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Comment by potatoyogurt | Hacker News Reader

in other words, "I used a chainsaw to cut an apple and it SUCKED at it."

If you're processing an amount of data that comfortably fits in memory on a single machine, then obviously Hadoop is going to perform poorly in comparison. The costs of scheduling a job onto N mappers/reducers, transferring code to each node, waiting for the slowest mapper/reducer to finish, transferring data from mappers -> reducers, replicating output on HDFS, etc. are well-understood. It's true that many people try to use Hadoop when they'd be better served with simpler solutions, but that does not justify the amount of shade that the author throws at it.

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> are well-understood. It's true that many people try to use Hadoop when they'd be better served with simpler solutions

I posit that these two assertions are contradictory.

My own understanding of the term "well understood" is that it is synonymous with "widely understood". If many people are still making the mistake of using Hadoop when those costs outweight the benefits, it seems that understanding isn't quite wide enough.

That said, although I have a grasp of when the tradeoff is so loopsided as to be obvious, I don't know where to go (or where to point other people to go) for a better understanding of where the boundary is.

Where should we go to better learn that understanding of those costs?

They're well understood by anyone who has used these technologies professionally. I probably should have been ore precise with my language, though. It's really a grey area as to where the boundary is and it depends a lot on your specific application. But as a general rule of thumb, my feeling is that for tens to hundreds of GB, you should consider it. And for TBs or more, you almost certainly want to be doing something distributed. Hadoop isn't necessarily the best option then, but it's a powerful tool. I don't know if there's any resource out there that really goes deep into the tradeoffs involved though. There probably is, given how popular the subject is, but I'm not aware of one.

The problem with the article is that if it's for a general audience that doesn't understand the tradeoffs of a system like Hadoop, it really paints a picture that it is just a bad, slow tool. It barely acknowledge just how rigged the comparison is at all, aside from mentioning that you might need something like Hadoop for really big data in the conclusion, while it is peppered with unnecessarily snide comments about Hadoop that will probably be more memorable. I think it is liable to leave readers more confused about the tradeoffs involved after reading than before.

> They're well understood by anyone who has used these technologies professionally. I probably should have been ore precise with my language, though

So.. It's well understood by True Scotsmen? :) I certainly understood that there are experts in the field who have a deep, even intuitive understanding of how and when to use which tools. To the extent that those experts don't communicate that knowledge to a broader audience while at the same time may be advocating for the use of the tools, they bear some responsibility for the misuse.

My point wasn't so much that you used imprecise, but rather, that the statement about how well it's understood was inaccurate or irrelevant (depending on which definition you were going for).

> But as a general rule of thumb, my feeling is that for tens to hundreds of GB, you should consider it. And for TBs or more, you almost certainly want to be doing something distributed

While a 3-4TB cutoff makes some sense if ones workload has to remain in-memory for performance reasons, that can't be anywhere near the cutoff for any kind of workload that could stand to read from SSDs.

> I don't know if there's any resource out there that really goes deep into the tradeoffs involved though. There probably is, given how popular the subject is, but I'm not aware of one.

I would hope so, but I'm not so sure. It may not even need to be very deep, something akin to the "5 minute rule" for memory/disk caching. Mostly, I'm not convinced that the subject of tradeoffs is actually popular, so much as just using the tool without considering them is.

> The problem with the article is that if it's for a general audience that doesn't understand the tradeoffs of a system like Hadoop, it really paints a picture that it is just a bad, slow tool.

If we're talking about the adamdrak.com 233x article, I have to disagree, as my read of it was that it focused on evangelizing the "under-used approach for data processing" of "standard shell tools and commands".

> it is peppered with unnecessarily snide comments about Hadoop that will probably be more memorable

That's certainly not a charitable interpretation, and I would hazard that it's not even fair or factual (as to "peppered", at least). It's mentioned only a handful of times:

> Command-line Tools can be 235x Faster than your Hadoop Cluster

I agree that click-bait can be considered snide.

> I was skeptical of using Hadoop for the task, but I can understand his goal of learning and having fun with mrjob and EMR

To me, this comment, this very first mention of Hadoop in the intro, made it clear that this was "rigged" in that the "competition" was neither competing nor truly concerned about performance.

> while the Hadoop processing took about 26 minutes (processing speed of about 1.14MB/sec).

Merely a factual summary. Nothing snide that I could detect.

> Although Tom was doing the project for fun, often people use Hadoop and other so-called Big Data ™ tools for real-world processing and analysis jobs that can be done faster with simpler tools and different techniques.

