MySQL Limit query by time when there's not enough results - mysql

Question

I have a big table, with 670k rows and I'm running a SELECT with a lot of WHEREs to search and filter useful results, the thing is sometimes there are NO results with the selected filters, and the query just goes all over the table and takes a lot of time, I'd like to stop the query if there are no results found in, say, 30 seconds.
This is my query:
SELECT date, s.name, l.id, l.title,ratingsum,numvotes,keyword,tag
from news_links l
LEFT JOIN sources s on s.id = l.source
WHERE
l.date BETWEEN STR_TO_DATE(?,'%Y-%m-%d')
AND STR_TO_DATE(?,'%Y-%m-%d')
AND s.name like ?
AND ((numvotes-1) *?) <= l.ratingsum
AND numvotes > ?
AND matches = 1
AND tag >= ?
AND tag <= ?
AND (l.title like ? or l.keyword like ?)
AND category >= ?
AND category <= ?
order by date desc
limit ?,15
I tried running a sub-query instead of joining but it didn't speed up the query.
News table(640k rows)
-----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | UNI | NULL | auto_increment |
| link | varchar(450) | NO | PRI | NULL | |
| date | datetime | NO | MUL | NULL | |
| title | varchar(145) | NO | MUL | NULL | |
| source | int(11) | NO | MUL | NULL | |
| text | mediumtext | YES | | NULL | |
| numvotes | int(3) | NO | MUL | 0 | |
| ratingsum | int(3) | NO | | 0 | |
| matches | int(1) | NO | | 0 | |
| keyword | varchar(45) | YES | | NULL | |
| tag | int(1) | NO | | 0 | |
+-----------+--------------+------+-----+---------+----------------+
I have indexes set up on date,title,source,numvotes as well as the primary key on link

Answer 1

670k rows should run VERY fast in MySQL. You should have a closer look at your indices. Start adding a combined HASH index on news_links.source and news_links.matches:
ALTER TABLE news_links ADD INDEX myIdx1 USING HASH (source, matches)
What does EXPLAIN SELECT ... gives you with that?
After that you can try to improve the Performance further by including more Information in your index (Note that MySQL will use only one index per table). Add a BTREE index:
ALTER TABLE news_links ADD INDEX myIdx2 USING BTREE (source, matches, `date`)
BTREE will be good for range-queries (eg with a BETWEEN in it). HASH is good for equal/unequal conditions. If you want to index several columns with mixed conditions (range an equal) use BTREE
What does EXPLAIN SELECT ... gives you now?