GM Cruise raises $1.15B at a $19B valuation from Softbank and Honda - <AUTHOR> https://techcrunch.com/2019/05/07/gm-cruise-raises-1-5b-at-a-19b-valuation-from-softbank-and-honda/ <comment><USER3> Having worked for GM I can say, one of the best things GM did was after they bought Cruise they kept it as a separate company and away from GM bureaucratic style of management where everything comes to die.

<comment><USER4> They've also relegated it to a sideshow on only one of their models, rather than incorporating it into the core of their business.

I wonder if they're underestimating its importance or if there might be internal fighting within GM.

This is another advantage Tesla has being all in towards the goal.

<comment><USER5> When an experimental project is made core to the company's traditional business, the experimental project is usually slowed down. The fewer dependencies between GM cars and Cruise, the better.

<comment><USER4> Maybe - an alternative historical example is Kodak and the digital camera.

They could have it as a standard feature on their cars rather than a high trim level on one.

<comment><USER6> the problem with this analogy is that digital cameras worked, self driving cars don't

<comment><USER7> That's a bit of hindsight; digital cameras didn't work for many use cases for a long time.

<comment><USER8> Digital cameras also didn't kill or injure people when their limitations were reached.

I remember the QuickTake and all that. Yes, those small pixelated images weren't the same quality as film but they had other benefits instead.

Self driving cars currently aren't in a state where they can do anything, even waymo still has safety drivers.

<comment><USER9> Did pre-digital cameras kill people?

Because dumb cars with dumb humans in them kill far more than self driving cars do.

<comment><USER10> Vast majority of accidents are caused by drivers (or cyclers, pedestrians) who fail to safely engage in traffic. For the most part, cars don't kill people - people kill people (or, get themselves killed).

<comment><USER9> > people kill people

which is exactly why removing people out of the equation is the best way to solve the problem. even fully educated and hyper responsible person is not immune to judgement lapses, hallucinations, heart attacks, strokes, losses of consciousness and many more modes of failure.

what's worst - even if i'm 100% sure about myself, _even if_ i take myself out of the equation - there are still thousands murderous humans driving around me.

humans should not be driving cars.

<comment><USER11> Unfortunately we don't have anything other than humans that can do the job yet. And it's possible we might never have.

<comment><USER9> we should try though

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER12> For all of the criticism that Tesla gets for a incremental approach - <USER2> still have the best semi-autonomous car in actual production and a difficult but obvious path to full autonomy.

These guys could completely flame out without ever getting anything of value out into the market.

</comment><comment><USER13> I have a decent sense of where Tesla and Waymo are at in the SDC development competition, but where does Cruise stand? What kind of sensors, computation, vehicles, where are they testing? In my limited knowledge, I'd guess Waymo is ahead of these other players, but do we know who is "in second" or who is second-closest to rolling out actual fully autonomous services?

<comment><USER14> Nobody knows for sure since nobody is releasing anything meaningful (the disengagement reports are both voluntary and self-policed, with no standard for what constitutes a reported disengagement), but the general consensus is that Cruise is second behind Waymo.

<comment><USER15> Reporting the number of miles driven and the number of disengagements is required by law in CA. It is not voluntary.

The reason some larger companies don't have reports is because they either didn't do autonomous testing in CA (many test in AZ) or that they do not consider their tests "autonomous" ( level 4 or above). This is the case for Tesla autopilot.

<comment><USER16> Thanks for providing additional context

</comment></comment></comment></comment><comment><USER17> It gets really confusing talking about GM when they have an organization named Cruise and also a product called the Cruze.

<comment><USER18> Never fear; the Cruze has been discontinued, along with the Volt, which was frequently confused with the Bolt.

<comment><USER19> It's even worse - GM is not the same company that it was 10 years ago (and many people lost money buying the stock because they didn't know that!) !!

[https://www.thestreet.com/story/10544259/1/not-your- fathers-...](https://www.thestreet.com/story/10544259/1/not-your-fathers-gm- shares.html)

</comment></comment></comment><comment><USER20> $20B valuation for companies without products is a very, very frothy signal.

This kind of thing is waaay beyond what went on during the dot-com bubble, where there was a lot of value being created without any business model either.

</comment><comment><USER21> Curious about the corporate structure behind this. Is Cruise a subdivision of GM or is it an independent company with GM just being majority shareholder?

<comment><USER22> Cruise is a separate, privately-held corporation that is partially owned by GM (I'm not sure if they're majority or not any more).

<comment><USER23> GM owns like 80%. I think the plan is to IPO it at some point, but if its actually successful I can't see why they wouuldn't just make it a decision.

There's probably some value in locking themselves in as the exclusive provider of Cruise-enabled cars

<comment><USER24> Well the fact they are getting funding from Honda says

Economy of scale and bigger r&d with a shared platform is better than getting out innovated by Uber/google

<comment><USER25> Why would Honda invest in a company 80% controlled by a competitor? Why would GM let Honda invest?

<comment><USER22> [https://www.theverge.com/2018/10/3/17931786/gm-cruise- honda-...](https://www.theverge.com/2018/10/3/17931786/gm-cruise-honda- investment-self-driving-car)

<comment><USER26> I don't think the article answers the question.

</comment></comment></comment></comment></comment></comment></comment><comment><USER27> $19 billion valuation and it doesn't work yet?

Saw one of those making a left turn in San Francisco last week. The driver was cranking the wheel. It was not autonomous.

<comment><USER28> I work for Cruise. For safety, our drivers keep their hands on the wheel at all times, including when the vehicle is autonomous. The vehicle you saw may have been in manual mode, but seeing the driver crank the wheel usually isn't a good way to tell.

</comment></comment><comment><USER29> I wonder how softbank's vision fund has been doing, and whether that info is available somewhere. Seems like they're in on every late stage splashy tech investment

</comment><comment> 33MHz-i486 that is an absurd valuation ... you're telling me a pre-revenue company is worth comparable amount to Lyft or United Airlines.

<comment><USER30> Isn't Lyft also essentially a bet on autonomous driving? With (probably) an even shorter time horizon to burn all their cash? Otherwise it's hard to see them making enough profit to justify a 17B valuation.

<comment><USER31> > Isn't Lyft also essentially a bet on autonomous driving?

No. It's an app-based taxi hailing service.

<comment><USER30> Yeah right. But other than self driving cars I fail to see how they'll un-dig themselves out of the money losing setup before burning through all the fresh cash collected in the IPO. Hopefully I'll be wrong.

<comment><USER32> I see this criticism about Lyft and Uber all the time, but I don't understand how both companies could not at some point simply raise their prices to make the unit economics work. Sure, they'd lose some business… but given there is almost no fixed costs to running their business, they'd still have large profitable businesses. The only reason they don't is they're fighting for marketshare with each other while in growth mode. But once both companies have established their places in the world, saturated their markets, I don't see why they wouldn't simply raise their prices accordingly.

Revenue would drop, profit would rise. Eventually, the market reach an equilibrium.

Note they could also just raise the share they take for themselves and prices simultaneously. If prices go up 20% and they up their fee from 20% -> 33%, their income goes up 60% and their unit economics look a LOT better.

<comment><USER16> Well, up to now the mainly compete on price and booking comfort (apps) with traditional taxis. So taxi prices are somehow giving an upper price limit, maybe plus something for the better CX.

</comment></comment></comment></comment></comment></comment><comment><USER33> I would value the common shares with a pretty steep discount. I think we can just ignore the 19 and focus on the 1.15 for now.</comment>


At Seattle Art Fair, the Interaction Between Technology and Modern Life - <AUTHOR> http://www.nytimes.com/2016/08/08/arts/design/at-seattle-art-fair-the-interaction-between-technology-and-modern-life.html?ribbon-ad-idx=5&rref=technology&module=ArrowsNav&contentCollection=Technology&action=swipe&region=FixedLeft&pgtype=article <comment><USER2> I asked the person operating the booth that had the VR headset if anyone had gotten sick from it. She laughed and said no, last year's was far worse—people actually got sick from that. The big difference was that last year's apparently didn't give people the ability to control how or where they looked.

<comment><USER3> Was it Rachel Rossin? Her art is incredible. I really love how she uses the work she creates in a new medium, VR, as influence for her work in a traditional medium, oil painting.

The NYT did an excellent write up of one of her shows last year. [http://www.nytimes.com/2015/11/06/arts/design/in-rachel- ross...](http://www.nytimes.com/2015/11/06/arts/design/in-rachel-rossins- lossy-the-virtual-reality-of-living-in-a-painting.html)

</comment></comment><comment><USER2> I'd add this as an edit to my previous comment, but I no longer can modify it. Seattle's alt-weekly rag, The Stranger, published a _fantastic_ writeup of the art fair earlier today: [http://www.thestranger.com/features/2016/08/10/24443834/dear...](http://www.thestranger.com/features/2016/08/10/24443834/dear- seattle-art-fair-i-love-you-and-i-want-you-to-live)</comment>


Mio – Cross-platform header-only C++11 library for memory-mapped file IO - <AUTHOR> https://github.com/mandreyel/mio <comment><USER2> Author here. Long time lurker, but made an an account now.

Wow, I did _not_ expect this. I'm really touched. I wrote this as a small utility for my own consumption because I was unsatisfied with the existing selection at the time, so I'm both surprised and delighted to learn that people are finding it useful. Although to be completely frank, I think this library is way too small and insignificant to deserve a spot on HN's front page, but it definitely made my day. So thank you kind stranger who posted it!

<comment><AUTHOR> Op here. Thank you for creating mio! Your project clearly deserves the attention. I just found it and thought it would belong here. A lot of people seem to share that opinion :)

I am sure this won't be the last top HN post about one of your projects.

Perfect is the enemy of good.

<comment><USER2> Thank you for the kind words. I'll buy you a beer if we ever meet!

</comment></comment></comment><comment><USER3> The name definitely made me think of Rust's mio. On the other hand, `namespace cplusplus` and `mod rust` maybe are disjoint.

