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Advanced Text Indexing and Searching Techniques Using SQL and NoSQL Technologies

This article provides a comprehensive guide on effective text indexing and searching methods using SQL, Lucene, and various NoSQL technologies. It demonstrates the limitations of SQL LIKE queries and emphasizes the use of FULLTEXT indexes for optimal performance. Key technologies discussed include Lucene, Solr, ElasticSearch, and Sphinx, each with its unique features for efficient text search. Practical examples are provided, highlighting how to implement and utilize these tools for successful text search, indexing strategies, and geolocation features.

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Advanced Text Indexing and Searching Techniques Using SQL and NoSQL Technologies

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  1. PeWe 2011 Tools for Text Indexing and SearchING DušanZeleník FIIT STU zelenik@fiit.stuba.sk

  2. Searchingusing SQL LIKE • CREATE INDEX names_index ON heroes(name) • SELECTname FROM heroesWHERE name LIKE “zelen%” • will use names_index, ok • SELECTname FROM heroesWHERE name LIKE “%ik” • won’t use names_index (seriously don’t do that) • CREATE FULLTEXT INDEX names_fullindex ON heroes(name) • SELECTname FROM heroesMATCH(name) AGAINST(“%ik”) • will use names_fullindex • SELECTname FROM heroesMATCH(name) AGAINST(“ze%ik”) • won’t use names_fullindex(seriously don’t do that)

  3. Search Engines for TEXT • Lucene • Lucene Core - Java (library) • Ferret … • Solr - Java (standalone server) • Sunspot … • ElasticSearch - Lucene Core • Tire … • Sphinx – C++ • Thinking Sphinx

  4. Lucene vs. Sphinx

  5. Sphinx • Standalone server (http://sphinxsearch.com/) • Thinking Sphinx (Rails Gem – MVC) • http://freelancing-god.github.com/ • works directly with DB and Sphinx server

  6. Thinking Sphinx class Hero < ActiveRecord::Base define_indexdo indexes description, :sortable=> true indexes sidekick(:name), :as => :sidekick, :sortable => true has sidekick, summoned_at, died_at end end Hero.search “zelenik” Hero.search:conditions=> {:sidekick=> “simko”}, :match_mode=> :any#(:all, :any, :phrase, :boolean) :order=> :died_at

  7. Thinking Sphinx Excerpts • heroes = Hero.search “gigant” • heroes.excerpts.description • … has abnormally gigant muscles …. Facets • indexes sidekick.name, :as => :sidekick, :facet => true Geolocation • has "RADIANS(latitude)", :as => :latitude, :type => :float • has "RADIANS(longitude)", :as => :longitude, :type => :float • Place.search “zelenik", :geo => [@lat, @lng], :with => {"@geodist" => 0.0..10_000.0}

  8. Solr • Standalone server (http://lucene.apache.org/solr/) • Sunspot (Rails Gem) • http://outoftime.github.com/sunspot/ • communicates with DB and Solr server

  9. Sunspot Hero.searchdo fulltext ‘muscles' with(:died_at).less_thanTime.now order_by :summoned_at, :desc paginate :page => 2, :per_page => 15 facet :sidekick end class Hero < ActiveRecord::Base searchable do text :description string :sidekick do sidekick.name end time :summoned_at time :died_at end end …

  10. Sunspot DSL Solr highlighting Class hierarchy Facets Geographical searches WillPaginate support Lucene analyzers (tokenizers, filters …)

  11. ElasticSearch • Standalone server based on Solr • (http://www.elasticsearch.org/) • Tire (Rails Gem), better than nothing • https://github.com/karmi/tire • communicates with DB and ElasticSearch server

  12. Tire class Hero < ActiveRecord::Base include Tire::Model::Search include Tire::Model::Callbacks mapping do indexes :description, :type => 'string‘, :analyzer => 'snowball‘ indexes :name, :type => 'string' indexes :died_at, :type => ‘time‘ indexes :summoned_at, :type => ‘time‘ end end Hero.search ‘muscles'

  13. ElasticSearch ADVANTAGES OF SOLR REST DISTRIBUTED!!! http://www.youtube.com/watch?v=l4ReamjCxHo For instance, Hadoop … http://www.elasticsearch.org/guide/reference/modules/gateway/hadoop.html

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