Scylla – Real-Time Big Data Database

https://www.scylladb.com/

by andrewstuart • 5 years ago

96 50 5 years ago

scylladb.com

andrewstuart• 5 years ago

I posted this because I'm interested to hear from anyone using it - how has it worked out for you?

I note it's written in C++ which is a bit of a surprise - I'd expected Rust or Golang.

Interesting as well is is AGPL - licensing is always contentious:

https://github.com/scylladb/scylla/blob/master/LICENSE.AGPL

milesward• 5 years ago

We're using it with several customers: fast, reliable, straightforward.

zinclozenge• 5 years ago

I think the main reason it's in C++ is because of its async executor, Seastar. There's a similar Rust project called Glommio but seems still very early.

biggestdummy3• 5 years ago

Glommio was created by Glauber Costa, one of the early contributors to Seastar (and Scylla). The resemblance between the two is not coincidence. https://glaubercosta-11125.medium.com/c-vs-rust-an-async-thr...

throwaway815232• 5 years ago

Seastar is sort of a C++-ification of node.js. Now that C++20 has coroutines, I wonder if those could have been used instead of all that chained method stuff.

krapht• 5 years ago

Only on Hackernews would somebody be surprised that high-performance system software would be written in C++...

masterof02• 5 years ago

You read my mind. LOL. "Mr. Developer, can you please write your project in Rust, or __insert_your_meme_language_here__, or Javascript?"

enedil2• 5 years ago

Quoting the interview with ScyllaDB CTO, Avi Kivity ( https://www.scylladb.com/2020/06/30/ask-me-anything-with-avi... )

Q: Would you implement Scylla in Go, Rust or Javascript if you could?
Avi: Good question. I wouldn’t implement Scylla in Javascript. It’s not really a high-performance language, but I will note that Node.js and Seastar share many characteristics. Both are using a reactor pattern and designed for high concurrency. Of course the performance is going to be very different between the two, but writing code for Node.js and writing code for Seastar is quite similar.
Go also has an interesting take on concurrency. I still wouldn’t use it for something like Scylla. It is a garbage-collected language so you lose a lot of predictability, and you lose some performance. The concurrency model is great. The language lacks generics. I like generics a lot and I think they are required for complex software. I also hear that Go is getting generics in the next iteration. Go is actually quite close to being useful for writing a high-performance database. It still has the downside of having a garbage collector, so from that point-of-view I wouldn’t pick it.
If you are familiar with how Scylla uses the direct I/O and asynchronous I/O, this is not something that Go is great at right now. I imagine that it will evolve. So I wouldn’t pick Javascript or Go.
However, the other language you mentioned, Rust, does have all of the correct characteristics that Scylla requires. Precise control over what happens. It doesn’t have a garbage collector so it means that you have predictability over how much time your things take, like allocation. You don’t have pause times. And it is a well-designed language. I think it is better than C++ which we are currently using. So if we were starting at this point in time, I would take a hard look at Rust, and I imagine that we would pick it instead of C++. Of course, when we started Rust didn’t have the maturity that it has now, but it has progressed a long time since then and I’m following it with great interest. I think it’s a well-done language.

robmccoll2• 5 years ago

I'd be careful with the idea of predictability and allocation. The best way to get predictabile performance is to avoid dynamic allocation altogether. The next best is to do your own allocation (slab-base per request, memory pools, etc.). General purpose dynamic memory management is a bin-packing problem (NP-hard).

jandrewrogers3• 5 years ago

If you are building a database engine that strongly prioritizes performance, and Scylla does position itself that way, then C++ is the only practical choice today for many people, depending on the details. It isn't that C++ is great, though modern versions are pretty nice, but that it wins by default.

Garbage collected languages like Golang and high-performance database kernels are incompatible because the GC interferes with core design elements of high-performance database kernels. In addition to a significant loss of performance, it introduces operational edge cases you don't have to deal with in non-GC languages.

