Database - RDS, Dynamo, PostgreSQL, Aurora, MySQL, MariaDB, Elasticache

Question 1

What is a relational database?

Answer 1

a traditional database that is made up like a spreadsheet with tables, rows, and fields.

Question 2

Name the database Types in AWS

Answer 2

SQL server Oracle MySQL Server PostgreSQL Aurora MariaDB

Question 3

Describe how a non-relational database works

Answer 3

collection = table document = row key value pairs - fields

Question 4

What is data warehousing?

Answer 4

It is used to pull in very large and complex data sets. Usutally used by management to do queries on data (such as current performance vs targets, etc.) It is used for business intelligence. Tools like Cognos, Jaspersoft, SQL Server Reporting Services, Oracle Hyperion, and SAP Netweaver.

Question 5

What is OTLP?

Answer 5

Online Transaction Processing

Question 6

What is OLAP?

Answer 6

Online Analytics Processing

Question 7

How do OLAP and OTLP differ?

Answer 7

They differ in terms of queries you will run. OTLP example: 2120121 -pulls up a row of data such as NAME, Date, Address to deliver to, delivery status, etc. OLAP example: Pulls in large number of records. Net profit for EMEA and Pacific for the digital record product. Sum of radios sold in EMEA Sum of radios sold in pacific Unit cost of Radio in each region Sales price of each radio Sales price - unit cost

Question 8

T or F data warehousing databases use the same type of architecture from a db perspective and infrastructure layer.

Answer 8

False data warehousing uses different type of architecture both from a DB perspective and infrastructure layer.

Question 9

A web server that makes it easy to deploy, operate, and scale in memory cache in the cloud is called what?

Answer 9

Elasticache

Question 10

T or F Elasticache improves the performance of web apps by allowing you to retrieve info from fast, managed, in-memory caches, instead of relying entirely on slower disk based databases.

Answer 10

True

Question 11

Name the types of Elasticache:

Answer 11

Memcached and Redis

Question 12

Name the two types of RDS backups for AWS:

Answer 12

Automated backups and DB snapshots

Question 13

_____ allows you to recover your DB to any point in time within a retention period.

1. Automated backups
2. DB Snapshots

Answer 13

automated backups

Question 14

These types of backups are done manually (user initiated)

1. Automated backups
2. snapshots

Answer 14

Snapshots

Question 15

The retention period for autometed backups can be between _____ and ___ days.

1. 1 and 5
2. 1 and 35
3. 1 and 100
4. infinite

Answer 15

2) 1 and 35

Question 16

Automated backups will take a full daily snapshot and will also store

____ logs during the day

Answer 16

transaction

Question 17

T or F

When you do a recovery, AWS will first choose the most recent daily backup and then apply transaction logs relevant to that dayl. This allows you to do a point in time recovery down to a second, within the retention period.

Answer 17

True

Question 18

T or F

Automated backups are disabled by default.

Answer 18

False

Automated backups are enabled by default

Question 19

Where are automated backups stored?

Answer 19

S3

Question 20

T or F

With automated backups, you get unlimited, free storage space in S3.

Answer 20

False.

You get free storage space = to the size of your DB.

Question 21

T or F

Backups are taken every time a change is made to the DB.

Answer 21

false.

Backups are taken within a defined window.

Question 22

T or F

During the backup window, storage IO may be suspended while your data is being backed up and you may experience elevated latency.

Answer 22

True

Question 23

T or F

Snapshots are stored even after you delete the original RDS instance, unlike automated backups

Answer 23

True

Question 24

T or F

Whenever you restore either an Automated backup or a manual snapshot, the restored version of the DB will be a new RDS instance with a new DNS endpoint.

Answer 24

True

Question 25

_____ allows you to have an exact copy of your DB in another AZ

Answer 25

multi-az

Question 26

T or F

AWS handles multi-AZ DB replciation for you, so when your prod DB is written to, this write will automatically be syncronized to the standby database.