<comment><USER2> This is definitely unfortunate, but in my defense I was not aware of Rust's mio (or anything related to Rust beyond its existence) at the time of writing and naming my library. I have no emotional investment in the name, so I'm open to suggestions should anyone take issue with it.

</comment></comment><comment><USER4> For those of you already using Boost, Boost also has a MMAP in their IOStreams library and it works pretty well (like most things boost).

[https://www.boost.org/doc/libs/1_68_0/libs/iostreams/doc/cla...](https://www.boost.org/doc/libs/1_68_0/libs/iostreams/doc/classes/mapped_file.html)

<comment><USER5> And? I am not sure what is your comment about.

<comment><USER2> It's a valid point, I think. I'd probably also trust something so established as Boost more than some random guy's lib on GitHub. However, I specifically wrote mio because I prefer not to use Boost, and from what I understand, many others don't either.

<comment><USER6> boosts quality varies

I've seen parts that weren't much better then someones lib on github, because essentially that's what boost is.

</comment></comment></comment></comment><comment><USER7> I wish people used mmap less.

Creating a new memory mapping can be pretty expensive! On both Windows and Linux, it involves taking a process-wide reader-writer lock in exclusive mode (meaning you get to sit and wait behind page faults), doing a bunch of VMA tree manipulation work, doing various kinds of bookkeeping (hello, rmap!) and then, after you return to userspace, entering the kernel _again_ in response to VM faults just to fill in a few pages by doing, inside the kernel, what amounts to a read (2) anyway!

Sure, if you use mmap, you get to look at the page cache pages directly instead of copying from them into some application-provided buffer, but most of the time, it's not worth the cost.

There are exceptions of course, but you should always default to conventional reads.

<comment><USER2> This is a valid point. My use case was very frequent reads of large files at pretty much unpredictable positions, so in theory mmap seemed justified. However, I never got around thoroughly testing this assumption, and may indeed just have been better off using read(2) and its variants.

You seem very experienced, so I hope you don't mind a question. In my use case the files were as large as tens of gigabytes and I was creating read-only mappings of 256KB-1MB chunks in them, keeping the mmap handles around according to a cache policy and RAM usage limit. Do you think in this case using mmap could in theory introduce performance gains?

[edit: typo]

<comment><USER8> I think that this is the wrong way to use mmap. Just map the whole file at once. The operating system will automatically read the pages you access from disk. And if memory gets tight, these pages will be flushed to disk if they are dirty and then discarded before the system starts paging. These mmapped pages essentially live in the disk cache.

<comment><USER7> > The operating system will automatically read the pages you access from disk. > And if memory gets tight, these pages will be flushed to disk if they are > dirty and then discarded before the system starts paging.

You can tell that you understand how modern OS memory management works when you realize that the OS "automatically read[ing] the pages...from disk" and "flush[ing them] to disk" on memory pressure _is_ paging whether those pages are anonymous pages or mmaped file pages. :-)

[Edit: flushing _dirty_ file-paged pages is analogous to swapping anonymous memory to the swapfile. Discarding clean file-backed pages is a bit like discarding anonymous pages that have been made unused through munmap, process death, etc.]

But to the GP's point: you don't need (except to conserve address space) to limit file mapping size. I think he really wants something like MADV_FREE. But it's complicated.

<comment><USER8> Therr is a subtle difference between anonymous and mapped readonly pages: the later can be discarded right away because their contents were read from permanemt storage to begin with. Anonymous pages need to be written to disk first and that is significantly slower.

</comment></comment></comment></comment></comment><comment><USER9> Bit of a plug here. But I used this library in a small side project (C++ publisher-subscriber library) and it worked like a charm. There are a few things you can customize with mmapping but most use cases will do fine with this. Great work.

[https://github.com/drali/pubsub](https://github.com/drali/pubsub)

</comment><comment><USER10> I wonder if this could replace the cross platform memory mapping in LibreOffice. This is part of the Operating System Layer (OSL) which is at least several decades old and uses a C interface.

[https://opengrok.libreoffice.org/xref/core/include/osl/file....](https://opengrok.libreoffice.org/xref/core/include/osl/file.h#811)

<comment><USER11> That would not be a good idea at all. The memory mapping works cross platform to prevent an unsubstantiated configuration of the elon-burrow mechanisms.

</comment></comment><comment><USER12> not a C++ person here but is header-only library an advantage?

<comment><USER13> Yes because there is no standardised build system for C++, which makes integrating non-header only libraries a pain (or at least somewhat more painful), especially if your aim is cross platform code. In that case you can not rely on a reasonable package manager being present and will have to essentially include all your dependencies in the build, this is trivial for header only libraries.

<comment><USER5> Is there a reason not to have a standard build system?

<comment><USER14> There's no reason not to have one, but there isn't one. There are a few build systems for C++, but none of them are perfect, and none has won out.

</comment></comment></comment></comment><comment><USER15> I wonder: is there something like this written in rust?

<comment><USER16> [https://crates.io/crates/memmap](https://crates.io/crates/memmap) is the most used mmap package, followed by [https://crates.io/crates/mmap](https://crates.io/crates/mmap)

</comment></comment><comment><USER17> Pretty cool, must be something in the air. This is a useful technique, and having it in a self-contained header-only lib is handy too.

I made a similar library for writing data into memory mapped files, also a self-contained header-only lib:

[https://github.com/Morgan- Stanley/hobbes/blob/master/include...](https://github.com/Morgan- Stanley/hobbes/blob/master/include/hobbes/fregion.H)

This one also serializes a representation of the type structure of recorded data so that it can be safely concurrently mmapped and read either with the same code or with the generic PL/compiler that I've developed in this hobbes project.

Where unpredictable disk latency is a problem, we've got a similar header-only lib for logging into shared memory (then have another process to consume this shared memory ring buffer and dump it to disk for concurrent querying):

[https://github.com/Morgan- Stanley/hobbes/blob/master/include...](https://github.com/Morgan- Stanley/hobbes/blob/master/include/hobbes/storage.H)

This pipeline works well for having lightweight C++ processes feeding large volumes of data to generic query processes that we can run out of band to look at this data in various ways (with a Haskell-like query language).

We did hit a slight problem doing things this way that the straightforward representation of data (as in memory) for some cases just used too much space and too much time wasted in I/O. Basically for complex market data, where data structures aren't trivial and recording ~100GB/day makes it very awkward to keep around a few weeks of data for random querying.

So I also made this header-only lib to write data into these mmapped files with a simple compression method (I like to describe it as generalizing Curry- Howard to probabilities) that gives us much better throughput, much smaller files, faster query times, and still support concurrent constant time random access queries:

[https://github.com/Morgan- Stanley/hobbes/blob/master/include...](https://github.com/Morgan- Stanley/hobbes/blob/master/include/hobbes/cfregion.H)

It gives us compression ratios about the same as EOD gzip, but much faster and importantly works online and with these query use-cases we have with hobbes.

Anyway, maybe I should write up those details somewhere else, I just mean to say that this is a useful technique and you can push it very far and do many things with it in a very straightforward way.

</comment><comment><USER18> Already tons of projects called mio. Please rename

</comment><comment> loup-vaillant Why, _why_ do they make it header only? Is it so difficult to integrate a couple source file along with the existing headers?

We should not forget compilation times. A project I use depends on spdlog, a header-only C++ logging library. The thing adds almost _two seconds per compilation unit_ to single threaded build times. And since logging is kinda used everywhere, the whole project takes forever to build (trice the build time it would have had without spdlog, I've measured).

What benefit is so great that it is worth killing compilation times?

<comment> ur-whale Doesn't your compiler support pre-compiled headers?

<comment> loup-vaillant The "rebuild from scratch" integration server does not.

</comment></comment></comment><comment><USER19> The code seems clean. I'm not sure this is a great idea in practice, though. Generally the only good reason for mapping stuff out of the filesystem is performance, and VM behavior with mmap() varies _wildly_ across systems (and filesystem backends, and drivers if it's a hardware device, and hardware if it's a framebuffer, and...). Frankly on windows this is AFAIK a mostly- unheard-of technique. No one does mapping.

This just isn't really something that can be cleanly abstracted to do what you want it to do, even if you can make the code "look" the same.

But again, it looks like a nice, clean, modern C++ library. Just IMHO misapplied.

<comment><USER20> MMapping is used in most fault tolerant software as a simplified method of data persistence. Granted, not the only method in play, but it is a common data safety net.

<comment><USER19> Flushing behavior is precisely the kind of thing that varies the most between systems. I'd be _very_ suspicious of a "fault tolerant" system that tried to use a library like this to be "cross platform". That's almost a contradiction in terms.

<comment><USER20> Was not talking about that library, just memory mapped files.</comment></comment></comment></comment>


Teen's TikTok video about China's Muslim camps goes viral - <AUTHOR> https://www.bbc.com/news/technology-50559656 <comment><USER2> Posted 20 hours ago: [https://news.ycombinator.com/item?id=21640351](https://news.ycombinator.com/item?id=21640351)</comment>


Ask HN: Typical referral rates - <AUTHOR>

I am trying to enter my pre-launch startup in a b-school business plan competition. One of the things I am trying to do is project new user growth based on referral rates. Dropbox would be an "extreme" example of a wildly successful referral system. What does the median look like in the referral marketing world? Specifically, what percentage of users might be interesting in referrals and how many new users do they bring in on average? <comment><USER2> you mean a viral distribution system? it very much depends on the value the app provides..

[http://www.secondshares.com/2010/06/09/metrics-that- matter-f...](http://www.secondshares.com/2010/06/09/metrics-that-matter-for- social-gaming-investors/) here is some information for you to understand this "referrals" thing better :)</comment>


Ask HN: Why are we so reluctant to use IPv6? - <AUTHOR> its been about for a long time now and weve known about the IPv4 shortage for as long. while addresses in IPv6 may be a bit of a pain surely there must be a bigger reason that its not yet become the default system<p>Why is it that were not using it more? <comment><USER3> I have been working with IP based networks for close to two decades. I have yet to have a client who really wants and needs IPv6. The main reason being that the majority of nodes do not need to access any arbitrary node over the internet. Thus for the most part nodes happily exist behind RFC1918 private networks. Their edge NAT and the carrier's NAT provide accessibility in spite of the address space limitations of IPv4.

