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Why HN was down

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Re: Why HN was down

#141

Post by mr_luc »

lmm wrote: post #117
chernevik wrote: post #95

Earlier quoted context omitted.

I am but an egg, I have two questions. One, if the data were held in a database, should a change like this be captured in the database logs? I am seeing more and more situations where I want these, I notice that they are by default turned off for mysql and wonder if this reflects a de facto judgment that logging slows performance more than is usually worthwhile. Two, if the data were kept in a database, wouldn't some…

Databases, at least the SQL kind, really aren't good at dealing with hierarchical data, and I don't know how you'd even begin to express that kind of constraint. I don't think a traditional database is the answer here. (If it were me, once I'd done it more than twice I'd write a "move thread" admin tool in the UI, and after I screwed it up like this I'd have a place to add such a check to).

If you were using some kind of representation for Nested Sets -- left-to-right depth-first numbering, or a human-readable id.id.id chain -- then it's really easy to write a constraint for that: parent left myright, or dotted_id.split('.').filter{|first, rest| return false if rest.contains first} (yeah, yeah, that second pseudocode would be unrealistically PITA for some DBs).

More generally:

I'm not a big SQL wonk anymore, but I find a lot of people have the intuition that relational databases are ill-suited for trees.

An intuition that is much closer to the truth is that almost all databases can handle trees pretty well, because there's still an unambiguous concept of ordering and containment, and you can usually arrange things so as to do range/ancestor/inclusion queries efficiently.

It's graphs with loops/without unambiguous concept of ordering/containment that are really hard.

Re: Why HN was down

#142

Post by Aardwolf »

mhurron wrote: post #132
furyofantares wrote: post #46

Earlier quoted context omitted.

There is a line from Futurama that perfectly applies ton a lot of debugging. Farnsworth: My God, is it really possible? Fry: It must be possible, it's happening. Fry: By the way, what's happening?

Extremely appropriate as Fry is his own grandfather and the site software can't handle that relationship.

That's one of my favorite lines from Futurama, 'Ohh, a lesson in not changing history from Mr. "I'm My Own Grandfather"!'

Re: Why HN was down

#143

Post by darkarmani »

wpietri wrote: post #113
luser001 wrote: post #89

Earlier quoted context omitted.

> I eventually realised that typing sudo every time he touched a box was no defence against doing the wrong thing. IIRC, sudo logs all commands to syslog. Which might come in handy. Yes, root commands will be logged by bash to .bash_history, but there are limits of # of commands lots, what happens if you are logged in multiple times into same account etc. Anyway, that's why I like sudo.

Beyond the logging, which I love, I use it for the differentiation of states. I'm just a little more attentive when I type "sudo" before something. At work, a relatively young engineer accidentally typed a command meant for a test database server into a production window. There was a big rush to restore from backups, and there was a small amount of data loss. One thing that came out of the retrospective, requested by…

Another cheap solution is colorizing the prompt red for dangerous consoles and green for dev machines. This makes it very easy to notice when you selected the wrong terminal.

Re: Why HN was down

#144

Post by alex_c »

lucb1e wrote: post #29
sgt wrote: post #22

Earlier quoted context omitted.

I think I get what you're hinting at. Ok, so this is Hacker News , it's in the name, and most of us are aware that HN is also a research/hobby project. It's not made to be an rock-stable enterprise system doing bank transactions or what not, so I think what pg did was prefectly excusable. People make mistakes. Nobody will die without HN for a day or two, and it won't affect the site's popularity one bit.

No that's right, but I worry about apache2 being down for potentially one or two users or bots that visit/crawl my website during a one-minute reboot. Meanwhile the big boys are down for 16 hours because they do things that any other person would have gotten a decent scolding for. Just look at the points per hour this thread is getting, if I had posted this about my website on my website people would have said I was…

>Just look at the points per hour this thread is getting, if I had posted this about my website on my website people would have said I was stupid.

For what it's worth, I upvoted this thread specifically because we've all done something this stupid (or worse) :)

Re: Why HN was down

#145

Post by amorphid »

DanielBMarkham wrote: post #7

Amazing that such a large percentage of debugging involves determining exactly what you are debugging. The definition of the problem, many times, is the solution. Might be a good time to mention Rubber Duck Debuggging. http://en.wikipedia.org/wiki/Rubber_duck_debugging

This. Even with the best test coverage in the world, you still bump into edge cases that you couldn't have predicted. As a former QA Engineer, I used to say there's still room for QA in a test driven environment. Now I say there's no replacement for a sharp mind with enough knowledge, curiosity, and good judgement.

Re: Why HN was down

#146

Post by Spoom »

wpietri wrote: post #113
luser001 wrote: post #89

Earlier quoted context omitted.

> I eventually realised that typing sudo every time he touched a box was no defence against doing the wrong thing. IIRC, sudo logs all commands to syslog. Which might come in handy. Yes, root commands will be logged by bash to .bash_history, but there are limits of # of commands lots, what happens if you are logged in multiple times into same account etc. Anyway, that's why I like sudo.

Beyond the logging, which I love, I use it for the differentiation of states. I'm just a little more attentive when I type "sudo" before something. At work, a relatively young engineer accidentally typed a command meant for a test database server into a production window. There was a big rush to restore from backups, and there was a small amount of data loss. One thing that came out of the retrospective, requested by…

I use a different background color for the terminal in question; in this case, I use a dark red to signify a production system, and a dark blue to signify a development system. I find it quite useful. You can do this through Xterm profiles (Edit -> Profiles, Terminal -> Change Profile) in Linux and OS X, and I'm sure there's a way to do it in Windows / PuTTY.

Re: Why HN was down

#147

Post by ibudiallo »

When hacker news is down, I finally lifted my head and realized that there is life beyond the screen on my phone.

Now that it's back. I realized that it's finally time to create an account :)

Re: Why HN was down

#148

Post by robotic »

z-e-r-o wrote: post #64
DanielBMarkham wrote: post #7

Amazing that such a large percentage of debugging involves determining exactly what you are debugging. The definition of the problem, many times, is the solution. Might be a good time to mention Rubber Duck Debuggging. http://en.wikipedia.org/wiki/Rubber_duck_debugging

For me, this should be called stackoverflow debugging. I genuinely solved a lot of my problems by trying to write a _good_ question on SO about my problem. The problem seems really difficult when I try to ask it in one sentence, just out of my head. However once I try to describe the background, what I'm trying to achieve, what I'm using, when does the problem happen, simplified down to sub-cases, usually by the time…

I've made several posts to SO and then realize the answer moments later. I usually just self-answer.

Re: Why HN was down

#149

Post by ztravis »

short_circut wrote: post #119
banachtarski wrote: post #97

Earlier quoted context omitted.

Is this the forward time machine episode?? I love futurama more than any man could love any tv show.

I feel like your name reflects that fact. It seems to be a reference to the Banach-Tarski duplashrinker

More likely it is a reference to its eponym, the Banach-Tarski paradox.

Re: Why HN was down

#150

Post by benatkin »

badgar wrote: post #131
oh_sigh wrote: post #94

Earlier quoted context omitted.

> pg just runs this site out of the good of his heart Hilarious. I would have believed you if you appended "and his wallet"

One core. One HD. Bandwidth is trivial with no images. How much do you think this site costs to run?

How much do you think the time of YC partners is worth?
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