![]() ![]() You're really, really, really unlikely to allocate more than 2 63-1 primary key values, even if you delete all your rows and re-load them many times a day. Like any other integer data type, it can be signed or unsigned. UNSIGNED (and SIGNED, which is the default) are MySQL extensions that can be useful to store higher unsigned numbers in the same amount of bytes, and disallow negative numbers. In SQL standard, all numeric types are signed. Any table that would exceed the maximum signed integer value 2 31-1 is likely to continue to grow, so you should just use a BIGINT for these tables. MySQL BIGINT data type is a b byte or 64 integer value that can store huge integer values. They dont support the SIGNED and UNSIGNED keyword because theyre not standard. Either way, you get the same absolute number of distinct values.īut since AUTO_INCREMENT starts at zero by default and increments in the positive direction, it's more convenient to utilize the positive values than the negative values.īut it hardly matters that you get 2X as many positive values. If the number is signed, you get values from -max/2 to max/2-1. If the number is unsigned, you get values from 0 to that max value minus one. to your MySQL server version for the right syntax to use near unsigned integer. If UNSIGNED is specified, no portion of the numeric type is reserved for the sign, so for integer types range can be larger. ![]() You get the same number of distinct values whether you declare an integer signed or unsigned: 2 32 for an INT and 2 64 for a BIGINT. ID - Unsigned integer Name - Variable-length string with maximum 40. `foo_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT, ![]() Go ahead try it: CREATE TABLE test.foo (foo_id SERIAL PRIMARY KEY) For numeric operators (such as + or -) where one of the operands is an unsigned integer, the result is unsigned by default (see Section 12.6.1, Arithmetic Operators). This data type is just shorthand that creates a BIGINT UNSIGNED. MySQL supports an optional SERIAL data type (presumably for compatibility with PostgreSQL, since SERIAL is not standard ANSI SQL). You will have to upgrade to BIGINT anyway. I have a table that has a primary key like id int(11) unsigned autoincrement primary key.The table has 100 mln rows and I estimated its size to 28GB. Use next larger type: then there is no any space saving while users may think that they have it. Here's a table of the ranges of values each INTEGER type can store: UNSIGNED ranges from 0 to n, while signed ranges from about -n/2 to n/2. On the other hand, signed can store negative numbers (i.e., may have a negative sign ). On the other hand, if your table uses 2 31 values, it will probably also use 2 32 values in a short time, so having twice the range of values isn't a big difference. Use sign bit and always move: but this makes calculation logic complicated. UNSIGNED only stores positive numbers (or zero). You might as well make it unsigned, and you get twice the range of values. TL/DR: Yes, but it almost doesn't matter.Īuto-increment always increases, so it will never use negative values. ![]()
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