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Certified Assoc 2024 > Database > Flashcards

Database Flashcards

1
Q

RDS Features

A
  1. Hardware, OS, and database software deployment and maintenance
  2. Built-in monitoring
  3. Data encryption at rest and in transit
    4.Industry compliance Automatic Multi-AZ data replication
  4. Compute and storage scaling
  5. Minimal application downtime
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2
Q

RDS DB Engines?

A

Amazon Aurora
*
PostgreSQL
*
MySQL
*
MariaDB
*
Oracle Database
*
SQL Server

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3
Q

Amazon RDS Multi-AZ deployments

A

Amazon RDS synchronously replicates the data to a standby instance in a different Availability Zone.

Not used for read only

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4
Q

Read replicas

A

create read replicas of your database kept in sync with the primary DB instance.

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5
Q

Read replica DB engines

A

Read replicas are available in Amazon RDS for Aurora, MySQL, MariaDB,
PostgreSQL, Oracle, and Microsoft SQL Server.

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6
Q

Read replica use cases

A

*
Relieve pressure on your primary node with additional read capacity.
*
Bring data close to your applications in different AWS Regions.
*
Promote a read replica to a standalone instance as a disaster recovery (DR) solution if the primary DB instance fails.

With Amazon RDS for MySQL and MariaDB, you can also set the read replica as Multi-AZ, and as
a DR target.

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7
Q

RDS Data Encryption at Rest

A

RDS provides encryption of data at rest by using the AWS Key Management Service (AWS KMS)

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8
Q

Amazon Aurora

A

Amazon Aurora is an enterprise
-class relational database. It is compatible with MySQL and PostgreSQL . It is faster than standard MySQL databases and PostgreSQL databases.

Aurora helps to reduce your database costs by reducing unnecessary I/O
operations,

Consider Aurora if your
workloads require high availability. It replicates six copies of your data across three Availability Zones and
continuously backs up your data to Amazon Simple Storage Service (Amazon S3).

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9
Q

Amazon Aurora DB cluster

A

Amazon Aurora DB cluster consists of one or more DB instances and a cluster volume that manages the data for those DB instances.

Aurora cluster volume is a virtual database storage volume that spans multiple Availability Zones. Each
Availability Zone has a copy of the DB cluster data.

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10
Q

Aurora offers two instance types?

A

*Primary instance
–
Supports read and write operations and performs all the data modifications to the cluster
volume. Each Aurora DB cluster has one primary instance.
*Aurora replica
–
Supports read operations only. Each Aurora DB cluster can have up to 15 Aurora replicas in
addition to the primary instance. Multiple Aurora replicas distribute the read workload. You can increase
availability by locating Aurora replicas in separate Availability Zones. You can have a read replica in the same
Region as the primary instance.

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11
Q

Aurora Serverless v2

A

Aurora Serverless v2 is an on-
demand, auto scaling configuration for Amazon Aurora. Aurora Serverless v2 helps
to automate the processes of monitoring the workload and adjusting the capacity for your databases based on demand

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12
Q

DynamoDB

What do you pay for?

A

a fully managed NoSQL database service. The service manages the complexity of running
a scalable, distributed NoSQL database

pay for the storage that you are consuming and the I/O throughput that you have provisioned

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13
Q

DynamoDB Structure

A

Structured in key value pairs

Partitions data by key

Table has partition key and name
Each table consist of items (row - uniquely id by primary key), attributes (columns or key/value)

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14
Q

DynamoDB Features

A

DynamoDB supports end-to-end encryption and fine-grained access control.

Concurrent read-writes

DynamoDB replicates table data across three Availability Zones in a Region

Eventually consistent across all storage locations (~1 sec) by default but you can request strong consistent read

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15
Q

DynamoDB capacity configuration

A

provision capacity based the storage and throughput requirements

If you choose auto scaling, additional capacity is provisioned when the required I/O throughput increases,
within limits that you set.

The on-demand choice permits an application to seamlessly grow to support users concurrent requests to the database

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16
Q

DynamoDB primary Keys

A

Simple primary key– is composed of
just one attribute, which is designated as the partition key
No two items can have the same value.

Composite primary key – composed of both a partition key and a sort key. In this case, the partition key value for multiple items can be the same, but their sort key values must be different.

17
Q

How does DynamoDB measure read and write capacity

A

RCU - read capacity unit - read request for up to 4 kb of items
WCU - write capacity unit -write number of write request per second for up to a 1kb item

18
Q

How can you manage capacity of DynamoDB

A

Two options:

On demand - pay per request on reads and writes

Provisioned - Set maximum RCU and WCU; when traffic exceeds limits request will be throttled

19
Q

What are things you have to consider

A

expected number of read/write request per second

size of requests

20
Q

When is on demand DynamoDB capacity mode best?

