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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.
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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:
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Indexing Support: Defines, creates, and populates full-text indexes for the
database.
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Querying Support: Processes full-text search queries. These supported queries
include searches for:
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- Words or phrases
- Words in close proximity to each other
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