Of course, there are use cases for IPv6 and where it is the best solution it is being used. But where IPv4 gets the job done it is very hard to justify replacing equipment just for the sake of being IPv6 compliant.

The use of NAT64 is helping many organisations to delay migrating to IPv6. From a purists point of view it is probably not an ideal solution. But it seems to keep the pragmatists happy.

<comment><USER4> I have been working with IP based networks for over 20 years, and specifically IPv6 networks for over 17 of those. IPv6 is the main reason I got my current job, FWIW.

> The use of NAT64 is helping many organisations to delay migrating to IPv6.

That's...not how NAT64 works. NAT64 is fairly dependent upon deploying IPv6, like T-Mobile's 11+ million IPv6-only users who use their NAT64 platform.

I do agree that from a purist's point of view, it's not ideal, but it enables network operators to stay largely single-stack (on v6), while still facilitating access to the IPv4 internet.

</comment></comment><comment><USER5> I tried IPv6 on my business modem years ago. Per the ISP's top engineer, many firmware bugs made a static setup impossible at that point in time.

Amazon only added it to EC2 instances a year or so ago.

Most corporate network and infosec guys I've talked to about it are dragging their feet as much as they can--network guys because if they don't _have_ to have it, they don't want it, and infosec guys because it's one more attack surface, and is not as easy to enumerate as IPv4.

Personally, if it gets us back to old-school disintermediated communications, I'm excited about it. In the back of my mind, I fear the powers-that-be will come up with some bullshit to NAT the hell out of IPv6 as well. Disintermediation will de-rail quite a few gravy trains!

<comment><USER6> Same for me: Had to use IPv6 via my home cable uplink. The IPv4 gateway was located at the ISP. This translation service was called "DSLite". The performance was horrible, connections frequently dropped. This was basically last year.

Now I pay more (like 35€/m instead of 20€/m) to get an IPv4 only connection.

<comment><USER7> Funny. For me the carrier grade NAT via DSLite performs better. If i run full dual stack my router is getting warmer, and there are dropouts/pauses. IPv4 only is nothing special. Best performance of all is when only IPv6 is involved, like unbelievable pings and rtts over the atlantic. I tested that a long time ago because it could switch it at will, and after a reconnect it worked like ordered. Anyways, it also depends on the peering of your ISP and the involved devices.

<comment><USER6> Interesting, I never heard of practical advantages of IPv6 for the end user, such as dramatically better ping times. Given the simplified routing, I can imagine this to be true. Are there applications where this pays off, such as reduced delays in cross-atlantic video chats?

</comment></comment></comment></comment><comment><USER8> Because dual stack is a hassle. It doubles your operational workload - <USER2> is a big deal in a large network. IMHO, we'll only see large scale IPv6 adoption when it becomes possible to deploy an v6 only network and translate to/from v4 at the edge for legacy edge cases.

Facebook already does this - everything is IPv6 only inside their datacentres, and the only dual stack devices are their load balancers at the edge. They had to do this because they were running out of RFC1918 address space to use internally for IPv4, and the traffic was already going through the dual stack load balancers anyway.

On the access side, mobile networks are also going v6 only. EE here in the UK (sometimes) only gives you an IPv6 network and uses 464XLAT to NAT you when you want to reach an IPv4 only address. They can do that because they know what devices all their users are using, and can whitelist recent versions of both Android and iPhone which have CLATs in them which makes 464XLAT possible.

Fixed line residential and business connectivity is much harder - laptops and smartphones will work just fine with IPv6 only, but people expect their games console or old networked print server to work, and frequently they only support IPv4. What's needed there is islands of IPv4 on their LAN and a 464XLAT compatible CLAT inside the customer's router - then the entire ISP network can be v6 only apart from a few NAT64 devices at the edge. I'm sure that will come, but it hasn't happened yet.

It will happen - mass adoption is inevitable IMHO. There are new internet users and services being added every day, and there aren't enough IPv4 addresses for all of them. It's either IPv6 and 464XLAT or IPv4 only with CGNAT. And CGNAT is expensive - keeping state for all those connections makes for expensive boxes with lots of memory.

</comment><comment><USER9> I disabled it a long time ago on Arch because of kernel/driver bugs and haven't had any reason to enable it since. There is no compelling need for ipv6, which is a shame, because the protocol is much simpler than ipv4. So much of the internet could be much better if we didn't have to keep compatibility with protocols developed in the 70's.

<comment><USER10> What bugs? I find Arch works nearly flawlessly with IPv6. The only "bug" I found was that wiki.archlinux.org did not respond via IPv6.

<comment><USER9> I don't remember. I think it was something with the iwlwifi driver. It could also have been the "broken dns servers breaks ipv6 in FF"-issue. Probably has been fixed by now but there is no reason for me to turn ipv6 on.

</comment></comment></comment><comment><USER11> One reason it hasn't been adopted very quickly is because the RFC basically rearchitected layer 3 in the OSI. The network topology for IPv6 changes significantly. It wasn't just, "let's make up addresses longer". Adoption has been slow enough to call the RFC a failure at this point. I personally think it will slowly fizzle out and then be viewed as a waste of time and a less drastic step will then be introduced by a corporation that we'll all end up adopting.

<comment><USER12> What? There's no alternative to IPv6. Nobody is making one. If someone did make one, it would be stuck on hundreds of vendors making thousands of new pieces of equipment in just the same way as IPv6. It would be stuck on the immense training costs of a new IP system, just the same as IPv6. It would get stuck on the inertia and change-aversion of network people and purse-holders, just the same as IPv6.

IPv6 was a clean break from IPv4 with a lot of changes because the authors knew that there was a very high 'minimum cost' to _any_ IPv4 replacement. Even if they only added more octets to the addresses, there were still billions of networking devices which would need replacing, millions of people to retrain to some degree, mountains of software to modify or rewrite, and a similar conscious decision to switch. If we had to go through this pain anyway, then the obvious choice was to go all-out designing a greenfield new protocol which solved as many problems as possible and which would last for as long as possible. That's IPv6.

IPv6 is here to stay. It's already 30% of the internet, and has industry-wide buy-in and backing. All OS' support it, Apple even requires apps to work in IPv6 only environments to get on the app store. New IPv6 deployments go online every day.

IPv6 will win. One day. The costs of keeping IPv4 around are high and increasing. ISPs are spending millions on specialized CG-NAT infra to keep their dwindling pool of IPs usable, in return for tremendous capital and maintenance costs, reduced performance, increased support burden from angry customers who had their app broken by CG-NAT. And anyone who wants to buy an IP address has to deal with the price - which just keeps going up.

</comment></comment><comment><USER13> it just takes time. there are a _LOT_ of systems that need to be updated/ perhaps replaced. have not installed a ipv4 only system for a few years. but still have a huge amount of systems that is not migrated. and probably will not be until there is a revision or some reason to touch it.

</comment><comment><USER14> I'd have to call my ISP to get it.</comment>


Messaging-App Kik Plans to Raise $125M Through an Initial Coin Offering - <AUTHOR> https://www.wsj.com/articles/messaging-app-kiks-big-bet-on-a-digital-coin-offering-1504041396 <comment><AUTHOR> "Kik is creating 10 trillion tokens, called "kin," and plans to sell 1 trillion in a Sept. 12 offering. Its goal is to raise $125 million."

Is this company really just making up $1,250,000,000 out of thin air?</comment>


Surprisingly little evidence for usual wisdom about teeth - <AUTHOR> https://www.nytimes.com/2016/08/30/upshot/surprisingly-little-evidence-for-the-usual-wisdom-about-teeth.html <comment><USER2> Anecdotal comments, in my opinion, are particularly unhelpful when it comes to dentistry. Many people have teeth prone to all kinds of problems despite perfect hygiene and brushing. Others have, essentially, indestructible teeth. The last time I went to the dentist was 27 years ago. I was told I had three cavities that needed filling. Never got it taken care of. Nearly 30 years later, teeth are working great. But, like I said, I don't draw conclusions from this as there are others — apparently — who brush twice a day, see the dentist regularly, and nevertheless have a mouthful of problems.

<comment><USER3> I have largely stopped trusting dentists, unless I have pain. When my lifelong dentist fell out of network I went to a new dentist and they pushed all kinds of procedures and nonsense, saying I needed 3 fillings, etc. I've been to another dentist and they said things completely different. I don't understand how two professionals can draw polar opposite conclusions. It really seems they recommend needless procedures to fill their books of business and fleece costumers.

It's visible cavities and decay, it's not like you're diagnosing based on symptoms someone is describing to you, which I can understand for general doctors or specialists drawing blanks or different conclusions.

<comment><USER4> An old acturian at my current job usually tease new developers that they are just like dentists - never satisfied with anyone elses work and always suggesting serious rework that is critically important.

<comment><USER5> Living with a dentist I learned that the single most important factor (by far) in the health of teeth is the genetic factor. Some people do not brush their teeth for years, never floss, have bad diets, etc. and still barely have a cavity. Others do it "by the book" and yet their teeth are a ruin. This is not to say that brushing teeth or flossing won't help. It will just not compensate if you pulled the genetic short straw.

But as in every job dentists also feel pressured to point out other people's lack of quality work to promote their own. You'll see this in the IT guy who immediately recognizes that whatever the previous one did on your computer was amateurish and they can do it better, same with the electrician, the plumber, the mechanic, the plastic surgeon, etc.

</comment></comment></comment></comment><comment><USER6> Bogus headline, article confirms basic beliefs are true:

> brushing with fluoride toothpaste that matters, not the brushing alone. > Doing that doesn't just prevent gingivitis and plaque formation; it also > prevents cavities, which is the outcome that we care most about.

> powered toothbrushes reduce both plaque and gingivitis more than regular > toothbrushes

> toothbrushing with flossing versus toothbrushing alone most likely reduced > gingivitis, or inflammation of the gums

Article seems to miss that gingivitis is a bigger concern than cavities for adults

<comment><USER7> I guess people wouldn't click on "Most of the standard advice about dental health is spot on but there's some doubt around the edges."