Rust has an issue unique to Rust in the specific case of high-performance database kernels. The internals of high-performance databases are full of structures, behaviors, and safety semantics that Rust's safety checking infrastructure is not designed to reason about. Consequently, to use Rust in a way that produces equivalent performance requires marking most of the address space as "unsafe". And while you could do this, Rust is currently less expressive than modern C++ for this type of code anyway, so it isn't ergonomic either.

C++ is just exceptionally ergonomic for writing high-performance database kernels compared to the alternatives at the moment.

nhourcard• 5 years ago

At QuestDB we chose zero-GC Java for 80% of the code base, which resulted in superior performance on ingestion compared to the alternatives.

dralley• 5 years ago

Zig might be a good option -- eventually, once it's past 1.0.

staticassertion2• 5 years ago

Rust has an issue unique to Rust in the specific case of high-performance database kernels. The internals of high-performance databases are full of structures, behaviors, and safety semantics that Rust's safety checking infrastructure is not designed to reason about. Consequently, to use Rust in a way that produces equivalent performance requires marking most of the address space as "unsafe". And while you could do this, Rust is currently less expressive than modern C++ for this type of code anyway, so it isn't ergonomic either.

None of that sounds right to me.

More likely the developers already know C++, there's already a lot of KV stores built in C++, and Rust is a relatively new player. Scylla was released in 2015, Rust hit 1.0 in 2015, seems obvious why Scylla didn't go with Rust.

edit: Yep, from further down

So if we were starting at this point in time, I would take a hard look at Rust, and I imagine that we would pick it instead of C++. Of course, when we started Rust didn’t have the maturity that it has now, but it has progressed a long time since then and I’m following it with great interest. I think it’s a well-done language.

robmccoll2• 5 years ago

I wouldn't write off plain old C either.

nerpderp822• 5 years ago

I always love your take even if I don't agree, SpaceCurve was a phenomenal system, one of the most pragmatic, high performance, easy to use MPP database systems I have ever used. We never met btw, was just a user.

But I think you are wrong about Rust not having the right machinery for making high performance dbs. Two examples are Noria and Materialize

https://github.com/mit-pdos/noria

and it its 50k lines, in the immediate codebase, there are 40 uses of unsafe.

In Materialize's 125k of Rust, there are 76 direct uses of unsafe.

https://github.com/MaterializeInc/materialize

RussianCow• 5 years ago

Consequently, to use Rust in a way that produces equivalent performance requires marking most of the address space as "unsafe". And while you could do this, Rust is currently less expressive than modern C++ for this type of code anyway, so it isn't ergonomic either.

Based on my (admittedly limited) experience with Rust, this isn't true. Yes, you'd likely have to use "unsafe" a few times in order to implement a database system in Rust, but you would only need to do this for certain types of low-level data structures. The uses of those data structures—which would represent the majority of your code—would almost certainly be written in safe Rust. Don't throw the baby out with the bathwater.

I also contest the assertion that Rust is "less expressive" than C++; I have found Rust to be very expressive and concise for such a safe language. But I also don't have a ton of experience with either one, so don't take my word for that.

The real answer as to why Scylla does not use Rust is that the language simply wasn't very mature when they started. It also helps that there are significantly more engineers that know C++ than those that know Rust.

criticaltinker• 5 years ago

The benchmarks against DynamoDB, Bigtable, & CockroachDB [1] appear quite impressive - anyone have real world experience that can attest to these claims of improved performance and reduced cost?

Scylla vs DynamoDB – Database Benchmark
20x better throughput in the hot-partition test
Scylla Cloud is 1/7 the expense of DynamoDB when running equivalent workloads
Scylla Cloud: Average replication latency of 82ms. DynamoDB: Average latency of 370ms.
Scylla vs Bigtable – Database Benchmark
Scylla Cloud performs 26X better than Google Cloud Bigtable when applied with real-world, unoptimized data distribution
Google BigTable requires 10X as many nodes to accept the same workload as Scylla Cloud
Scylla Cloud was able to sustain 26x the throughput, and with read latencies 1/800th and write latencies less than 1/100th of Cloud Bigtable
Scylla vs CockroachDB – Database Benchmark
Loading 10x the data into Scylla took less than half the time it took for CockroachDB to load the much lesser dataset.
Scylla handled 10x the amount of data.
Scylla achieved 9.3x the throughput of CockroachDB at 1/4th the latency.

