“The benchmark numbers are completely wrong for both databases”
github.com
github.com
I don't see any marketing here, just the "do your own benchmark" best practice, and the "share with community" best practice... Does it make it a perfect benchmark? No, but at least he tried... and the author has corrected the discrepancies since then.
Now imagine the benchmark was against [your favorite DB here] with even stronger results against RethinkDB. Notice how the most upvoted comment is joking about MongoDB. The second one is a pro-mysql comment. What's the point? Would it have been a better benchmark if it read "mysql is 10x faster than RethinkDB?" or "MongoDB is even slower than RethinkDB"?
Maybe he wanted to know where each DB shines compared to each other, to see if some workloads are better suited to one or the other.
Of course, benchmarks "should" include concurrent reads/updates/writes/deletes because it can make a huge difference depending on the DB's implementation.
Of course, the author "should" also have tested sharding / durability / resistance to partition / resource consumption in his tests... Maybe he didn't have the resources to test properly. I also do quick&dirty benchmarks like these, mostly because exhaustive benchmarks cost so much more (time, money, expertise)...
As of the time I posted this comment, the blog post still seems to be comparing indexed MongoDB operations against non-indexed RethinkDB operations. Under those conditions I'd expect RethinkDB to be at least 1000x slower than MongoDB. The fact that he's finding that RethinkDB is only 3x slower than MongoDB makes me think that there are still other major problems with this benchmark.
> No, but at least he tried...
It's true that the author tried; but that doesn't change the fact that people are going to read this blog post and assume that the numbers are at least approximately correct. As a RethinkDB employee, it really frustrates me to see RethinkDB being judged according to benchmarks that are conducted so carelessly that they are essentially random.
I think this is the fourth time in the past year that I've seen a third party try to benchmark RethinkDB and get something wrong. Maybe we need to start a "best practice" of checking in with the maintainers of a project before publishing benchmark results about the project.
I would say that you probably should look at your API because I've never used a database that required me to explicitly define which indexes I want to use for a read. But I've never used RethinkDB so maybe there is a legitimate reason.
> [...] I've never used a database that required me to explicitly define which indexes I want to use for a read. [...]
In a way, it's traditional (IBM IMS/DB, 1960s).
- I don't see any mongodb index creation, so mongodb is inserting with no index while rethinkdb is inserting with the index. That's probably why there's a gap between the two
- there's no mongodb index, and rethinkdb queries do not make use of the index (this is probably why rethinkdb is not 1000x slower: both aren't using indexes)
- the $in query should be last_update: random_timestamp(), there's no need for $in here
- his insertion code creates 100K memory clones of the object to insert in the mongodb version only, not in rethinkdb
I'm sad to add: what the author is benchmarking here is the likely performance of a system he could build with either db. It's not necessarily bad (save for bad press) that he's bad at benchmarking: the mistakes he's made in his benchmark are similar to the mistakes he'll make in his code.
But yes, the author may use some help!
[1] https://github.com/martinrusev/rethinkvsmongo-benchmark/blob...
When I wrote this, I'd read a rethinkDB employee say "it's not using the index on rethinkdb", and performance was similar (3x) between the two. I trusted the "no index" path, and couldn't find an ensureIndex command... So I assumed there was no index on mongodb.
Truth is, this kind of performance can only come with indexes, on RethinkDB and mongodb.
It's madness to expect someone new to database benchmarking to implement a correct fully featured benchmark client. They are going to stumble enough on database and instance configuration as it is.
Is this a best practice? It seems like we've been delivered evidence that it is really hard to do good benchmarks unless you're already intimately familiar with what you're testing, which says something about how hard it is to make a good choice.
I don't know about other industries, but this sort of result is what stuff like the STAC M3 Benchmark suite was designed for: Typical usecases that experts can implement so you can get realistic performance comparisons.
Running benchmarks is an engineering practice. If you failed to get meaningful results, you failed. Yes, he cares, yes, he tried, yes, the comments are dumb, but he still failed. Sure, I'll give the guy kudos for trying, but I'm not going to pretend he didn't fail. As far as I'm concerned, telling someone they failed is a favor, because now they can change their methodology, try again, and maybe succeed. It's part of the process of achieving meaningful results. The entire point of what he's doing is to achieve meaningful results, not to get a participation medal.
Your response reminds me of this: https://www.youtube.com/watch?v=gSjLiQxEZlM
I don't think anybody is saying that.