I wonder how many people will toss their toothbrushes after only reading the headline and develop problems as a result. Seems like journalistic malpractice.

<comment><USER8> > Seems like journalistic malpractice.

It's not 'malpractice' and it's a mistake to think that what you consider journalism is anything other than a vehicle to sell advertising in the end. There seems to be this assumption that what is written (especially and actually in the NY Times (which I do read and pay for)) is pure and good and the people writing spend untold hours to get the story right and fairly balanced. My anecdote is when I was interviewed a few times in the past by the NYT the writer fed me conclusions and it was very easy to figure out what to say in order to get my name printed. (A contrary position to the point and stated vehemently was almost certainly the way to go..)

<comment><USER7> You're talking about what is. I'm talking about what should be. It's not somehow ok to harm people in the pursuit of advertising money just because it's the norm.

<comment><USER8> > I'm talking about what should be.

What about journalism to you means it should have some kind of a higher calling? The people working in that industry have jobs and families to feed. If they simply did the right thing they wouldn't be employed very long if their competitors didn't follow the same path.

When 'journalists' write either left leaning or right leaning pieces are they being circumspect and covering all angles with fairness? Or are they just making sure they have food on the table and/or ensuring that readers continue to patronize the paper (or broadcast) that they work for?

It's nice to think that someone else who has to earn a living and feed their family should be 'above it all' but in reality that is never going to be the case.

Maybe a better idea is to teach children in school over and over that what you read and what is reality are two different things. Don't believe what you read.

<comment><USER7> You could write almost the same thing about doctors, yet we have no problem using the term "malpractice" with them, to the point that it's just assumed you mean medical malpractice if you don't qualify the word.

<comment><USER8> Doctors take an oath and it is very clear what they are expected to do. (Some of them stray of course but it is atypical). Additionally 'Physicians' (if that is what you mean by 'Doctors') are a more homogeneous and generally trustworthy group than 'journalists'.

</comment></comment></comment></comment></comment></comment></comment><comment><USER9> Dentist here, AMA

By the way: \- there _is_ scientific evidence in dentistry just like any other branch in medicine \- there are good and bad dentists just like in any other profession \- the good ones tend to be very scientific and evidence-based (I know I am, everything I recommend and do is based on solid evidence, and I provide links to pubmed to any patient that asks for information) \- a good dentist should be able to answer any of your questions or doubts in a split second, I often draw simple sketches to explain concepts to patients \- please use your common sense: even though it might be hard to prove with 3 standard deviations that flossing makes a big difference (for all sorts of reasons that statisticians know very well, including the difficulty of tracking a large group of patients), it's pretty obvious that removing rotting food from your gums is _good_ and leaving it there to putrefy is _bad_ , don't you think? same goes for all the other claims...a powered toothbrush is better simply because it does more iterations per minute than a manual one...again, common sense

<comment><USER10> "it's pretty obvious that removing rotting food from your gums is good and leaving it there to putrefy is bad, don't you think?"

But is that actually true? Has anyone actually confirmed it with replicable scientific studies? Did early human teeth rot to hell over the first 10 years of their lives? Why don't cats and monkeys need to brush and floss?

"please use your common sense"

The problem with common sense is that it can be deceptively nonsensical, and we tend to ignore that we haven't proven it because we "know" it's true already.

<comment><USER11> Pets, cats, and dogs only live until they're 20. AND pets DO have lots of problems with dental health. What is with all these people questioning flossing here? Floss your damn teeth. Worst that can happen is the poor guy you work with doesn't have to smell the decomposing food coming out of your mouth. JFC

<comment> village-idiot We've changed pet food just like we've changed our own food. Notice how pets and animals that eat human food (like raccoons) are all getting fat together.

Looking at modern dog dental hygiene to learn about how wild animals' teeth work is as silly as looking at our dental hygiene to see how a hunter gatherer's teeth work.

</comment></comment></comment></comment><comment><USER12> Good dental hygiene does what it's supposed to, but the biggest factor is basically luck - you either "have good teeth" or you don't.

There's evidence that your mom's prenatal diet (and not strictly genetics) may be a salient factor.

[https://www.amazon.com/Nutrition-Physical-Degeneration- Westo...](https://www.amazon.com/Nutrition-Physical-Degeneration-Weston- Price/dp/0916764206)

This book is eye-opening. A dentist traveled the world in the early 20th century when there were a lot more indigenous people to visit who had had no previous contact with modern processed flours etc. Those still on their traditional diets almost all had excellent teeth, without ever owning a toothbrush. But when modern foods were introduced, their teeth went to shit within a generation. Probably some epigenetics playing a role, though they didn't know about that then. Also I believe this may have been before flours started being fortified, so you would probably see a less pronounced decline if you somehow did this today. But the takeaway seems to be that a high protein paleo-ish diet kind of takes care of everything.

<comment><USER13> I don't know. Chalking things to luck seems... like an admission that we don't actually understand the causal factors that well. Especially combined with your other evidence that there was a clear delineation between folks with good/bad teeth.

Actually, your point about flour heavy diets basically sending folks that used to have perfect teeth to cavities sounds very not luck based. Which is it? Genetically some folks have cavities, or that common modern diets lead to cavities?

<comment><USER12> The luck aspect, under this particular hypothesis, would be that either your mom ate well or she didn't.

<comment><USER13> But it literally goes against the other argument. That isn't luck, that is prior choices having a larger impact than current choices.

If diet of the mother is important, we can start educating future mothers to have diets that help. Sure, there is no panacea for people with bad teeth today, but that is true for a lot of things we take corrective action on.

<comment><USER12> Getting into the existential weeds a bit here with free will and all, but that's OK with me. I'm not using a strict definition of purely random luck here. I'm using a looser colloquial definition under which choices by yourself or others can affect your luck. Like if the dictator chooses to chop off all heads with my hair color today, that's bad luck for me, even though he caused it. Or if I choose to drive drunk, and hit a utility pole, that's bad luck for me, even though I caused it!

Here's a trans-generational example: My dad makes a bunch of awesome choices that result in his becoming rich. Then I get born, and someday inherit that fortune. I'm much more inclined to describe my own outcome as luck than his, probably because my own decisions had less to do with it.

On the other hand it's not really so straightforward, because so many occurrences are attributable partly to random chance and partly to free will by somebody or somebodies. Maybe my rich dad benefited from luck, like not being crippled by polio or war, or not being born into a repressed social group. And of course my own "good luck" is a result of dad's explicit choices (your point), plus it also hinges on my own actions, such as not doing anything particularly atrocious to alienate him such that I get written out of the will. So is he a genius or just lucky? Probably a bit of both. Am I lucky or just shrewd/a good son? Probably a bit of both.

<comment><USER13> Ok, I was following "luck" as in "non-deterministic."

Pulling it back to what I think you are saying, though; there are still some obvious points that need more exploration for a causal factor. And if it can be found, then it should be exploited more.

So, if there really is a link between mother's diet and bone health, we should find out what that link is. If it is diet related, we should find out what about the diet leads to it.

I'll note my bias. I have the best teeth of my siblings. I likely have the worst brushing habits. Even in grade school, when I had braces, I would brush the night before the dentist, and would generally chew gum/whatever whenever I wanted. Easy to say I got lucky genetically. But what if there is more to it than that? What if my genetic luck was my allergy to damned near all food which knocked out some specific food that caused issues? (Would be almost poetically ironic if it was milk or some such.)

So, colloquially, I don't disagree that luck is a big factor. I just don't think luck should rule out looking for causal factors that can be exploited. Pretty sure that is standard for exploration/exploitation strategies in any learning scenario, no?

<comment><USER12> Yep it is, and we should most definitely nail it down with further study. Especially since, as you kind of hinted, it's so hard to isolate or control all the variables when you're dealing with people just living their lives.

</comment></comment></comment></comment></comment></comment></comment><comment><USER14> As a 20-something I often skipped brushing, never flossed and would rather have a leg amputation without anesthetic than visit a dentist.

In my thirties, I experienced a lot of dental problems such as toothache, bad breath and gum disease. Eventually it got the point where I was in so much daily pain that visiting a dentist didn't seem such a bad idea after all.

For the past 18 years or so I've followed a strict regime of brushing twice daily, flossing and three-monthly sessions with my hygienist.

My hygienist is fastidious and is always disappointed in me, no matter how hard I try she'll always find a spot I'm missing or not cleaning thoroughly enough.

Regardless of this though, my dentist checks me over every 12 months, I have x-rays every 18 - 24 months and there are seldom any problems.

I've had a couple of treatments for chipped enamel over the past 18 years but, apparently, that's a result of aging rather than poor hygiene. Nothing else.

So, yeah, the scientific evidence for regular brushing my be lacking but I'll take my personal experience any day of the week thanks.

<comment><USER15> As a 20-something, I moved away from home and neglected to find a new dentist. I kept putting it off, but to make myself feel better, I brushed more aggressively and more often (after every meal and snack). After 8-10 years of this, I didn't have any cavities, however I had the start of gum erosion. This grew worse, and I eventually had to have a gum graft. That's a procedure that I would not recommend to anybody.

<comment><USER16> Did your dentist or doctor posit a reason why your gums started eroding? Is it hereditary? What else could you have done to prevent the erosion?

<comment><USER17> Aggressive/harsh brushing is generally what is identified as causing gum recession, and that matches their story.

</comment></comment></comment></comment><comment><USER9> Also, regarding the guy that doesn't trust dentists that posted below...consider this \- You had a very good dentist for several years that never suggested you do unnecessary procedures

This dentist had the balls to drop out of network, probably because he's good and has enough patients to not cave in to the absurd demands of insurance companies (they pay far less than a FFS practice, just FYI)

So you decide to drop your good dentist, and go to lower quality ones, just because they are in-network (guess what? these guys actually need to drop their fees because they don't have enough patients otherwise)...and then you find out that these new dentists _are_ lower quality and need to prescribe unnecessary procedures to make ends meet

Solution: like in any other field, value quality over price, go back to your old dentist.

