mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-10 09:32:06 +00:00
Merge pull request #52359 from rschu1ze/docs-integer-promotion
Docs: Add another reason for integer promotion rules in ClickHouse
This commit is contained in:
commit
a73f621bf4
@ -6,9 +6,20 @@ sidebar_label: Arithmetic
|
||||
|
||||
# Arithmetic Functions
|
||||
|
||||
The result type of all arithmetic functions is the smallest type which can represent all possible results. Size promotion happens for integers up to 32 bit, e.g. `UInt8 + UInt16 = UInt32`. If one of the inters has 64 or more bits, the result is of the same type as the bigger of the input integers, e.g. `UInt16 + UInt128 = UInt128`. While this introduces a risk of overflows around the value range boundary, it ensures that calculations are performed quickly using the maximum native integer width of 64 bit.
|
||||
Arithmetic functions work for any two operands of type `UInt8`, `UInt16`, `UInt32`, `UInt64`, `Int8`, `Int16`, `Int32`, `Int64`, `Float32`, or `Float64`.
|
||||
|
||||
The result of addition or multiplication of two integers is unsigned unless one of the integers is signed.
|
||||
Before performing the operation, both operands are casted to the result type. The result type is determined as follows (unless specified
|
||||
differently in the function documentation below):
|
||||
- If both operands are up to 32 bits wide, the size of the result type will be the size of the next bigger type following the bigger of the
|
||||
two operands (integer size promotion). For example, `UInt8 + UInt16 = UInt32` or `Float32 * Float32 = Float64`.
|
||||
- If one of the operands has 64 or more bits, the size of the result type will be the same size as the bigger of the two operands. For
|
||||
example, `UInt32 + UInt128 = UInt128` or `Float32 * Float64 = Float64`.
|
||||
- If one of the operands is signed, the result type will also be signed, otherwise it will be signed. For example, `UInt32 * Int32 = Int64`.
|
||||
|
||||
These rules make sure that the result type will be the smallest type which can represent all possible results. While this introduces a risk
|
||||
of overflows around the value range boundary, it ensures that calculations are performed quickly using the maximum native integer width of
|
||||
64 bit. This behavior also guarantees compatibility with many other databases which provide 64 bit integers (BIGINT) as the biggest integer
|
||||
type.
|
||||
|
||||
Example:
|
||||
|
||||
@ -22,8 +33,6 @@ SELECT toTypeName(0), toTypeName(0 + 0), toTypeName(0 + 0 + 0), toTypeName(0 + 0
|
||||
└───────────────┴────────────────────────┴─────────────────────────────────┴──────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
Arithmetic functions work for any pair of `UInt8`, `UInt16`, `UInt32`, `UInt64`, `Int8`, `Int16`, `Int32`, `Int64`, `Float32`, or `Float64` values.
|
||||
|
||||
Overflows are produced the same way as in C++.
|
||||
|
||||
## plus
|
||||
@ -68,7 +77,7 @@ Alias: `a \* b` (operator)
|
||||
|
||||
## divide
|
||||
|
||||
Calculates the quotient of two values `a` and `b`. The result is always a floating-point value. If you need integer division, you can use the `intDiv` function.
|
||||
Calculates the quotient of two values `a` and `b`. The result type is always [Float64](../../sql-reference/data-types/float.md). Integer division is provided by the `intDiv` function.
|
||||
|
||||
Division by 0 returns `inf`, `-inf`, or `nan`.
|
||||
|
||||
@ -84,7 +93,7 @@ Alias: `a / b` (operator)
|
||||
|
||||
Performs an integer division of two values `a` by `b`, i.e. computes the quotient rounded down to the next smallest integer.
|
||||
|
||||
The result has the same type as the dividend (the first parameter).
|
||||
The result has the same width as the dividend (the first parameter).
|
||||
|
||||
An exception is thrown when dividing by zero, when the quotient does not fit in the range of the dividend, or when dividing a minimal negative number by minus one.
|
||||
|
||||
@ -135,7 +144,7 @@ intDivOrZero(a, b)
|
||||
|
||||
Calculates the remainder of the division of two values `a` by `b`.
|
||||
|
||||
The result type is an integer if both inputs are integers. If one of the inputs is a floating-point number, the result is a floating-point number.
|
||||
The result type is an integer if both inputs are integers. If one of the inputs is a floating-point number, the result type is [Float64](../../sql-reference/data-types/float.md).
|
||||
|
||||
The remainder is computed like in C++. Truncated division is used for negative numbers.
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user