Speeding up MySQL query searching multiple tables using MATCH AGAINST - php

Question

This is my first time trying to build more complex search functionality than just using the LIKE function. The results returned are pretty much perfect from this search but it's running really slow. Is there anything I can improve code wise to speed things up or anything I should look at on the database? or would I need to be looking at more server power?
Thanks a lot of any and all help. It's much appreciated!
function new_live_search($q){
$title_score = 5;
$tags_score = 10;
$upvote_score = 1;
$subdomain = $this->config->item('subdomain_name');
$query = "SELECT DISTINCT results.*,
(
".$title_score."*(MATCH(title) AGAINST('$q' IN BOOLEAN MODE)) +
".$tags_score."*(MATCH(tags.name) AGAINST('$q' IN BOOLEAN MODE)) +
".$upvote_score."*usefulness
) AS score
FROM results
LEFT JOIN tags ON results.id = tags.result_id
WHERE (scope = 'all' OR scope = '$subdomain')
AND (published = 1)";
$query .= "
HAVING score - usefulness > 0
ORDER BY score DESC, title";
$query = $this->db->query($query);
$results = array();
foreach ($query->result() as $row){
$results[] = $row;
}
return $results;
}

Answer 1

From MySQL documentation
Unfortunately it is not possible to combine Fulltext field and normal (i.e integer) field into one index. Since only one index per query can be used, that seems be a problem
Table layout:
id(integer primary key)|content(text fulltext indexed)|status(integer key)
Note that executing following query, MySQL will use only one index. Either fulltext, or status (Depending on intern statistics).
Query 1:
SELECT * FROM table WHERE MATCH(content) AGAINST('searchQuery') AND status = 1
However it is still possible to use both indexes in one query. You will need a new index on id,status pair and use join. Thus MySQL will be able to use one index for each table.
Query 2:
SELECT t1.* FROM table t1
LEFT JOIN table t2 ON(t1.id=t2.id)
WHERE MATCH(t1.content) AGAINST('searchQuery') AND status=1
Query 2 will run significantly faster than Query 1, at least in my case :)
Note the overhead: You will need an id for each row and a key which is spanned over needed fields starting with id.
Refer Fulltext search on MySQL Documentation
Hope it help you

Answer 2

If you look at your query, your fulltext part of the query does not actually limit the search. Using something like the following should increase performance a bit.
SELECT DISTINCT results.*, (
$title_score * (MATCH(title) AGAINST('$q' IN BOOLEAN MODE)) +
$tags_score * (MATCH(tags.name) AGAINST('$q' IN BOOLEAN MODE)) +
$upvote_score * usefulness
) AS score
FROM results
LEFT JOIN tags ON results.id = tags.result_id
WHERE (scope = 'all' OR scope = '$subdomain')
AND (published = 1)
AND (
(MATCH(title) AGAINST('$q' IN BOOLEAN MODE)) OR
(MATCH(tags.name) AGAINST('$q' IN BOOLEAN MODE)))
HAVING score - usefulness > 0
ORDER BY score DESC, title