Lecture 4 Flashcards

1
Q

OLTP?

A

Online Transaction Processing

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2
Q

OLAP

A

Online Analytical Processing

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3
Q

Where is OLTP used?

A

E-commerce
Banking
Airline Reservations

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4
Q

OLTP (User facing)

A

Real-Time
Low latency
Highly-concurrent

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5
Q

OLTP (Tasks)

A

Relatively small set of standard transactional queries

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6
Q

OLTP (Data access pattern)

A

Random leads
Updates
Writes

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7
Q

Where is OLAP used?

A

Business intelligence

Data mining

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8
Q

OLAP (Back-end processing)

A

Batch workloads

Less concurrency

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9
Q

OLAP (Tasks)

A

Complex analytical queries

Ad-hoc

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10
Q

OLAP (Data access pattern)

A

Table scans

Large amounts of data involved per query

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11
Q

OLAP Example?

A

Amazon analyzes purchases by its customers to come up with an individual screen with products of likely interest to the customer

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12
Q

Downsides of co-existing OLTP and OLAP workloads?

A

Poor memory management
Conflicting data access patterns
Variable latency

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13
Q

Solution for having both OLTP and OLAP with no downsides?

A

Separate databases
User-facing OLTP database for high-volume transactions
Data warehouse for OLAP workloads

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14
Q

How to connect OLTP with OLAP?

A

ETL

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15
Q

What does ETL stand for?

A

Extract
Transform
Load

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16
Q

`What is Data Warehouse?

A

A physical repository where relational data are specially organized to provide enterprise-wide, cleansed data in a standardized format

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17
Q

Characteristics of DWs?

A
Subject oriented
Integrated
Time-variant
Nonvolatile
Summarized
Not normalized
Metadata
Web based
Client/server
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18
Q

What is Data Mart?

A

A departmental small-scale DW that stores only limited/relevant data

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19
Q

Two types of Data Mart?

A

Dependent data mart

Independent data mart

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20
Q

Dependent data mart?

A

A subset that is created directly from a data warehouse

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21
Q

Independent data mart?

A

A small data warehouse designed for a strategic business unit or a department

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22
Q

Other DW Components?

A

ODS
Oper marts
EDW
Metadata

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23
Q

ODS?

A

Operational Data Stores

A type of database often used as an interim area for a data warehouse

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24
Q

Oper Marts?

A

An operational data mart

25
EDW?
Enterprise Data Warehouse | A data warehouse for the enterprise
26
Metadata?
Data about data
27
Types of DW Architectures?
Three-Tier Architecture | Two-Tier Architecture
28
Three-Tier Architecture?
1. Data acquisition software (backend) 2. The DW that contains the data and the software 3. Client (Front-end) software that allows users to access and analyze data from the warehouse
29
Two-Tier Architecture?
First two tiers in 3Tier architecture are combined into one
30
Example of Three-Tier Architecture?
Client Workstation Application Server Database Server
31
Example of Two-Tier Architecture?
Client workstation | Application and database server
32
What does Web-based DW Architecture contain?
Client (Web browser) Web server -> Web pages Application server Data warehouse
33
Data warehouse development approaches?
Inmon Model | Kimball Model
34
Inmon Model?
EDW approach (top-down)
35
Kimball Model?
Data mart approach (bottom-up)
36
Characteristics of DM approach?
One subject area Months to develop Costs 10k to 100k plus Low to medium difficulty Data prerequisite is common within the business area Sources include only some operational and external systems Size can range from megabytes to gigabytes Time horizon - near current and historical data Data transformation - low to medium
37
Characteristics of EDW approach?
Several subject areas Years to develop Costs 1mil plus Hard difficulty Data prerequisite is common across the enterprise Sources include many operational and external systems Size can range from gigabytes to petabytes Time horizon - historical data Data transformation - high
38
Tables in DW?
Fact table | Dimensional tables
39
Fact table?
A very large accumulation of facts such as sales
40
Dimension tables?
Smaller, generally static information about the entities involved in the facts
41
Representation of Data in DW?
Dimensional Modelling Star Schema Snowflakes Schema
42
Dimensional Modelling?
A retrieval-based system that supports high-volume query access
43
Star Schema?
The most commonly used and the simplest style of dimensional modeling Contain a fact table surrounded by and connected to several dimension tables
44
Snowflakes Schema?
An extension of star schema where the diagram resembles a snowflake in shape
45
What is multidimensionality?
The ability to organize, present, and analyze data by several dimensions, such as sales by region, by product
46
Multidimensional presentation contents?
Dimensions Measures Time
47
Dimensions?
``` Product Salespeople Market Segments Business units ```
48
Measures?
Money Sales volume Head count Inventory profit
49
Time?
Daily Weekly Monthly
50
Two classes of fact-table attributes?
Dimension attributes - The key of a dimension table Dependent attributes - A value determined by the dimension attributes of the tuple
51
Warehouse Data Models?
Relations Stars and snowflakes Cubes
52
Warehouse Operators?
Slice and dice Roll-up, drill down Pivoting Other
53
Slice?
A subset of a dimensional array
54
Dice?
A slice on more than two dimensions
55
Drill down/Up?
Navigating among levels of data ranging from the most summarized (up) to the most detailed (down)
56
Roll Up?
Computing all of the data relationships for one or more dimensions
57
Pivot?
Used to change the dimensional orientation of a report or an ad hoc query-page display
58
ROLAP?
Relational Online Analytical Processing
59
MOLAP?
Multi-Dimensional Online Analytical Processing