Explanation
References:
After you create a load balancer, you can apply policies to control traffic distribution to your backend servers.
The Load Balancing service supports three primary policy types:
Round RobinLeast ConnectionsIP Hash

Explanation
You can permanently terminate (delete) instances that you no longer need.By default, the instance's boot volume is deleted when you terminate the instance, however you can preserve the boot volume associated with the instance, so that you can attach it to a different instance as a data volume, or use it to launch a new instance.
You can use a boot volume backup to create an instance or you can attach it to another instance as a data volume. However before you can use a boot volume backup, you need to restore it to a boot volume.

An Oracle Data Guard implementation requires two DB systems, one containing the primary database and one containing the standby database. When you enable Oracle Data Guard for a virtual machine DB system database, a new DB system with the standby database is created and associated with the primary database. For a bare metal DB system, the DB system with the database that you want to use as the standby must already exist before you enable Oracle Data Guard.
Requirement details are as follows:
- Both DB systems must be in the same compartment.
- The DB systems must be the same shape type (for example, if the shape of the primary database is a virtual machine, then the shape of the standby database can be any other virtual machine shape).
- If your primary and standby databases are in different regions, then you must peer the virtual cloud networks (VCNs) for each database.
- Configure the security list ingress and egress rules for the subnets of both DB systems in the Oracle Data Guard association to enable TCP traffic to move between the applicable ports. Ensure that the rules you create are stateful (the default).

Explanation
You can scale up/down your Autonomous Database to scale both in terms of compute and storage only when needed, allows people to pay per use.
Oracle allows you to scale compute and storage independently, no need to do it together. these scaling activities fully online (no downtime required) in Details page Autonomous Database click Scale Up/Down. Click on arrow to select a value for CPU Core Count or Storage (TB).
Or Select auto scaling to allow the system to automatically use up to three times more CPU and IO resources to meet workload demand, compared to the database operating with auto scaling disabled.

Explanation
References: https://www.terraform.io/docs/extend/writing-custom-providers.html