The g instance is a Graviton processor, which tend to be cheaper, and preform pretty well. It's ARM, but you can switch to that without affecting your data.

Primarily with instance types within RDS the key differences are as follows:

• Available Memory
• Available CPU
• Maximum Network Throughput
• Burstable vs non-burstable (T instance family uses burstable credits, once this is depleted your CPU is capped).

As you're using a T2.micro you only have a single CPU available. Once the credits are depleted you will only be capped at 20% maximum CPU too which will limit what you're able to do.

I would also note if you are able to invest more in the AWS platform there is a dedicated data warehouse solution for analytics which is Redshift, this is likely to perform better but will cost more, its also forked from Postgres.

If sticking to Postgres in RDS is what you're looking to do you should also consider Aurora Postgres, it generally provides 2-3 times the performance of regular Postgres on RDS.

m1.xlarge instances (the 64-bit/15GB you mention) get a NIC all to themselves and therefore have the best network (and by extension, EBS) performance. With striping you can sustain 1500 disk iops, as oppossed to the standard 100 iops.

When used in RDS, you will see highest iops by setting your storage size to at least 300GB, which triggers back-end striping.

If you need more RAM or CPU, only the c1.xlarge and m2.4xlarge instance types have the full NIC to themselves- they would also required 300GB storage allocation to take advantage of it.

To determine the appropriate memory size for your RDS instance, you will need to consider the size and usage patterns of your databases. From the information you provided, it seems that the majority of your databases are relatively small and have low usage, with the exception of Database 5, which is larger and has a higher usage rate. Based on the information you provided, I would recommend starting with an RDS instance with at least 4GB of memory. This should provide enough memory to comfortably handle your smaller databases, while also providing some headroom for growth. However, to handle the load of Database 5, you may want to consider upgrading to a larger instance type or using a separate RDS instance solely for that database. When deciding whether to use a separate RDS instance for Database 5, you will need to consider factors such as the amount of traffic it receives, the complexity of its queries, and the impact it could have on the performance of your other databases. If it is critical to your business and receives a lot of traffic, it may be best to isolate it in a separate instance to ensure optimal performance. However, if it is not heavily used or is not likely to impact the performance of your other databases, it may be fine to keep it in the same instance and simply increase the memory allocation. > Always try to have the Database of latest generation. For you, If the load is normal, then t4g.medium or db.m6g.large should work well. (As I am considering a normal load pattern). You might want to do the performance testing and then take a final call on the DB Instance size.