I've similarly spent a decade in the streaming space, started a stream processing startup, built three streaming platforms at various large companies... and I basically agree.
Streaming always felt like it was about to happen, and it kept not happening, in a year of the linux desktop sort of way. I (and others, who also optimistically started stream processing startups) thought it was a technology problem but ultimately it's a demand problem: very few companies actually need low latency processing. And continuously running, stateful systems are inherently more complex to operate and evolve compared to batch systems.
Now that relatively low-latency ingest into warehouses and datalakes is easily achieved, it's really hard to make the argument to invest in complicated streaming systems.
That said, it still feels like we've landed in a suboptimal spot. Stream processors (in particular, those following the dataflow model) solve two problems that are hard in batch systems:
1. Determining and signaling completeness for a time period (when have I likely received all of the data for 12:01pm, such that I can now safely process it)
2. Avoiding expensive recomputations for periodic queries
I do think long term we'll see some amount of streaming influence moving back into the batch systems, particularly as object storage gives us the ability to run stateful workloads with less operational headache.
(If anyone else finds these problems interesting, I'm hiring for my stream processing team at Cloudflare. Email in my profile)
During my time in the space, my pithy saying about the system I worked on [1] was that we could scale up or down. If you wanted to do streaming packet filtering with microsecond latency, we could do that. If you wanted to do complex analytics on structured data, we could do that. We did have deployments that "scaled down" and were more stream processing rather than streaming analytics. But analytics is by far the dominant use case, and SQL and relational databases are the better abstraction there. And for the stream processing cases, folks tend to stick to their existing lower-level stacks.
I'm increasingly of the opinion that "basically a data warehouse, but incrementally maintained materialized views under the hood as an implementation detail" (e.g. Materialize, Feldera, anything based on Differential Dataflow / DBSP) is a good point in the design space. I get that they're more complicated than batch, and for many orgs the low latency isn't necessary for pure analytics/dashboards.
I wonder if there's a place for such architecture in the operational path, not just analytics. If you squint, "this microservice reads data from this operational DB and passes it to this other microservice / puts it in a cache / sends it in response to a request" looks sort of like an "ad hoc, informally specified, bug-ridden, slow"[0] implementation of incremental view maintenance (in that a cache, or a service's data model in memory, is a sort of "materialized view" over the source data). I've seen some success in replacing a tangle of imperative-languages-and-network-requests with a declarative, incrementally maintained model in SQL, if the read latency can be kept under control.
I'm curious about the "some amount of streaming influence moving back into the batch systems, particularly as object storage gives us the ability to run stateful workloads with less operational headache" part. could you expand on that?
[and yes, I do find these sort of problems interesting! :)]
I’m not sure you have to squint; an mview is just a cached query. The only difference between an mview and a cache is the “incremental” part of the equation.
That is, my only disagreement is the lack of gusto
1. completeness is still a very desirable behavior for many use cases, but it's gonna be tricky to build these use cases on top of the new wave of IVM-like streaming systems, which provides no completeness marker.
2. periodic queries declared in non-streaming declarative form can and should be computed incrementally, but as far as I know, there's still not much mature support for automatic optimizations
the fact that traditional database infrastructure handles many people's needs doesn't really obviate dataflow style architectures. personally I think (3) composition is a real potential win. I would also note that streaming is a really great base on which to build a distributed database that looks more like Postgres on top.
I guess I'm mostly confused about the idea that streaming systems should be trying to supplant sql databases, or that a failure to do so implies that they don't have utility. it looks like the GP has done some really interesting work on automatic parallelism. that isn't pointless just because most people building operational systems still reflexively reach for PG.
That work is still relevant! It's just that end-users don't need to be aware of it. The position of the paper I submitted, which I basically agree with, is that "streaming" shouldn't need to be something end-users care about. It's something the system does based on needs.
Databases already have a dataflow style architecture: that's how they implement queries. Because SQL is relational, SQL queries become dataflow execution plans.
One way to think about the programming model I worked on is that it was like exposing a query plan API directly to users, instead of giving them SQL.
A project to watch in that space is Rama from Red Planet Labs [0]. It pushes further the trend of destructuring databases into a very flexible streaming engine and database.
It has no query engine, instead the platform offers powerful primitives to partition and distribute both data and compute, effectively destructuring transactions and query engine into microbatch and stream topologies.
I think the real value of such platform is in how it can replace tons of microservices and nosql databases into a single platform with a coherent model.
Replacing 1M LOC across 100 services and databases by one cluster with 10000 LOC is an operational dream come true.
Also I expect LLMs limitations to force us to resolve ourselves the operational complexity of IT, as I can't imagine letting LLMs multiply the number of services and databases like PRs on github. Platforms like Rama provide the necessary constraints to channel LLM output into a coherent whole easy to operate and observe.
It is indeed interesting, and it's from Nathan Marz, who was the creator of Storm. That was the first major open source streaming platform. It predated what I consider the default open source streaming platform, Flink.
Glancing through the docs, my main three reactions are: 1) It's sophisticated system which, as you say, effectively opens up the components of a database engine to be used as needed. 2) Folks will still want to eventually land their data in a "normal" data-at-rest storage format like Hive tables or Parquet. 3) Folks will still want SQL.
Streaming always felt like it was about to happen, and it kept not happening, in a year of the linux desktop sort of way. I (and others, who also optimistically started stream processing startups) thought it was a technology problem but ultimately it's a demand problem: very few companies actually need low latency processing. And continuously running, stateful systems are inherently more complex to operate and evolve compared to batch systems.
Now that relatively low-latency ingest into warehouses and datalakes is easily achieved, it's really hard to make the argument to invest in complicated streaming systems.
That said, it still feels like we've landed in a suboptimal spot. Stream processors (in particular, those following the dataflow model) solve two problems that are hard in batch systems:
1. Determining and signaling completeness for a time period (when have I likely received all of the data for 12:01pm, such that I can now safely process it)
2. Avoiding expensive recomputations for periodic queries
I do think long term we'll see some amount of streaming influence moving back into the batch systems, particularly as object storage gives us the ability to run stateful workloads with less operational headache.
(If anyone else finds these problems interesting, I'm hiring for my stream processing team at Cloudflare. Email in my profile)