AWS CLOUD

RDS SQL & NOSQL 

RDS/ Elasticache:

1. On a MySQL DB instance, avoid tables in your database growing too large. Provisioned storage limits restrict the maximum size of a MySQL table file to 16 TB. Instead, partition your large tables so that file sizes are well under the 16 TB limit.
2. Read Replicas are supported by Amazon Aurora, Amazon RDS for MySQL, MariaDB and PostgreSQL Unlike Multi-AZ deployments, Read Replicas for these engines use each’s built-in replication technology and are subject to its strengths and limitations. In particular, updates are applied to your Read Replica(s) after they occur on the source DB instance (“asynchronous” replication), and replication lag can vary significantly.
3.  Multi AZ deployments for the MySQL, MariaDB, Orade, and PostgreSQL engines utilize synchronous physical replication to keep data on the standby up-to-date with the primary. Multi-AZ deployments for the SQL Server engine use synchronous logical replication to achieve the same result, employing SQL Server-native Mirroring technology.
4. Amazon Aurora employs a highly durable, SSD-backed virtualized storage layer purpose-built for database workloads. Amazon Aurora automatically replicates your volume six ways, across three Availability Zones Amazon Aurora storage is fault-tolerant, transparently handling the loss of up to two copies of data without affecting database write availability and up to three copies without affecting read availability. Amazon Aurora storage is also self-healing. Data blocks and disks are continuously scanned for errors and replaced automatically.
5. Amazon Aurora Replicas share the same underlying storage as the primary instance. Any Amazon Aurora Replica can be promoted to become primary without any data loss and therefore can be used for enhancing fault tolerance in the event of a primary DB Instance failure. To increase database availabday, simply create 1 to 15 replicas, in any of 3 AZs, and Amazon RDS will automatically include them in failover primary selection in the event of a database outage.

Dynamo DB:

1. Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability.
2. Amazon DynamoDB stores three geographically distributed replicas of each table to enable high availability and data durability. Read consistency represents the manner and timing in which the successful write or update of a data item is reflected in a subsequent read operation of that same item.
3. Eventually Consistent Reads (Default)-also supports Strongly Consistent Reads.
4. A table is a collection of data items – just like a table in a relational @tabase is a collection of rows.
5. Each table must have a primary key. The primary key can be a single attribute key or a “composite” attribute key that combines two attributes. The attribute(s) you designate as a primary key must exist for every item as