how do indices in mysql tables (MyISAM) work?
- by understack
Few basic doubts I have:
1. Is primary key column automatically indexed?
2. What should be criteria to select index column?
3. When should I club multiple columns?
4. Does MyISAM or InnoDB has any affect on this?
5. Are they really required, specially in case if primary key column is automatically indexed?
Thanks.