Query-By-Example (QBE) Parser
The query-by-example (QBE) parser supports searching for similar documents, a search method sometimes referred to as similarity searching. The QBE parser supports searching over the full text of documents only. The QBE parser does not support searching over collection fields and zones. The QBE parser does not support Verity query language except topics as described below.
Sometimes the Verity products and documentation refer to the QBE parser as the Free Text Parser. These two parsers are identical in behavior.
Meaningful words are automatically treated as if they were preceded by the MANY modifier and the STEM operator. By implicitly applying the STEM operator, the search engine searches not only for the meaningful words themselves, but also for words that have the same stem. By implicitly applying the MANY modifier, the search engine calculates each document's score based on the word density it finds for meaningful words; the denser the occurrences of a word in a document, the higher the document's score.
By default, common words (such as "the," "has," and "for") are stripped away, and the query is built based on the more significant words (such as "personnel," "interns," "schools," and "mentors"). Therefore, the results of a query-by-example search are likely to be less precise than a search performed using the simple or BooleanPlus parser.
The QBE query parser interprets topic names as topic objects. This means that if the specified text block contains a topic name, the query expression represented by the topic is considered in the search.
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