[1] https://www.scylladb.com/product/benchmarks/

kasey_junk• 5 years ago

I was unwilling to sign up to read the actual benchmark report for the comparison to cockroachdb but it jumped out at me as odd. They solve completely different kinds of problems in my experience so I’m not surprised Scylla did better in raw throughout. That’s not interesting though. It would be just as weird for cockroach to put up a benchmark showing it outperforms in distributed sql queries.

That said I’ve seen the value Scylla brings in its core value prop, replacing Cassandra. It’s real good at that.

biggestdummy3• 5 years ago

Full report is posted here with no registration wall: https://www.scylladb.com/2021/01/21/cockroachdb-vs-scylla-be... And they admit that it's an odd comparison. "Obviously, the comparison is of the apples and oranges type..."

manigandham2• 5 years ago

They're technically both KV stores capable of offering you a tabular data model with multi-regional replication and leaderless horizontal scaling.

CockroachDB is focused on consistency with full SQL support while ScyllaDB focuses on availability with high-performance.

PeterCorless6• 5 years ago

We just posted this today. Latest Cassandra 4.0 vs. Scylla 4.4. Note: Cassandra 4.0 is a HUGE improvement over Cassandra 3.11. But we're still many times faster:

https://www.scylladb.com/2021/08/24/apache-cassandra-4-0-vs-...

manigandham2• 5 years ago

Yes, Scylla does what it says. Used it in a prior adtech company and it beat everything else at that time for a very intensive key/value workload that also needed multi-regional replication.

The adtech industry also uses Aerospike heavily but that (at the time) had many replication data model issues compared to Scylla/Cassandra.

steeve• 5 years ago

We (@zenlyapp) have been using it for 4 years, it is as fast as advertised, it’s insane. We personally benchmarked the 10x of Cassandra.

mianos• 5 years ago

It is interesting in that this is here on the front page and an old article about Discord moving to Cassandra is also here considering Discord went from Cassandra to Scylla I beleive.

actually_a_dog• 5 years ago

Whenever I hear Scylla mentioned, I often wonder: where is Charybdis? They do work as a team, after all. :-)

PeterCorless6• 5 years ago

Charybdefs is our fault injection filesystem. Though it's based in Thrift, the ol' API that predated CQL.

https://github.com/scylladb/charybdefs

More modern is Project Circe, our efforts to make Scylla into an even more monstrous database:

https://www.scylladb.com/2021/01/12/making-scylla-a-monstrou...

DSingularity• 5 years ago

Yeah not surprised. They squeeze all the performance out of a single node using the seastar framework.

jiggawatts2• 5 years ago

(Just in case some Scylla employees see this YC News post)

Sigh...

I know this sounds like a nitpick, and I know it sounds like a broken record, and I know you probably work in a different team and there's "nothing" you can do about it...

But.

I went to your website, interested in your product. I'm your target market! This site needs to impress me, and people like me.

What's the first thing that I see? The website oh-so-slowly animates, sliding down to show some TechCrunch ad.

I don't care about TechCrunch. I care about high-performance databases.

But okay, I move to close it, but "No!" says your website, helpfully overlapping it with another animated slider asking me to accept your cookie policy so that I can be tracked by your marketing group.

Fine. I close both popups, and try to read the content of your site despite the animations every paragraph or so trying to distract me from the content. As soon as I scroll too far past the animations, a stupid chat bot pops up to overlay the bottom of the content as well.

