MySQL 表中 varchar 长度的重要性
我有一个 MySQL 表，其中的行是动态插入的.因为我不能确定字符串的长度并且不希望它们被切断，所以我使它们 varchar(200) 通常比我需要的大得多.为 varchar 字段提供比所需更长的长度是否会对性能造成很大影响?
I have a MySQL table where rows are inserted dynamically. Because I can not be certain of the length of strings and do not want them cut off, I make them varchar(200) which is generally much bigger than I need. Is there a big performance hit in giving a varchar field much more length than necessary?
推荐答案
不，如果您存储在该列中的值始终(例如)少于 50 个字符，则将该列声明为 varchar(50) 或 varchar(200) 具有相同的性能.
No, in the sense that if the values you're storing in that column are always (say) less than 50 characters, declaring the column as varchar(50) or varchar(200) has the same performance.
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