in one secondary memory (disk) input or output (I/O) operation. For I/O with a magnetic tape, the equivalent term is record block.
Blocking Factor
The number of physical records per page.
Denormalization
The process of transforming normalized relations into unnormalized physical records specifications
Stripe
The set of pages on all disk in a RAID that are the same relative distance from the beginning of the disk drive.
Sequential file organization
The storage of record in a file sequence according to a primary key value.
Indexed file organization
The storage of records either sequentially or nonsequentially with an index that allows software to locate individual records