This seems like just a restatement of the admission in the introduction plus the assertion (that I believe even you agree with) that many people mis-use Hadoop when it's not called for.

> The resulting stream processing pipeline we will create will be over 235 times faster than the Hadoop implementation and use virtually no memory.

Again, just another factual summary, with no snideness I could detect.

> While we can certainly do better, assuming linear scaling this would have taken the Hadoop cluster approximately 52 minutes to process.

This next mention is after at least half of the bulk of the article. It may be an assuming-spherical-cows estimation, but it doesn't strike me as grossly misleading on its face, and there's no editorializing.

> This gets us up to approximately 77 times faster than the Hadoop implementation.

> about 174 times faster than the Hadoop implementation.

> gets us down to a runtime of about 12 seconds, or about 270MB/sec, which is around 235 times faster than the Hadoop implementation.

The next three mentions, near the end, are just comparisons of the evolving demonstration implementation to the reference implementation. No detectable snideness.

> Hopefully this has illustrated some points about using and abusing tools like Hadoop

> but more often than not these days I see Hadoop used

Here in the conclusion paragraph is where I agree that there is both snideness and where a reader may be confused about tradeoffs, if that's what they were expecting to be enlightened about.

However, because that's not what the introduction promised, my criticism would be merely that the conclusion doesn't match the introduction (and maybe goes too far into inflammatory territory with "abuses").

Pretend that section isn't even in the article, and the article still reads OK.

I agree with your first two points. It's definitely possible to efficiently process quite a bit of data on a single machine, although I think that past a terabyte, there begin to be strong arguments to a distributed approach even if you can theoretically handle it on one machine (scalability if requirements change, resilience to machine failures, etc.).

I still disagree about the article itself (even outside of the conclusion), but perhaps I am reading it uncharitably and other people are not getting the same impression. I do feel that it would be easy for someone who is not very familiar with these technologies to get the wrong impression. Misusage does probably go mainly in the other direction (of people overusing Hadoop rather than underusing), though, so maybe that is not so important a concern.

> I think that past a terabyte, there begin to be strong arguments to a distributed approach even if you can theoretically handle it on one machine

I've elaborated on these in another comment, as well.

Today, drawing the line at a single terabyte is way too early, even for all-in-memory workloads, if only because there exists an almost 4TB AWS instance now. Any smaller than 3.5TB (or whatever RAM is available to applications) is, at best, living in the past.

> scalability if requirements change

This reads as premature optimization, which turns the strong argument into either a weak argument or even an argument against.

Now, if you know or have reasonable certainty that your requirements will change (and will do so faster than, say Moore's Law) and change soon, then that's different. I suspect there are people who think this, but that it's little more than wishful thinking or a delusion as to how large their slice of "web scale" actually is.

> resilience to machine failures

Machine failures just aren't a legitimate consideration for modern, high-end (but still commodity) hardware. You wouldn't bet your whole business on it, of course, but a 1% chance every year of losing an hour or two of batch processing? Sure.

Sadly, the flip side of this is that I see Hadoop clusters being built with such reliable servers, including redudant PSUs and fans, instead of taking full advantage of the resilience at the software level in order to save as much as possible at the hardware level. The original company behind map-reduce is certainly not splurging on hardware.

I'm not saying that past a terabyte is a point where you definitely want to use distributed processing, just that at that point, you should really strongly consider it. There is usually a lot of fuzziness around estimates you get about what sort of data volume you'll need to deal with, and it's not uncommon for it to vary by integral factors between days. If you're pushing the limits of what your system can handle without needing a dramatic rearchitecting, then that's a big risk, and it's not necessarily premature to build in the flexibility to have the option of scaling in the future if you need to. If you hit that 4TB and you still need more, it will be a big headache.

I can't really comment on rates of machine failures, but I have seen it happen before, even just for stupid reasons like someone in a data center unplugging a machine.

Fair enough, for in-memory only, if 1TB is your raw data, by the time it's indexed, it's going to be bigger.

Surely, though, workloads that require in-memory performance are fairly niche, and jumping from there to distributed (even in-memory) seems non-obvious, at best. Why aren't large arrays of fast SSDs a better alternative? The bandwidth is comparable, but the latency is terrible (still comparable to ethernet to a remote node, though?)

What about workloads that don't require fully-in-memory in the first place? If the cutoff is, then hundreds of TB, wouldn't that cover the vast majority of common use cases?

> I can't really comment on rates of machine failures, but I have seen it happen before, even just for stupid reasons like someone in a data center unplugging a machine.

