Huge Traffic On Wikipedia's Non-Profit Budget

miller60 writes "'As a non-profit running one of the world's busiest web destinations, Wikipedia provides an unusual case study of a high-performance site. In an era when Google and Microsoft can spend $500 million on one of their global data center projects, Wikipedia's infrastructure runs on fewer than 300 servers housed in a single data center in Tampa, Fla.' Domas Mituzas of MySQL/Sun gave a presentation Monday at the Velocity conference that provided an inside look at the technology behind Wikipedia, which he calls an 'operations underdog.'"

Comments

Impressive

[locokamil]

Given that their topic sites are generally in the top three for any search engine query, the volume of traffic they're dealing with (and the budget that they have!) is very impressive. I always thought that they had much beefier infrastructure than the article says.

Re:Impressive

[VeNoM0619]

Yes, and seeing how slashdot decided to try and slashdot them also helps...

Re:Impressive

[sm62704]

I was always impressed with how fast pages loaded, after seeing how small their operation is I'm even more impressed now!

Go to any newspaper from the NYT to any one in a smaller city (say, Springfield's State Journal-Register) and the difference in load times is HUGE. Probably has to do with all the ads served from third party servers in the newspapers, what's the use of having a humungous server with giant pipes if your readers' pages have to wait for a flash ad served from a 486 powered by gerbils?

If I link to the SJR form one of my journals it slows down! I mean, I can see if it's a front page slashdotting a little paper like that but come on, a user journal?

And Wikipedia isn't all their servers serve; iinm the uncyclopedia shares servers. Impressive, indeed.

Re:Impressive

[Bandman]

Yea, a single datacenter seems really risky, especially considering some of the shenanigans that have been going on

Re:Impressive

[Achromatic1978]

Except there's not. There's data centers in Europe and Asia, too, including one at some Yahoo facilities - at least on this note, the article (or summary) is utterly wrong. Single datacenter? No.

Re:Impressive

[Bandman]

That would make a lot more sense.

Given the sheer amount of people who access it, it seems like the perfect use for GSLB

Re:Impressive

[David Gerard]

No, actually - the Wikimedia servers serve all Wikimedia projects (all the Wikipedias, Wikimedia Commons, all the other projects), but Uncyclopedia is part of Wikia, which is a private company owned by Jimmy Wales to do wikis and isn't actually linked to the Wikimedia Foundation in any way.

Re:Impressive

[David Gerard]

Single database, though. All the databases for all the projects are in Tampa - one master for English Wikipedia and two for all the other 700+ Wikimedia projects.

(They tried running the databases for Asian languages from the Yahoo!-sponsored datacentre in Seoul for a while, but it didn't actually work much faster than it did with everything in Tampa.)

Re:Impressive

[kv9]

I was always impressed with how fast pages loaded, after seeing how small their operation is I'm even more impressed now! you can skip TFA entirely and look here for detailed info on their servers, locations, pictures, software, pretty graphs and charts. and lots more, just keep clicking.

Re:Impressive

[mcrbids]

As somebody who has been serving the Internet for a good length of time, I remember when busy web servers serving a 10 Mb stream were "ultra-high capacity" with a Pentium II 350 Mhz chip and 256 MB of RAM.

The reality is that today, if you pay any attention at all to performance and a reasonable architecture, modern commodity hardware has just utterly incredible delivery capacity. A cheap, 1U 4-core x86 with 8 GB of RAM and a couple of SCSI 10k drives can easily saturate a 1 Gb stream of static pages, or even dynamic pages if the core algo is reasonable. This server can cost about $2500 without too much trouble, and even with heavily database-driven applications, a couple of these can deliver an insane amount of traffic.

