[Hadoop Wiki] Update of "Hbase/PoweredBy" by FuadEfendi

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The following page has been changed by FuadEfendi:
http://wiki.apache.org/hadoop/Hbase/PoweredBy

The comment on the change is:
Hope to provide more tecnical details soon

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  [http://www.mahalo.com Mahalo], "...the world's first human-powered search engine". All the markup that powers the wiki is stored in HBase. It's been in use for a few months now. MediaWiki - the same software that power Wikipedia - has version/revision control. Mahalo's in-house editors produce a lot of revisions per day, which was not working well in a RDBMS. An hbase-based solution for this was built and tested, and the data migrated out of MySQL and into HBase. Right now it's at something like 6 million items in HBase. The upload tool runs every hour from a shell script to back up that data, and on 6 nodes takes about 5-10 minutes to run - and does not slow down production at all. 
  
+ [http://www.tokenizer.org Shopping Engine at Tokenizer] is a web crawler; it uses HBase to store URLs and Outlinks (AnchorText + LinkedURL): more than a billion. It was initially designed as Nutch-Hadoop extension, then (due to very specific 'shopping' scenario) moved to SOLR + MySQL(InnoDB) (ten thousands queries per second), and now - to HBase. HBase is significantly faster due to: no need for huge transaction logs, column-oriented design exactly matches 'lazy' business logic, data compression, MapReduce support. Number of mutable 'indexes' (term from RDBMS) significantly reduced due to the fact that each 'row::column' structure is physically sorted by 'row'. MySQL InnoDB engine is best DB choice for highly-concurrent updates. However, necessity to flash a block of data to harddrive even if we changed only few bytes is obvious bottleneck. HBase greatly helps: not-so-popular in modern DBMS 'delete-insert', 'mutable primary key', and 'natural primary key' patterns become an
  a big advantage with HBase.
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