That sort of anecdata isn't very useful, because a human can cause any failure at any layer, including someone stop a whole cluster, which I've seen happen before.

My point about it not being a legitimate concern is that what is now common practice with what is now common equipment means it's uncommon. These practices and equipment had to evolve, but that evolution happened on the order of over a decade ago.

Also, be wary of selection bias. It's very easy to remember the "fire drill" because of the one machine failure, and it makes a much more interesting story to tell that gets passed around and modified enough, eventually sounding like multiple stories and therefore multiple machines. The hundreds of servers that operated unheard and unseen for years, sometimes beyond their specs (e.g. with only only blower out of four still turning and only half-speed at that), get nary a thought, let alone mention.

> They're well understood by anyone who has used these technologies professionally.

We need to substitute the word "professionally" with more precise terms when talking about our industry. Because if one was to read "professionally" as "at work", then your statement is absolutely false - both the lower bound and average amounts of critical thinking and caring in this industry are extremely low. Even ignoring people who obviously have no clue, I can still imagine Hadoop and other big data stacks being sanctioned by "professionals" in management for buzzword-generating reasons, and implemented by "professional" "engineers" for CV padding reason.

You're probably right. I'm thinking of specific coworkers when I think of the level of knowledge that should be expected, and generally the standard I would hold coworkers to would include understanding this. But it is probably not as widely understood as I would hope.

> My own understanding of the term "well understood" is that it is synonymous with "widely understood". If many people are still making the mistake of using Hadoop when those costs outweight the benefits, it seems that understanding isn't quite wide enough.

I's entirely possible that 9 out of 10 people on a project using Hadoop know it's a waste but there are non-technical reasons for doing so. Resume padding and PHB demanding some technology of the week would be the two most common ones.

That said it probably is contradictory much of the time. I'd say the majority of current developers don't know about the simpler tools.

> If many people are still making the mistake of using Hadoop when those costs outweight the benefits, it seems that understanding isn't quite wide enough.

That's probably true but, cynically, I tend to think a lot of the time when people use Hadoop they're not doing it because Hadoop is the best solution: they're doing it because the solution allows them to use Hadoop.

I'd venture that's a little too cynical, as it violates the "never attribute to malice what can adequately be explained by ineptitude" rule :)

I'm not suggesting that something like resume-padding is never a motivation, just that it seems unlikely to be the sole or even primary motivation.

Now, I may be wrong, but my reasoning behind this is that, for all its purported power as a tool, as potatoyogurt has alluded [1], it's really only the true experts who can wield that power effectively. The ones who merely succeeded at getting on their resume would only be able to use it where its power isn't truly needed (as was the case before).

If the technology falls out of fashion, then those resume-holders will be in a position of needing to deliver the cargo, rather than carved wooden headphones.

As such, I believe their motivation is actually to attempt to learn the true power of the tool (i.e. true resume building, rather than mere padding) and that they're grossly underestimating the costs through ignorance and a desire to learn by doing.

The trouble is, without well-published non-distributed reference implementations and, instead, ultra-popularity of the distributed tools instead, they never end up learning those costs, and we're in a state of perpetuated ignorance and perpetuated over-use.

[1] by saying that the cost trade-offs are well understood by the experts, which strongly implies that the experts have a pretty deep understanding of the actual mechanics of distributed computing in general.

Many of the alternates (including linux cli stuff) that are much faster require a re-thinking of attitude, don't work where there are tens to hundreds of people submitting queries, or require different skills. It's tragic to think of all of the computrons and watts wasted with Hadoop-ish stuff (map-reducing without filters, Java itself for most implementations) - but still I wouldn't recommend to most CIOs they replace Hadoop in all or maybe even most cases, even for few-TB data sets and smaller.

Both because of familiarity with querying and the solidity of running a multi-tenant system.

But I do recommend that they switch to MapR [c++ core and a passable central FS for unix-based super fast queries] if they're concerned with efficiency.

[For context, in my day job we do multiple clusters of millions of network traffic summaries/sec and are often replacing Hadoop, or more recently, ELK, as people tried to use them for that use case. All well >>> will fit in ram. We have our own in-house column-store + streaming combo db done in go/c/c++ that started as clustering fastbit.]

> Many of the alternates (including linux cli stuff) that are much faster require a re-thinking of attitude, don't work where there are tens to hundreds of people submitting queries, or require different skills.

I doubt the point of the article was to suggest that linux cli stuff would scale to hundreds of users on the same host, but, if each of those users has a host of their very own, such as a laptop, the model could scale very well indeed, for small enough datasets.

