1. Which will be faster out of these two queries – one with OR or one with IN?
2. Where does MyISAM cache table records?
3. Which will be faster out of queries with explicit INNER JOIN and implicit one?
4. Is InnoDB faster/better than MyISAM?
5. Is CHAR faster than VARCHAR?
6. Is VARCHAR(80) faster than VARCHAR(255)?

7. Are there performance issues when joining tables from different storage engines?
8. If I change a derived table to a view, will performance increase?
9. If I see Using temporary; Using filesort” in the Extra column of EXPLAIN output, does that mean a temporary table is created on disk?
10. Is it possible to do a FULL OUTER JOIN in MySQL?