As an example, I use LAMP stack software to serve school districts. I went into one larger school with our software, and they had a half-dozen higher-end systems to serve a Filemaker Pro based application to their several hundred staff. Delays of 5 minutes or more were commonplace. Our computing cluster, consisting of four, 4-core servers with SCSI drives satisfied all their needs much faster than their existing solution, while simultaneously serving almost 100 other schools and school districts. Our software was cleaner and more efficient, and got a much bigger job done with greatly reduced resources.

LAPP (Linux/Apache/Postgres/PHP) can be damned efficient if you do it right.

So it really doesn't take much, anymore to serve a huge audience if you pay attention to systemic efficiency. That Wikipedia can do so much with just 300 systems actually seems heavy to me - I'm surprised that they need that many! I'd personally guessed something like 20-50 servers total, with dynamic pages heavily cached with static files and some kind of expiration algorithm, along with some spendy communications hardware.

I've always wondered...

[mnslinky]

It would be neat to have a deeper look at their budget to see how I can save money and boost performance at work. It's always nice having the newest/fastest systems out there, but it's rarely the reality.

Re:I've always wondered...

[Anonymous Coward]

"It would be neat to have a deeper look at their budget to see how I can save money and boost performance at work."

Since they are using LAMP, obviously they could save money by following Microsoft's "Get The Facts" advice!

Re:I've always wondered...

[midom]

I covered most of Wikipedia technology bits at my previous year MySQL Conference presentation: http://dammit.lt/uc/workbook2007.pdf (thats quite detailed report)

The power of low standards

[Itninja]

From TFA: "But losing a few seconds of changes doesn't destroy our business."

Our organizations' databases (also a non-profit) get several thousand writes per second. Losing 'a few seconds' would mean potentially hundreds of users' record changes were lost. If that happened here, it would be a huge deal. If it happened regularly, it would destroy the business.

Re:The power of low standards

[robbkidd]

Okay. So pay attention to the sentence before the one you quoted which read, "I'm not suggesting you should follow how we do it."

Re:The power of low standards

[Anonymous Coward]

Don't be too harsh -- the standards are dependent on the application. Your application, by the nature of the information and its purposes, requires a different standard of reliability than Wikipedia does. You're certainly entitled to be proud of yourself for maintaining that standard.

But don't let that turn into being derogatory about the Wikipedia operation. Wikipedia has identified the correct standard for their application, and by doing so they have successfully avoided the costs and hassle of over-engineering. To each his own...

Re:The power of low standards

[WaltBusterkeys]

Exactly. A bank requires "six nines" of performance (i.e., right 99.9999% of the time) and probably wants even better than that. Six nines works out to about 30 seconds of downtime per year.

It seems like Wikipedia is getting things right 99% of the time, or maybe even 99.9% of the time ("three nines"). That's a pretty low standard relative to how most companies do business.

Re:The power of low standards

[MinuteElectron]

Changes are never just lost, when an error does happen and the action cannot be completed then it is rejected and the user notified of this so they can try what they were doing again. You have vastly overstated the severity of such issues.

Re:The power of low standards

[Nkwe]

A bank requires "six nines" of performance (i.e., right 99.9999% of the time) and probably wants even better than that.

Banks don't require "six nines"; banks require that no data (data being money), once committed, get lost. The "nines" rating refers to the percentage of time a system is online, working, and available to its users. It does not refer to the percentage of acceptable data loss. It is acceptable for bank systems to have downtime, scheduled maintenance, or "closing periods" -- all of these eat into a "nines" rating, none of which lead to data loss.

Re:The power of low standards

[Waffle Iron]

Indeed. Some of us are old enough to remember the days of "banker's hours" and before ATMs, when banks used to make their customers deal with less than "one two" (20%) availability.

Re:The power of low standards

[astrotek]

Thats amazing considering I get an error page on bank of america around 5% of the time if I move to quickly though the site.

Re:The power of low standards

[Anonymous Coward]

Right, banks actually traditionally used such techniques as planned downtime to allow for maintenance. The "banker's hours" allowed for a large period of time, daily, where little-to-no 'data' was changing in the system and the system could be 'balanced'.

