upvote
I might get flak for saying this but if you aren't a postgres expert already: just use RDS or a similar cloud DB. The amount of money you're saving by hosting and managing your own postgres instance is absolute peanuts compared to having battle-tested infrastructure for HA, backup and restores, point-in-time recovery, read replicas, etc.
reply
At $dayjob we have the same mentality and as a result have a load of managed read replicas that are never used for anything (not reporting, not read only queries, not backups because $cloud handles it) that cost every month. Plus managed database restricts what you can do with the database - sometimes in really annoying ways.

So while I partly agree with you, a lot of companies don't really need HA, read replicas, or even PITR (though I would argue the last one is so trivial and cheap to enable that why not), but they click the expensive check box, and I would argue that companies who do need these features should consider hiring at least a couple of DBAs and get more flexibility instead of the current status quo of everyone being scared of the database and everyone just hoping cloud support will come to their rescue if ever needed

reply
> hiring at least a couple of DBAs and get more flexibility

Every place I’ve ever worked at that had DBAs had the complete opposite of more flexibility. You have to do things the DBA’s way, and if their way doesn’t work for your service, you need to fight for their time and priority.

Meanwhile every place I worked at where every team completely owned their databases + did periodic data recovery drills had much more flexibility and no data loss.

reply
That’s usually because they’ve seen a lot of failure modes over the years, and what seems fine to you can have surprising outcomes later.

My personal experience has been the opposite of yours: lots of data inconsistency issues, data loss only resolved by the database team spinning up backups, etc. And somehow, even after yet another incident, there’s never been appetite to properly fix things.

reply
> At $dayjob we have the same mentality and as a result have a load of managed read replicas that are never used for anything (not reporting, not read only queries, not backups because $cloud handles it) that cost every month.

Obviously "let RDS manage your database" doesn't require egregious read replicas. The decision to use read replicas or not is completely orthogonal to whether you use RDS to manage them.

reply
> Obviously "let RDS manage your database" doesn't require egregious read replicas

Of course not, but an easy checkbox, a best practice AWS or terraform guide and someone doing AWS certified X associate makes it easier to happen without anyone ever really discussing it.

> The decision to use read replicas or not is completely orthogonal to whether you use RDS to manage them.

Assuming you're talking about letting RDS manage anything, then sure - apart from it being more likely to slip through the net if nobody has to configure them. Database is just an expensive cost nobody necessarily drills into.

However if you mean the decision to let $cloud manage the replicas (and keep the primary managed), that totally depends on the cloud and the options. For example have you ever tried having a primary in GCP Cloud SQL but the replica not in cloud SQL?

reply
> Of course not, but an easy checkbox, a best practice AWS or terraform guide and someone doing AWS certified X associate makes it easier to happen without anyone ever really discussing it.

I'm defending your employer or their mindset, I'm just disagreeing with your claim that this follows from the parent's cost analysis claims. It _seems_ like your organization's problems are precisely because they _weren't_ doing the kind of cost analysis that the parent advocated. In other words, nothing in the parent's comment advocated for blindly following some Terraform guide. It feels unfair to the parent to suggest that their mindset caused your organization problems when it seems like your organization's problems were caused by _not having_ the parent's mindset.

reply
And then.. you're basically trapped inside the AWS cloud (due to egress costs and db latency). No thanks!
reply
deleted
reply
RDS is nice even if you just want basic functionality with backups.
reply
FWIW, we use: https://pgbackrest.org/

Offers point-in-time recovery which is an improvement over a custom solution we used to have which gave us nightly backups.

We have it backing up to Backblaze B2 (S3 like). Was relatively easy to setup and no problems really.

reply
There was some recent uncertainty about pgBackRest getting discontinued due to lack of funding. But the maintainer secured funding, and pgBackRest development will continue.

https://pgbackrest.org/news.html

reply
Can't recommend pgbackrest enough. It's fantastic software, and I love the work they put into doing inter-file deltas for backups (so if 8kb of a 1gb file changes, you only backup the difference). It saved my last company a ton of money on storage while keeping good RTO/RPO.
reply
It's great, but it's not incremental like git, e.g. you do need to make a full backup periodically, unfortunately.

