Nutch 研究與隨筆

前言

• 目前開發NutchEz 已經可以運作了，但都是基本功能，也找出某些問題
• 希望在完整的看完Nutch的官方網頁後，得到更好的靈感與改進方式

更多指令

readdb

• read / dump crawl db
• Usage: CrawlDbReader <crawldb> (-stats | -dump <out_dir> | -topN <nnnn> <out_dir> [<min>] | -url <url>)
• -stats [-sort] print overall statistics to System.out

  $ nutch readdb /tmp/search/crawldb -stats
  
  09/06/09 12:18:13 INFO mapred.MapTask: data buffer = 79691776/99614720
  09/06/09 12:18:13 INFO mapred.MapTask: record buffer = 262144/327680
  09/06/09 12:18:14 INFO crawl.CrawlDbReader: TOTAL urls:	1072
  09/06/09 12:18:14 INFO crawl.CrawlDbReader: status 1 (db_unfetched):	1002
  09/06/09 12:18:14 INFO crawl.CrawlDbReader: status 2 (db_fetched):	68
  

• -dump <out_dir> [-format normal|csv ] dump the whole db to a text file in <out_dir>

  $ nutch readdb /tmp/search/crawldb/ -dump ./dump
  $ vim ./dump/part-00000
  

• -url <url> print information on <url> to System.out

  $ nutch readdb /tmp/search/crawldb/ -url http://www.nchc.org.tw/tw/
  URL: http://www.nchc.org.tw/tw/
  Version: 7
  Status: 6 (db_notmodified)
  Fetch time: Thu Jul 09 14:34:48 CST 2009
  Modified time: Thu Jan 01 08:00:00 CST 1970
  Retries since fetch: 0
  Retry interval: 2592000 seconds (30 days)
  Score: 3.1152809
  Signature: ce0202bbd593b09b86ce8a9aa991b321
  Metadata: _pst_: success(1), lastModified=0
  
  $ nutch readdb /tmp/search/crawldb/ -url http://www.nchc.org.tw
  URL: http://www.nchc.org.tw
  
  not found
  
  

• -topN <nnnn> <out_dir> [<min>] dump top <nnnn> urls sorted by score to <out_dir>

inject

• inject new urls into the database
• Usage: !Injector <crawldb> <url_dir>

readlinkdb

• read / dump link db
• Usage: LinkDbReader? <linkdb> {-dump <out_dir> | -url <url>)

  $ nutch readlinkdb /tmp/search/linkdb/ -dump ./dump
  $ vim ./dump/part-00000
  

readseg

• read / dump segment data
• Usage: SegmentReader (-dump ... | -list ... | -get ...) [general options]
• SegmentReader -dump <segment_dir> <output> [general options]

  $ nutch readseg -dump /tmp/search/segments/20090609143444/ ./dump/
  $ vim ./dump/dump
  

• SegmentReader -list (<segment_dir1> ... | -dir <segments>) [general options]

  $ nutch readseg  -list /tmp/search/segments/20090609143444/
  
  NAME		GENERATED	FETCHER START		FETCHER END		FETCHED	PARSED
  
  20090609143444	1		2009-06-09T14:34:48	2009-06-09T14:34:48	1	1
  
  

• SegmentReader -get <segment_dir> <keyValue> [general options]

  $ nutch readseg -get /tmp/search/segments/20090609143444/ http://bioinfo.nchc.org.tw/
  

updatedb

• update crawl db from segments after fetching
• Usage: CrawlDb <crawldb> (-dir <segments> | <seg1> <seg2> ...) [-force] [-normalize] [-filter] [-noAdditions]

  $ nutch updatedb /tmp/search/crawldb/ -dir /tmp/search/segments/
  

dedup

• remove duplicates from a set of segment indexes
• Usage: DeleteDuplicates <indexes> ...

  $ nutch dedup /tmp/search/indexes/
  

筆記