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Full-Text Search

Full-Text Search

Daffodil DB full-text search feature is based on the ANSI Structured Query Language (SQL), which is a standard interface language for accessing databases. Daffodil DB supports rich text retrieval without compromising on the format of the text. Daffodil DB full-text search enables you to:

  • Search a table by specifying required columns
  • Specify the search criteria thereby enabling search for specific words or phrases

Why Full-Text Search is Used?

With a full-text query, you can perform a linguistic search of character data.
  • A linguistic search can operate on words and phrases, such as predicate LIKE? which works only on character patterns.
  • A full-text query returns the results in ranked order, which is not possible with predicate LIKE because it only returns those results that contain the query term.
  • Full-text search can remove noise words from the search criteria, hence makes the search more effective, which is not possible with LIKE.
  • Full-text search is extremely efficient at searching large tables (greater than 1 million rows) because it uses a pre-composed index. In comparison to it, LIKE searches the entire table for the required string at the time of query.
  • Full-text search permits language specific search, which is not possible with LIKE.
How to Use Full-Text Search in Daffodil DB

Full-Text Search is a new feature, which was not supported in the previous versions of Daffodil DB. This feature allows you to create special indexes for Daffodil DB character-based data. These special indexes, called full-text indexes, support proximity searches on character data. By using full-text indexes, you can search by words, phrases, words in close proximity to each other, and in flexional forms of verbs and nouns. Full-text indexes can be created on the following Daffodil DB character-based data types:
  • CHAR, CHARACTER
  • VARCHAR, CHARACTERVARYING, CHARVARYING
  • CLOB, CHARACTERLARGEOBJECT, CHARLARGEOBJECT, LONGVARCHAR
Daffodil DB provides a rich text retrieval system. It uses a full-text search engine, which also supports full-text indexing. Daffodil DB Search service performs two primary roles:
  • Indexing Support: Defines, creates, and populates full-text indexes for the database.
  • Querying Support: Processes full-text search queries. These supported queries include searches for:
    • Words or phrases
    • Words in close proximity to each other