Answer 26

True

Question 27

T or F

IN the evnet of planned DB maintenance, DB intance failure, or an AZ failure, RDS will auto failover to the standby so that DB ops can resume quickly without administrative intervention.

Answer 27

True

Question 28

T or F

Multi-AZ is for disaster recovery only

Answer 28

True

Question 29

T or F

Multi-AZ is also designed to improve performance

Answer 29

False

It is not primarily used for improving performance. For performance improvement , you need read replicas.

Question 30

Which DBes are types of multi-az databases:

1. SQL server
2. aurora
3. oracle
4. mysql
5. postgreSQL
6. mariaDB

Answer 30

All of the above

Question 31

_________ allow you to have a read only copy of your production DB.

Answer 31

read replicas

Question 32

Read replicas achieve syncronization from the primary DB by using ______ replication.

Answer 32

asyncronous

Question 33

Why would you use read replicas for your DB?

Answer 33

You want to use read replicas when you have very read heavy db workloads.

Question 34

Read replicas are availabe for the following DBes:

1. SQL
2. mysql
3. postgreSQL
4. mariDB
5. aurora

Answer 34

mysql

postgreSQL

mariaDB

aurora

They are not available for SQL

Question 35

T or F

read replicas are used for disaster recovery, not scaling.

Answer 35

false

read replicas are used for scaling, not DR

Question 36

T or F

You must have automated backups turned on in order to deploy a read replica

Answer 36

True

Question 37

You can have up to ____ read replica copies of any DB

Answer 37

5

Question 38

T or F

You can have read replicas of read replicas

Answer 38

True, but you must watch latency

Question 39

T or F

read replicas share DNS endpoints

Answer 39

False

each read replica will have its own DNS endpoint

Question 40

T or F

You can have read replicas that have multi-AZ

Answer 40

True

Question 41

T or F

you can create read replicas of multi-AZ source databses

Answer 41

True

Question 42

T or F

read replicas can be promoted to be their own databses

Answer 42

true, but it breaks replication

Question 43

T or F

you can’t have read replicas in another region

Answer 43

False

read relicas can be located in another region.

Question 44

______ can be used to significantly improve latency and throughput for many read-heavy application workloads (such as social networking, gaming, media sharing, and Q&A portals or compute intensive workloads such as recommendation engines)

1. magnetic storage
2. elasticache
3. load balancing
4. container

Answer 44

Elasticache

Question 45

_______ improves app performance by storing critical pieces of data in memory for low-latency access.

Answer 45

caching

Question 46

T or F

cached info may include the results of IO intensive DB queries or the result of computationally intensive calculations.

Answer 46

True

Question 47

A widely adopted memory object caching system. Elasticache is protocol compliant with _____, so popular tools that you use today with existing _____ environments will work seamlessly with the service.

Answer 47

memcached

Question 48

A popular open source in-memory key-value store that supports data structures such as sorted sets and lists. Elasticache supports master/slace replication and multi-az, which can be used to achieve cross AZ redundancy.

Answer 48

Redis

Question 49

Because of the replication and persistence features of ______, elasticache manages ______ more as a relational DB.

Answer 49

Redis

Question 50

______ Elasticache clusters are managed as stateful entities tht include failover, similar to how Amazon RDS manages database failover.

Answer 50

Redis

Question 51

Because _______ is designed as a pure coding solution with no persistence, Elasticache manages ______ nodes as a pool that can grow and shrink, similar to an EC2 ASG. Individual nodes are expendable and Elasticache provides additional capabilities here, such as auto node replacement and auto discovery.

Answer 51

memcached

Question 52

Is object caching your primary goal, for example to offload your DB, if so, use this….

1. memcached
2. redis

Answer 52

memcached

Question 53

are you interested in as simple caching model as possible? if so use this….

1. memcached
2. redis

Answer 53

memcached

Question 54

Are you planning on running large cache nodes and require multi-threaded performance with utilization of multiple codes? if so use this….

1. memcached
2. redis

Answer 54

memcached

Question 55

Do you want the ability to scale your cache horizontally as you grow, if so use this….

