-2
votes
3answers
169 views

True or False: a table with large records (rows) and lots of fields (columns) will take longer to return a SQL query? [closed]

True or False: a table with large records (rows) due to lots of fields (columns) will take longer to return a SQL query? That is, if I have a SELECT ... WHERE...query in SQL that operates on a table ...
0
votes
1answer
816 views

Weird MySQL query plan: why is this query using temporary & filesort? How to optimize it?

I have a query: SELECT * FROM amp_ads,amp_c,amp_c_countries WHERE (amp_c.zone = '24' OR amp_c.zone = '25') AND amp_ads.ad_complete = '1' AND amp_ads.ad_type = '17' AND amp_ads.accept = '1' ...