Why is My MySQL Fulltext Search Failing with Insufficient Data and Stop Words?

MySQL Fulltext Search Failure: Insufficient Data and Stop Words

The Problem

When attempting to perform full-text searches on a MySQL table containing product information, results are not returned despite the presence of matching terms. For instance, a search for "pen" or "one pen" in the "Product" column returns no results.

The Investigation

Upon examining the table schema, it was discovered that the "Product" column was defined as a FULLTEXT index. However, the table only contained two rows of data, which included the terms "pen" and "one pen."

The Solution

1. Increasing Data Variety:

Full-text search algorithms require a sufficient amount of data to detect meaningful patterns. With only two rows of data, the algorithm was unable to differentiate between common and uncommon words, resulting in poor search results.

Example:

CREATE TABLE testproduct
(
    Id                VARCHAR(16),
    prod_name           TEXT,
    ProductIdType     VARCHAR(8),
  PRIMARY KEY (Id),
  FULLTEXT (prod_name)
) ENGINE=MyISAM;

insert into testproduct (id,prod_name,productidtype) values ('B00005N5PF','one pen and a good price for a pen','ASIN');
insert into testproduct (id,prod_name,productidtype) values ('B570J5XS3C',null,'ASIN');

By inserting more data with a variety of terms and phrases, the algorithm can better classify words and improve search accuracy.

2. Overriding Stop Words:

MySQL maintains a list of common words, known as stop words, which are typically excluded from full-text searches. However, in some cases, stop words may be relevant to the search.

Example:

-- Disable stopword filtering
SET ft_stopword_file = '';

-- Rebuild FULLTEXT indexes
ALTER TABLE testproduct REBUILD INDEX prod_name;

By overriding the default stopword list, relevant terms like "years" or "score" can be included in the search results.

3. Using Boolean and Natural Language Modes:

Boolean mode requires exact matches, while natural language mode allows for variations and synonyms. Using natural language mode can broaden the search results.

Example:

SELECT * FROM testproduct WHERE MATCH(prod_name) AGAINST('+harpoon +article' IN NATURAL LANGUAGE MODE);

By using these techniques, the full-text search functionality can be enhanced to provide accurate and meaningful results for a wider range of queries.

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