1. memcached
2. redis

Answer 55

memcached

Question 56

are you looking for more advanced data types, such as lists, hashes, and sets? if so use this….

1. memcached
2. redis

Answer 56

redis

Question 57

does sorting and ranking data sets in memory help you, such as with leaderboards? if so, use this…

1. memcached
2. redis

Answer 57

redis

Question 58

is persistence of your key store important? if so, use this…

1. memcached
2. redis

Answer 58

redis

Question 59

do you want to run with multiple AWS AZ with failover?

if so, use this…

1. memcached
2. redis

Answer 59

redis

Question 60

______ is a fast and flexible NoSQL DB service for all apps that need consisten, single digit millisecond latency at any scale.

Answer 60

DynamoDB

Question 61

_______ is a fully managed DB and supports both documents and key-value data models. Its flexible data model and reliable performance make it a great fir for mobile, web, gaming, ad-tech, IoT, many other apps.

Answer 61

DynamoDB

Question 62

T or F

DynamoDB is stored on magnetic storage

Answer 62

False

DynamoDB is stored on SSD storage

Question 63

DynamoDB is spread across ___ goegraphically distinc data centers

1. 2
2. 3
3. 4
4. 5
5. 6

Answer 63

2. 3

Question 64

Which of these is the default for DynamoDB

Eventual Consistent reads

Strongly consisten reads

Answer 64

Eventual consistent reads

Question 65

DynamoDB

Consistently across all copies of data is usually reached within a second. Repeating a red after a short time should return the updated data. Best read performance)

1. Eventually consistent read
2. Strongly consistent read

Answer 65

Eventually consistent read

Question 66

DynamoDB

This returns a result that reflects all writes that received a successful response prior to the read.

1. Eventually consistent read
2. Strongly consistent read

Answer 66

Strongly consistent read

Question 67

T or F

DynamoDB tables are made up of Items and Attributes

Items (think of a row of data in a table)

Attributes (Think of a column of data in a table)

Answer 67

True

Question 68

T or F

DynamoDB supports key-value and document data structures

Answer 68

True

Question 69

DynamoDB

The name of the data = ____

The data itself =_____

Answer 69

key

value

Question 70

DocDB documents can be written in:

1. JSON
2. HTML
3. HTTP
4. XML
5. JAVA

Answer 70

JSON

HTML

XML

Question 71

DynamoDB stores and retrieves data based on a ______ key

Answer 71

primary

Question 72

2 types of primary keys:

______ key and ____ key

Answer 72

partition and composite key

Question 73

This Dynamo DB key is a unique attribute (userID) value of the part key is input to an internal hash function which determines the partition or physical location on which the data is stored.

Answer 73

partition key

Question 74

T or F

If you are using the partition key as your primary key, then no two items can have the same partition key.

Answer 74

true

Question 75

DynamoDB

The composite key is made up of the ____ key and the ____ key

Answer 75

partition and sort key

Question 76

DynamoDB

Primary key can be a composite key consisting of _____ key and ___ key.

Answer 76

primary and sort

Question 77

___key = user ID

____ key = timestamp of the past

Answer 77

partition and sort

Question 78

T or F

DynamoDB

2 different items may have the same partition key, but they must have a different sort key.

Answer 78

True

Question 79

T or F

DynamoDB Composite Key

All items with teh same partitionkey are stored together, then sorted according to the sort key value.

Answer 79

True

Question 80

T or F

DynamoDB Composite key

Allows you to store multiple items with same partition key

Answer 80

True

Question 81

T or F

DynamoDB Authentication and Access control is managed using AWS cognito

Answer 81

False

DynamoDB Authentication and Access control is managed using AWS IAM

Question 82

T or F

YOu can create an IAM user within your AWS Account which has specific permissions to access and create DynamoDB tables.

Answer 82

True

Question 83

T or F

You can create an IAM role which enables you to obtain temp access keys which can be used to access DynamoDB.

Answer 83

true

Question 84

T or F

You can also use a special IAM condition to restrict user access to only their own records.

