Author: spierzchala

Notebook Lust: Archimedes Palimpsest

For history fiends, enthusiasts of lost treasures, and lovers of a good mystery, the discovery of the Archimedes Palimpsest has been one of those stories that must be followed.

The texts contained in the Palimpsest were lost to humanity for hundreds of years as a result of a common Medieval European tradition — the re-use of parchment. To quote the site:

“The word Palimpsest comes from the Greek Palimpsestos, meaning “scraped again”. Medieval manuscripts were made of parchment, especially prepared and scraped animal skin. Unlike paper, parchment is sufficiently durable that you can take a knife to it, and scrape off the text, and over write it with a new text. In this case, [the text of Archimedes’] five books were taken apart, the text was scraped off the leaves, which were then stacked in a pile, ready for reuse.”

Using a new x-ray scanning technology, the original Greek text is exposed to the Western world for the first time since 1229.

A page from the Archimedes Palimpsest

This holds more than a passing interest to me, as one of the most influential history courses I took during my undergrad tenure was taught by a paleographer and historian at the University of Victoria, Michèle Mulchahey (she is now part of the faculty at the University of Toronto). I still often wish I had continued my Medieval European history studies, but my lack of latin prevented me from go much further than I did.

Glad to see a truly old classic resurrected.

Notebook Lust: Minutiae to the max!

For those who capture the minutiae of their lives in a Moleskine or Rite in the Rain, I present the example to which we should all bow.

The Domesday Book is online.

To quote the site

“Domesday is our most famous and earliest surviving public record. It is a highly detailed survey and valuation of all the land held by the King and his chief tenants, along with all the resources that went with the land in late 11th century England. The survey was a massive enterprise, and the record of that survey, Domesday Book, was a remarkable achievement. There is nothing like it in England until the censuses of the 19th century.”

It is a truly amazing work, and a goldmine for researchers and social historians around the world.

GrabPERF: Some bad data leaked in

I was trying yesterday to debug an issue that was appeared to be affecting the PubSub Agent — yes, I re-started it at the request of their sysadmin.

The issue was that it was showing data that appeared to have no relationship with the data appearing from all of the other measurement locations. I tried blocking it off using IPTables, MySQL restrictions, etc.

This afternoon, I figured out the problem.

Yesterday, I had been using this query to diagnose the problem:

select
       *
from
    data
where
    agent_id = 11
    and date between subdate(now(),interval 30 minute) and now()
order by
    date DESC

And everytime I looked, there was new data. I couldn’t seem to stop the agent from delivering data. Then I had a flash.

select
       count(*)
from
    data
where
    agent_id = 11
    and date > now()

157,000 rows of data. From the future.

Thankfully I know the guy who is responsible for keeping the PubSub servers running, and he is going to adjust the time, etc. But he makes no promises about how long the agent machine will stay running.

I apologize for the bad data.

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Web Performance: Some posts of interest

This morning’s bounty of posts brought in two that will make you think.

First was Port80 Software’s comments on using the Cache-Control mechanism embedded in all browsers. This is interesting to read, as I have been trying to get companies to use this mechanism more intelligently for a number of years. I know that the Port80 team gets it, but it is always nice to have some outside validation of a position you have tried to evangelize for a long time.

The second was Tim O’Reilly’s post on Cal Henderson’s new book on Web scalability. While I am likely to purchase the book for a professional interest, I have one problem with Flickr’s current configuration: static.flickr.com does not use HTTP persistence, something I noted last week. This strikes me as weird.

It’s always good to see Web performance rear its head.

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