The wider message is that DBs are way more complex beasts that is meaningful to test this way.
Obviously there are cases in which MongoDB is a great choice, but equally obviously tests like this should not be a reason for the choice.
At work, we're also Mongodb users. If tomorrow we try to benchmark against Cassandra, performance will probably be the selling point. I don't think it's absurd to compare mongodb and rethinkdb, they're very similar dbs.
As for the benchmark, I agree it doesn't explore every facet of both databases and focus on performance... That's what benchmarks do.
The intent of the author may have been to challenge his existing choice (mongodb) which is a good thing. The (corrected) results may lead to: expect no performance gain if we migrate to RethinkDB... What's wrong with that?
There are at least 3 things here which invalidate this post because they make the numbers uncomparable:
1. Is the hardware adequate to run the tests, or does it favor one database?
2. Are both databases tuned to the use case?
3. Running only one type of action at a time is meaningless. Contention between reads and writes is what normally drives performance stats.
The title of the post is "RethinkDB reviewed by a MongoDB fan"
> In RethinDB, you have to create databases and tables manually and it will raise an exception if they already exist. Compared to MongoDB that could be an inconvenience for some(and me) - one of the things I find appealing in MongoDB is the fluid interaction with databases
... well at least now I don't feel so bad about having some old MySQL stuff still in production. MySQL already has too much "fluidity" in dealing with my data...
He does have a point there. It is slightly annoying having to type out a query when I just want to browse the data. (No real biggie though..)
It does affect the initial experience though. The admin panel looks so slick I just assumed I would be able to click on the table and it would jump to the data. When it didn't I was surprised and initially blamed myself and fired up the console to see if there were any errors showing. It just affects the polish of the panel.
As I said though it is a minor point for an excellent product.
Still we don't know the hardware, what versions were installed, configuration changes etc.
The whole thing is pretty meaningless.
It seems unfair and restrictive, but benchmarking is hard, and even where users get everything else right every data load is different.
It's easy to see why companies don't want writeups like this one dominating searches for "<database> performance".
If you prohibit benchmarks, it's essentially saying "we have something to hide" (like bad performance...), or "we don't want competition".
I think it's far better to point out the flaws and specifics than to censor any attempt at comparison.
This seems a totally imaginary dichotomy when literally the comment you're replying to presents an alternative option, namely; "We don't want you to publish things that are almost always going to be wrong and misleading"
It's the job of the reader to judge their sources wisely, and interrogate what they read, rather than the job of the author to conduct their explorations in private.
Understandably, it can be frustrating for people involved in the projects but that's just the nature of the beast. They can do things to help their cause by championing good examples of benchmarking, even those which don't look upon them favourably.
Benchmarking programming languages got better. E.g.: http://benchmarksgame.alioth.debian.org/ gives roughly idea about performance of programing languages.
I wish something similar existed for databases. I think exact figures would be hard to get, but I believe there are many 2x 10x differences that we should be aware of.
I wish we got this kind of benchmark for the altjs solutions.
In this case we were presented with a benchmark setup that failed to perform the task it supposedly benchmarked. That's not hard to avoid, and it makes the benchmark completely useless and misleading.
I don't think that this problem can be generalized in the sense you do here, since the problem with benchmarks usually isn't a complete failure to perform the task to be benchmarked, but things like finding a set of tests that give a fair representation of what you'd typically use the subjects for, or performing the tasks in idiomatic and optimal ways.
They're neat and all and it is called the benchmarks game but I wish they'd remove the ones that end up getting gamed like that.
No.
>> …how fast they can all call out to PCRE. <<
No. Have you looked at the programs?
Of some artificial scenario that people will claim does not reflect [their] reality?
> As this illustrates, there aren't any good ones out there.
The only good benchmarks are the ones that you define to be representative of something you'll actually see in reality.
And it's an important (albeit just one part) of deciding which product to use.
The risk of a colored benchmark is quite high when benchmark is done by owner of product or by "fan" of product. With the exception of a well explained, clear benchmark that everyone can understand and reproduce easily.
Perhaps, once you've winnowed the choices down to just a few, it might make more sense, but I think good public benchmarks can be a helpful thing for that selection process.
An internal benchmark indeed requires knowledge on the subject, but most of the times people at the mailinglists are quite helpful when you explain what you are trying to do. Especially when you post a benchmark which is not in favorite of their product.
So I don't see how any claim of bias applies here.