Re:The power of low standards

[AK Marc]

Screw that, I want a bank with six twos of performance. 22.2222%. Of course, any number of nines is easy to achieve. Want six nines? 9.99999% is easy.

Re:The power of low standards

[PMBjornerud]

If there's a 30-second period per year when data doesn't properly move, and that requires manual cleanup, that's acceptable. And if there is a 1-hours downtime, EVER, you just blew through the scheduled downtime for the next 120 years.

"Six nines" is meaningless. Unrealistic.

It is a promise that you cannot be hit by a single accident, fuckup, pissed-off-employee or act of god.

Re:The power of low standards

[az-saguaro]

Your reasoning may be a bit specious. If your databases get "several thousand writes per second", it sounds like this may be massive underuse of your bandwidth - i.e. your servers or databases may be able to handle hundreds of thousands or millions of writes per second. If a few seconds were lost or went down, then the incoming traffic might get cached or queued, waiting for services to come back on line. Once the connection is re-established, the write backlog might take only a few seconds or a few fractions of a second to catch up and be back to real time. Users might be unaware of the whole thing, or they would re-log and try again, and there would be no perceptible throttle or bottleneck to data logging. Any system that presses its bandwidth limits, any system that walks dangerously close to its top capacity, with no capacitances or reserves, is likely to be down quite a bit. A system such as yours, which hardly taxes its bandwidth at all (I am guessing) could certainly tolerate lost seconds. Admittedly, your system may have had problems like this in the past, and the system was upgraded to handle higher capacity. . . . Which is why Wikipedia no longer runs on just one machine. It does sound as though Wikipedia may have found a sweet spot, balancing load against reserve capacity or bandwidth, for robust up-time versus economic efficiency. I am sure that this is a topic that computer and network engineers have studied exhaustively - perhaps someone else knows?

Re:The power of low standards

[Kingrames]

Screw that, it needs to be a prime number.
or at least irrational.

Re:The power of low standards

[Qzukk]

You can achieve 100% service availability by clustering

Is that where when I run "DROP TABLE reallyimportanttable;" it drops it on all the servers at once?

Re:The power of low standards

[mpeskett]

I can promise you 6 i's of uptime.

But i^6 being -1, that's not a lot of uptime... if I ever provided you with anything it would be in excess of what I promised.

I was just thinking that

[imstanny]

Every time I Google something, Wikipedia comes near the top most of the time. Maybe that's why Google doesn't want to disclose its processing power, it may very will be a lot smaller than people assume.

Re:I was just thinking that

[imstanny]

But why would they think it was a bad thing to expose? The whole "Look what we can do with so little" angle seems appealing; efficiency is something to boast about nowadays. On one hand, you're right, efficiency is admirable. But on the other hand, if Google has insane amounts of processing power, it would likely mean much higher barriers to entry for its competitors. The threat of Google's power in processing such data could deter others from even attempting to compete with Google. After all, when Google started it was only funded with a few hundred thousand dollars.

Re:I was just thinking that

[Chris Burke]

I don't actually know anything about the total computing power Google employs, but I do know that they will purchase on the order of 1,000-10,000 processors merely to evaluate them prior to making a real purchase.

Re:I was just thinking that

[dubl-u]

But why would they think it was a bad thing to expose? The whole "Look what we can do with so little" angle seems appealing; efficiency is something to boast about nowadays. Turn it around. What does Google gain from exposing data about their internal performance?

Maybe they do well because they are amazingly CPU-efficient on a per-query basis. Maybe it's the opposite; they may be masters at lavishing CPU on every query, but know how to do that very cheaply. Most likely, it's a clever mix of the two.

Regardless, Google's engineering-fu and operations-fu are mighty, and a major competitive advantage. Releasing detailed data doesn't boost their reputation, as everybody already knows they are great. But it does give potential competitors an idea of what works well, making it easier for them to catch up with Google. As a rule, expect that any details you see from inside Google are old, boring, or vague. As Intel's Andy Grove said, "Only the paranoid survive."

