Changing plans (hint hint)
 
 
- Most database systems provide some way to influence the execution plan - typically via ‘hints’
- Oracle supports a very large and complex range of hints
- 
- Hints must be contained within special comments /*+ … */
 
		SELECT /*+ INDEX(table1 index1) */ foo, bar
		FROM table1 WHERE key1=1 AND key2=2 AND key3=3;
		
- MySQL has a very limited set of hints
- 
- Hints can optionally be placed inside comments /*! … */
 
		SELECT foo, bar FROM table1 /*! USE INDEX (key1,key2) */
		WHERE key1=1 AND key2=2 AND key3=3;