It's like Apple charging more for an iPhone simply because it's higher quality and is time-tested, of course if you buy cheap cell phones they are worse and screw you up some other way.

The real problem is insurance companies here, they are screwing both dentists and patients extracting money in a place where they shouldn't be (why do you need a middleman between a doctor and a patient anyways?)

<comment><USER18> > why do you need a middleman between a doctor and a patient anyways?

I agree, we don't.

Problem is right now if I pay for dentistry via "insurance" then it is pre-tax dollars and or my employer pays some/all of the premium. If I pay it completely out of pocket, I am now using post-tax dollars and my employer isn't picking up a percentage.

Our incentives themselves are irrational. You're essentially forced to go through insurance/your employer, and punished if you don't.

I'd love to see both dental + health insurance "unbundled" from employment, and a large HSA-like pre-tax savings account which can be used on premiums, that employers can choose to contribute to (in cash dollars). That way if you wanted to skip dental insurance, and pay per-treatment you could (and pick any health insurance plan you liked, including ones that could include dental benefits).

PS - The reason the existing HSA structure doesn't work for well for dental is two fold: It requires high-deductible health insurance, and the cap is low when you start using it for other areas (vision/dental).

</comment></comment><comment><USER19> I tried to find studies for the effects of teeth brushing frequency but the only ones I could find were cohort analyses as opposed to randomised trials. It seems like despite a lack of evidence, it would be very hard to ethically approve a randomised trial of teeth brushing over a long period. I honestly believe brushing teeth twice a day is very much a ritual which achieves very little on a per effort basis.

Reducing our intake of sugary and acidic foods and drinks would have a much greater effect with much less effort. The problem is that the profit margins on carbonated flavored water are massive so the opposition to such change will be huge.

<comment><USER20> > It seems like despite a lack of evidence, it would be very hard to ethically > approve a randomised trial of teeth brushing over a long period.

This is the exact same argument that was used to evade studying the effects of low doses of aspirin on heart disease. Everyone "knew" it worked, so it was thought to be unethical to put people at risk of heart disease into a control group. Many millions of people spent money for years to consume a constant supply of aspirin.

When the question was finally studied, it all turned out to be nonsense. In fact, it turned out to increase death rates from higher cancer risk. All that money could have been spent on actually improving health.

[https://utswmed.org/medblog/aspirin-heart- disease/](https://utswmed.org/medblog/aspirin-heart-disease/)

<comment><USER21> I am pretty sure that low dose aspirin has some benefits for some people/conditions. At least I remember reading studies that suggest as much.

So naturally I was curious about it being "nonsense" for heart disease.

A quick skim of the article + a quick search shows it's not as clear cut and conclusive as you suggest.

Interestingly, neither is the increased risk of cancer discussed in the article. Aspirin has been shown to have the opposite effect too.

I found it hard to glean what dosages where used in the studies mentioned in the article but the couple I saw were 100mgs per day. I didn't see mention of if they were enteric coated or taken with meals.

In the US baby aspirin is 81mg and in the UK there are 75mg available. Both are enteric coated. In Australia it seems 100mg might be considered low dose and widely available.

It would be interesting to see more studies on this topic using lower dose, coated, aspirin taken with a meal. The US/UK low dose aspirin are 19-25% lower than at least a couple of dosages the studies mentioned. Those lower dosages may help mitigate bleeding risk.

Seeing as some of aspirins effects are longer lasting, perhaps alternative dosing schedules could also be looked at (every other day etc.) - this may further help mitigate the bleeding risk whilst still providing benefit.

<comment><USER22> The doses were different for legal reasons. Aspirin for children is unnecessarily risky in most cases but different countries set different cutoffs for restricted doses vs. unrestricted adult doses.

But ya, dosing is underrated. Something that's bad at X dose may be beneficial at 1/Yth the dose.

</comment></comment></comment></comment><comment><USER23> A similar article in The Atlantic was submitted a few days ago:

[https://www.theatlantic.com/magazine/archive/2019/05/the- tro...](https://www.theatlantic.com/magazine/archive/2019/05/the-trouble-with- dentistry/586039/)

There's even less evidence for pulling wisdom teeth:

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1963310/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1963310/)

("The Prophylactic Extraction of Third Molars: A Public Health Hazard")

I'm lucky like the author. 47. Zero cavities. Gums are healthy. Brushed infrequently as a kid and never flossed. Teeth were treated with fluoride by a dentist as a kid. Didn't start brushing daily till high school. Didn't start flossing daily till my thirties. Skipped going to the dentist at all for maybe 5 years in my mid-twenties. Typical western diet. Never had braces. Straight teeth.

Both parents, both sisters, and my brother all have several to many fillings.

No smokers.

I see my dentist twice a year but they only take x-rays every 18 months.

<comment><USER24> I'll add one. I had bad cavities and several root canals by the time I was 22. Dentist told me to start using a fluoride mouthwash. I use it occasionally (few times a week?), no new cavities for 10 years straight. Seriously no other change.

<comment><USER25> No change in diet at all?

<comment><USER24> Nope, if anything it's worse.

</comment></comment></comment></comment><comment><USER26> That there are no randomized control studies is hardly surprising: nobody would ethically assign a person into the "no dental care" control group.

I am reminded of the randomized control study they did on parachutes which showed that parachutes were useless. Of course, to ethically allow people to jump out of an airplane without a parachute, they made sure the jump was not more than a meter and a half off the ground.

What that satirical study actually showed is that randomized control studies don't always make sense.

<comment><USER27> >That there are no randomized control studies is hardly surprising: nobody would ethically assign a person into the "no dental care" control group.

They're not saying "no dental care". They are saying "no dental floss", or "no fluoride toothpaste", or "no fluoride in water", or "brush once a day". The reality is that a significant percentage of the population falls into one of these three categories (I was surprised you could by toothpaste without fluoride, but you can - there's a market for it).

And yes, while you can't do true randomization, you can compare dental outcomes between these groups.

And finally, saying it's "unethical" is a stretch. It's not unethical if there is no good reason to believe these measures are good for health. Until there's a clear study, these all fall into the same category as other traditional/folk medicine. When I first went to my current dentist years ago, he said "Your insurance covers two cleanings a year, and we'll give that to you. However, I'll have you know that there's no evidence that twice a year is better than once" and he proceeded to tell me a bunch of other common dental practices, their origins, and the lack of studies on them.

It reminds me of the whole 8 glasses of water a day belief, which until about 10 years ago was commonly promoted by doctors. Then in about 2005-2007, someone published a literature survey showing no studies had ever recommended 8 glasses with good reason. All my doctor friends knew of this survey and promptly stopped recommending it.

<comment><USER26> I agree with everything you are saying. Let me rephrase what I was saying so you can see we more or less agree.

The article is complaining that there are no randomized control studies and using this to conclude that there is little evidence to support flossing. They are simply disregarding other types of studies like the observational study you are pointing out have value. These observational studies show such clear benefits to flossing that directing a person to stop would be considered unethical. I am pointing to a more facile example where you would never imagine performing a randomized control study because it is obvious that the no treatment control is dangerously unethical.

Doctors end up being susceptible to public misconceptions just as much as the general public. Not everybody reads original research or health guidelines. So someone hears that the official guide recommends 2.5 liters of water, with no mention of the accompanying note that most of this comes through ordinary food intake, and they misinterpret it as needing 8 glasses of water a day. That is the case for the 8 glass a day myth: no scientific study ever recommended it, but half readings of some literature seemed to imply it.

If you like myths like those, read through [https://www.snopes.com/fact- check/water-works-2/](https://www.snopes.com/fact-check/water-works-2/) especially when it gets to the diuretic effects of caffeinated beverages. I mostly learned about this when I started talking to foreigners about it and realized it just wasn't common knowledge outside of North America that caffeine causes dehydration.

</comment></comment></comment><comment><USER28> I think individual dentists will often go on anecdotal evidence. A single dentist may fix 10k+ teeth or more and treat the same patients over 20 years or more and is therefore often well placed to consider what worked in their practice.

This is often exactly what you want actually ... controlled trials typically can't take into account enough useful variation in patient conditions to be a useful guide for any given patient. Meanwhile the dentists mental database can be ... if your dentist is a good one.

<comment><USER29> Anecdotal evidence is widely considered inferior to controlled studies, and for good reasons: Confirmation bias, survivorship bias, etc. are incredibly hard to avoid for a single person even if they're aware of them.

<comment><USER28> Anecdotal evidence doesn't have to have any of those qualities but I do think that's exactly right, yet most decisions just won't have a basis in controlled trials due to the variation in the patient group and because you just can't have controlled trials for most things .

For example, implant placement at a 45 degree angle are totally weird mechanically speaking given that the biting force runs down but dentists may do them to recruit better quality bone because they know that implanting into low density bone or calcious mass will likely lead to an implant failing but they just don't see much failure due to weird angles ... this particular case happens so often actually that some companies now recommend placement at 45 degrees.

Personally experience, conferences, etc . It's not how the world ought to work but it is how it mostly does.

</comment></comment></comment><comment><USER30> _Surely the twice-a-year teeth cleanings matter? In 2005, Evidence-Based Dentistry highlighted a systematic review on the effects of routine scaling and polishing (you call it teeth cleaning)._

It very obviously works aesthetically, especially if you drink a lot of tea. I had no idea it was even supposed to have any health benefits besides the free check-up which some (my) dentists throw in.

</comment><comment><USER31> This recent article on the Atlantic is more interesting read: [https://www.theatlantic.com/magazine/archive/2019/05/the- tro...](https://www.theatlantic.com/magazine/archive/2019/05/the-trouble-with- dentistry/586039/)

Covers both lack of evidence-based science in dentistry, and also culture (thankfully doesn't seem to be the norm) of over treatment.

