dbms quiz 3

Read

transfer data from disk to main memory (RAM)

Write

transfer data from RAM to disk

Seek Time

moving arms to position disk head on track

rotational delay

waiting for block to rotate under head

transfer time

actually moving data to/from disk surface

Disk Array

arrangement of several disks that gives abstraction of a single, large disk.

Disk page

a fixed-size block of data in a disk storage system, managed by the operating system and used for efficient data transfer.

free freame

a memory page not currently assigned to any process, allowing for efficient allocation of resources in a memory management system.

buffer pool

a collection of memory buffers used to store data temporarily to reduce the frequency of disk access and improve overall system performance.

file

A collection of pages, each containing a collection of records

Disks

Can retrieve random page at fixed cost

Tapes

Can only read pages in sequence

File organization

Method of arranging a file of records on external storage

Architecture

Buffer manager stages pages from external storage to main memory buffer pool. File and index layers make calls to the buffer manager.

index on a file

A structure that improves the speed of data retrieval operations on a database table, allowing for faster access to records.

B tree indexes

a type of data structure that maintains sorted data and allows for efficient insertion, deletion, and search operations, commonly used in databases for indexing.

B tree Leaf pages

Pages that contain actual records or pointers to records in a B-tree structure, usually at the lowest level of the tree.

B tree Non-leaf pages

pages that contain index entries in a B tree structure, assisting in navigation and indexing.

clustered index

A type of database index that sorts and stores the actual data rows in the table according to the indexed column, allowing for faster retrieval.

unclustered index

A type of index in a database that does not sort the actual table rows but contains pointers to the rows, allowing for alternative ways to access data.