python - Django内存数据库模型创建失败

Question

我正在使用 MariaDB MEMORY 引擎。我在my.cnf中定义了max_heap_table_size，重新启动了数据库服务。现在，我运行迁移并得到:

django.db.utils.ProgrammingError:存储引擎 MEMORY 不支持 BLOB/TEXT 列

我的错误模型是:

class Department(models.Model):
    name = models.CharField(max_length=100)
    tag = models.CharField(max_length=10)
    dtype = models.PositiveSmallIntegerField()
    info = models.CharField(max_length=64000)

但是，最大 VARCHAR 是 65535。问题是什么？

Answer 1

正如文档所述 here , 65.535 实际上是字节，如果使用 UTF-8，则最多可容纳 21.844 个字符。

A variable-length string. M represents the maximum column length in characters. The range of M is 0 to 65,535. The effective maximum length of a VARCHAR is subject to the maximum row size (65,535 bytes, which is shared among all columns) and the character set used. For example, utf8 characters can require up to three bytes per character, so a VARCHAR column that uses the utf8 character set can be declared to be a maximum of 21,844 characters.

自 max_length Django 模型中的 CharField 指定字符长度而不是字节长度，我认为这就是导致错误的原因。