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Dataset Generation
Andy Jackson edited this page Aug 18, 2015
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The warc-hadoop-indexer project also contains metadata extraction (MDX) tools that can be applied as follows.
Breaking the whole 1996-2013 collection into 6 chunks (at least 86,000 ARCs or WARCs per chunk), we then run the WARCMDXGenerator to create a set of MDX metadata objects stored as text in sequence files, sorted by entity-body hash.
chunk | time | records | NULLs | Errors | HDFS bytes read |
---|---|---|---|---|---|
a | 33hrs, 57mins, 1sec | 538,761,419 | 116,127,700 | 0 | 5,661,783,544,289 (5.66 TB) |
b | |||||
c | |||||
d | 28hrs, 56mins, 11sec | 524,143,344 | 89,077,559 | 8 | 5,918,383,825,363 |
e | 35hrs, 26mins, 40sec | 501,582,602 | 101,396,811 | 1 | 6,505,417,693,908 |
f | 72hrs, 19mins, 35sec | 1,353,142,719 | 332,045,791 | 14 | 29,129,360,605,968 |
Merging all into one set, sorted by hash, and re-duplicating revisit records.
Note that when merging just chunks e and f (which are the only ones containing WARCs), there were 162,103,566 revisits out of 1,854,725,336 records, but 2,482,073 were unresolved!
At this point, we can run other profilers and samplers over the merged, reduplicated MDX files and generate a range of datasets for researchers.