If I was a user of this product I'd be really worried about the "We rewrote our software 5 months ago, but that didn't solve the issue we wanted to solve so we're doing it again, maybe this time we'll fix it" message of this post.
To me to key “insight” is that if you are going to spin up single VMs (or even groups) per-customer and then route queries, you need to be able to estimate the query cost first.
I know snowflake does this, they do the query optimization before sending it for execution. So it knows about how many resources will be needed (it can obviously be wrong).
How does Snowflake use that information? You still need to pick the warehouse. It would be cool if there was an "elastic warehouse" where heavier queries are routed to bigger Warehouses, but that's not the case
The entire website is a bit of a red flag to me, starting with the cookie banner featuring an image of Ursula von der Leyen and some misinformation (cookie banners are not legally required).
> Five months ago, we rebuilt our warehouse on DuckDB instead of ClickHoue
They switched from ClickHouse to DuckDB five months ago, then switched from DuckDB to their own Trino derivative?
The article then ends before saying if the new setup solved their problems.
It’s great that we can now make these migrations with little downtime (I assume?) and try different things, but I wish we could have read more about what testing they did before jumping. The fact that they jumped to DuckDB without realizing it wasn’t going to work at their scale and spent only a few months with it before jumping again is not convincing.
I hoe there’s more to this story that just didn’t make it into the blog posts. As written it’s giving me flashbacks to some teams I worked with who changed tech stacks every six months because they liked migrating more than tuning and maintaining.
I don’t know? They have blog posts about it but I don’t know how much I’d trust them because their chosen replacement only lasted 5 months before the next replacement.
The intro to that post is so bad: "PostHog's original data warehouse had a single goal: delay the moment a company needs to hire their first data engineer."
It is not to serve high quality and timely data to make good decisions, is to avoid hiring a specific role, lol. So bad.
I mean, mostly it just comes off as egregious self-indulgence to try one thing and then jump to "we built the solution ourselves!" when the problem is not novel at all. These things are just tiresome.
Sometimes a company just isn't able to manage a data warehouse; I've worked for a few.
I even phone screened with this one but couldn't cover their crazy quilt of requirements; at that time they were also looking for someone to rewrite the clickhouse optimizer, and they were stuck trying to reshard their cluster, which should take an afternoon.
I still like the company because their business prop reminds me of what we were doing in 2009, a kind of federated analytics organization on a centralized data warehouse that enables a lot of tools to be developed quickly at large scale.
But goddammit they keep picking these half-working platforms and flip-flopping from one to another. We were crushing millions of queries against 2T-row tables on Vertica in 2010, and it's only gotten better for customer-facing data apps, which is what Posthog is. The company doesn't seem to have a baseline of what to expect; the market is too saturated with slow tools that lower expectations.
I wonder if they have considered moving back to ClickHouse. ClickHouse Iceberg support has improved a lot over the past few months. You can easily run stateless ClickHouse on top of Iceberg. This solves the tenancy issue, and it can easily handle petabytes scale [1].
I actually like the menus. They work great on mobile too.
We built up all these UI conventions from decades of desktop development, then abandoned them for the web (and worse, electron). It's annoying learning a new convention for every website. We could do a lot worse than bringing back menus.
I kind of liked the originality. It's what happens when you give software developers free reign on the marketing pages as well, I guess.
But it seems to have gotten a re-skin recently, and I preferred the previous more pixelated version. Also, there used to be a way to render a "normal" version of the website, but I can't find it anymore.
And what's with that bs cookie banner?
If the only cookies are functional/essential, they don't need to show a cookie banner.
If it's for analytics, then I should be able to reject it.
Otherwise, it's just a dick-over.
The key insight I am getting from this is that as migrations get easier to do with agents, there will be a lot more of them.
But more importantly a lot of them will happen because we will all get more trigger happy to start one. On the other hand I also don't know if at scales like PostHog, a successful migration can be tested without doing all of it.
This reminds me so much of when we would bring a new marketing leader and they would plant their flag by nuking all of the existing marketing automation processes to bring in theirs, with no net impact on the business. Bike shedding.
I would have appreciated more technical details with methodologies and explicit failures observed. Oh and a human voice would be nice for a change.
> Customers ran more complex queries than we expected
Did the queries change after DuckDB was introduced? Did they do a study of query patterns that could have anticipated this ahead of time?
> Predicting CPU and memory for a specific query was even harder.
What attempts / methodologies were used to try this? What was hard? What failed?
