Databases

Question 1

One of the goals in web app development is

Answer 1

data persistence

Question 2

Application processes stop at some point.
Reasons:

Answer 2

• Hardware/software failure
• Need to upgrade or replace hardware
• Need to update software

Question 3

True or False

We want our application’s data to outlive the application’s process.

Answer 3

True

Question 4

• An open-source document-based database
• A NoSQL database

Answer 4

MongoDB

Question 5

Features of MongoDB

Answer 5

• High Performance
• High Availability
• Easy Scalability

Question 6

Data can be stored in:

Answer 6

• Flat files (txt, csv, binary, etc.)
• Databases (SQL, NoSQL, Relational, Document-based, etc.)

Question 7

Working with ________ is commonplace in today’s programming languages.

Answer 7

objects

Question 8

True or False

NoSQL DBs are the same as Relational Database Management Systems in Web Applications

Answer 8

False

NoSQL DBs are an alternative

Question 9

Schema-less collections are good for

Answer 9

semi-structured data

Question 10

True or False

MongoDB’s speed is good for applications requiring real-time data.

Answer 10

True

Question 11

MongoDB works with Documents in Collections.
This is analogous to ____ in Tables in Relational DBs.

Answer 11

Rows

Question 12

Serve as the container for collections.

Answer 12

Databases

Question 13

A MongoDB server will typically have several ________, each containing data from separate applications.

Answer 13

databases

Question 14

• ________ contain documents, and are schema-less.
• Several documents within the same collection can have a different set of fields

Answer 14

Collections

Question 15

Units in MongoDB collections are JSON-like objects called

Answer 15

Documents

Question 16

Data Types

Answer 16

• String
• Integer
• Double
• Object
• Array
• Boolean
• Object ID
• Date
• Timestamp
• RegEx
• Undefined
• Null
• JavaScript

Question 17

True or False

The object-like form of documents closely resembles native data types in many PLs.

Answer 17

True

Question 18

In MongoDB, new documents are automatically assigned a primary key called

Answer 18

_id

Question 19

• In version 3+ of MongoDB there is also a generated version key ___
• It is incremented after the execution of certain functions such as save or findOneAndUpdate

Answer 19

_v

Question 20

Data relationships are supported using

Answer 20

embedded documents or referenced documents

Question 21

MongoDB commands are centered around ________, which take the form of documents/JSON

Answer 21

queries

Question 22

MongoDB Commands

Answer 22

• Find
• Update
• Delete

Question 23

Examples of Find

Answer 23

db.subjects.find({ code: “CMSC100” })
db[‘some-collection’].find({ name: “...” })

Question 24

Example of Update

Answer 24

Update
db.<collectionName>.find(
<query>,
<update>,
<options>
)

Question 25

Example of Remove

Answer 25

`db..remove()`

Question 26

_\_\_\_\_\_\_\_ documents keep related data together.

Answer 26

Embedded

Question 27

Advantage and Disadvantage of Embedded Documents

Answer 27

Advantage: Keeping related data in a single document makes it easy to query and update.
Disadvantage: Extremely large embedded documents can impact read/write performance.

Question 28

_\_\_\_\_\_\_\_ documents take a normalized approach similar to Relational DBs. _\_\_\_\_\_\_\_ documents exist in their own collection. | Same Answer

Answer 28

Referenced

Question 29

Documents in other collections may reference them using an Object ID (or any identifying field).

Answer 29

Referenced Documents

Question 30

Advantages of Referenced Documents

Answer 30

1. Multiple documents can refer to the same external document. 2. Avoids the pitfalls of excessively large embedded documents.

Question 31

Disadvantage of Referenced Documents

Answer 31

Requires additional querying that many developers want to avoid.

Question 32

# Features of MongoDB - High Performance Support for embedded documents _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ and multi-document queries on the database.

Answer 32

reduces need for joins

Question 33

# Features of MongoDB - High Availability MongoDB supports _\_\_\_\_\_\_\_\_\_\_\_, which provide redundancy.

Answer 33

Replica Sets

Question 34

# Features of MongoDB - Scalability MongoDB supports _\_\_\_\_\_\_\_: Distribution of data across several machines.

Answer 34

Sharding

Question 35

Terms

Answer 35

Table --------------------- Table Relational -------- No SQL Database -------- Database Table -------------- Collection Row --------------- Document Column ---------- Field Table Join -------- Embedded Document Primary Key ----- Primary Key

Question 36

* Before you can use data stored in databases, you have to convert it to a data structure your PL can understand. * This goes for any kind data manipulation: creating, updating, and deleting data. * Thus, the need for _\_\_\_\_\_\_\_\_\_\_\_

Answer 36

Object Relational/Document Mapping

Question 37

Refers to the process of converting data between systems of incompatible data types, using object-oriented methods.

Answer 37

Object Relational Mapping

Question 38

_\_\_\_\_\_\_\_\_\_\_\_ is the equivalent term for NoSQL / Document-based databases.

Answer 38

Object Document Mapping

Question 39

Advantages of using ORD/ORM

Answer 39

1. In-depth knowledge of the DB is not required for application development. 2. DB querying optimization is independent from business logic. 3. Underlying DB Technology can easily be changed There are minimal disadvantages to using ORM. Just be sure to use one that is being maintained.