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  <title>Augmentations to Common Crawl</title>
  <author>Henry S. Thompson</author>
  <date>23 May 2024</date>
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  <div>
   <title>Introduction</title>
   <p>This site contains a copy of my augmented index files
for <link href="https://commoncrawl.org/blog/august-2019-crawl-archive-now-available">CC-MAIN-2019-35</link>.  This index contains all of <link href="https://commoncrawl.org/blog/august-2019-crawl-archive-now-available">the original index</link>, with one additional field, <code>lastmod</code>, in about 18% of the entries, giving the value of the <code>Last-Modified</code> header as a POSIX-format timestamp, enabling much finer-grained longitudinal study of the corresponding web resources.  The filename, offset and length fields in the augmented index are unchanged, and so can be used for retrieval from the original WARC files.</p>
   <p>The format of the Common Crawl's index files is described in <link href="https://commoncrawl.org/blog/announcing-the-common-crawl-index">this announcement</link>.</p>
  </div>
  <div>
   <title>Contents</title>
   <list>
    <item>My <link href="Thompson_WebSci24.pdf">paper</link>, presented at WebSci24, describing
the augmented index and its uses</item>
    <item>The <link href="CC-MAIN-2019-35/cdx/warc/cluster.idx">top-level index file</link></item>
    <item><link href="CC-MAIN-2019-35/cdx/warc/idx/">The directory containing
the individual gzipped index files themselves</link>, with names of the form
<code>cdx-00nnn.gz</code>, for <code>nnn</code> in <code>000&ndash;299</code></item>
    <item><link href="Thompson_WebSci24_slides.pdf">WebSci 24 conference slides</link></item>
   </list>
  </div>
  <div>
   <title>Efficient access to Common Crawl using Amazon S3<!--    <item> <link href="">eidf125_example.sh</link>.</item>--></title>
   <p>The University of Edinburgh's <link href="https://edinburgh-international-data-facility.ed.ac.uk/">Edinburgh International Data Facility</link> (EIDF) hosts a
copy of the augmented index in an Amazon S3 server.  It supports open
access to the index via unsigned requests to (range-restricted)
<name>s3:</name> URIs, for example using the <link href="https://aws.amazon.com/cli/">Amazon <code>aws</code>
Command Line Interface</link>.</p>
   <p>The best way to understand how this works, once you've read how
the index itself works <link href="Thompson_WebSci24.pdf">in the paper, section 2.1</link>, is to work through <link href="eidf125_example.sh">an example</link> of using the augmented index to access an individual
Common Crawl retrieval record using a timestamp.</p>
  </div>
  <div>
   <title>Licence and citation</title>
   <p>The paper and data contained herein are Copyright © 2024 Henry S. Thompson <link href="http://creativecommons.org/licenses/by-sa/3.0/deed.en">CC-BY-SA</link></p>
   <p>Please cite information from here as follows:</p>
   <list type="1defn">
    <item term="For the paper"><display>Henry S. Thompson. 2024. "Improved methodology for longitudinal Web
analytics using Common Crawl". In <emph>ACM Web Science Conference (Websci ’24)</emph>,
May 21–24, 2024, Stuttgart, Germany. ACM, New York, NY, USA, 11 pages.
<link href="https://doi.org/10.1145/3614419.3644018">https://doi.org/10.1145/3614419.3644018</link>
</display></item>
    <item term="For the data"><display>Henry S. Thompson. 2024. <emph>Augmented index
for Common Crawl August 2019, with Last-Modified timestamps</emph>.
<link href="https://markup.co.uk/ccrawl/">https://markup.co.uk/ccrawl/</link>. Retrieved ...</display></item>
   </list>
  </div>
  <div>
   <title>Acknowledgements</title>
   <p>Without the vision of those responsible for Common Crawl and the
generosity of Amazon in hosting it this work could never have happened.</p>
   <p>Access to the <link href="http://www.cirrus.ac.uk">Cirrus UK National Tier-2 HPC Service</link> at the Edinburgh
Parallel Computing Centre used to produce the augmented index was supported
by EPSRC and UKRI HPC Access awards to Henry S. Thompson.</p>
   <p>Thanks to Sebastian Nagel of Common Crawl for many prompt and helpful
replies to many emails over the years, and to Greg Lindahl of Common
Crawl and Tom Morris for more recent help with consistency problems in the index
and the challenges of increasing load on the Common Crawl servers.</p>
  </div>
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author	Henry Thompson <ht@markup.co.uk>
date	Thu, 23 May 2024 16:51:36 +0200
parents	268fe5fd117f
children