I find it strange that Postgres has features like these, but lacks bit_count, which is required for hamming distance. It's easy to write a C-Language User Defined Function, but then you can't use RDS.
One of greatest things about Postgres is its extension system which is meant for things like this. RDS not supporting custom extension is RDS problem and frankly I wouldn't recommend using RDS. You are losing a lot of functionality, upgrades are tougher etc. Postgres maintenance is quite low the hardest part is probably running and RDS doesn't save you from that.
Anyway this feature discussed (searching based on a distance) is part of PostGIS extension they are demonstrating here SP-GiST index.
> RDS not supporting custom extension is RDS problem and frankly I wouldn't recommend using RDS.
We are using RDS and would like to have a standard PostgreSQL instead. Is there some community supported AMIs that could help us to get started quickly?
One of nice things about RDS is seamless replication and backups, this is not available out of the box, and you kind of need to set it up yourself, it is not that hard, especially if you have a CMS (such as salt, chef) helps a lot with it.
There is already RDS functionality available through open source, if you're on premises I would highly recommend repmgr[2] and barman[3] the former is making setting replication and failover easy, the later is performing streaming backups and PITR.
In AWS in place of barman, you could perhaps use WAL-E[4] or WAL-G[5] these basically do the same thing barman does, but instead of running an instance that keeps the backup WAL-E and WAL-G stores backups directly in S3.
There's also Patroni[6] which is an alternative to repmgr. I have used personally repmgr and barman, and there wasn't really much overhead maintaining it. Although in public cloud the other solutions might be more suited?
The nice thing for maintaining your own setup is greater control over the database, for example you have full control over what extensions you use or which version of PG you deploy. Many changes that in RDS require server restart, you can just restart the process and have lower downtime. In my company we also went with Aurora PG 9.6 there's already Aurora PG 10, but there's currently no upgrade path without taking everything down, backing up and restoring on another instance. Supposedly AWS is working on it, but they won't tell when it is available. Also there's no PG 11 or heh, 12. With own PG setup also major version upgrade is quite quick, I think it took 2 minutes, if you were sure you have backups and performed upgrade in place.
Honestly what RDS offers isn't something that isn't available outside, it's just that might require some prior investment, in our case was writing salt roles that set up and configured the nodes.
[1] https://www.postgresql.org/download/
[3] https://www.pgbarman.org/index.html
[4] https://github.com/wal-e/wal-e