Re:I was just thinking that

[kiwimate]

You know what I thought was interesting? This story (which was linked to from this /. story titled A Look At the Workings of Google's Data Centers contained the following snippets.

On the one hand, Google uses more-or-less ordinary servers. Processors, hard drives, memory--you know the drill.

and

While Google uses ordinary hardware components for its servers...

But this was immediately followed by:

it doesn't use conventional packaging. Google required Intel to create custom circuit boards.

For some reason I'd always believed they used pretty much standard components in everything.

Re:I was just thinking that

[Crazyswedishguy]

After all, when Google started it was only funded with a few hundred thousand dollars. Then again, when Google started, the Internet itself was considerably smaller, and the pages indexed by Google were much fewer. It was also slower and processing power wasn't as much of a limiting factor as your network connection.

Although the idea that Google may in fact be serving all our searches with just one server seems kind of appealing, let's not kid ourselves, they have many large data centers. They use relatively cheap, commonplace equipment, but in every data center they have guys with shopping carts (really) swapping out defective servers as they walk down the aisles. (their infrastructure and file system is really interesting, actually)
But don't forget that Google doesn't just provide search. They also provide storage-intensive services such as email (more than 6GB of storage space per account now I think) or video (youTube). One of the main reasons for having many data centers is to be able to push content (email, youTube videos, etc.) as close as possible to the end user before the user asks for it to minimize latency. User A in NY wants to watch a video, it goes much faster to send it from a data center in NY than to have to send it from CA. Serving video content or generally large amounts of data is a very capital intensive business that requires a lot of network and server infrastructure.

Easy to Increase the budget or add servers

[Subm]

How hard can it be to increase the budget or add more servers?

Just go to the Wikipedia page with those numbers and change them. You don't even need to have an account.

Re:Easy to Increase the budget or add servers

[elrous0]

In their defense, if you're going to run your entire site off a single server farm,a coastal city in Florida is the logical place to put it.

Maybe...

[nakajoe]

Datacenterknowledge.com might want to take lessons from Wikipedia as well. Slashdotted...

Note to self

[Anita Coney]

If you ever find yourself in a flamewar on Wikipedia you cannot win, bomb Tampa, Florida out of existence.

Re:Note to self

[canajin56]

That's your solution to everything.

Re:Note to self

[Ron Bennett]

Or do a hurricane dance, and let nature do its thing...

Having all their servers in Tampa, FL (of all places given hurricanes, frequent lightning, flooding, etc there) doesn't seem too smart - I would have thought, given Wikipedia's popularity, their servers would be geographically spread out in multiple locations.

Though to do that adds a level of complexity and costs that even many for-profit ventures, such as Slashdot, likely can't afford / justify; Slashdot's servers are in one place - Chicago ... to digress a bit, I notice this site's accessibility (ie. more page not found / timeouts lately) has been spotty since the servers move.

Ron

Re:Note to self

[TubeSteak]

That's your solution to everything. I did ask if you wouldn't prefer a nice game of Chess.
-WOPR

Re:Note to self

[OverlordQ]

They're not all in Tampa, they have a bunch in Netherlands and a few more in South Korea.

Re:Note to self

[Rick Genter]

an invading country which the one superpower of the world already hates?

China hates North Korea?

Re:Some thoughts

[TheLazySci-FiAuthor]

"... you need to focus on a handful highly-talented IT people rather than an army of droids."

This is so true; I've always said, "you get what you pay for."

Do you want to pay for software, or do you want to pay for people?

Only one can create the other.

Re:Some thoughts

[bsDaemon]

Which is somehow different from any other open source project how?

More importantly

[wolf12886]

I don't care how few servers they have, whats more interesting to me is that they run an ultra-high traffic site, which they aren't having trouble paying for, and do it without adds.

