Databases Flashcards

1
Q

What is ElasticCache?

A

an in memory cache in the cloud. * Allows you retrieve data a lot quicker, by pulling data from memory cache in the cloud rather than slower disk-based databases. supports master and slave replication.

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2
Q

What are the two types of Elacticcache ?

A

Memcached Redis (opensource in-memory key-value store)

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3
Q

AWS Database types?

A

RDS-OLTP DynamoDB (No SQL) RedSHift (Amazon’s OLAP data warehouse product) Elasticache

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4
Q

AWS Database RDS OLTP examples:

A

SQL MySQL PostgreSQL Oracle Aurora (AWS MySQL & PostgreSQL compatible DB) MariaDB

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5
Q

RDS Backups.

A

There are two: 1) Automated backups 2) Database snapshots

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6
Q

RDS Backup - Automated backup - key points:

A

1) Retention 1 - and 35 days. 2) Backup is a fully daily snapshot 3) Stores transactional logs 4) Recovery will first choose the most recent daily backup then apply transaction logs for that day. 5) enabled by default

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7
Q

RDS Backup - database snapshots - key points:

A

1) Always manual. (User initiated) 2) Are restored even after you delete the original RDS instance. A restored RDS instance will be a new RDS instance with a new DNS endpoint.

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8
Q

Database Encryption:

A

Encryption at Rest: * MySQL, Oracle, SQ Server, PostgreSQL, MariaDB and Aurora. * Encryption is done using the AWS key management service. * backups, replicas and snapshots are encrypted.

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9
Q

Database and Multi AZ :

A

Designed for DR recovery. Writes to 1 Database is replicated to database 2. * Failover is automated. * not a performance improvement. Available: SQL Server, Oracle, MySQL, PostgreSQL, MariaDB, Aurora.

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10
Q

Databases and Read Replicas:

A

This is designed to increase Database performance by reading out, but not for redundancy. you have a read replica of a read replica (some latency) you have 5 read replicas per production database. This is asynchronous. Read replicas can have multi-AZ enabled. Read Replicas can be promoted to their own DB. Must have automatic backups turned on in order to deploy a read-replica. Can enable encryption even if the primary database is not encrypted.

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11
Q

What is DynamoDB ?

A

It is a fast and flexible NoSQL Database service. It provides: consistent, single digit millisecond latency at scale. Great fit for: mobile, web, gaming, ad-tech, IoT.

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12
Q

DynamoDB Data points:

A

1) Stored on SSD. 2) Spread across 3 geographically distinct data centres. 3) Eventual consistent reads. (best read performance) 4) Strongly consistent reads. (best write performance)

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13
Q

DynamoDB Pricing ?

A

Provisioned through capacity. * Write throughput. * read throughput * storage costs.

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14
Q

What is RedShift ?

A

RedShift is Amazon’s dataware house service in the cloud. (petabyte scale)

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15
Q

Red Shift Costs ?

A

1) Compute node hours 2) backup 3) data transfer within a VPC.

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16
Q

What is OLAP ?

A

Online Analytics Processing

17
Q

Redshift Config :

A

Single Node or Multi node config. In a multi node setup there is a leader node and compute nodes. (max 128 compute nodes)

18
Q

RedShift Node Info:

A

Single Node (160Gb)

19
Q

RedShift data points:

A

1) columnar data storage: data is stored in columns not rows. (fewer I/O, improved performance on queries). 2) Adv. compression. 3) Massively parallel processing (MPP) It scales fast and easily))

20
Q

RedShift Security:

A

1) Data in transit uses SSL 2) Data at rest uses AES-256 3) RedShift takes care of key management (you can manage your own however)

21
Q

RedShift Availability:

A

Only available in 1 AZ. Can restore snapshots to new AZs in the event of an outage.

22
Q

What is Aurora?

A

A bespoke database created by AWS. It is compatible with MySQL and PostgreSQL.

23
Q

Aurora Data Points:

A

1) 5x better performance than MySQL 2) 1/10th of the cost of MySQL.

24
Q

Aurora Scaling:

A

Storage: starts with 10GB, then auto scales at 10GB increments. Compute: scale up to 32vCPUS & 244GB Ram Availability: 2x copies of your data per availability zone, with 3 availability zones. (Can handle the loss of up to 2 copies of data with affecting DB write availability, and can handle the loss of 3 copies of data before affecting DB read availability).

25
Q

Aurora Replicas:

A

2 types of replicas are available. it supports up to 15 replicas. it allows for MySQL read replicas (up to 5 replicas) replicas can be multi AZ.

26
Q

List all Amazon Database Services

A
  • Amazon RDS
  • Amazon Aurora
  • Amazon RedShift
  • Amazon DynamoDB
  • Amazon DocomentDB
  • Amazon ElastiCache for Memcached
  • Amazon ElastiCache for Redis
  • AWS DB Migration service
27
Q

What is RDS ?

A

Cost-efficient and resizable manages time consuming DBs Fast to deploy isolated DB environment in the cloud Example: MySql, PostgreSQL, MS SQL, MariaDB, Oracle, Amazon Aurora.

28
Q

What is Amazon DynamoDB ?

A

Similar to MongoDB / Cassandra NoSQL. No limit on storage fully managed. need to spec the Read and Write throughput.