MySQL json字段索引添加及使用

在业务系统中，由于上级接口的变化，我们需要不断的在一张特别大的表上新增字段、同时修改源码。为了后续新增字段方便，我们在表上添加了一列 extra_config，用来存储后续添加的字段

建表

sql 复制代码

create table outer_order
(
    id           bigint primary key auto_increment,
    extra_config json,
    create_time  datetime(3) DEFAULT CURRENT_TIMESTAMP(3),
    update_time  datetime(3) default null ON UPDATE CURRENT_TIMESTAMP(3)
);

插入数据

sql 复制代码

insert into outer_order (extra_config)
values ('{"zipcode":"430101","price": 1.92, "quantity": 1, "alias_array":  [1,3]}'),
       ('{"zipcode":"430102","price": 2.92, "quantity": 2, "alias_array":  [2,3]}'),
       ('{"zipcode":"430103","price": 3.92, "quantity": 3, "alias_array":  [4,3]}'),
       ('{"zipcode":"430104","price": 4.92, "quantity": 4, "alias_array":  [5,3]}'),
       ('{"zipcode":"430105","price": 5.92, "quantity": 5, "alias_array":  [6,3]}'),
       ('{"zipcode":"430106","price": 6.92, "quantity": 6, "alias_array":  [7,3]}'),
       ('{"zipcode":"430107","price": 7.92, "quantity": 7, "alias_array":  [8,3]}'),
       ('{"zipcode":"430107","price": 8.92, "quantity": 8, "alias_array":  [9,3]}')
;

添加虚拟列

sql 复制代码

alter table outer_order add column extra_config_price decimal(11,2) generated always as (extra_config->>'$.price') not null;

添加索引

sql 复制代码

alter table outer_order add index idx_vm_extra_config_price (extra_config_price);

使用索引

sql 复制代码

explain select id from outer_order where extra_config_price = 1.92;

结果如下

复制代码

*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: outer_order
   partitions: NULL
         type: ref
possible_keys: idx_vm_extra_config_price
          key: idx_vm_extra_config_price
      key_len: 5
          ref: const
         rows: 1
     filtered: 100.00
        Extra: Using index
1 row in set, 1 warning (0.00 sec)