Off-topic, I know, but...what about /.'s hardware?

[kiwimate]

I.e. the promised follow-up to this story about moving to the new Chicago datacenter? You know, the one where Mr. Taco promised a follow-up story "in a few days" about the "ridiculously overpowered new hardware".

I was quite looking forward to that, but it never eventuated, unless I missed it. It's certainly not filed under Topics->Slashdot.

Re:Some thoughts

[morgan_greywolf]

Do you want to pay for software, or do you want to pay for people?

Only one can create the other.

Oh, gods, let's hope so!

Works great because it's not "Web 2.0"

[Animats]

Most of Wikipedia is a collection of static pages. Most users of Wikipedia are just reading the latest version of an article, to which they were taken by a non-Wikipedia search engine. So all Wikipedia has to do for them is serve a static page. No database work or page generation is required.

Older revisions of pages come from the database, as do the versions one sees during editing and previewing, the history information, and such. Those operations involve the MySQL databases. There are only about 10-20 updates per second taking place in the editing end of the system. When a page is updated, static copies are propagated out to the static page servers after a few tens of seconds.

Article editing is a check-out/check in system. When you start editing a page, you get a version token, and when you update the page, the token has to match the latest revision or you get an edit conflict. It's all standard form requests; there's no need for frantic XMLHttpRequest processing while you're working on a page.

Because there are no ads, there's no overhead associated with inserting variable ad info into the pages. No need for ad rotators, ad trackers, "beacons" or similar overhead.

Re:Works great because it's not "Web 2.0"

[Tweenk]

If you haven't noticed, "Web 2.0" is a long estabilished buzzword - which means it carries little meaning, but it looks good in advertising. Just like "information superhighway", "enterprise feature" or "user friendly".

Re:What is the role of Open Source

[KokorHekkus]

The wiki software, MediaWiki, was written for Wikipedia and is licensed under the GPL ( http://www.mediawiki.org/wiki/How_does_MediaWiki_work%3F. According to Wikipedia they use MySQL as their database and run it all on Linux servers.

Re:Tampa?

[nickull]

Not to mention hurricanes and faulty electronic voting machines.... ;-)

Confused by the title

[Just Some Guy]

What does "Non-Profit Budget" mean, anyway? There are non-profits bigger than the company I work for. Non-profit isn't the same as poorly financed.

Re:Confused by the title

[quanticle]

Good point. Perfect example: the Bill and Melinda Gates Foundation has a budget of billions of dollars, easily exceeding the budget of many private corporations.

Link to wikipedia?

[Luyseyal]

The summary was wrong to include a link to the Wikipedia homepage without a Wikipedia link about Wikipedia in case you don't know what Wikipedia is. I myself had to Google Wikipedia to find out what Wikipedia was so I am providing the Wikipedia link about Wikipedia in case others were likewise in the dark regarding Wikipedia.

-l

P.s., Wikipedia.

Re:Link to wikipedia?

[hansamurai]

Wait, what's this Google thing you're talking about?

Re:Link to wikipedia?

[hansamurai]

Nevermind, found it:

http://www.google.com/search?q=google

Re:Link to wikipedia?

[felipekk]

http://en.wikipedia.org/wiki/Google

Re:Link to wikipedia?

[srollyson]

[citation needed]

Simplicity

[wsanders]

Although much of the Mediawiki software is a hideous twitching blob of PHP Hell, the base functionality is fairly simple and run perpetually and scale massively as long as you don't mess with it.

What spoils a lot of projects like this is the constant need for customization. Wikimedia essentially can't be customized (except for plugins obviously, which you install at your own peril) and that is a big reason why it scales so massively.

As for Wikipedia itself, I suspect it is massively weighted in favor of reads. That simplifies circumstances a lot.

Re:What amazes me...

[ceejayoz]

Slashdot is great at taking down sites on crappy shared hosting, but anything with a decently configured dedicated server will likely survive just fine.