I didn't understand that, and after 5 months of usage caught my backblaze to be using 40TB, and nightly restores taking forever for other reasons. So: not ideal, and be careful to check!

reply
Heh, yeah I suppose there are still some foot guns if you don't understand how things work.
reply
There’s no need to get all complicated and fancy or introduce more dependencies. For most people, a cron job calling pg_dump_all piped to zstd and copying the output to s3/ftp/whatever is plenty good enough.

Obviously past a certain point carting around full backups becomes time/dollar prohibitive, but this can take you very far.

reply
FWIW, we started with a system that was essentially this. We eventually moved to pgbackrest and it wasn't any harder to setup. But the ROI on that investment is a lot higher because pgbackrest does a lot more for us than the home rolled solution.

Having done both, I'd recommend just starting with pgbackrest.

reply
If you can afford to lose the data created between backups, sure.
reply
Better than losing all the data created between no backups.
reply
But the other option is just doing it right from the start and using a tool like pgbackrest. It's no harder to setup, and it puts you into best practices by default rather than having to work at it later.

I just don't understand why people seem so drawn to the bad solution just because it ships with the database.

reply
I think you need to analyze the disaster scenarios and recovery costs you are trying to balance before you can really evaluate these different options.

If you are on reasonable storage, I think it is arguable that the main reason you would have to recover is due to a software failure leading to corruption of the PostgreSQL backing state files. Otherwise, you would simply be restarting PostgreSQL on your durable and available storage. So, if the content has been corrupted by bugs, can you trust the recent WAL log in this scenario? Or can a plain dump be a more reliable "known-good" database recovery point?

And what is the business cost to rolling back to a less frequent dump such as nightly? Not every DB is some kind of multi-party OLTP ledger. Sometimes, a day of lost "new data" may be just a day of labor to repeat some data entry or other repeatable work...

A really robust contingency plan probably has both of these kinds of backup, and scenarios where one recovery versus the other is attempted. But if you are starting at a very small scale, hosted on some reasonable cloud storage like EBS, a cron-based dump that goes into a normal hierarchical file backup system may be totally sufficient for the extreme disaster scenario where you cannot simply restart your DB server on top of the surviving and available storage volume?

reply
Using something like EBS for your postgres data directory is, IMO, a bad idea. If you've already made that mistake, yeah I suppose using PG dump isn't that bad.

I'd much rather just do it right though.

Direct attached storage (or whatever storage is fastest / lowest latency for the environment you have available).

Setup pgbackreset or barman, use WAL archiving and setup block incremental backups with a new full backup every so often.

Now you have point in time recovery with very low RPO/RTO, and your database infrastructure can be treated a bit more like cattle instead of a pet, as you should be testing restores often, and this will become part of your yearly major postgres upgrade strategy.

You also get the ability to have a replica for almost free, as replicas can be created from the backup repo very cheaply, and get caught up to the primary without requiring the primary keep around the WAL for a long time. It just pulls it from the repo until caught up.

Any case where you think EBS was the right choice is better handled by having one (or more) replicas and a failover strategy.

Just do the right thing from the start and you save a lot of headaches. People have run production systems already, and have hit the pain points. Why keep hitting the same ones?

reply
To play devils advocate, something that doesn't ship with the database is harder to setup than something that does
reply
An atomic volume snapshot should work for any database that's durable on power failure. Ideally preceded by a checkpoint, to minimize recovery time. Atomicity of the snapshot mechanism is essential to prevent data corruption using this approach.

We used EBS snapshots on AWS for multi-TB MongoDB to get incremental backups that are fast to create and fast to restore (with some performance degradation after restore).

It doesn't support point-in-time recovery, but since it's fast you can create frequent snapshots (e.g. hourly). I'd consider adding this as a secondary backup strategy, even if you use a higher-level postgres-specific backup tool.

reply
If you already run k8s, why not just use cnpg?

https://github.com/cloudnative-pg/cloudnative-pg

reply
Backups are mandatory for any serious deployment. But it's more devops and the guide is more about SQL layer.

This guide is only satisfactory if the database is managed, otherwise there are a whole bunch of things going on.

reply
pgdump / pgrestore, using native binary format
reply