Question

Okay, so I’m trying to make a full text search in multiple columns, something simple like this:

SELECT * FROM pages WHERE MATCH(head, body) AGAINST('some words' IN BOOLEAN MODE)

Now i want to order by relevance, (how many of the words are found?) which I have been able to do with something like this:

SELECT * , MATCH (head, body) AGAINST ('some words' IN BOOLEAN MODE) AS relevance 
FROM pages
WHERE MATCH (head, body) AGAINST ('some words' IN BOOLEAN MODE)
ORDER BY relevance

Now here comes the part where I get lost, I want to prioritize the relevance in the head column.

I guess I could make two relevance columns, one for head and one for body, but at that point I’d be doing somewhat the same search in the table three times, and for what i’m making this function, performance is important, since the query will both be joined and matched against other tables.

So, my main question is, is there a faster way to search for relevance and prioritize certain columns? (And as a bonus possibly even making relevance count number of times the words occur in the columns?)

Any suggestions or advice would be great.

Note: I will be running this on a LAMP-server. (WAMP in local testing)

Answer 1

This might give the increased relevance to the head part that you want. It won’t double it, but it might possibly good enough for your sake:

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

-- alternatively:
ORDER BY title_relevance + relevance DESC

An alternative that you also want to investigate, if you’ve the flexibility to switch DB engine, is Postgres. It allows to set the weight of operators and to play around with the ranking.