Wikipedia's probably getting hit with hundreds of times the traffic Slashdot is at all times.

Sure they do it without ads...

[DerekLyons]

Sure they do without ad income. But they also do it without having to pay salaries, or co location fees, or bandwidth costs... (I know they pay some of those, but they also get a metric buttload of contributions in kind.)

When your costs are lower, and your standard of service (and content) malleable, it is easy to live on a smaller income.

Nonsense. Wikipedia is THE web 2.0

[Nicolas MONNET]

Web 2.0 is not just about flashy Ajax or what not, it's about user generated dynamic content. WP's "everything is a wiki" architecture might /look/ a bit archaic compared to fancy schmancy dynamic rotating animated gradient-filled forums, but it's much more powerful.
Moreover, WP is not a collection of static pages, if you're logged in at least, every pages is dynamically generated, and every page's history is updated within a few seconds.

Wikipedia = much more traffic than slashdot

[Anonymous Coward]

Slashdot does .. what? 40 mbit of traffic at peak? Wikipedia
is roughly 100 times larger. (And WP has three datacenters, not one)

Slashdot traffic hasn't created noticeable blips on Wikipedia's radar for years.

OTOH, if Wikipedia linked slashdot on every page slashdot would go down, if do to nothing else but bandwidth exhaustion.

Re:Wikipedia = much more traffic than slashdot

[hostyle]

OTOH, if Wikipedia linked slashdot on every page slashdot would go down, if do to nothing else but bandwidth exhaustion.

Sounds like a dare to me. Gentlemen, start your packets!

Re:Wikipedia = much more traffic than slashdot

[Haoie]

That's pretty obvious because Wiki has, literally, millions of topics covering every possible field. Whereas /. is very limited in scope.

Re:Wikipedia = much more traffic than slashdot

[beav007]

bandwidth exhaustion

Welcome to ************ broadband tech support. How can I help?

"My internet is running very slowly tonight. Why is that?"

Well sir, it looks like you've been downloading from the other side of the continent. I'd say that your packets are just very tired by the time they reach you...

Re:Wikipedia = much more traffic than slashdot

[BooRolla]

If only there were some way to put links on to Wikipedia!

Re:Out like a light

[timstarling]

We've never lost external power while we've been at Tampa, but if we did, there are diesel generators. Not that it would be a big deal if we lost power for a day or two. There's no serious problem as long as there's no physical damage to the servers, which we're assured is essentially impossible even with a direct hurricane strike, since the building is well above sea-level and there are no external windows.

Servers and locations

[Anonymous Coward]

According to http://meta.wikimedia.org/wiki/Wikimedia_servers Wikimedia (and by extension, Wikipedia):

"About 300 machines in Florida, 26 in Amsterdam, 23 in Yahoo!'s Korean hosting facility."

also: http://meta.wikimedia.org/wiki/Wikimedia_partners_and_hosts

Re:Tampa?

[midom]

add power costs, difficulty to travel to, possible flooding, etc. it is all historic reasons, we can't just migrate datacenters at wish - that requires quite a high investment. and the datacenter choice was simply because the founder lived there in 2001, when all we needed was single server. --Domas

Re:What is the role of Open Source

[guruevi]

I don't know what else but open source you could use especially on the database side. You have only a few choices:

Microsoft ($$$) (approx. $50,000 per server per year in licensing costs since it's a public (unlimited CAL) enterprise-level site)
IBM ($$) (approx. $500,000 per year for leasing the whole operation, another load for support)
Oracle ($) (approx. $20,000 per backend and about 30 contractors for the next 5 years for the implementation)
Linux, MySQL, PHP (Free)

Not to mention, with Microsoft you'll need more servers to handle the same amount of load especially if you use Microsoft-based software package for the frontend as well (ASP.NET, MS CRM or SharePoint).

For IBM you'll have special hardware that nobody can handle but IBM certified support personnel.

