mysql - BIT(1) vs ENUM('unknown', 'male', 'female') in MySQL

Question

In performance terms, what will be faster, use a BIT(1) NULL (null = unknown, 0 = male, 1 = female) or ENUM('unknown', 'male', 'female') NOT NULL DEFAULT 'unknown' in MySQL MyISAM?

Or this is considered micro-optimization?

[EDIT]

I think I'm going to use ENUM('male', 'female') DEFAULT NULL

Answer 1

Yes, this is microoptimization. Performance will be dominated by other things, and anyway nullable fields take more space (for a null flag) so use the meaningful enumeration.

Answer 2

我认为这种微优化。

我会选择 ENUM 选项，因为所有值的含义都是完全清楚的，无需阅读文档。位选项有点模糊。

关于性能，我似乎记得 NULL 通常很糟糕，但现在找不到参考。