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Asked: 2026-05-11T03:23:15+00:00

I wonder is there any positive effect in using UNSIGNED flag on defining some

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I wonder is there any positive effect in using UNSIGNED flag on defining some integer field in MySQL? Does it make queries faster or database smaller? Or should I only bother with it if I’m concerned about upper limit?

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  1. According to section 10.2 of the MySQL 5.1 Manual:

    In non-strict mode, when an out-of-range value is assigned to an integer column, MySQL stores the value representing the corresponding endpoint of the column data type range. If you store 256 into a TINYINT or TINYINT UNSIGNED column, MySQL stores 127 or 255, respectively. When a floating-point or fixed-point column is assigned a value that exceeds the range implied by the specified (or default) precision and scale, MySQL stores the value representing the corresponding endpoint of that range.

    So using UNSIGNED is really only necessary when you are concerned about the upper bound. Also adding UNSIGNED does not affect the size of the column just how the number is represented.

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