</comment><comment><USER32> For some history of teeth (not just human teeth) try the BBC _In Our Time_ podcast episode _The Evolution of Teeth_ :

[https://www.bbc.co.uk/programmes/m0003zbg](https://www.bbc.co.uk/programmes/m0003zbg)

Being a Melvyn Bragg podcast, it includes a reading list:

Barry K. B. Berkovitz, _Nothing But the Tooth: A Dental Odyssey_ (Elsevier, 2016)

John A. Long, _The Rise of Fishes. 500 Million Years of Evolution_ (The Johns Hopkins University Press, 1996)

Neil Shubin, _Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body_ (Vintage, 2009)

T. M. Smith, _The Tales Teeth Tell: Development, Evolution, and Behaviour_ (MIT Press, 2018)

Peter S. Ungar, _Teeth: A Very Short Introduction_ (Oxford University Press, 2014)

Peter S. Ungar, _Evolution's Bite: A Story of Teeth, Diet and Human Origins_ (Princeton University Press, 2018)

</comment><comment><USER33> The main differences in outcome, like the anecdote the article leads with, might be due to different micro-flora in the mouth.

I used to get plaque build up something awful, but since I started taking probiotics a few years ago for another problem, I don't seem to have that problem anymore.

</comment><comment><USER34> There's also evidence that brushing with toothpaste ("dentifrice" in scientific papers) does not remove plaque any more effectively than brushing with plain water:

[https://www.ncbi.nlm.nih.gov/pubmed/27513809](https://www.ncbi.nlm.nih.gov/pubmed/27513809)

Toothpaste can also deliver fluoride, but I drink a lot of tea (which concentrates fluoride from the soil) so I'm more concerned about excessive fluoride exposure than too little. I've been brushing my teeth with plain water for years and they are as healthy as ever.

<comment><USER35> You can use toothpaste with some of the other enamel supporting materials popular overseas, like nano-hydroxyapatite.

</comment></comment><comment><USER36> Sample size of 1, but I've done several A/B tests to see what works better for me.

Works:

Xylitol. Been trying this recently, and it is amazing. Using the Xlear sinus mist has massively reduced snoring and sleep apnea issues. Using Xylitol as a mouth wash - my teeth feel much smoother now. Go do the research and check it out for yourself.

Apagard toothpaste. Its pricey, but switching to this dramatically reduced the drama during dental visits.

<comment><USER37> > Its pricey, but switching to this dramatically reduced the drama during > dental visits

What drama was there during dental visits? Found cavities? How often do you go to dentist/how often did the drama happen before you switched toothpaste? Sorry for blunt questions, I really don't know what that could mean.

<comment><USER36> No cavities since I found this toothpaste. Also, greatly reduced tooth sensitivity. I go to the dentist every 6 months.

</comment></comment></comment><comment><USER38> I had dental insurance a couple years back and went to the dentist for a cleaning after probably 10 years and the dentist and the cleaning tech both said my teeth looked about like I skipped my last 6month visit (before I told them it had been a decade)

Now that I'm not spreading the cost out over the year it is harder for me to get motivated to go and pay $250.

</comment><comment><USER39> Surprised to see nothing about carbohydrates in the article, nor here. I have been following a diet very low in carbs recently, and one thing that surprised me is that my teeth never hurt anymore. It wasn't the reason for my diet, but it's a really nice benefit.

I noticed a causal relationship between eating eating sugary foods and toothaches, so I cut out sugar a few years ago, which reduced the pain by 80%. But there was still a subtle aching after every meal, sometimes even if I immediately brushed my teeth (can't reach every single place).

But cutting carbs altogether, has _completely_ eliminated the mild background toothaches (and not so mild ones) I just took for granted.

I heard recently that with the advent of agriculture, humans switching to a carb-rich diet, cavities (in found skulls) increased by 500%.

</comment><comment><USER40> I've read similar articles before, and yet I still feel the need to follow all the suggestions.

I floss daily and brush a little more than 2 minutes each time. Still get dental issues, but I feel like it would be worse without it.

Maybe just doing something makes it feel like I have some control in the process.

</comment><comment><USER41> I've found through personal experience that diet and general health are most important for teeth. I used to get a cavity a year. Once I cut sugar out 100%, reduced carbs, and started eating healthy, I've had no cavities for 10 years. I don't even use a fluoride toothpaste, and sometimes forget to brush. The dentist always compliments me on my teeth.

</comment><comment><USER42> I met some dentists the other day that waterpicks may be doing more harm to gum density, while still helping get food particles out to avoid plaque building (which itself will do harm to gum density and cause other forms of decay)

yeah well its not like my non-existent flossing habits will supplant my waterpick half-solution. But I do wonder the support for any of this wisdom.

<comment><USER27> When I first discovered Waterpiks a year ago, I was extremely frustrated at the fact that all dentists hate it, and that there were very few studies on it. The universal belief, found all over the Internet, is that Waterpik is good for removing food particles, but is ineffective at removing the film, which regular floss does.

This _really_ should not be hard to validate.

The only study I could find showing this was done in the late 70's. Waterpiks have changed a lot since then. And you'll find _plenty_ of studies showing how effective Waterpiks are at removing that film. All these papers were funded by Waterpik.

Why are dentists insisting Waterpiks are bad when there is no independent study comparing modern Waterpiks with regular floss? And why doesn't anyone do the damn study?

<comment><USER43> My dentist and his team of hygienists are big fans of waterpiks, but not as a substitution to anything. You would still brush and floss (with string) as usual.

A waterpik used incorrectly may cause gum problems, so maybe that's why dentists don't like them across the board. If you put the thing on the highest setting and aim it so it pushes your gums up that may cause damage.

But if you keep it at a low / medium setting (a lot of waterpiks go from 1 to 10 in terms of pressure) and aim the water straight at your teeth and trace your gums then you should be good (there's videos showing how to do it). Not only does it remove all sorts of food particles, but it also stimulates your gums.

<comment><USER27> >My dentist and his team of hygienists are big fans of waterpiks, but not as a substitution to anything. You would still brush and floss (with string) as usual.

Same as mine. Well, sort of. They never recommend Waterpiks, but they all say "Cool! You use a Waterpik! I hope you're still flossing with string, though".

>A waterpik used incorrectly may cause gum problem

Evidence?

Also, are there incorrect ways of using string floss that can cause dental problems?

>If you put the thing on the highest setting and aim it so it pushes your gums up that may cause damage.

"May" is not good enough. What is the evidence? There are plenty of people who use it at the full setting. It's not hard to study the topic. Of course, Waterpik muddles the issue because the highest setting differs from product to product - but when they publish their papers they specify a precise pressure, which is easy to measure. The other reason I ask: Their papers showing that Waterpiks are as good at removing film than string floss use fairly high settings.

>But if you keep it at a low / medium setting (a lot of waterpiks go from 1 to 10 at 0.5 intervals in terms of pressure) and aim the water straight at your teeth and trace your gums then you should be good (there's videos showing how to do it). Not only does it remove all sorts of food particles, but it also stimulates your gums.

If I do this, can you explain why I still need to use string floss? Do you have any studies showing that string floss is more effective than Waterpik when a Waterpik is used properly?

I appreciate your willing to share the information you have heard/read, and please don't take this as an attack on you, but your comment is a classic example of what I'm complaining about. Lots of claims, but not pointing to a concrete study.

<comment><USER43> > Evidence?

None, other than asking my hygienist which setting I should personally use, and she told me don't go above 5. I trust her judgment so I left it at that.

Also one of the waterpik tips (mine came with like 6 different tips) literally has a warning label that says "CAUTITION: Only use this tip on the lowest setting". It's a much sharper tip and for fun I put the waterpik on 10 with that tip and aimed it at my sink. The stream looked so powerful I'm surprised it didn't cut the Earth in half. I can't say for sure what would happen if I aimed that at my gums but I'm not trying.

> Also, are there incorrect ways of using string floss that can cause dental > problems?

Yes absolutely. If you jam the floss into your gums as hard as you can sure I'm sure you'll be able to do damage.

> "May" is not good enough. What is the evidence? There are plenty of people > who use it at the full setting.

I think it's because everyone is different. I know people who are 70+ and brush their teeth once a day, never floss, haven't visited a dentist in 20+ years and have little to no cavities and very little plaque build up. That's with smoking too.

> If I do this, can you explain why I still need to use string floss?

From personal experience the waterpik I have on setting 5 with the standard tip has a much different feel to it than string floss. String floss feels like it cleans the side edges of my teeth better where as the waterpik seems better for dislodging things that I have trouble getting out even with string floss.

> Do you have any studies showing that string floss is more effective than > Waterpik when a Waterpik is used properly?

No, I'm not a medical doctor or dentist. I'm just a dude who brushes their teeth.

<comment><USER27> >> Do you have any studies showing that string floss is more effective than Waterpik when a Waterpik is used properly?

>No, I'm not a medical doctor or dentist. I'm just a dude who brushes their teeth.

I hope you realize that the whole discussion, and submission, is about the lack of scientific evidence to back these claims. Everyone is welcome to do whatever makes them feel better, but medical professionals should not give guidance that is not based on much evidence. Unfortunately, the dentists do not appear to have any more information than you do. Some have literally told me "Oh, we were just taught that in dental school" (regarding Waterpiks).

<comment><USER43> I just go by the results I see with my own eyes.

I see food particles that come out of my mouth after using a waterpik (even after string flossing and brushing). Normally I waterpik first but during the testing phase I did it last because I was skeptical on what it would actually do for me.

None of the staff at the place I goto say they learned it in dental school or hinted at doing it for the sake of doing it. They've been in practice for 20+ years and have seen a lot of patients. I'm guessing they have a large enough sample size to come up with something. In my opinion experience is often a good deciding factor when you have nothing else to work with.

</comment></comment></comment></comment></comment></comment></comment><comment><USER44> When I switched to a low/no carb diet my gums were much less inflamed and stopped experiencing bleeding in my gums (w/ regular flossing). I also stopped getting that "filmy" feeling in my mouth when I'd occasionally sleep/take a nap before brushing after a carb-heavy meal.

</comment><comment><USER45> It's mostly genetic. George Washington took fastidious care of his teeth yet they still all fell out anyway

</comment><comment><USER46> How come no one has mentioned that image?

That QUIVERING image?

That SWAYING image?

That WOBBLING image?

I cannot accept we now live in a world where such things go without saying.