For Oracle you're pretty much on your own anyway and you'll have to find a frontend.

Re:What amazes me...

[HarvardAce]

(link to Alexa graph) One problem about Alexa is that it only gathers statistics from those who install the Alexa toolbar...I would tend to think that the Slashdot crowd would be a group that predominantly avoids installing that sort of thing. I actually think there was a discussion on this on Slashdot many months ago.

That said, I'm sure that the traffic to Wikipedia is probably several orders of magnitude higher than that of Slashdot.

Re:What amazes me...

[dubl-u]

Slashdot is great at taking down sites on crappy shared hosting, but anything with a decently configured dedicated server will likely survive just fine. Sounds right to me. I don't have any terribly recent data on a slashdotting, but I think the Slashdot-as-server-killer meme is pretty stale.

Looking at some old data and extrapolating, I'd guess a modern slashdotting would peak at 200 pageviews/min, or ~3 pv/sec. Get mentioned on Good Morning America or Oprah, on the other hand, and you're looking at 20-200 pageviews/sec. I'd guess that getting on Digg's front page is somewhere in the 20-40 pv/sec range.

A slashdotting was a big deal back when every nerd used it and the Internet was mainly nerds. Neither is true anymore.

What about the Internet Archive

[Xtifr]

Wikipedia's pretty impressive, but how about the Internet Archive? Also a non-profit that doesn't run ads, and not only do they, like Google and Yahoo, "download the Internet" on a regular basis, but the Archive makes backups! Plus, they have huge amounts of streaming audio and video (pd or creative-commons). The first time I ever heard the word "Petabyte" being discussed in practical, real world terms (as in, "we're taking delivery next month") was in connection with the Internet Archive. Several years ago. And it was being used in the plural! :)

They may not have as much incoming traffic as Wikipedia, but the sheer volume of data they manage is truly staggering. (Heck, they have multiple copies of Wikipedia!) When I do download something from there, it's typically in the 80-150 MB range, and 1 or 2 GB in a pop isn't unusual, and I know I'm not the only one downloading, so their bandwidth bills must still be pretty impressive.

The fact that these two sites manage to survive and thrive the way they do never ceases to amaze me.

Re:It's easy...

[Hillgiant]

Why? If you want search, go to google. If you want an encyclopedia, go to wikipedia. Its pretty simple, really.

That's easier than it sounds

[Cajun Hell]

I don't care how few servers they have, whats more interesting to me is that they run an ultra-high traffic site, which they aren't having trouble paying for, and do it without adds.

I can do that too; I just emulate the adds. x+y is the same as x-(0-y). You have to be careful to use signed numbers for everything (or else have a lot of casting), but that's not really all that hard.

Where are the PHP/MySQL doom criers?

[trawg]

I notice they are conspicuously absent in the comments. They tend to jump up and down in any other post about PHP and MySQL. This is such a great example of the scalability and performance of it WHEN USED CORRECTLY.

Re:Cached on servers all over the interweb?

[adri]

It exists. Its called "validators". There are strong and weak validators. You can Vary on your validators, and thus have multiple copies of the same object but in different forms (so given a text document, you can have it in different languages, compressed/uncompressed, etc.)

Your browser will then quite happily ask the origin server (which may not be the "origin" origin) for an object and provide validators. (Last-Modified -> If-Modified-Since; ETag->If-None-Match) which the origin (or the cache which is pretending to be the origin) can check against its local copy and then return a "yes, use your local copy" or "no, don't bother."

Its all there, right now, in HTTP/1.1. I swear. People just don't have a clue how to use caching, they've been bitten by the difference between "expiry" and "revalidation", and they just turn off all hope of caching. Maybe they're scared; maybe their job is to sell bits; maybe they're just clueless about it and turning off caching fixed an obscure problem. In any case, its right there in HTTP/1.1 and you can use it any time you like.

Adrian

(I'm a Squid developer.)