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Fuzzy Search with Stopwords
Usage
Stopwords are terms that are less significant for a search and are therefore not used to generate the result set. In
other words, the search is carried out as if the stopwords are not present (either in the user input or in the
database column).
However, stopwords influence the score that is calculated. A record with stopwords identical to the user input
gets a higher score than a record with differing or missing stopwords.
Stopwords can be defined either as single terms or as stopword phrases consisting of multiple terms. Stopword
phrases are only applied when all terms of the stopword appear in exactly the given order.
Use case example: When searching for company names, the legal form (Ltd, SA, AG, and so on) is less significant
and less selective than the other parts of the name.
Stopwords are stored in a column-store table with the following format:
CREATE COLUMN TABLE mystopwords
(
stopword_id VARCHAR(32) PRIMARY KEY,
list_id VARCHAR(32) NOT NULL,
language_code CHAR(2),
term NVARCHAR(200) NOT NULL
);
Stopwords are language dependent. It is possible to define the language that a stopword is valid for. You can also
define stopwords for all languages by not setting a language.
(It makes sense to add the language information now so that you can make use of the feature when it is available,
without having to change the stopword definitions.)
As with term mappings, stopwords can be grouped together in multiple groups. Groups of stopwords are
identified by the value of the list_id column that is part of the stopword table.
INSERT INTO mystopwords VALUES (1, 'legalform', '', 'Ltd');
INSERT INTO mystopwords VALUES (2, 'legalform', 'de', 'GmbH');
INSERT INTO mystopwords VALUES (3, 'legalform', 'de', 'Gesellschaft mit
beschränkter Haftung');
INSERT INTO mystopwords VALUES (4, 'legalform', 'de', 'AG');
INSERT INTO mystopwords VALUES (5, 'legalform', 'de',
'Aktiengesellschaft');
To activate stopwords for a search on a TEXT column, you need to provide two search options (similar to the
options used for term mappings):
● stopwordListId=mylist1,mylist2,mylist3
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