questions

• Selecting access methods
  • Table scan
  • Index scan
  • Ref accesss
  • Range scan
  • Index merge
  • Losse index scan
• 全表扫描怎么扫？
• 最左前缀是什么意思？
• 1亿条记录的B+树高度是多少？
• Row是怎么存储在磁盘上面的？
• 多个字段进行索引，顺序有什么区别？哪种最优？
• Looser index scan? how ?
• 下面的查询索引怎么扫描？
  • select * from tbl_name where key =?
  • select * from tbl_name where key IN (?,?,?....)
  • select * from tbl_name where key between ? and ?;
  • select * from tbl_name where key < ?;
  • select * from tbl_name where key > ?;
  • SELECT * FROM tbl_name WHERE key1 = 10 OR key2 = 20;
• Index merge?