Answer 84

True

Question 85

In SQL, and _____ is a data structure which allows you to perform fast queries on specific columns in a table. You select the columns that you want included in the ____ and run your searches on the _____ rather then on the entire dataset.

Answer 85

index

Question 86

IN DynamoDB, there are 2 types of indexes that are supported to help speed up your DynamoDB queries:

_______Secondary index

______Secondary index

Answer 86

Local and Global

Question 87

DynamoDB

This can only be created when you are creating your table

1. Local secondary index
2. Global secondary index

Answer 87

Local secondary index

Question 88

DynamoDB

You can’t add, remove, or modify it later.

1. local secondary index
2. global secondary index

Answer 88

local secondary index

Question 89

DynamoDB

It has the same partition key as your original table

1. local secondary index
2. global secondary index

Answer 89

local secondary index

Question 90

DynamoDB

It uses a different sort key

local secondary index

global secondary index

Answer 90

local secondary index

Question 91

DynamoDB

it gives you a differnt view of your data, organized according to an alternative sort key

local secondary index

global secondary index

Answer 91

local secondary index

Question 92

DynamoDB

any queries based on this sort key are much faster using the index than the main table

local secondary index

global secondary index

Answer 92

local secondary index

Question 93

DynamoDB

YOu can create when you create your table, or add it later

local secondary index

global secondary index

Answer 93

global seconday index

Question 94

DynamoDB

different partition key as well as a different sort key

local secondary index

global secondary index

Answer 94

global secondary index

Question 95

DynamoDB

gives a completely different view of the data (speeds up any queries relating to this alternative pertition and sort key)

local secondary index

global secondary index

Answer 95

global secondary index

Question 96

A ____ operation finds items in the table based on floor on the primary key attribute and distinct value to search for.

IE: select an item where the user id = 212, will selecct all the atributes for that item, -first name, surname, email, etc.

Answer 96

query

Question 97

T oR F

Dynamo DB

You can use an optional sort key name and value to refine the results of your query.

ie: if your sort key is a timestamp, you cna refine the query to only select items with a time stamp of the last 7 days.

Answer 97

True

Question 98

DB queries

By default, a query returns all the attributes for the items but you can use the projection expression parameter if you want the query to only return the specific attributes you want. Ie: if you want to see the email address ranter than all the attributes.

Answer 98

True

Question 99

T or F

Query results are always sorted by the partition key

Answer 99

False

Query results are always sorted by the sort key

Question 100

T or F

DB queries

Numeric order - by default is in ascending order (1,2,3,4)

Answer 100

true

Question 101

T or F Db queries

ASCII characters code value

Answer 101

true

Question 102

T or F

Db queries

YOu can reverse the order by setting the ScanIndexForward

parameter to True

Answer 102

False

YOu can reverse the order by setting the ScanIndexForward

parameter to False

Question 103

T or F DB queries

by default, queries are eventually consistent

Answer 103

true

Question 104

T or F

DB queries

you need to explicitly set the query to be strongly consistent

Answer 104

True

Question 105

DB

a ____ operation examines every item in the table

Answer 105

scan

Question 106

scans return all data atributes by default?

T or F

Answer 106

True

Question 107

Use the ProjectionExpression parameter to refine the scan to only return the attributes you want.

T or F

Answer 107

True

Question 108

T or F

Scan is more efficient than a query

Answer 108

False.

Query is more efficient than a scan

Question 109

Scan dumps the entire table, then filters out the values to provide the desired result - removing the unwanted data.

T or F

Answer 109

True

Question 110

Scna dumps add an extra step of removing the data you don’t want.

T or F

Answer 110

True

Question 111

as a table grows, scan operations take longer

T or F

Answer 111

True

Question 112

Scan operations on a large table cna use up the provisioned throughput for a large table in just a single operation.

T or F

Answer 112

True

Question 113

DB queries and scans

You can improve the impact of the query or scan by setting a smaller page size which uses fweer read ops. IE: set page size to return 40 items.