> I wouldn't recommend to most CIOs they replace Hadoop in all or maybe even most cases, even for few-TB data sets and smaller.

Well, as you point out later, regarding familiarity, once it's in, it's probably too late. What about for a new implementation?

In answering this question, don't get too hung up on a literal interpretation of "single" server being exactly one. For example, a traditional RDBMS with one or more replicas (for performance, redundancy, or both) would still fall under the single server model. Really, it's about the non-distributed-computing option.

> if they're concerned with efficiency.

The fact that this is an "if" (and I do know that it is, even for startups) is bewildering to me, even more so in the context of distributed architectures where scaling is less linear the more data that has to be shared.

Absolutely a believer in the power of single machine analytics on GB or TB vs PB datasets. But I've found that whether it's a new data system or just showing csv/tsv tool magic, if people aren't into data systems (for the former) or unix cli (for the latter), it's a whole culture/training thing vs. most technically efficient wins.

So I think the latter issues dominate (culture/training) for new implementations as well as existing.

Re: efficiency overall, and of distributed systems, it's interesting to see both that MapR has made a business selling more efficient Hadoop-ishness, but also depressing how infrequently I see them deployed, even for pretty massive clusters.

Unfortunately, it's hard to see a startup focusing on single-machine solutions for GB->TB sets (even scaled out with replicas) as the way many in the space get started is with an open core model and the thing they charge for is the clustering and/or monitoring needed to become a distributed system.

But... I am optimistic we'll see a generational effect over the next 10 years in openness/interest in composable ad-hoc analytics tools, especially with Windows incorporating unix cli components.

> MapR has made a business selling more efficient Hadoop-ishness, but also depressing how infrequently I see them deployed, even for pretty massive clusters.

I'm only very slightly familiar with their features/value-add and not at all with their pricing. Could the pricing model be particularly unpalatable for some reason?

Not that I expect there has to be a deeper reason beyond simply not caring about cost/efficiency. I've certainly both seen and heard described plenty of Hadoop installations that seemed to have missed the "cheap" point in Google's M-R paper and subsequent Hadoop hardware selection advice from, for example, Hortonworks, or misunderstood what it meant. There may also be some misunderstanding of "commodity" or "industry standard" to mean server hardware of a certain "class" (such as brand name or with redundancy features), even if it conflicts with cheapness.

Some of it may be that the hardware selection advice articles (e.g. Hortonworks, Cloudera) are very old, with excellent general advice, but potentially misleading specific numbers. Even extrapolating from those numbers in a naive way can easily lead to needless expense and/or sub-optimal performance (that time some Xeons had 3, not 2, not 4, memory channels).

The latest article I found in an (admittedly quick) search was https://hadoopoopadoop.com/2015/09/22/hadoop-hardware/ from late 2015, which is still remarkably long ago and is rather verbose.

It's actually an interesting question you can get 192 cores and 12 TB RAM in a single x86 box. At what point does it actually make sense to go for Hadoop.

It makes sense if you are handling millions of requests from all over the world per second and need failovers if machines go down.

But...if you just want to run your own personal search engine say...

Then for Wikipedia/Stackoverflow/Quora size datasets (50GB with with 10GB worth of every kind of index(regex/geo/full text etc) ) you can run real time indexing on live updates with all the advanced search options you see under their "advanced search" page one any random Dell or HP Desktop with about 6-8GB of RAM.

Lots of people do this on Wall Street. People don't get what is possible on desktop cause so much of it has moved to the cloud. It will come back to desktop imho.

It won't come back to desktops because as they get cheaper the costs of people to maintain them increases.

There will always be people who need them and use them but that proportion is going to keep decreasing (I'm somewhat sad about this, but the math is hard to argue with).

Just temporary. Nature did not need to invent cloud computing to perform massive computation. The speed and data involved in computation going on in a cell or an ants brain show us how far we can still go on desktop. The breakthroughs will come.

In the meantime (unless you are dealing with video) most text and image datasets out there that avg Joe needs can easily be stored/processed entirely locally thanks to cheap terabyte drives/multicore chips these days. People just haven't realized there isn't that much useable textual data OR that local computing doesn't require all the overhead of handling millions of requests a second. This is Google problem not an avg Joe problem that is being solved with cloud compute.

You seem to have missed everything the comment you are replying to says.

There is no dispute with the size or amount of compute available on desktops.

No idea what cost that comment refers too. If you are Facebook or YouTube or Twitter or Amazon sure you need your five thousand man PAID army of content reviewers to keep the data clean cause the data is mostly useless. But if you are running Wikipedia search or Stackoverflow's search or the team at the library of congress please go and take a look at the size of these teams and their budgets and their growth rates.

