WEBVTT
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Language: en

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The “onosecond” is the second after you
make a terrible mistake.

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The second when you realise
what you just did

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and that there’s nothing
you can do about it,

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the second when all the now-inevitable consequences
flash through your mind.

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It is the second after you send a text message
to the wrong person,

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after you delete the wrong file,

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after you spill the secret that you thought
they already knew.

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The “onosecond” is that stomach-dropping,

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breath-stopping moment when all you can do
is say “oh, no”.

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This is the story of the
worst typo I ever made.

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I was maybe 18 or 19,

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in charge of converting an old web site to
a new and faster platform.

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A half-dozen volunteers had spent days transferring
all the articles over,

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copying them from the old site, updating them,

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and then saving them in their new place.

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It had been a lot of effort,
but everything was pretty much sorted now.

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There was one thing I needed to do:

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a search-and-replace across all those pages
of content.

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And I was wise to the mistake
that people usually make there:

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it’s called the clbuttic mistake,

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where someone wants to censor the word “ass”

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and the search-and-replace gets a little bit
more enthusiastic than they thought it would.

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This problem: much simpler.

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the volunteers had just written the articles
in plain text,

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and I needed to add some simple formatting.

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Anywhere there were three dashes,

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I just needed to replace that with a tag for a
horizontal line.

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There’s no way that search-and-replace could
go wrong. Right?

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This was the mid-2000s, so the site wasn’t
anything fancy:

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it was a standard SQL database.

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SQL is Structured Query Language:

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it’s an international standard for sending
commands to basic databases,

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and it’s still used today.

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I hadn’t bothered to set up any tools to
help me along with it.

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I was the only one working on the site,
so I was just using the command line.

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Which meant that with a single instruction,

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I could change every record in the live database,
every single page, at once. 

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Working on a live database is a bit like working
with a live mains electricity cable.

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Sure, it’s physically possible,
it’d make things quicker,

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and there are very, very rare occasions where
it might actually be the only option.

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But in general, if you’re working on
mains electricity, you turn the power off first.

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And if you’re working on a database,
you don’t work on the live version.

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I was working on the live version.

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Because I was young, and careless,
and besides, the difficult part was over, right?

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After all that conversion work,
and it was a lot of work,

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I just had to issue a few final commands.

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Update the list of articles,
and set the content field to itself,

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just with the dashes replaced with the tag.

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So I typed in the command, hit enter, and...

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Oh, no.

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Reading 5,000 pages, doing a search and replace
across all that text,

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and putting it all back into the database,

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should have taken a bit more than
one-hundredth of a second.

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I didn’t know what had happened yet,
but I knew something had gone wrong.

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Hold that thought.

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In the history of computer science,

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the undo command was invented independently
several times.

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In the 1970s, programmers at the Xerox PARC
research centre

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were the first to assign it to that easy-to-reach
keyboard shortcut of Ctrl-Z. Or "Zed".

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Their work there later, uh, inspired many
features that ended up in Apple computers.

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And most of the time undo is linear:

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there is an ordered list of commands that
we’ve issued,

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and we can undo -- or redo -- our way
back and forth through that list.

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The most basic way to implement that is to
store the exact state of the document after

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every single command, or even after each
keystroke, and just roll back to that.

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It’s memory-intensive, and there are a lot
of ways to optimise it,

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but that’ll work.

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It’s also an easy mental model for users
to deal with:

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you just step back and forth in time.

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But if you go back in time, and then make
a small change,

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you won’t be able to redo your way
back forwards.

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Like a time traveller in science fiction,
you’ve broken the future.

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So if you do want to recover something you
deleted and bring it forward in time with you,

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you’ll have to be really careful not to
accidentally hit the wrong key 

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while you’re back there.

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Now, plenty of folks have tried to create
‘undo trees’:

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so if you do back and change history,

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it just creates a new timeline,

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and you can move around the timelines
however you want.

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There are some text editors which’ll do
that for you,

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and even visualise all the branches.

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But it’s a complicated thing to keep in
your head,

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and it’s never found mainstream appeal.

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There are source control systems that work
the same way, like Git:

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every time you save your file and ‘commit’ it,

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that copy is available forever.

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Multiple people can work on files
at the same time,

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make changes in different ‘branches’,

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and everything just gets merged
back together afterwards.

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It’s incredibly useful for any software
development project.

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But trying to do that for every keystroke,

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rather than every saved version of a file,
is a bit much.

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Saving keystrokes works in memory,
which is fast;

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saving files works on disk,
which is comparatively slow.

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Microsoft Word used to have a Fast Save feature,

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where if you’d updated a few things in the
document,

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it didn’t actually save the whole thing
all over again:

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it just appended those changes on the end,

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so you didn’t have to wait five or ten seconds
every time you hit Control-S

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to save on an old 90s computer.

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It turned out that leaving stuff in files
that users thought they’d deleted

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was a massive privacy and security risk,

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and that got turned off in 2003.

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That model: quick undo for live work in memory,

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and a slower save to disk
when you’re done with a task,

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is still used in a lot of places…
although it is slowly changing.

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If you write text in Google Docs or other
cloud-based platforms,

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then your keystrokes are constantly
saved and synchronised.

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You never actually have to hit ‘save’.

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Which means that depending on which app you’re
working in,

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you have to change your mental model of how
your work is saved.

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And sometimes you don’t want to save every
single keystroke and command.

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If you got frustrated at your boss,

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typed some… colourful comments into your
code, and then deleted them,

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they probably shouldn’t be stored forever.