I figure I'll just go to the meat of it, some whitepaper or technical documentation. Despite their miriad flaws, PDFs are thankfully not commonly animated.

The download link for your benchmarks asks for my contact details. It's not a link. It's a sign-up form for spam. I'm not an idiot. I don't want spam. I want to read about your database.

Your marketing team actively stops your target market from looking at your products. Perhaps that's an issue you should look into, because right now there are potential customers that simply never get to find out just how amazing your technology is, because their first experience of your products makes used car salesmen look upstanding and trustworthy.

PeterCorless6• 5 years ago

Peter Corless here from ScyllaDB's marketing team. Your feedback is 100% heard, understood & appreciated. I'll share it with the team.

The good news is that we just provided a new benchmark today and it is 100% ungated.

Scylla 4.4 vs Cassandra 4.0: https://www.scylladb.com/2021/08/24/apache-cassandra-4-0-vs-...

Also, here are a few other free and open blogs where we have benchmarked vs. competitors:

Scylla vs. DynamoDB: https://www.scylladb.com/2018/12/13/scylla-vs-amazon-dynamod...

Scylla vs. Google Cloud Bigtable: https://www.scylladb.com/2019/05/02/going-head-to-head-scyll...

jiggawatts2• 5 years ago

To also provide some constructive feedback:

A good point of comparison is this website: https://www.jetbrains.com/idea/

It's also a product targetted at technical people, including people working at startups and also large enterprise.

No popups.

When you click the community edition download link -- bam -- it is immediately downloading! No form to fill in.

I don't even use their tools much any more, except for the Rust plugin. Nonetheless, I read through their "what's new" release notes, even for Java, because it is so well presented: https://www.jetbrains.com/idea/whatsnew/

I don't have to sit through an hour-long YouTube video watching some guy introducing some other guy I don't care about for five minutes. https://knowyourmeme.com/memes/the-wadsworth-constant

Instead they have GIFs showing short, to-the-point snippets of exactly what each feature does. Note that these don't animate by default! You have to click them to play the clip. I love that. They're helpful without being distracting while I'm reading nearby text.

It also gives you an idea of what the product looks like in actual use.

You have no idea how much crap people wade through to find this! I often spend hours googling terms like "Product X Screenshot", "Product X real-world", "Product X tutorial" in the futile attempt to just find out what the heck to expect. Is it a green-screen terminal app kept alive like some sort of crime against nature? Is it a web application? Does it come with a Windows-only GUI? If so, is it at least a usable one? Does it have command-line tools? PowerShell? Tab-complete?

You go to a site like JetBrains, and you see exactly that! Real-world code being manipulated, showing you the product in all its glory.

So show this! Show ScyllaDB doing something. Don't just talk about how it's 47% more snazzy than a competing product I haven't used.

Show it doing a schema change nearly instantly on a terabyte of data, or whatever. But show me the product, or I walk away until I find a website that isn't afraid of letting me see what they're selling...

haswell• 5 years ago

These are classic enterprise software lead gen tactics and somewhat hint at the future you might expect should you do business with them.

Hopefully this was a poorly thought out gate and not a signal that they’ve gone full enterprise tactics.

rakshazi• 5 years ago

Welcome to modern web

Notanothertoo• 5 years ago

Been using it since 2017 for IoT time series data. Works great, very fast.

I think the one criticism is that it seems the company has some intentional rough edges on it, in favor of their SaaS over the open source release. It used to be around backing up and managing updates long term ect. They have gotten better but their helm chart for example is very opinionated and uses custom resources in place of say a statefulset. I think their SaaS is overpriced especially compared to reserved instances but that's just me.

Also from my calls with support, they lack direction internally. One time our sales rep and customer success director argued on the phone in front of us if they could bill us for some migration work. We silently let them finish and then said we expect it to be included in our support package based on their argument.

biggestdummy3• 5 years ago

So an open exchange of ideas, and some free assistance. Sounds like it was a good outcome for you. :)

Scylla – Real-Time Big Data Database

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