Thanks baron for you reply. Here is the result from the explain: 1 SIMPLE t2 ref PRIMARY,url url 194 const 1 Using where; Using temporary; Using filesort 1 SIMPLE tm1 index PRIMARY PRIMARY 8 NULL 149115 Using index 1 SIMPLE t1 eq_ref PRIMARY,url PRIMARY 4 rubbetdev.tm1.tag_id 1 Using where 1 SIMPLE tm2 eq_ref PRIMARY PRIMARY 8 rubbetdev.t2.id,rubbetdev.tm1.ad_id 1 Using where; Using index
2008/3/5, Baron Schwartz <[EMAIL PROTECTED]>: > > Hi, > > > On Wed, Mar 5, 2008 at 9:11 AM, Johan Thorvaldsson <[EMAIL PROTECTED]> > wrote: > > I need help to optimize this following query. It runs very slow and I > cant > > find any direct errors in it. > > SELECT > > 1 * t1.termfreq as viktatantal, > > t1.tag, t1.url FROM tag_keys t1 > > LEFT JOIN tag_ad_map tm1 ON t1.id = tm1.tag_id > > LEFT JOIN tag_ad_map tm2 ON tm1.ad_id = tm2.ad_id > > LEFT JOIN tag_keys t2 ON t2.id = tm2.tag_id > > WHERE > > t2.url = 'motor' AND t1.url != 'motor' > > GROUP BY t1.id > > ORDER BY viktatantal DESC, RAND() > > LIMIT 80 > > > > Any help would be very appriciated! > > > You should use EXPLAIN. If you don't understand the output of > EXPLAIN, post the output back to this list and we can help you > understand it. > > Cheers > > Baron >
