And the numeric values in numeric fields will be treated as numeric values, which equal, greater than, less than, or other range based comparisons can be used to query against these fields and used to locate the documents. If the sentence is stored in a StringField, then the entire sentence is considered as one token. Lucene would associate this document with all these words. If a sentence is stored in a text fields, all the words are extracted and each is a searchable token. For English language, a sentence is created with words separated with spaces, and punctuation marks.
The difference between TextField and StringField is that any value of a TextField will be broken into words (tokens). The reason there are so many field types is that different types of values can be analyzed differently and yet added into the same searchable index as a single document. For this tutorial, I am using only TextField, and StringField. IndexableField is an abstract type, its sub types included TextField, StringField, IntPoint, FloatPoint, IntRange, FloatRange, and many other field types.
BUILD APACHE LUCENE ECLIPSE FULL
Once a document with multiple indexable fields are created, it can be added into the full text search index. A document contains multiple indexable fields. Apache Lucene library provides two object types, one is called a Document the other is called an IndexableField. In order to perform a full text search operation, the first thing you have to do is add some documents into the index. Let's start with the way in which indexing a document works. After documents are added into an index, you will see that the directory looks like this: Finding the documents in the index can be done with the same way, by specifying the search terms against the fields of the documents.įor this sample application, I will use the file system to store the document index. As we all know, when query a table in a relational database is specifying query criteria against the columns. Then finding documents in an index is like querying the table to find the data rows that match the query criteria. So, adding a document is like adding a row into a table. These fields are like columns in a table of a relational database. In a document, there can be one or more fields. As we all know, there can be one or more columns in a table. But it is quite simple if you compare it with relational databases. Working with Lucene seems to be complicated. We only needed the lucene-core library to get all these to work. The version of Apache Lucene used in this is 8.2.0.
The program will use file directory as index repository. The program also performs some other miscellaneous functions like deleting all documents from the index, or deleting just some documents from index. Full text search to find the target document.I will have a simple Java console application, which will perform three different functions: This time, I want to explore it without mixing with other technology. I used this before, wrote a tutorial about it with Hibernate. The common one that people use is Apache Lucene. For this one, I was going to do some research on one of my favorite subjects - full text search engine. This is the fourth tutorial I am writing for this year.
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