T or F

Answer 113

True

Question 114

DB queries and scans

Larger number of smaller ops will allow other requests to succeed without throttling.

T or F

Answer 114

True

Question 115

Db queries and scans

Avoid using scan ops if you can: design tables in a way that you can use the query, get, or BatchGetItem APIs.

T or F

Answer 115

True

Question 116

improving scan performance

by default, s scan operation processes data sequentially in returning 1MB increments before moving on to retrieve the next 1MB of data. It can only scan one parition at a time.

T or F

Answer 116

True

Question 117

IMproving scan performance

YOu can configure DynamoDB to use parallel scans instead by logically dividing a table or index into segments and scanning each segment in parallel.

T or F

Answer 117

true

Question 118

improve scan performance

Best to avoid using parallel scans if your table or index is already incurring heave read/write activity from other apps.

T or F

Answer 118

true

Question 119

A scan operation finds items in a table using onlyt eh primary key attrribute

T or F

Answer 119

False

A query operation finds items in a table using onlyt eh primary key attrribute

Question 120

Queries and scans

You privide the secondary key name and a distinct value to search for.

T or F

Answer 120

False

You privide the primary key name and a distinct value to search for.

Question 121

A scan operation examines every item in teh table.

T or F

Answer 121

True

Question 122

a scan operation returns all data attributes by default

T or F

Answer 122

True

Question 123

You cna use the projection expression parameter to refine the results of a scan or query.

T or F

Answer 123

True

Question 124

Query results are always sorted by teh sort key if there is one.

T or F

Answer 124

True

Question 125

Query operation is generally more efficient than a scan

T or F

Answer 125

True

Question 126

The following can improve scan performance:

T or F

Reducs the impact of a query or scan by setting a smaller page size, which uses fewer read operations.

• Isolate scan operations to specific table sand segregate them from your missions critical traffic
• try parallel scans, rather than the default sequential scan
• avoid using scan operations, if you can, design tables in a way that you cna use the query , Get or BatchGetItem API.

Answer 126

True

Question 127

DynamoDB provision throughput is measured in _____ units

Answer 127

capacity

Question 128

when you create your table, you specify your requirements in terms of _____ capacity unit and ____ capacity units.

Answer 128

read and write

Question 129

1x ____ capacity unut = 1x 1KB _____/second

Answer 129

write

Question 130

1x _____ capcacity unit = 1x strongly consistent ____ of 4kb/second

or

2x _______consisten reads of 4kb/second (default)

Answer 130

read, read, eventually

Question 131

This is an example configuration of what?

Table with 5x read capacity units and 5x write capacity units

This consig will be able to perform 5x 4kb strongly consistent reads = 20kb/second

twice as many eventually consistent =40kb

5x1kb writes = 5kb/second

Answer 131

provisioned throughput

Question 132

T or F

I your app reads or writes longer items, it iwll consume more capacity units and will cost you more as well.

Answer 132

True

Question 133

T or F

Strongly consistent reads calculation

Your app needs to read 80 items (table rows)/ second

each item is 3kb in size

you need strongly consistent reads

first, calculate how many read capacity units needed for each read:

size of each items /4kb

3kb/4kb=.75

Rounded up to the nearest whole number, each read will need 1x

read capacity unit per operation.

multiplied by the number of reads per second = 80 read capacity units required.

Answer 133

true

Question 134

If you need ______ consistent reads,

you do the same calculation as stronly consistent. However as this is for ______ consistent reads, you get 2x 4kb reads/second or double the throughput of strongly consistent reads.

size of each item/4kb

3kb/4kb=.75

round up to the nearest whole number, =1

multiply by the number of reads per second = 80

dicide 80 by 2, so you only need 40 read capacity units for ____ consistent reads

Answer 134

eventually

Question 135

_____ capacity units calculation.

you want to write 100 items/second

each item is 512 bytes in size

First calculate how many capacity units for each _____:

size of each item /1kb (for _____ capacity units)

512 bytes/1kb = .05

rounded up to the nearest whole number, each ____ will need 1x ____ capacity unit per ____ operation.

multiplied by the number of _____ per second = 100 ______ capacity units required

Answer 135

write

Question 136

_____ _____ is measured in capacity units

Answer 136

provisioned throughput

Question 137

1x ____ capacity unit = 1x 1kb _____/second

Answer 137

write

Question 138

1 x ___ capacity unit = 1 x 4kb _____consistent ____ or

2 x 4kb _____ consistent _____/second

Answer 138

read, strongly, read, eventually, read

Question 139

T or F

In DynamoDB on demand, charged apply for reading, writing, and storing data.

