RDS Configuration Notes
Warning: auto-generated passwords
When creating an RDS instance, if you choose "auto-generate a password", it will only appear in the blue AWS notification after you create it - don't dismiss that notification or you'll have to reset the password!
Parameter Groups
To use stored procedures and functions, make sure to use a custom parameter group, which has log_bin_trust_function_creators set to 1.
Storage
Use the gp3 storage option - it's cheaper and has better throughput than gp2.
Maximum active connections
The max connections for a given DB instance depends on the instance type, based on its total memory. Note that it's not a straight formula, since some of the total memory is reserved for other purposes than just connections.
The first three types of DB have the following connection limits by default (tested Jan 3, 2024):
| Instance type | Memory (GiB) | Max active connections (default) |
| t4g.micro | 1 | 30 |
| t4g.small | 2 | 68 |
| t4g.medium | 4 | 151 |
You can technically increase this limit - the max_connections parameter in the DB's parameter group controls this value. The default is set to LEAST({DBInstanceClassMemory/25165760},12000), so you can adjust this by changing the divisor on the class memory. It's not recommended, as if there's too much memory use the DB server will crash.