<comment><USER47> These quirky, looping 3d renders have become fashionable in the illustration world.

</comment></comment><comment><USER48> "To recap, there's good evidence that brushing twice a day with fluoride toothpaste is a good idea, especially with a powered toothbrush. For children, there's good evidence that the use of fluoride varnish or sealants can be a powerful tool to prevent cavities. The rest? It's debatable."

</comment><comment><USER49> I have read that one of the reasons for the lack of evidence is that it is really hard to run randomized the trials for these things. Getting a cohort to brush or floss exactly according to instructions fof a long period of time can be challenging.

</comment><comment><USER50> I have never seen so many ads for tooth-related things on a single web page.

</comment><comment><USER9> Dentist here, 35yo, ask me anything.

<comment><USER22> Why the huge variation in interventions for the same inputs?

If the same software was giving different outputs for the same inputs in 2 different locations, everyone here would see that as a concern to be addressed.

<comment><USER9> A software analogy would be: if a client asks for a simple website with a shopping cart and a newsletter, and you ask 10 programmers, you're almost guaranteed to get 10 different platforms (different CMS, different language like PHP vs Ruby vs .net)

It's kind of the same thing with dentists: a good surgeon will tend to lean towards surgery, and there are usually at least 2-3 different ways of solving a particular problem

</comment></comment></comment><comment><USER51> At least with flossing, regardless of whether there are double-blinded controlled studies for it, it makes my mouth feel much cleaner when I do it, I can see a lot of plaque coming out when I floss, and there certainly doesn't seem to be any evidence against it.

With twice yearly dental X-rays, though, even though the doses are really small, all X-rays carry a risk of cancer, so it seems close to malpractice to request these X-rays without evidence to back it up. Try refusing X-rays at your dentist's office because you've done your own research, though, and they look at you with the "Oh I bet you don't vaccinate your kids either" look.

<comment><USER52> [Please check my numbers.]

The Banana Equivalent Dose (BED) of a mouth xray is apparently 15 for 2 xrays.

Personally I hate bananas (well, just the smell, taste, look, and texture).

Aeroplane flights (4 hrs of flying is about 2 xrays) might be a greater exposure source for people who travel a lot.

<comment><USER53> Banana equivalent doses assume that the radiation is distributed over the body. This is true for backscatter and other nonspecific radiation. It is not true for collimated radiation such as an x-ray. One explanation for "cell phone cancer" is that people who have annual dental radiographs have develop neuromas which are then (probably incorrectly) blamed on cell phones.

[https://www.ncbi.nlm.nih.gov/pubmed/23211211](https://www.ncbi.nlm.nih.gov/pubmed/23211211)</comment></comment></comment>


Spritestack – 3D pixelart editor based on sprite stacking technique - <AUTHOR> https://spritestack.io/ <comment><USER2> For anyone trying to understand this better, jump to the Help introduction:

[https://spritestack.io/editor/help/#introduction](https://spritestack.io/editor/help/#introduction)

It helps at least a little.

But unfortunately this is yet another site where the home page doesn't seem to give much context if you're not already part of whatever community it is. (What's sprite stacking? How is it different for a voxel editor? What need does this site meet that hasn't been met by other things?)

<comment><USER3> Thanks! This is exactly a feedback you will not hear from your niche that's already familiar with the subject. I will improve the landing page.

<comment><USER4> Any plans to open-source this? The open-source game development community desperately needs better tools :)

<comment><USER5> is there not enough tools? what do you miss?

<comment><USER4> As far as I know, the available open-source tools that are suitable for producing pixel art, are strictly flat-2D-only.

Not that you can't do 3D pixel art with them, but they certainly won't help you get there.

Edit: I just realized that maybe your question is broader than just pixel art. Open-source game development in general is a very underserved field; in terms of integrated game development environments, the best option I know of is Godot, and that's still miles behind a tool like Unity in terms of capabilities.

Audio production tools aren't great either, none of them integrate particularly well with the few game development tools that do exist. Good texture generators are difficult to come by; I believe Blender does have some functionality to this end, but it's not very accessible.

In terms of 3D modelling, Blender is _decent_ , but suffers from bad UX (although that's being increasingly fixed, so that's great!).

I'm not aware of any production-ready general-purpose release/infrastructure tooling existing that's equivalent to something like Steam Workshop.

In short... there are basically almost no good, accessible open-source tools for game development, no matter what aspect of the process you look at.

<comment><USER6> > As far as I know, the available open-source tools that are suitable for > producing pixel art, are strictly flat-2D-only.

There are plenty of voxel editors out there:

[https://ephtracy.github.io/](https://ephtracy.github.io/)

I'm not sure how "stacked sprites" differ from voxels, since this appears to be the same technique Westwood used in it's voxel engine; but voxels are the traditional "3d" pixel art.

<comment><USER4> That voxel editor isn't open-source either, though.

</comment></comment></comment></comment></comment></comment></comment><comment><USER7> Hopping into the editor and throwing down a couple pixels makes sense, but once I get to the "extrude" part to make it 3D, I don't understand the controls. It's not intuitive at first play.

I would suggest having the demo editor load a familiar shape, perhaps a house or a boat, to allow me to modify the object which is already in 3D space. That might help me understand the controls better (unsure).

<comment><USER3> Hello there. Thank you for sharing the first experience. I will put example models in welcome screen. There are also a few very short tutorial videos on the help screen. [https://spritestack.io/editor/help/#the- basics](https://spritestack.io/editor/help/#the-basics)

</comment></comment><comment><USER8> This is cool... accessibility is rather limited though. Appears the only way to freely rotate is with a middle mouse button my laptop doesn't have.

<comment><USER9> Look out, you may get replies similar to what I got (another app) when I asked what mobile users are going to do ... "They can play something else", "what about apple watch users", "internet connected toaster" ...

Ah, HN. Why ye do not let me delete my account.

</comment></comment><comment><USER10> This is made by Przemysław Sikorski (Rezoner), pretty famous IO indie game developer (wilds.io, wanderers.io etc) with a unique art style that's reflected in this tool.

</comment><comment><USER11> I learned about this technique from 2kliksphilip [1] early last year. I've always wanted to use this technique in a game, so I'm excited that there is a tool for it!

[1]: [https://www.youtube.com/watch?v=kjFlIxGzABY](https://www.youtube.com/watch?v=kjFlIxGzABY)

</comment><comment><USER12> How is this different from any other voxel editor?

It appears to just be a stack of 1 pixel high sprites you draw one at a time, like a 3D printer might extrude.

...I mean, fair enough, but don't invent a whole new word for a concept that already exists unless it's actually different?

<comment><AUTHOR> In a voxel editor you edit a 3D world using the smallest unit as cubes/spheres/etc. in 3D space. This is a 2D pixel editor with "stacks" of sprites.

<comment><USER13> Isn't the stack then just the third dimension of the original two dimensions?

<comment><USER14> It is, e.g. I think tools like MagicaVoxel can construct a voxel object based on a stack of sprites, as you describe.

However, not every engine supports 3d models / voxels, so sprite stacking is commonly used in combination with engines that only support 2d, by simply drawing each layer on top of the previous one but one pixel higher on the y axis.

</comment></comment></comment></comment><comment><USER15> Note, stacking pixels is exactly how most volume rendering works.

Source: was an expert in rendering CT and MR data.

</comment><comment><USER16> This is really cool. How can I rotate the figure in order to draw on the back?

<comment><USER8> There's some hot keys but you need a middle mouse button: [https://spritestack.io/editor/help/#hotkeys](https://spritestack.io/editor/help/#hotkeys)

</comment></comment><comment><USER17> Is there going to be an editor for composing these into a larger map?

<comment><USER3> Yes although for now my priority is to find a proper way to implement animations.

</comment></comment><comment><USER18> Very nice work. I really like it.

The scroll controls are very difficult to use on OSX with a track pad. It scrolls 3 or 4 levels at once. And I wish it had undo.

</comment><comment><USER19> Neat tool! Remembered the good old days where I used to make fake 3D in Adobe Flash using this very technique :)

</comment><comment><USER20> This is cool. Would love to see it as a downloadable standalone app!

<comment><USER3> I am working on that.

</comment></comment><comment><USER21> I am missing what formats it supports for exporting.

<comment><USER5> It exports turntable animation gifs and spritesheets in png</comment></comment>


Google has several million lines of Go - <AUTHOR> https://groups.google.com/forum/#!msg/golang-codereviews/DrGaD8OdQqM/Er1HfmsI3joJ

<comment><USER2> I find it doubtful that's all developed internally at Google; it's plausible that they pull in a lot of third-party code to make things easy on themselves.

See, e.g., [https://github.com/golang/go/issues/1605](https://github.com/golang/go/issues/1605)</comment>


Bag of Tricks for Efficient Text Classification - <AUTHOR> https://research.facebook.com/publications/bag-of-tricks-for-efficient-text-classification/ <comment><USER2> Link to source code: [https://github.com/facebookresearch/fastText](https://github.com/facebookresearch/fastText)

The big result here is the 15,000x speedup compared to a neural network, and which increases as the size of the dataset increases. But this doesn't mean neural networks are worthless. From the paper:

 _Although deep neural networks have in theory much higher representational power than shallow models, it is not clear if simple text classification problems such as sentiment analysis are the right ones to evaluate them._

</comment><comment><USER3> That FB hand-off page has an annoying auto refresh with NoScript enabled.

So, here's the PDF it points to. I guess I'll change it from linking the PDF document to a link to its abstract page, while I'm at it.

[http://arxiv.org/abs/1607.01759v3](http://arxiv.org/abs/1607.01759v3)

</comment><comment><USER4> Is this unsupervised classification? How good are the practical results?

</comment><comment><USER5> this is great, just what i needed for a project at work.

thanks for sharing this link!!</comment>


Mongo DB is web scale - <AUTHOR> http://www.xtranormal.com/watch/6995033/ <comment><USER2> To the good folks at 10Gen, Antirez, the Cassandra project, LinkedIn, Google, Amazon, and everyone working to advance the state of datastores available for increasingly specific applications, your work is undeniably important. The team I work with has been evaluating a handful of emerging datastores for some applications and are making plans to migrate a few types of data in some of our systems from one to another. Thank God that we have choice beyond a standard RDBMS and BDB.

