AWS Database Types

  • RDS OLTP
    • SQL
    • Oracle
    • MariaDB
    • PostgreSQL
    • MySQL
    • Aurora
  • DynamoDB – No SQL
  • RedShift- OLAP
  • Elasticache- In memory caching
    • Memcached
    • redis

 

The following table shows the IOPS and storage range for each database engine.

Range of Provisioned IOPS Range of Storage Range of IOPS to Storage (GB) Ratio
MySQL 1000 – 30,000 IOPS 100 GB – 6 TB 3:1 – 10:1
MariaDB 1000 – 30,000 IOPS 100 GB – 6 TB 3:1 – 10:1
PostgreSQL 1000 – 30,000 IOPS 100 GB – 6 TB 3:1 – 10:1
Oracle 1000 – 30,000 IOPS 100 GB – 6 TB 3:1 – 10:1
SQL Server Express and Web 1000 – 20,000 IOPS 100 GB – 4 TB 3:1 – 10:1
SQL Server Standard and Enterprise 1000 – 20,000 IOPS 200 GB – 4 TB 3:1 – 10:1

You can modify an existing Oracle, MySQL, or MariaDB DB instance to use Provisioned IOPS storage, and you can modify Provisioned IOPS storage settings.

Elasticache:

Elasticache is a web service that makes it easy to deploy, operate and scale an in-memory cache in the cloud. The service improves the performance of web applications by allowing you to retrive information from fast, managed, in-memory caches, instead of relying entirely on slower disk-based databases. Elasticache supports two open-source in-memory caching engines:

Redshift:

  • single node (160GB)
  • Multi-node
    • Leader node (manages client connections and receives queries).
    • Compute node(store data and perform queries and computations. Up to 128 compute nodes.

 

When replicating data from your primary RDS instance to your secondary RDS instance, what is the charge?

Charge is free

What AWS service is best suited for non relational databases?

DynamoDB

One read capacity unit represents one strongly consistent read per second, or two eventually consistent reads per second, for items up to 4 KB in size. If you need to read an item that is larger than 4 KB, DynamoDB will need to consume additional read capacity units. The total number of read capacity units required depends on the item size, and whether you want an eventually consistent or strongly consistent read.

  • One write capacity unit represents one write per second for items up to 1 KB in size. If you need to write an item that is larger than 1 KB, DynamoDB will need to consume additional write capacity units. The total number of write capacity units required depends on the item size.

DynamoDB uses eventually consistent reads, unless you specify otherwise. Read operations (such as GetItem, Query, and Scan) provide a ConsistentRead parameter: If you set this parameter to true, DynamoDB will use strongly consistent reads during the operation.

6 KB / 4 KB = 1.5 --> 2
2 read capacity units per item × 100 reads per second = 200

Thus, you would need to set the table’s provisioned read capacity units to 200. (If you wanted eventually consistent reads instead of strongly consistent reads, then you would only need to provision 100 read capacity units.)

To read a single item, you use the GetItem operation. If you want to read multiple items, you can use BatchGetItem to retrieve up to 100 items from a table.

To work with a single item, use the PutItem, UpdateItem, or DeleteItem operation as appropriate. You can also use BatchWriteItem to put or delete up to 25 items in a single operation. (Note that BatchWriteItem supports PutItem and DeleteItem operations, but not UpdateItem.)

Response code HTTP 200 returns result ok, code HTTP 400 returns result bad request accompanied by aProvisionedThroughputExceededException.

Secondary Indexes Per Table

You can define a maximum of 5 local secondary indexes and 5 global secondary indexes per table.

When you add a rule to an RDS security group you do not need to specify a port number or protocol? False

If you are using Amazon RDS Provisioned IOPS storage with MySQL and Oracle database engines what is the maximum size RDS volume you can have by default?

DynamoDB vs RDS:

Dynamodb offers “push button” scalling, meaning that you can scale your database on the fly, without any down time.

RDS is not so easy and you usually have to use a bigger instance size or to add a read replica.

Instance downgrade is not possible, If need then export the whole database into db formate. Reupload the db into a larger instance.

Service outage take place in snapshot

 

BACKUP, Multi-AZ & Read Replica:

 

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