Are you conflating "single server" and "desktop computer" here? It sounds a lot like you might be?

Because almost everyone already uses the model of co-locating the search index and query code on a single computer (both Wikipedia and Stackoverflow use Elastic Search which does this).

They use multiple physical servers because of the number of simultaneous requests they serve.

This has never been the use-case for Hadoop.

I've built Hadoop based infrastructure for redundantly storing multiple PB of unstructured data with Spark on top for analysis. This is completely different to search.

That's very different to the Wall St analyst running desktop analysis in Matlab, or the oil/gas exploration team doing the same thing.

That's a good point. It's really hard to give a clear cutoff because there is quite a bit that you can potentially do on a single machine now. But there are disadvantages to doing your processing on a single really big machine even when you can find a way to handle it. If you have inconsistent workloads, a single machine may be harder to schedule to be close to fully allocated, and if it goes down, then your workflow is dead, possibly until you take some sort of manual action, whereas a cluster of machines is already built to be resilient to individual node failures. It all depends on the use case, which makes it really tough to give hard and fast rules.

> a single machine may be harder to schedule to be close to fully allocated

That seems remarkably unlikely if there truly is only the one. Maybe I don't understand what you mean, though. How is that any different from having a single distributed cluster, instead?

> if it goes down

I hear (read) this quite a bit, especially recently, and I'm a bit mystified that it's even brought up in this day and age.

Firstly, having worked with (what is now) commodity hardware for over a decade, I believe that people who haven't grossly over-estimate how often "it goes down", especially today. This overestimation is trotted out as a reason that operating ones own hardware is such a "nightmare" and therefore one must always use cloud or a VPS.

With a "large" enough server, the risk goes up, of course. More DIMMs means more memory can fail, but we're still talking about low single digit percent for all errors (including correctable). IIRC, CPUs have even lower failure rates. Everything else tends to be redundant.

Even then, your workflow isn't dead. It's just missing a DIMM or a CPU, possibly after a reboot (which won't be, if you configured it right).

In many cases, downtime isn't actually caused by hardware but by software (or humans). That's not going to be unique to centralized processing versus distributed.

Also, if the single machine is on a cloud provider, many hardware and utilization issues can be abstracted anyway, for a huge price premium.

Just replying to the top bit, since we're exchanging multiple comment chains. Hadoop, Spark, etc. are built on top of a job scheduler, so if you have multiple competing jobs, it will allocate tasks to resources in a fairly reasonable way. If there is too much contention at some point in time, your jobs will all still run, and portions that can't be scheduled immediately will be delayed while they wait for free nodes. The processing model also generally leads to independence between jobs. You can do job scheduling on a single machine too, of course, but you get it for free with Hadoop/YARN. You don't get it for free with chained bash scripts or a custom single-node solution. And without sophisticated job scheduling, you can't really come too close to fully allocating your machine (when you're not watching carefully), because you'll accidentally exhaust resources and break random jobs.

edit: if you're running on a cloud, you also may be able to autoscale to deal with spiky usage patterns.

> You can do job scheduling on a single machine too, of course, but you get it for free with Hadoop/YARN. You don't get it for free with chained bash scripts or a custom single-node solution.

I'd venture to say that "for free" is a bit of a stretch, other than under the "already paid for" definition of "free". Being built on top of a job scheduler means one always has to exert the effort/overhead of dealing with a scheduler, even for the simplest case.

On a single machine, you can decide if you want to add the complexity of something like LSF or not. (I would call a custom single-node solution a strawman in the face of pre-Hadoop schedulers. Batch processing isn't exactly new).

> And without sophisticated job scheduling, you can't really come too close to fully allocating your machine (when you're not watching carefully), because you'll accidentally exhaust resources and break random jobs.

I'm pretty sure I'm still missing something. Since my goal is to gain a better understanding, I'll put forward where I believe the disconnect is (but definitely, anyone, correct me if my assumptions are off):

You're coming from a distributed model, where the assumption is that "resources" are divisible and allocatable in such a way that, for any given job, there's an effective maximum number of nodes it can use (e.g. network-i/o-bound job that would waste any additional CPUs). Any leftover nodes need other jobs allocated to them to reach full utilization.

