Synonym Tables
To implement a synonym table, define the table as a persistent class that extends the iFind.Synonym abstract class.
This class defines two properties, FromTerm and ToTerm. A pair of FromTerm and ToTerm properties define ToTerm as a synonym for FromTerm. SQL Search would use ToTerm to expand the query if the query contains FromTerm.
The query uses the GetMatch() method of this class to search the synonyms in the synonym table against the query terms.
During query execution, SQL Search checks if any synonyms exist for a single word unit or a positional search phrase. For example, two synonym pairs ("persons","people") and ("walk","run") are defined in a synonym table. A SQL Search query is executed on the phrase "persons walk". If the synonym table is associated with the query, SQL Search returns not only documents matching the original query, it also returns documents matching any one of the queries: "persons run", "people walk" and "people run".
However, if the search_items string is '"persons walk"', query expansion would not happen, because SQL Search does not expand any word in a positional phrase search. The positional phrase itself is the minimum unit for query expansion. If, however, you define a synonym pair like ("persons walk","persons walk and run"), SQL Search would expand the query '"persons walk"' to '"persons walk and run"'. SQL Search treats a ToTerm as a positional phrase if it contain multiple words. A ToTerm can be any valid positional phrase; it can contain * or ? wildcards.
Note:
Synonym tables cannot be used with Regular Expression search (search_option=4).
