final cit

flashcards

17 cards·by warnerdouglasr

Data Sparcity

refers to the different number of values a column could possibly

Query optimizer

analysis the SQL query and finds the most effecient way to access the data

database statistics

number of measurements about database objects processors used, processor speed, or temporary space available

I/O request

in and out is a low level (read or write) data access operation to and from computer devices

What are three ways to prevent deadlocks?

Prevention, Detection, and Avoidance

Data Cache

is a shared, reserved memory area that stores the most recently accessed data blocks in RAM

SQL Cache

is a shared, reserved memory area that stores the most recent SQL statements

Database Performance Tunning

Refers to the activities and procedures designed to reduce the response time of the database system

Parsing

parses the SQL query and chooses the most effecient access/execution plan

Execution

executes the SQL query, using the chosen execution plan

Execution

executes the SQL query, using the chosen execution plan

fetching

fetches the data and sends the result set back to the client

Access Plan

is the result of parsing an SQL statement

wait/die

the older transaction waits for the younger to complete and releases its lock

wound/wait

the older transaction rolls back the younger transaction and reschedules it

what is a transaction?

unit of work

Uniqueness

ensures that no equal time stamp values can exist