Answer 139

True

Question 140

T or F

in DynamoDB, with on demand, you don’t need to specify your requirement.

Answer 140

True

Question 141

T or F

DynamoDB on demand is great for unpredicatable workloads

Answer 141

True

Question 142

WIth DynamoDB on-demand, you want to pay only for waht you use (pay per request)

T or F

Answer 142

True

Question 143

DynamoDB

unknown workloads

1. on-demand capacity
2. provisioned capacity

Answer 143

on-demand capacity

Question 144

DynamoDB

you can forecast read and write capacity units

1. on-demand capacity
2. provisioned capacity

Answer 144

provisioned capacity

Question 145

DynamoDB

unpredictable app traffic

1. on-demand capacity
2. provisioned capacity

Answer 145

on-demand capacity

Question 146

DynamoDB

predictable app traffic

1. on-demand capacity
2. provisioned capacity

Answer 146

provisioned capacity

Question 147

DynamoDB

app trffic is consistent or increases gradually

1. on-demand capacity
2. provisioned capacity

Answer 147

provisioned capacity

Question 148

DynamoDB

you want to pay per use model

1. on-demand capacity
2. provisioned capacity

Answer 148

on-demand capacity

Question 149

DynamoDB

spiky, short lived peaks

1. on-demand capacity
2. provisioned capacity

Answer 149

on-demand capacity

Question 150

This is a fully managed, clustered in-memory cache for DynamoDB

Answer 150

DynamoDB Accelerator (DAX)

Question 151

DAX delievers up to a ____x read performance improvement

1. 5
2. 10
3. 20
4. 30

Answer 151

10

Question 152

DAX delivers microsecond performance for millions of requests per second.

T or F

Answer 152

True

Question 153

DAX is ideal for read heavy and bursty workloads

Ie: auction apps, gaming, and retail sites during black Friday promotions.

T or F

Answer 153

True

Question 154

DAX is a _____ through caching service. This means data is written to the cache as well as the back end store at the same time.

Answer 154

write

Question 155

DAX allows you to point your DynamoDB API calls at the DAX cluster

Answer 155

True

Question 156

IF the item you are querying is in the cache (cache hit), DAX returns the result to the application

T or F

Answer 156

True

Question 157

If the item is not available (cache miss), then DAX performs an _______ consistent get item operation against DynamoDB

Answer 157

eventually

Question 158

retrieval of data from DAX reduces the read load on DynamoDB

T or F

Answer 158

true

Question 159

DAX may be able to reduce ______ read capacity

Answer 159

provisioned

Question 160

DAX caters for _____ consistent reads only - so not suitable for apps that require strongly consistent reads.

Answer 160

Eventually

Question 161

DAX is not suitable for ____ intensive apps

Answer 161

write

Question 162

DAX is suitable for apps that do not perform many read ops

T or F

Answer 162

False

DAX is suitable for apps that do not perform many write ops

Question 163

DAX is not suitable for apps that do not require microsecond response times

T or F

Answer 163

True

Question 164

T or F

DAX provides in-memory caching for DynamoDB table

Answer 164

True

Question 165

DAX is not suitable for write intensive apps or apps that require ______ consistent reads.

Answer 165

strongly

Question 166

Elasticache is in memory cache in the cloud

T or F

Answer 166

True

Question 167

Elasticache inproves performance of web apps, allowing you to retrieve info from fast in-memory caches ratherthan slower disk based databases

T or F

Answer 167

True

Question 168

Elasticache sites between your app and the database.

ie: an app frequently requesting specific product info for your best selling products.

