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The startup's Postgres survival guide

hatchet.run

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Re: The startup's Postgres survival guide

#2
Having been early at a startup that relied on Postgres I think this post doesn't put enough focus on monitoring and alerting. Postgres has a few key failure modes that you want to avoid ever happening, and you can use alerting to get early warning that you're danger of it happening.

For example, AWS will send you an email if you're approaching XID wraparound. In a startup that email is very likely to be missed, especially if it's sent on Boxing day. You want whatever AWS is watching to send you that email to be something connected to a pager.

Re: The startup's Postgres survival guide

#3
Should one of the first things you do with a database not be to have a backup strategy? I understand that HA would be a "nice to have" when first starting out, but surly if you have a production db, a backup and restore plan should be on a survival guide? Neither appear to be mentioned here.

What do you all use for your pg backups? Is Barman ( https://pgbarman.org/) still the way many do it? (I haven't deployed a new pg instance for a while, but thinking about it for a new project).

Re: The startup's Postgres survival guide

#4
To this articles credit, it does start out with normalization and design!

There needs to be more emphasis how important this is! I cant tell you how often I see it done "badly" (we let our ORM build the db for us). The best text I have ever found on this is "Database Design for Mere Mortals", over the years I have bought more that a few copies and I always end up giving them away to those in need (and there are always people around in pretty dire need).

The one thing I would say is missing from this article is to not be afraid of using postgres for "stupid" things. Cache, queue's, and so on, especially on the road to launch.

One should also not be afraid of having more than one Postgres instance, especially if you're using it as a work queue.

Lastly there is a stupid amount of power in Postgres roles (its "user" system). The manual here is somewhat OK, but really undersells richness that it makes available to you.

Re: The startup's Postgres survival guide

#5
post #3

Should one of the first things you do with a database not be to have a backup strategy? I understand that HA would be a "nice to have" when first starting out, but surly if you have a production db, a backup and restore plan should be on a survival guide? Neither appear to be mentioned here. What do you all use for your pg backups? Is Barman ( https://pgbarman.org/ ) still the way many do it? (I haven't deployed a ne…

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.

Re: The startup's Postgres survival guide

#6
On migrations, there's a .Net tool called Grate that I tend to use for schema migrations... I don't use all the features, but it works well... using a migration stack in a repository for deployments and a similar tool is IMO more reliable than magic comparison tools or hand migrations in practice. You should defensively write your migrations as much as possible so that re-runs are relatively safe, though the tool helps to handle this.

One bit not mentioned, and particularly useful in more modern RDBMS with JSON binary expressions in the database are to leverage JSON columns and avoid joins altogether for a lot of use cases. There are a lot of times where you have variance of sub-information, or other data where table normalization and joins work against you. Even with indexes, joins are costly, especially under load at scale with millions of simultaneous users. You can avoid a lot of this by simply having that sub-table information inside a JSON field with the row in question.

For example, logs and notes related to a specific field. Variable transaction data (paypal vs amazon vs google payments), where the logs/details from the API aren't something that really needs to be in a separate table but related to the transaction.

Another would be something like a classifieds site where many fields are repeated, but sub-fields can vary dramatically by the type of item or category.

Knowing how/when to leverage denormalization and JSON can be one of the most impactful things you can do in terms of performance in practice, short of falling back to a search database (Elastic, Quickwit, etc), which can also be practical depending on your needs, but adds complexity.

Similarly, knowing how your datagase uses certain types of data/serialization... for example UUIDv7 if you don't mind storing creation time (utc) of a record, or COMB if using say MS-SQL in particular... the serialization of said field in practice helps in terms of understanding how indexes update and impact performance.

I do wish the guide was expanded a bit with lots of specific examples and details... a lot of it is hand-wavy blurbs.

Re: The startup's Postgres survival guide

#7
post #5
post #3

Should one of the first things you do with a database not be to have a backup strategy? I understand that HA would be a "nice to have" when first starting out, but surly if you have a production db, a backup and restore plan should be on a survival guide? Neither appear to be mentioned here. What do you all use for your pg backups? Is Barman ( https://pgbarman.org/ ) still the way many do it? (I haven't deployed a ne…

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.

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.

Re: The startup's Postgres survival guide

#8
Postgres is my favourite thing, but I find it's prohibitively costly when bootstrapping something that is lean and frugal.

I end up with a mixture of serverless storage like DynamoDB, S3, DuckDB on S3, and SQLite.

Am I crazy? How can one have a decent Postgres and not pay at least $100/mo (yes, when I say frugal I mean really frugal ... think solo founder that likes to stay on free tiers haha) -- I am aware of Neon/Supabase, but last time I tried them they ended up becoming a tightly coupled annoying dependency after scale that defeated the cost savings as they grew in costs and we ended up migrating to Aurora / RDS lol

EDIT: I'm aware of the self-hosted path but I find configuring the above things faster/cheaper in terms of my admin hours than the self hosted postgres db. Maybe I just suck at being a DBA or need better education on it, that said, I have AI now so I should give it a chance again as it's been a minute since I created a fresh thing

Re: The startup's Postgres survival guide

#10

Postgres is my favourite thing, but I find it's prohibitively costly when bootstrapping something that is lean and frugal. I end up with a mixture of serverless storage like DynamoDB, S3, DuckDB on S3, and SQLite. Am I crazy? How can one have a decent Postgres and not pay at least $100/mo (yes, when I say frugal I mean really frugal ... think solo founder that likes to stay on free tiers haha) -- I am aware of Neon/S…

It runs easily on a vps at your scale, even the same vps serving your app. That used to mean having a modicum of sysadmin knowhow but it’s straightforward these days, especially if you just use a premade docker file.
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