I, however, am considering that the single-server model assumes that there won't be any obvious bottlenecks or limiting resources, instead prefering to run a single job at one time, as fast as possible. This would completely obviate the need for any complex scheduling and avoids accidental resource exhaustion (which, I suppose, is really only disk or memory).

hah, you're right, I definitely am looking at it with distributed system goggles on. With just one machine, yes, it will probably make sense to fully process one job before moving onto another (although there are some cases where this may not be true, such as if you're limited by having to wait for external APIs. But this isn't a strong argument because calling external APIs probably isn't something you want to be doing in Hadoop anyway). If your workload scales, though, you will eventually have to spread out onto multiple machines anyway. At that point, even if you process each job on a single machine, you either need a system to coordinate job allocation across machines, or you have to accept some slack if you only schedule jobs on individual machines. In the former case, we're taking rapid steps towards YARN anyways. I'm sure non-Hadoop, pre-packaged systems exist that can handle this, although I'm not personally familiar with them, but my point is just that the more steps we take towards the complexity of a distributed computing model, the more it starts to seem reasonable to just say "okay, let's just use hadoop/spark/etc. and get the extra benefits they offer as well (such as smooth scaling without having to think about hardware), even if it's more expensive than a setup with individual nodes optimized for our purpose." It's now really easy to spin up a cluster, and with small scale, costs are not that big a deal. With large scale, your system is distributed in some way anyway.

I don't think it's an obvious decision, and you're absolutely right that people are usually too quick to jump to distributed systems when they really don't need them. But I think there are a lot of arguments for using something like Hadoop even before it's strictly necessary. I think part of the disconnect is that we have different backgrounds, so we both look at different things and think "oh, that's easy" vs "oh, thats like a pain."

> calling external APIs probably isn't something you want to be doing in Hadoop anyway

And yet I've seen it done. At least they weren't truly external, just external to Hadoop.

> In the former case, we're taking rapid steps towards YARN anyways. I'm sure non-Hadoop, pre-packaged systems exist that can handle this, although I'm not personally familiar with them

There's those goggles again :) Batch schedulers have existed for decades (e.g. PBS started in '91).

> (such as smooth scaling without having to think about hardware),

This neatly embodies what I believe is the primary fallacy in most of the decision making, including the fact that it's often parenthetical (i.e. a throway assumption).

Does anyone really value the "smoothness" of scaling? I'd expect the important feature to be, instead, that the slope of the curve doesn't decrease too fast.

The notion that Hadoop someone frees one from having to think about hardware flies in the face of hardware sizing advice from, Cloudera, Hortonworks, and others that discuss sizing node resources based on workload (mostly i/o and ram) expectations and heterogenous clusters. It does, however, explain my observation, in the wild of clusters built out of nodes that seem undersized in all respects for any workload.

>It's now really easy to spin up a cluster,

It's really easy if it's already there? That borders on the tautological. Or are you talking about an additional cluster in an organization where there already is one?

>and with small scale, costs are not that big a deal.

That's just too broad a generalization, just as "cost is a big deal" would be. Cost is always a factor, just not always the biggest one.

Small scale is often (though not always) associated with limited funds. Doubling, or even tacking on 50% to, the cost could be catastrophic to a seed startup or a scientific researcher.

>With large scale, your system is distributed in some way anyway.

This strikes me as little more than a version of the slippery slope fallacy. Even some web or app servers behind a load balancers could be considered distributed [1], but that doesn't make them a good candidate for anything that's actually considered a distribute framework.

It also hand-waves away the problem that, even if costs weren't a big deal at small scale, they don't somehow magically become less of an issue at large scale. Paying a 50% "tax" on $40k is one thing. At $400k, you could have hired someone to think about hardware for a year, instead.

[1] I just recently pointed out, slightly tongue-in-cheeck, an architectural similarity, one layer down, between app server and database https://news.ycombinator.com/item?id=17521817

Sorry.. I forgot to respond to the last part of your message:

> I don't think it's an obvious decision

Certainly, which is why I even bother with discussion like this, in the hopes of making the decision clearer (of not obvious) to me in the future.

A response to my footnoted (in my other comment) comment pointed out how oversimplified my understanding of distributed databases was. Well, I knew it was an oversimplification, but not in which way.

There's plenty of computer science research from the 70s and 80s covering these topics, but they're both tough to translate to practical considerations, and they're woefully out of date (e.g. don't account for SSDs or cheap commodity hardware).

> But I think there are a lot of arguments for using something like Hadoop even before it's strictly necessary.

Well, philisophically, I would disagree with such an assertion on the grounds of premature optimization, absent the "strictly".

I would advocate for switching from scaling "up" (aka "vertically", larger single machines) to scaling "out" (aka "horizontally" or distributed) around the point of cost parity, not at the point it is no longer possible to scale up a single machine (unless that point can reasonably be expected to occur first, I suppose).

