我们应该使用float作为sql-server中的主键

Question

some one suggested me its a better idea to use float as a primary key of a table instead of using the BIGINT. can we make float primary key to be identity ?

Answer 1

Considerations:

• you CAN make a float field primary key.
• you CANT make a float field IDENTITY. Identity columns must be of data type int, bigint, smallint, tinyint, or decimal or numeric with a scale of 0
• you ABSOLUTELY SHOULD NOT use a float field as a PK. Again, you CAN, SQL Server will allow you but its not recommended mainly because floats are inaccurate as @Andy said.

why do you need a float as a PK anyway? Do you need a value like 3,1234235234534 to uniquely identify your row?

Answer 2

Notice how if you do float a=1f and float b=1f they are the same right ?

However if(a==b) will likely not be true as floats are inaccurate.

Answer 3

Why not use big data type for primary keys:

Keep the "width" of your indexes as narrow as possible. This reduces the size of the index and reduces the number of disk I/O reads required to read the index, boosting performance.

If possible, try to create indexes on columns that have integer values instead of characters. Integer values have less overhead than character values.

Don't use FLOAT or REAL data types for primary keys, as they add unnecessary overhead and can hurt performance.

Indexes on narrow columns are preferable to indexes on wide columns. The narrower the index, the more entries SQL Server can fit on a data page, which in turn reduces the amount of I/O required to access the data.

Reduce the size of the keys, thus decreasing read I/O during the join process, and increasing overall performance.

Answer 4

You can not make float as a identity.

And it is very bad idea to use float as the primary key. You must go with the bigint.