案例背景

  • 高峰期商品系统大量慢查询警告

    慢查询SQL(简化)

  • select * from products where category=’xx’ and sub_category=’xx’ order by id desc limit m,n

  • 慢查询原因：Expain后发现没有走索引: Index_category(category,sub_category)
  • 修改：强制走索引force index
  • select * from products force index(Index_category) where category=’xx’ and sub_category=’xx’ order by id desc limit m,n