> I think part of the disconnect is that we have different backgrounds, so we both look at different things and think "oh, that's easy" vs "oh, thats like a pain."

That would account for any overestimation of how difficult it is to work with hardware or how complex Hadoop is set up, administer, or use. Those are just initial conditions and may well unduly influence decision making that has far longer-lasting consequences.

However, I'd like to think I'm not often guilty of the latter overestimation when discussing solutions (and even advocating single-server), as I tend to assume that it can it least become easy enough for anyone out there, so long as the technology is popular enough (like Hadoop) or traditional/mature enough (like the tools in the original comment, or PBS) that plenty of documentation and/or experts exist.

My background also includes having seen, first-hand, over decades, various attempts at distributed processing and databases in practice, with varying degrees of success. This has included early "universal" filesystems like AFS, "sharding" MySQL to give it "web scale" performance [1], Glustre and its ilk, some NoSQLs, and of course Hadoop.

If anything, I'd say that, with most popular, new technologies, especially ones predicated on performance or scale, "it's a pain" is not the knee-jerk skeptical reaction my experience has ingrained in me. Rather, it's more like "sure, it's easy now, but you'll pay." TANSTAAFL.

[1] This worked well enough but did have a high up-front engineering cost and a high on-going operating cost for the large number of medium-small servers plus larger than otherwise needed app servers to do DB operations that could no longer be done inside the database because each one had incomplete data. Due to effort overestimation, it was unthinkable to move from a VPS to a colo so as to get a medium-large single DB server with enough attached storage to break the "web scale" I/O bottleneck for years to come.

Your comment is actually pretty funny as the entire point of Hadoop was to be able to use commodity, cheap, off the shell PC hardware as opposed to the exotic specifications you mention there.

Except that of course nowadays such hardware is just a couple of clicks away in AWS.

The point of hadoop might have been that, but it never actually delievered any real value to most users - it's an abysmal failure from a computing efficiency point of view; here's an example http://www.frankmcsherry.org/graph/scalability/cost/2015/01/...

I've been using Spark for many years going back to 1.0.

It is the foundation technology of almost every data science team around the world. And your misguided post (which for some weird reason only focuses on graph algorithms) doesn't change that. And not sure why you think it's inefficient. We run 30 node, autoscaling clusters which stay close to 100% for most of the time.

Spark is significantly more efficient than Hadoop.

I don’t know about your specific workload, but i’ve seen quite a few Hadoop setups that were at 100% load most of the time, and were replaced by relatively simple non Hadoop based code that used 2% to 10% of the hardware and ran about as fast.

I didn’t spend much time evaluating the “pre”, but at least one workload spent 90% of the 100% on [de]serialization.

It’s not my link, it is Frank McSherry who is commenting in this thread - I hope he can chime in on why he chose this specific example - but it correlates very well with my experience.

> We run 30 node, autoscaling clusters which stay close to 100% for most of the time.

I have exactly zero knowledge on Spark's efficiency as well as zero on how representative graph algorithms are, but I can confidently say that the above statement fails to refute the referenced article's thesis (which, arguably, criticizes assertions just like that).

Just because your implementation scales (even autoscales) to use more compute resources says nothing about its efficiency (overall or even marginal when adding more nodes, i.e. the shape of the curve).

Computer science has struggled with achieving even near linear-scalability ever since the advent of SMP.

Today's "exotic" (which is actually just high-end commodity) is tomorrow's middling.

I'm not sure it's fair to summarize any one thing as "the entire point" of Hadoop, but, as I recall, it was, originally, an open source implementation of Google's Map-Reduce paper. Put another way, it was a way to bring Google's compute strategy to the masses.

That said, the notion that there is "commodity, cheap, off the shelf PC hardware" and "exotic specifications" is completely a false dichotomy, especially in the face of what, for example, Google actually does.

Google goes cheap. Very cheap. It's custom and exotic, just optimized for cost, but not absolute cost per nod, rather the ratio of cost for performance.

That last part is what's missing from every single Hadoop installation I've personally seen (or that anyone I know has personally seen), the maximization of performance for cost. Instead, there's an inexplicable desire to increase node count by using cheaper nodes, no matter the performance.

> Except that of course nowadays such hardware is just a couple of clicks away in AWS.

I'm a bit unclear what the "except" means here. I don't believe AWS has the truly high-end specs available (and never has, historically, so we can reasonably assume it never will). It's also very not-cheap.

No, the point was to be able to process workloads much larger than would fit in memory on a single machine.