T or F

Answer 168

True

Question 169

Elasticache takes the load off your databases

T or F

Answer 169

True

Question 170

Elasticache is good if your database is ____ heavy and the data is not changing frequently

Answer 170

read

Question 171

Elasticache improves performance for read heavy workloads

T or F

Answer 171

True

Question 172

with elasticache, frequently accessed data is stored in memory for low-latency access, improving the overall performance of your app.

Answer 172

True

Question 173

Elasticache is good for computer heavy workloads

T or F

Answer 173

true

Question 174

elasticache can be used to store results of IO intensive DB queries or output of the compute intensive calculations.

T or F

Answer 174

True

Question 175

Name the two types of Elasticache…

Answer 175

redis and memcached

Question 176

Widely adopted memory object caching system

1. memcached
2. redis

Answer 176

memcached

Question 177

open source in-memory key-value store

1. memcached
2. redis

Answer 177

redis

Question 178

multithreaded

1. memcached
2. redis

Answer 178

memcached

Question 179

no AZ capability

1. memcached
2. redis

Answer 179

memcached

Question 180

supports complex data structures: sorted sets and lists

1. memcached
2. redis

Answer 180

redis

Question 181

supports master/slave replciation and multi-AZ for cross AZ redundancy

1. memcached
2. redis

Answer 181

redis

Question 182

what are the 2 strategies used in caching?

Answer 182

lazy loading and write-through

Question 183

Loads the data into cache only when necessary

1. Lazy Loading
2. Write-Through

Answer 183

Lazy loading

Question 184

if requested data is in the cache, EC returns the data to the app.

1. lazy loading
2. write-through

Answer 184

lazy loading

Question 185

if the data is not in the cache, or has expired, EC returns a null.

1. lazy loading
2. write-through

Answer 185

lazy loading

Question 186

Your app then fetches the data from DBs and writes tha data received into the cache so that its available next time

1. lazy loading
2. write-through

Answer 186

lazy loading

Question 187

Lazy loading - advantage or disadvantage?

Only requested data is cached: avoids filling up cache with useless data

Answer 187

advantage

Question 188

Lazy loading - advantage or disadvantage?

node failures are not fatal. a new empty node will just have a lot of cache misses initially.

Answer 188

advantage

Question 189

Lazy loading - advantage or disadvantage?

cache miss penalty: initial request query to DB writing of data to the cache.

Answer 189

disadvantage

Question 190

Lazy loading - advantage or disadvantage?

stale data - if data is only updated when there is a cache miss, it can become stale. doesn’t automatically update if teh data in teh DB changes.

Answer 190

disadvantage

Question 191

TTL = ____

Answer 191

Time to live

Question 192

TTL specifies the number of seconds until the ____ (data) expires to avoid keeping stale data in teh cache

Answer 192

key

Question 193

_____ _____ treats an expired key as a cache miss and causes the app to retreive the data from the DB and sequentially write the data into the cache with the new TTL.

Answer 193

Lazy loading

Question 194

____ does not eliminate stale data - but it helps avoid it.

Answer 194

TTL

Question 195

_____-_____ adds or updates data to the cache whenever data is written to the databases.

Answer 195

write-through

Question 196

write-through advantage or disadvantage?

write penalty: every write involves a write to the cache as well as write to the DBes.

Answer 196

disadvantage

Question 197

write-through advantage or disadvantage?

data in cache is never stale

Answer 197

advantage

Question 198

write-through advantage or disadvantage?

users are generally more tolerant of additionally latency when updating data than when retrieving it.

Answer 198

advantage

Question 199

write-through advantage or disadvantage?

wasted resources if most of the data is never read

Answer 199

disadvantage

Question 200

write-through advantage or disadvantage?

If a node fails a new node is spun up, data is missing until added or updated in the database (migrate by implementing Lazy Loading inconjunction with write-through)

Answer 200

disadvantage

Question 201

What does ACID transactions stand for?