To the armies of bloggers parroting slogan after slogan, ricing benchmarks so far removed from real-world applications as to place themselves somewhere on the spectrum between meaningless and malicious in the name of pageviews, well, that's not helping anyone.

It's great to see people get excited about new technologies. But if tech/startup culture is one that embraces and celebrates the fail, then we damn well better also talk about the different areas where many different datastores are not appropriate choices, and where some of them downright break, risking extensive downtime or corruption, require unreasonable amounts memory for indexes, or multiple machines to provide for durability, or return inconsistent "postmodern" results, or what have you -- _without_ it being understood as a personal attack on any one individual, company, or sector.

The productivity of this video is debatable, sure. But perhaps we can appreciate that it parodies the "magic scaling sauce" image that the "tech press" (face it, we're it) has given surprisingly young but maturing technologies. There's no magic sauce, no drop-in answer to "web scale," and certainly nothing fraught with difficulty. It's data. If you have a ton of it and it's valuable, it's worth mountains of expensive programmer time and effort to ensure its integrity, accessibility, and utility based on the storage and query requirements of an application.

<comment><USER3> Totally agree, as i am a beginner programmer, i am totally confused which database to use and when, particularly when. I have read up on so many, so many blog posts that contradict each other, i have looked into coudb, cassandra, mysql, neo4j, hbase, persevere and a few more. I have just decided to learn each one well and judge as my knowledge grows, so i have started with mysql and couchdb.

<comment><USER4> You should try a RBDMS too :P

<comment><USER5> There aren't any relational databases doing any thing useful, only non relational databases, like those based on SQL.

<comment><USER6> To clarify this comment a bit: The conventional RDBMSs people refer to as relational databases (Oracle, Postgres, MySQL, SQLite, etc.) shoot for compatibility with the SQL standard, which diverges from the relational model. For example, you can have duplicate rows in a table, which doesn't make any sense in the (set-based) relational model. SQL is not "purely" relational.

If you read Chris Date's books (I recommend starting with _An Introduction to Database Systems_), he really hammers this point.

There are people who hate SQL because it's too relational, and there are people who hate SQL because it's _not relational enough_.

</comment></comment></comment></comment></comment><comment><USER7> These videos are certainly funny, particularly the iPhone vs HTC one that was popular a few months ago. But as cscotta pointed out there's an interesting trend of picking certain flaws in particular databases and highlighting them without telling the whole story.

Anyone watching this might believe that MongoDB has a major flaw where data isn't written immediately and you have no idea if it has successfully been stored to disk. Whilst it's true that inserts are not immediately written by default, you can a) change the startup config to set the delay time b) force a write of all pending changes from the command line c) force the write from your call to the insert/update/remove/etc method in all the libraries and most importantly, d) request the library method wait and return the response from MongoDB so you can determine if the write was successful or not.

This means you have complete control over when you need fast inserts at the expense of potential data loss, or when you need to be certain the data has been written.

<comment><USER8> While you're correct, I don't believe the point was that you had no control over it. The point was that their benchmarks came from using delayed-write setting and compared it against databases that ARE writing to disk. He's saying that mongo is cheating the benchmark by doing work after the timer has stopped.

<comment><USER9> Maybe cheating is ok. Sure, there is a reason why it's faster. Maybe the guarantee of the write to disk is not as necessary as some people would believe.

It's certainly not the same as writing to /dev/null.

Maybe the developer can have other ways of guaranteeing consistency.

</comment></comment></comment><comment><USER10> Ironic that transactions and guaranteed data integrity as performance tradeoffs are now being used as arguments _for_ MySQL and _against_ those pesky new up-and-coming open source databases.

<comment><USER11> Funny: yes. Meaningful: no. The tradeoffs between MySQL and memory-backed k-v stores are in a different league than the old tradeoffs between MySQL, Postgres, and Oracle.

<comment><USER12> I wouldn't call it a different league.

MySQL had _severe_ data consistency issues before InnoDB came around and even today, on InnoDB, there is a variety of situations that will cause silent data truncation or silent data loss.

</comment></comment></comment><comment><USER13> tl;dw: 99% of web applications will never need to be "web scale," so quit worrying and just use an RDBMS.

<comment><USER14> 99% of web applications will never need relations, so just go the easy route and don't worry about a relational schema for your data.

<comment><USER15> Uhh, in the context of an RDBMS a "relation" doesn't mean a "relationship" in the sense of a foreign key, it means a relational algebra relation, saying most applications will never need relations is like saying most applications don't use data.

<comment><USER16> Oh Codd!

<comment><USER17> I'm laughing badly thanks to this comment :D

</comment></comment></comment></comment></comment><comment><USER18> This is hilarious:

"Why not write to /dev/null? It's fast as hell"

"Does /dev/null support sharding?"

<comment><USER19> I choked on that one too, but mainly because it echoes the kind of thing pseudo knowledgeable non-tech folk say in real life. At least in my real life.

<comment><USER18> Yeah right. And /dev/null jokes are as old as Unix and always good for a laugh.

</comment></comment></comment><comment><USER20> Hilarious video...but it reminds me of the painful fact that I know very little about databases so choosing between SQL and noSQL for my web app just seems arbitrary for me. I wish there were some simpler explanations out there.

<comment><USER21> First learn SQL and the relational paradigm.

SQL represents 40 years of experience designing general data stores that work for the widest set of applications. SQL databases solve many very hard problems which you are probably not aware of.

If you jump into NoSQL first you will be reimplementing SQL features in your application code, and doing a shitty job of it because you have experience with data stores that actually solve these problems well.

The reason for the existence of so many NoSQL databases is the rise of web applications and the need to scale massively. However the majority of apps will never need to scale beyond a single well-tuned database server anyway. By the time they do you will have hard problems to solve regardless of what data store you used. The advantage of SQL is that it's a fantastic hedge on the evolution of your data usage patterns because it is designed to support ad-hoc queries well, and the schema prevents bad application code from thrusting your data into chaos at the first occurrence of a small bug.

Realistically if you knew you had to build an app for 5 million daily users, and you knew exactly what it was going to do, then an SQL database very well might be the wrong choice. But in the real world you have a long road ahead before you hit that scale, and you'll have real data to determine what kind of alternate data stores can best handle your load. Personally I'm a _huge_ fan of redis, and its ability to scrape bottlenecks off a MySQL database in a piecemeal fashion.

<comment><USER22> NoSQL isn't just about scale. Sometimes, modeling data relationally is a real bitch, and a document store makes more sense.

<comment><USER20> Yeah, the reason I was thinking of using mongo is because I have to write a simple posting app (i.e. allow for blog or twitter style posts with tags) so defining a relational schema seems like overkill to me. But I can't be sure.

To the parent: thanks for the edifying comment. I do have some experience with SQL and relational DBs, but was thinking of using noSQL for some projects. Your point to thoroughly learn the relational model is well taken.

<comment><USER23> Even here, you might be surprised by how limited some NoSQL stores are. E.g., if you have a requirement like "find the first 20 blog posts written by X after this date."

</comment></comment></comment></comment></comment><comment><USER24> I'm currently using mongodb for a new project at work and the biggest surprise for me is that there is no elegant solution for doing the SQL equivalent of COUNT(DISTINCT field). Count exists, distinct exists to return the set to you, but the combination isn't there.

The only solutions i have found are to check the length of the distinct query, which takes too long for a large result set, or to write a map reduce function which takes longer than I'd like and is a large amount of code for functionality that should already exist in the db.

</comment><comment><USER25> I hate the fact that I want to upmod this submission.

(I withstood the urge, you probably should too)

</comment><comment><USER26> As usual, use the technology that fits your needs.

If you want a lot of speed and can tolerate the possible (even if unlikely) data loss, use NoSQL.

If your business requires that your data is guaranteed and always up-to-date at any moment, then use RDBMS.

<comment><USER27> Durability is a generic topic, not only the problem of NoSQL.

<comment><USER28> Some of the NoSQL solutions take durability very seriously, some put it second to looking good in benchmarks. NoSQL is about choice, and the most durable of the NoSQL stores are more durable than many of the venerable relational databases.

For instances, what CouchDB treated as a major bug, is the accepted behavior of many relational databases. (Eg, data isn't lost, but must be recovered via a long-running process should there be an uncontrolled shtudown.)

Riak and Cassandra also have modes that treat durability as paramount, and give you better assurances than MySQL or even commercial RDBMS products.

</comment></comment></comment><comment><USER29> How ironic – an article about "web scale" and a "503 Service Unavailable No server is available to handle this request." error when I try to open the link :) (I'm certain that Mongo DB is not the one to blame though)

</comment><comment><USER30> Is this some kind of generative cartoon? Plug in a dialogue in text, and it generates too teddy bears speaking the dialogue?

</comment><comment><USER16> Funny stuff. How did you make that and how do you synchronize, the mouth movement with the dialogue?

<comment><USER31> <http://www.xtranormal.com/>

"If you can type, you can make movies."</comment></comment>


Teaching my 10-year-old daughter to program - <AUTHOR> https://unsupervisedmethods.com/teaching-my-10-year-old-daughter-to-program-9e2d7963938 <comment><USER2> This is really cool. I tried introducing my 7 year old daughter to programming over the weekend and, while she was interested in being able to make things, I had a hard time keeping her attention (which is probably a reflection more on my lack of teaching ability). Maybe I'll give her a few more years and try again.

</comment><comment><USER3> I have an old Thinkpad x61 lying around. What would be the best way to introduce a 7-year-old to programming? I plan to be heavily involved of course. Can anybody recommend Linux distro that is responsive and programming enviroment? From the looks of it, Scratch requires Flash...

<comment><USER4> > From the looks of it, Scratch requires Flash...

Snap may be a good flash-free alternative: [http://snap.berkeley.edu](http://snap.berkeley.edu)

<comment><USER3> Thanks!</comment></comment></comment>