Citation needed! :)

Joking snark aside, I'm actually doubtful this is true. Specifically, I don't recall the impetus for Hadoop (or Google's original Map-Reduce, as described in the '04 paper) being an all-in-memory workload.

Despite it being repeatedly brought up in this sub-thread, I maintain that it's a niche use case and that disk-based data processing workloads are far more common.

ETA: Does anyone know of a canonical or early/initial document outlining the purpose, or at least design goals, of Hadoop?

That's kind of the point of that post it's pointing out that you should consider weather you actually need to use something like Hadoop and that most people aren't actually working with data sets large enough for it to make sense.

> Although Tom was doing the project for fun, often people use Hadoop and other so-called Big Data™ tools for real-world processing and analysis jobs that can be done faster with simpler tools and different techniques.

"Big Data™" is unnecessary shade.

> One especially under-used approach for data processing is using standard shell tools and commands. The benefits of this approach can be massive, since creating a data pipeline out of shell commands means that all the processing steps can be done in parallel. This is basically like having your own Storm cluster on your local machine.

It is entirely unlike having a Storm cluster on your machine, and trying to do your data processing as chained shell commands will rapidly become cumbersome if you try to do actual complex processing.

Yes, I get that the author is trying to point out that simpler tools can work for many cases, but the tone of the article makes it seem like that author is just generally saying that EMR/Hadoop is bad. He does not acknowledge just how weighted the test he did is against Hadoop or give any indication of what the tipping point is where you actually want to start considering something distributed. This paints a really misleading picture for anyone who does not already know a fair amount about these technologies.

Hadoop has a very narrow best fit use case but it has been oversold as the best solution for big data.

Best fit is something you can argue a lot about. There are a lot of data processing tools out there now, many of which have come out after Hadoop. But if the comparison is against some process running on a single machine, then the use case is not narrow. It includes basically anything where you're processing more than 1TB of data in non-trivial ways (i.e. not just a map operation) and are okay with batch processing.

The issue with that is that for most organizations their key business data (and all its recorded history) fits in RAM of a sufficiently beefy workstation. They want to call it Big Data to stroke their egos, and properly acquiring, cleaning and integrating that data can take a LOT of effort so that data can be quite expensive and worthy of any glorious label they can think of; but my experience is that processing more than 1TB of meaningful data actually is a narrow use case, which matters in two specific categories: the (relatively few) very large multinational companies, and processing of raw video/audio/image data; and the majority of people working on data analysis end up with business needs that can be satisfied by relatively simple methods on relatively small datasets.

I agree in general. But I think you underestimate how large the set of use cases are where people are processing > 1TB of data. This includes quite a bit of the adtech industry, for instance, even many startups. It also includes data warehouses for other industries, such as in health tech. Of course, these people generally are experts, since it is their core business, so they know well what tools they need. I agree that for some analytics department in a random company whose core business isn't processing data, Hadoop is more likely to be a resume item than something that's really needed.

In my experience, people generally go the other way: they say “we need spark/Hadoop/Cassandra because we have Big Data” when they have a 30GB dataset that is best handled on a beefy EC2 instance with boring tools.

A lot of those > 1TB data sources are very standardized, they can be mapped to a schema, in which case indexing the data supports interactive queries and analytics. Hadoop seems well suited for data that needs to be processed in very different and changing ways.

I think this is the other point that's so often missed/ignored in the "big data" discussion: there's a middle ground between everything-fits-in-memory and must-be-distributed.

The Adam Drake article alludes to it only in the last sentence by mentioning traditional relational databases as an alternative.

For workloads that are relatively I/O-heavy and CPU-light, it's very hard to beat local SSDs (or even HDDs in enough quantity) attached to a single [1] node, if the competition is distributed storage attached by ethernet. It only takes a couple 600MB/s SSDs to saturate a 10GE. A server with 48 lanes of PCIe 3 slots could take the I/O of 78 of them.

100Gb/s networks are getting close. For upwards of $1k per server (NIC and switch port) one can bring that ratio closer to 4:1 from 39:1. I'd expect this is the attractive route for anyone with CPU needs that can't be met by a 4-socket server.

[1] Yes, there can be more than one node with copies for redundancy, as has been complained about elsewhere in the sub-thread, or even scalability

You're absolutely right. Probably my estimate of "anything greater than 1TB" was not quite the right number. At that point, though, careful indexing is probably the more expert option. It's easy to throw data into EMR now if you're not super concerned about performance/cost, and it doesn't require you to think through how your data will need to be indexed to support your future needs.

but the chainsaw analogy was a winner on many levels.

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