How Can I Prioritize Relevance in MySQL Full Text Search Across Multiple Columns?

MySQL Full Text Search: Optimizing Relevance and Column Prioritization

When performing full text searches across multiple table columns, it's often desirable to order the results by relevance. MySQL's MATCH() AGAINST() function provides an efficient way to achieve this.

However, situations arise where it's crucial to prioritize relevance within specific columns. Say, for example, we have a table containing pages with head and body columns, where we want to give higher priority to matches found in the head column.

Solution: Incorporating Column-Specific Relevance

To address this requirement, we can leverage an additional MATCH() clause to calculate relevance separately for the head column. By combining this with the overall relevance, we can prioritize results that match both the overall search criteria and the specified column.

SELECT pages.*,
       MATCH(head, body) AGAINST('some words') AS relevance,
       MATCH(head) AGAINST('some words') AS head_relevance
FROM pages
WHERE MATCH(head, body) AGAINST('some words')
ORDER BY head_relevance DESC, relevance DESC

In this query, we calculate both the overall relevance (relevance) and head column-specific relevance (head_relevance). By ordering the results first by head_relevance in descending order (DESC) and then by relevance also in descending order, we effectively prioritize matches found in the head column.

Bonus: Counting Occurrences of Search Terms

While the above approach enhances column prioritization, it doesn't provide a count of the occurrences of search terms within the specified columns. To achieve this, we can use FULLTEXT() and LENGTH() functions:

...
SELECT pages.*,
       MATCH(head, body) AGAINST('some words') AS relevance,
       MATCH(head) AGAINST('some words') AS head_relevance,
       LENGTH(head) - LENGTH(REPLACE(head, 'some words', '')) AS head_count,
       LENGTH(body) - LENGTH(REPLACE(body, 'some words', '')) AS body_count
FROM pages
...

This extends the previous query to calculate the count of search term occurrences within both the head (head_count) and body (body_count) columns.

Additional Options: Postgres and Weighting

If suitable for your project, Postgres offers advanced features that allow for finer control over relevance ranking. Its search capabilities support weighting specific terms or operators, enabling greater customization of the search results.

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