A

Have unknown workloads

Have unpredictable traffic

Prefer to pay for only what you use

21
Q

When is provisioned DynamoDB capacity mode best?

A

Have predictable application traffic

Have traffic that is consistent or changes gradually

Can forecast capacity requirements to control costs

22
Q

DynamoDB Eventually Consistent

A

When you read data from a DynamoDB table, the response might not reflect the results of a recently completed
write operation. The response might include some stale data. If you repeat your read request after a short time,
the response should return the latest data

23
Q

Strongly consistent reads

A

When you request a strongly consistent read, DynamoDB returns a response with the most up-to-date data, which reflects updates from all prior successful write operations. A strongly consistent read might not be
available if a network delay or outage occurs.

24
Q

DynamoDB global tables

A

A global table is a collection of one or more DynamoDB tables, which are all owned by a single AWS account,
identified as replica tables.

Any given global table can only have one replica table per Region

DynamoDB global tables provide a fully managed solution for deploying a multi-Region, multi-active database

you specify the regions

DynamoDB communicates changes over the AWS network backbone

25
Q

DynamoDB replica

A

a single DynamoDB table that functions as part of a global table. Each replica stores the same set of data items

every replica has the same table name and the same primary key schema

26
Q

Cache Strategies

A

Lazy Loading - if cache miss (data not in cache) retrieve from DB and write to cache

Write Through - App writes data to DB and cache when initialized

TTL - key expiration integer value configured against cache

Eviction policy - when cache is full evict data based on policy - usually evals TTL, least recently or frequently used

27
Q

Amazon
ElastiCache

A

a web service that facilitates setting up, managing, and scaling a distributed in-memory
data store or cache environment in the cloud

ElastiCache supports two open-
source in-memory engines (in-
memory as compared to disk):
*Redis
*Memcached

28
Q

ElastiCache for Memcached

A

ideal candidate for use cases where frequently accessed data must be in memory

a simple caching model with multi threading

supports Auto Discovery

29
Q

ElastiCache for Memcached Features

A

Simple cache to offload database burden

Ability to scale horizontally for writes and storage

Multi AZ deployments

Multi threaded performance

30
Q

ElastiCache for Redis

A

provides sub millisecond latency at internet scale (fast)

31
Q

ElastiCache for Redis Features

A

Simple cache to offload database burden

Ability to scale horizontally for writes and
storage (when using cluster mode)

Multi AZ deployments

Advanced data types

Sorting and ranking datasets

Publish and subscribe capability

Backup and restore

32
Q

Amazon DynamoDB Accelerator (DAX)

A

a caching service compatible with DynamoDB that provides fast in
memory performance for demanding
applications

33
Q

How do you configure Amazon DynamoDB Accelerator (DAX)

A

You create a DAX cluster in your Amazon VPC to store cached data closer to your application. You install a DAX client on the EC2 instance that is running your application in that VPC. At runtime, the DAX client directs all of your application’s DynamoDB requests to the DAX cluster. If DAX can process a request directly, it does so.
Otherwise, it passes the request through to DynamoDB

34
Q

AWS Database Migration Service (AWS DMS)

what is it and how is it configured

A

replicates data from a source to a target database in the AWS
Cloud

You create a source and a target connection to tell AWS DMS where to extract from and load to.

schedule a task that runs on this server to move your data. AWS DMS creates the tables and associated
primary keys if they don’t exist on the target

35
Q

AWS DMS supported DBs? supported migrations?

A

Oracle, PostgreSQL, SQL
Server, Amazon Redshift, Aurora, MariaDB, and MySQL

supports homogenous (same engine) and heterogeneous (different engine migrations

Can migrate on prem to cloud or cloud to cloud but either source or target must reside in RDS or on EC2

can use snowball edge as target when DB is too big to move over the internet or poor connectivity

36
Q

AWS Schema Conversion Tool (AWS SCT)

A

automatically converts the source database schema and a majority of the database code objects. The
conversion includes views, stored procedures, and functions

They are converted to a format that is compatible with the target database. Any objects that cannot be automatically converted are marked so that they can be manually converted to complete the migration.

The AWS SCT can also scan your application source code for embedded SQL statements and convert them as part of a database schema conversion project

After the schema conversion is complete, AWS SCT can help migrate data from various data warehouses to Amazon Redshift by using built
in data migration agents

Certified Assoc 2024 (11 decks)

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