Answer 201

Atomic, Consistent, Isolated, Durable

Question 202

DynamoDB transactions

read or write multiple items across multiple tables as an all or nothing operation

T or F

Answer 202

True

Question 203

DynamoDB Transactions

Checks for a pre-requisite condition before writing to a table

T or F

Answer 203

True

Question 204

DynamoDB TTL

TTL ______ defines an expiry time for your data

Answer 204

attribute

Question 205

DynamoDB TTL

Expired items are marked for deletion

T or F

Answer 205

true

Question 206

DynamoDB TTL

Great for removing irrelevant or old data:

Session data

event logs

temporary data

T or F

Answer 206

True

Question 207

DynamoDB TTL

Reduces cost by automatically removing data when is no longer relevant

Answer 207

True

Question 208

Session data table

TTL expressed as _____ time

Answer 208

epoch

Question 209

session data table

expiration is set for ____ hours after the session began

1. 1
2. 2
3. 3
4. 4
5. 5

Answer 209

2

Question 210

session data table

when the current time is greater than the TTL, the item will be expired and marked for deletion.

T or F

Answer 210

True

Question 211

session data table

you can’t filter out expired items for your queries and scans

Answer 211

false

you can filter out expired items for your queries and scans

Question 212

DynamoDB Streams

These are Time ordered sequence of item level modifications

(insert, update, delete)

T or F

Answer 212

True

Question 213

DynamoDB Streams

Logs are encrypted at rest and stored for 24 hours

T or F

Answer 213

True

Question 214

DynamoDB Streams

Accessed using a dedicated endpoint

T or F

Answer 214

True

Question 215

DynamoDB Streams

By default the Secondary Key is recorded before and after images can be captured

T or F

Answer 215

False

By default the Primary Key is recorded

Question 216

Processing DynamoDB Streams

Events are recorded in near real time

T or F

Answer 216

True

Question 217

Processing DynamoDB Streams

Apps can take actions based on contents

T or F

Answer 217

True

Question 218

Processing DynamoDB Streams

Event source for Lambda

T or F

Answer 218

True

Question 219

Processing DynamoDB Streams

Lambda polls the DynamoDB stream

T or F

Answer 219

True

Question 220

Processing DynamoDB Streams

Executes Lambda code based on a DynamoDB treams event

T or F

Answer 220

True

Question 221

DynamoDB streams is stored for 24 hours only

T or F

Answer 221

True

Question 222

Processing DynamoDB Streams

Can be used as an event source for Lambda so you can create apps which table actions based on your events in your DynamoDB table.

T or F

Answer 222

True

Question 223

ProvisionedThroughputExceededException

You request rate is too hight for the readwrite capacity provisioned on your DynamoDB table

T or F

Answer 223

True

Question 224

ProvisionedThroughputExceededException

-SDK will automatically retry the request until successful

T or F

Answer 224

True

Question 225

ProvisionedThroughputExceededException

If you are not using teh SDK, you can:

• Reduce request frequency
• Use ‘Exponential Backoff’

T or F

Answer 225

True

Question 226

What is exponential Backoff?

-many components in a network can generate errors due to being overloaded

T or F

Answer 226

True

Question 227

What is exponential Backoff?

In addition to simple retries, all AWS SDKs use ‘Exponential Backoff’

T or F

Answer 227

True

Question 228

What is exponential Backoff?

Progressively longer waits between consecutive retries

ie: 50ms, 100ms, 200ms… for improved flow control

T or F

Answer 228

True

Question 229

What is exponential Backoff?

If after 1 min this doesn’t work, your request size may be exceeding the throughput for your read/write capacity

Answer 229

True

Question 230

T or F

If you use a ProvisionedThroughputExceeded Error, this means the number of requests is too low.

Answer 230

False

If you use a ProvisionedThroughputExceeded Error, this means the number of requests is too high.

Question 231

T or F

Exponential Backoff improves flow by retrying requests using progressively longer waits.

Answer 231

True