# Split Write Hotspot (B)

+ table schema
  + `AUTO_RANDOM` 
```
CREATE TABLE t (a bigint PRIMARY KEY AUTO_RANDOM, b varchar(255))
```

![left](./student-guide/diagram/21-Database-object-02-01.png)

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CREATE TABLE t (a bigint PRIMARY KEY AUTO_RANDOM, b varchar (255))
- AUTO_RANDOM
Use the Bigint primary key while using AUTO_RANDOM to complete the region predispersion. auto_random can be followed by an optional pair of parentheses that specify a positive integer not greater than the length of the column type, indicating how many bits (bits) the column reserves to “randomly” assign a value, that is, the degree to which it is automatically dispersed. The larger the integer, the greater the degree of dispersion. If omitted, the value defaults to 5.

The following two heat plots are the results of the Sysbench insert pressure test:
AUTO_RANDOM not used