> We'd rather have contributed to the existing community and helped it grow. But we couldn't land changes as fast as we needed, so we ended up carrying patches in a fork
This isn't a BAD approach per se. IME it's common (and necessary) for the large scale users of a platform to maintain a fork for their needs and work with the community and the maintainers to upstream changes when/if the community is ready to accept. That's called influencing. On the other hand, if you toss of a few slop grenades to the community and they reject you shouldn't be surprised. (Not suggesting that's what happening here but the defeatest conclusion may imply it?)
> Missing reconnects and managing TTLs and idle connections at scale is hard
This idiotic churn used to be restricted to front end devs and backend folks were spared. Thanks for Agents now every part of the stack is going to be in constant churn thanks to resume builders. At no point in the article did you get a sense they have a handle on what their problem is and why a certain technology and architecture would be a better fit. Just try it out, churn out, try it out.
6 months from now: We are moving our warehouse off of Trino + HogLake to newer technology XXX.
This is ridiculous. Why can you not foresee such issues? Do you not do testing with mock data at the size you need? Migrating production between stacks so often means you are not getting new features in. This is pure churn.
It feels like a lot of churn and not a lot of measurements or engineering.
I know snowflake does this, they do the query optimization before sending it for execution. So it knows about how many resources will be needed (it can obviously be wrong).
They are big on shipping slop at lightnigg speed. So this is not surprising. Checkout posts by their ceo on cringedin.
They switched from ClickHouse to DuckDB five months ago, then switched from DuckDB to their own Trino derivative?
The article then ends before saying if the new setup solved their problems.
It’s great that we can now make these migrations with little downtime (I assume?) and try different things, but I wish we could have read more about what testing they did before jumping. The fact that they jumped to DuckDB without realizing it wasn’t going to work at their scale and spent only a few months with it before jumping again is not convincing.
I hoe there’s more to this story that just didn’t make it into the blog posts. As written it’s giving me flashbacks to some teams I worked with who changed tech stacks every six months because they liked migrating more than tuning and maintaining.
https://news.ycombinator.com/item?id=33082224
Why did they write this post if they had not even allowed things to settle. It sounds like someone wanted to claim victory (and promo?)
https://posthog.com/blog/why-we-rebuilt-our-data-warehouse
It is not to serve high quality and timely data to make good decisions, is to avoid hiring a specific role, lol. So bad.
I even phone screened with this one but couldn't cover their crazy quilt of requirements; at that time they were also looking for someone to rewrite the clickhouse optimizer, and they were stuck trying to reshard their cluster, which should take an afternoon.
I still like the company because their business prop reminds me of what we were doing in 2009, a kind of federated analytics organization on a centralized data warehouse that enables a lot of tools to be developed quickly at large scale.
But goddammit they keep picking these half-working platforms and flip-flopping from one to another. We were crushing millions of queries against 2T-row tables on Vertica in 2010, and it's only gotten better for customer-facing data apps, which is what Posthog is. The company doesn't seem to have a baseline of what to expect; the market is too saturated with slow tools that lower expectations.
[1] https://clickhouse.com/blog/jump-trading-uses-clickhouse-wit...
We built up all these UI conventions from decades of desktop development, then abandoned them for the web (and worse, electron). It's annoying learning a new convention for every website. We could do a lot worse than bringing back menus.
But it seems to have gotten a re-skin recently, and I preferred the previous more pixelated version. Also, there used to be a way to render a "normal" version of the website, but I can't find it anymore.
But more importantly a lot of them will happen because we will all get more trigger happy to start one. On the other hand I also don't know if at scales like PostHog, a successful migration can be tested without doing all of it.
> Customers ran more complex queries than we expected
Did the queries change after DuckDB was introduced? Did they do a study of query patterns that could have anticipated this ahead of time?
> Predicting CPU and memory for a specific query was even harder.
What attempts / methodologies were used to try this? What was hard? What failed?
> We'd rather have contributed to the existing community and helped it grow. But we couldn't land changes as fast as we needed, so we ended up carrying patches in a fork
This isn't a BAD approach per se. IME it's common (and necessary) for the large scale users of a platform to maintain a fork for their needs and work with the community and the maintainers to upstream changes when/if the community is ready to accept. That's called influencing. On the other hand, if you toss of a few slop grenades to the community and they reject you shouldn't be surprised. (Not suggesting that's what happening here but the defeatest conclusion may imply it?)
> Missing reconnects and managing TTLs and idle connections at scale is hard
Wonder if they tried pgdog?
Who did the growth estimation of the data? This looks like an example of bad planning.
[0] https://github.com/PostHog/hoglake
This is ridiculous. Why can you not foresee such issues? Do you not do testing with mock data at the size you need? Migrating production between stacks so often means you are not getting new features in. This is pure churn.