APCSP Unit 4

creator of Napoelon's 1812 Infographic

Charles Minard

creator of the 1854 cholera outbreaks infographic

John Snow

Correlation does not equal causation

True

two-phase commit protocol

standardized way to make sure all data can be written without any inconsistencies. 1st phase: check if all processes can be completed. Second phase will commit all processes.

deadlock

when two transactions are trying to lock the same row and neither can continue until the other is complete.

keys

columns that hold unique values that distinguish each record from others

virtual table

temporary tables that help reduce redundant data

Structured Query Language (SQL)

Language used to manage, access, and manipulate relational databases

SELECT

DISTINCT

unique values

FROM

WHERE

only records of certain criteria

LIKE

used with wildcard underscore

ORDER

sort data

BY

sort data

ASC

ascending order

DESC

descending order

LIMIT

limit the results to a certain number of rows

JOIN

combine entries from two or more tables

fault-tolerance

ability of a system to continue to run properly even if pieces fail

big data

sets of data that are larger than a consumer software application can handle.

atomic transaction

transaction where all components must be carried out before the transaction is considered complete such that all occur or none occur

Consistency

the fact that information from one table does not contradict itself in any other table throughout a database

idempotency

when the operation results in same end result no matter how many times performed

relational database

database that has multiple tables that are connected by unique keys

rollback

returning back to database state before write-ahead log began

simpson's paradox

when multiple groups of data trend in one direction but when combined with other sets the trend disappears/reverses

write-ahead logging

method for avoiding inconsistencies in which all transactions are written and saved to a log