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Or maybe you pasted a password or security key
or credit card number into the wrong file,

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and you definitely don’t want Derek the
intern to have access to that forevermore.

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Anyway: the point is, there are all sorts
of systems, big and small,

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designed to allow you to undo and redo.

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In MySQL, the language I was using for
that database, they had “transactions”.

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And you could type the command
START TRANSACTION.

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Any edits you made would be accepted,

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but they wouldn’t be actually, properly, definitely,
irrevocably saved until you typed COMMIT.

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If you screwed up, you typed ROLLBACK,

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and the database just forgot those commands
had ever been sent in.

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Which is great, right?
Because everyone makes typos.

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Can you spot it? 'Cos it’s really subtle.

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The database had gone into the ‘articles’ table,
and for every single article,

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it had changed the ‘content’ field.

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Those words: ‘articles’ and ‘content’,
they’re surrounded by backticks,

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that odd character to the left of the 1 on
most keyboards.

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Backticks mean
“this is the name of a table or field,

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“I’m referring to something in the database”.

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That’s all fine.
Then it looked at the “replace” command.

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And I’d told it that for each article,
it should pull the content,

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and replace the dashes with the tag.

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Everything’s in the right order there,

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I remember checking that I’d got it all
the right way round.

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Except that’s where I messed up.

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Those, right there?
They’re not backticks. They’re apostrophes.

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And apostrophes mean ‘this is a
literal string of text’. Not a name.

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So, as I had ordered, the database promptly
took the literal word “content”, c-o-n-t-e-n-t,

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looked through it for dashes, found none,
replaced nothing,

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and then put that word ‘content’
into the content field.

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For 5,000 articles.

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And I looked at the web site.
All the volunteers’ hard work.

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5,000 pages. Every single page, just replaced
with the word “content”.

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Genuinely, my pulse rate is rising a little
as I think about that.

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I was nearly physically sick.
Because I knew what was going to happen next.

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Because that typo is an entirely reasonable
mistake to make.

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There’s nothing wrong with
screwing up like that.

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Everyone makes errors like that, all the time.
And we hit Control-Z. Or we click the ‘Undo’ button.

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In Gmail, we hit ‘undo send’,

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at least for the 30 seconds before it actually
does send the message.

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And if you happen to be enough of a prat to be
 working on a live SQL database,

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you type in ROLLBACK.

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I hadn’t told it to start a transaction.

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And there are all sorts of words I could use
to describe the idea of

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working on a live database without even a
transaction as a safety net.

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Ridiculous. Asinine. Unthinking.
But the one I think is most accurate is: negligent.

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The only reason that typo was
the worst I’ve ever made

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was because of all the poor decisions
that led up to it.

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Working on a live database. Thinking I
couldn’t screw up one simple command.

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Not having any sort of backup!

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Days of work by volunteers and at no point
during that had I thought,

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you know what, maybe we should get a copy
of that somewhere else just in case?

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Like, that should have been backed up daily,
or hourly.

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The root cause of all that,

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of all the days afterwards where I had to
apologise to so many people,

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the root cause wasn’t one typo.

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It was the overconfidence and negligence

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that meant I didn’t have any way to undo
my mistakes.

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It’s the sort of lesson you only learn once.

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Programmers and anyone who works with software,
we have this magical ability to undo.

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No professional that works with physical,
real-world things has that option.

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So if you don’t have a backup of your code,
or your thesis, or the photos on your phone,

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or your database, get a backup.
Don’t put it off for the future.

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And if you do have one ready: check it works.

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Because you don’t want to have the same
feeling of: oh, no.

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If you're techie enough to make it to the
end of this video,

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then you should definitely be using
a password manager.

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Every so often you'll see a big news article
about how a company's had a security breach

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and, yeah, sometimes, that's what's happened,
but other times,

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it's just that someone's found or bought a
list of usernames and passwords

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from another security breach
at a different company,

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and is just trying all of them
to see if there are any matches.

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Reusing the same password,
or variations on it, is a bad idea.

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00:10:03.090 --> 00:10:04.890
So I recommend Dashlane as a password manager,

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00:10:04.890 --> 00:10:06.890
partly because they are sponsoring this video,

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00:10:06.890 --> 00:10:09.640
but also because I've read their security
white paper.

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And so have a lot of other people who know
more about cryptography than me.

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Being able to easily use long, complicated,
symbol-filled passwords

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that are different for every
web site and app,

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automatically synchronised across
iOS, Android, Windows, Mac and Linux,

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is incredibly useful.

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Plus they'll autofill credit card info and
personal details if you want.

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And if you're working from home right now
for some big company, then sure,

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00:10:32.570 --> 00:10:36.750
your company's IT might be working great,
but maybe you're in the person where

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you've got ten people who all need to share
an account on some other company's service.

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00:10:40.960 --> 00:10:45.390
The one person who knows the password can't
just walk over to your desk and log you in any more.

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So instead of sending that password over email,
or Slack,

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or calling someone up
and having them write it down:

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00:10:50.650 --> 00:10:54.520
Dashlane for Business lets teams of people
share passwords securely.

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00:10:54.520 --> 00:10:58.370
Go to www.dashlane.com/tomscott
to try Dashlane for free,

205
00:10:58.370 --> 00:11:01.630
and you can use my code tomscott for 10% off
Dashlane Premium,

206
00:11:01.630 --> 00:11:02.910
and to support this channel.