Skip to main content

Apache Lucene Search Engine’s Features


Apache Lucene is a high-performance, full featured text search engine library written entirely in Java. It is part of Apache Jakarta Project. Lucene was originally written by Doug Cutting in Java. While suitable for any application which requires full text indexing and searching capability, Lucene has been widely recognized for its utility in the implementation of Internet search engines and local, single-site searching. Lucene is Doug Cutting’s wife’s middle name !

Features

1. Scalable, High-Performance Indexing

  • Over 95GB/hour on modern hardware
  • Small RAM requirements — only 1MB heap
  • Incremental indexing as fast as batch indexing
  • Index size roughly 20-30% the size of text indexed


2. Powerful, Accurate and Efficient Search Algorithms

  • Ranked searching — best results returned first
  • Sorting by any field
  • Multiple-index searching with merged results
  • Allows simultaneous update and searching


3. Flexible Queries

  • Phrase queries –>  like “star wars” –> search for the full word star wars.
  • Wildcard queries  –> like star* or  sta?  –> search for a single character or multi character replacements for the search words
  • Fuzzy queries  –> like star~0.8  –> search for the similar words with some weightage
  • Proximity queries  –> like  ”star wars”~10 –> search for a “star” and “wars” within 10 words of each other in a document
  • Range queries  –>  like {star-stun}  –>  search for documents in between star and stun. Exclusive queries are denoted by curly brackets
  • Fielded searching   –>  fields like  title, author, contents
  • Date-range searching   –> like [2006-2007]  –>  search for documents with field value in between 2006 and 2007. Inclusive queries are denoted by square brackets
  • Boolean Operators  –>  like star AND wars . The OR operator is the default conjunction operator.
  • Boosting a Term –>  like star^4  wars –> make documents with term star more relevant
  • + Operator  –>  like +star wars –>  search for documents that must contain “star” and may contain “wars”
  • - Operator  –>  like star -wars –>  search for documents that contain “star” and not contains “wars”
  • Grouping –>  like (star AND wars) OR website –>  using parentheses to group clauses to form sub queries
  • Escape special character –>  The current list special characters are   + – && || ! ( ) { } [ ] ^ ” ~ * ? : \  . To escape these character use the \ before the character.


4. Cross-Platform Solution

  • Available as Open Source software under the Apache License which lets you use Lucene in both commercial and Open Source programs
  • 100%-pure Java
  • Implementations in other programming languages available that are index-compatible


At the core of Lucene's logical architecture is the idea of a document containing fields of text. This flexibility allows Lucene's API to be independent of the file format. Text from PDFs, HTML, Microsoft Word, and OpenDocument documents, as well as many others (except images), can all be indexed as long as their textual information can be extracted.
Index  --> sequence of documents ( Directory)
Document  -->  sequence of fields
Field  --> named sequence of terms
Term  --> a text string (e.g., a word)
Terms:
A search query is broken up into terms and operators. There are two types of terms: Single Terms and Phrases. A Single Term is a single word such as "test" or "hello". A Phrase is a group of words surrounded by double quotes such as "hello dolly". Multiple terms can be combined together with Boolean operators to form a more complex query.

Fields:
When performing a search you can either specify a field, or use the default field. You can search any field by typing the field name followed by a colon ":" and then the term you are looking for.

Labels:

Comments

Post a Comment

Popular posts from this blog

ATG CA - BCC home screen : how to add a new link

          Activity source is the property which controls the links on the left nav on the BCC home screen. All activity sources are registered with the ActivityManager component at /atg/bizui/activity/ActivityManager . When rendering the BCC home page, the ActivityManager cycles through all the registered ActivitySource components and displays left navigation links for each of them on the BCC home page. For example if I want to add a new link "My New Link" , below screen shots exaplins how this can be done 1. Add  activityManager.properties to specify the activityresources. In this  activityManager, I specified one MyActivitySource. 2. Add  MyActivitySource.properties  to specify the name of the link and the other details . Here it refers to a bundle properties file.  3. Add  the bundle properties file  to specify the name of the link.  4. Now you could see the new link...
6 comments
Read more

ATG - how to prevent Cross-Site attacks using _dynSessConf parameter

Cross-site scripting attacks take advantage of a vulnerability that enables a malicious site to use your browser to submit form requests to another site. In order to protect forms from cross-site attacks in ATG, you can enable form submissions to automatically supply the request parameter _dynSessConf , which identifies the current session through a randomly generated long number. On submission of a form (using dsp:form tag) or activation of a property setting (using dsp:a tag), the request-handling pipeline ( DAFDropletEventServlet ) validates _dynSessConf  against its session confirmation identifier. If it detects a mismatch or missing number, it can block form processing and return an error. To disable this functionality, we could give the following properties (@ /atg/dynamo/Configuration to disable it globally) enforceSessionConfirmation  = false -->  specifies whether the request-handling pipeline requires session confirmation in order to proc...
1 comment
Read more

How the ATG Order flow manages a transaction

See more about ATG  Tx management @ http://tips4ufromsony.blogspot.com/2012/05/atg-how-to-use-transaction-manager.html Most of the ATG Commerce form handlers extend atg.commerce.order.purchase.PurchaseProcessFormHandler. The transaction management pattern in order flow is implemented through this form handler’s beforeSet, afterSet, and handler methods. The transaction will be started @ beforeSet method and is ended @ afterSet method. In general, the design pattern for updating an order is as follows: Acquire lock-manager write lock on profile id from the /atg/commerce/order/LocalLockManager Begin Transaction Synchronize on the Order object. Modify Order Call ((OrderImpl) pOrder).updateVersion(); --> atg.commerce.order.InvalidVersionException is thrown based on this Call OrderManager.updateOrder() Release Order synchronization End Transaction Release lock-manager write lock on profile id from the /atg/commerce/order/LocalLockManager     ...
Post a Comment
Read more

Eclipse Juno - good features of Eclipse 4.2 ( Eclipse Juno ) JDT/Workbench

Global search bar The workbench now has a global search field in the tool bar. Multi-drag sash You can now place the cursor at the intersection of two or more sashes and drag them all at the same time. When you are going to be dragging multiple sashes, the cursor will change to one with 4-way arrows. The image below indicates one such intersection with a red circle. Ant updated to 1.8.3 and JUnit to 4.10 The bundled version of Apache Ant in the platform has been updated to version 1.8.3. The JUnit 4 version shipped with Eclipse has been updated to 4.10. CamelCase in Quick Outline The Quick Outline (Ctrl+O) and Quick Hierarchy (Ctrl+T) in the Java Editor now also support camelCase matching on the element name, quite similar to the Open Type dialog and Content Assist. Quick Assist to convert enhanced for loop Ever encountered an enhanced for loop and needed access to the Iterator or to the loop index? Now, you can just use a Quick Assist (Ctrl+1)...
Post a Comment
Read more

How to simulate Browser back button

When someone asks how to simulate a back button, they really mean to ask how to create a link that points to the previously visited page. Most browsers tend to keep a list of which websites the user has visited and in what order they have done so. The DOM window object provides access to the browser's history through the history object. Moving backward and forward through the user's history is done using the   back(), forward(), and go() methods of the  history  object. To move backward through history, just do window.history.back() ; This will act exactly like the user clicked on the Back button in their browser toolbar. Find below a sample html code: <html> <head> <script type="text/javascript"> function goBack(){  window.history.back() } </script> </head> <body>    <input type="button" value="Back" onclick="goBack()" /> </body> </html>
Post a Comment
Read more