mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-15 19:02:04 +00:00
441 lines
14 KiB
Markdown
441 lines
14 KiB
Markdown
---
|
||
slug: /en/sql-reference/functions/bit-functions
|
||
sidebar_position: 20
|
||
sidebar_label: Bit
|
||
---
|
||
|
||
# Bit Functions
|
||
|
||
Bit functions work for any pair of types from `UInt8`, `UInt16`, `UInt32`, `UInt64`, `Int8`, `Int16`, `Int32`, `Int64`, `Float32`, or `Float64`. Some functions support `String` and `FixedString` types.
|
||
|
||
The result type is an integer with bits equal to the maximum bits of its arguments. If at least one of the arguments is signed, the result is a signed number. If an argument is a floating-point number, it is cast to Int64.
|
||
|
||
## bitAnd(a, b)
|
||
|
||
## bitOr(a, b)
|
||
|
||
## bitXor(a, b)
|
||
|
||
## bitNot(a)
|
||
|
||
## bitShiftLeft(a, b)
|
||
|
||
Shifts the binary representation of a value to the left by a specified number of bit positions.
|
||
|
||
A `FixedString` or a `String` is treated as a single multibyte value.
|
||
|
||
Bits of a `FixedString` value are lost as they are shifted out. On the contrary, a `String` value is extended with additional bytes, so no bits are lost.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
bitShiftLeft(a, b)
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `a` — A value to shift. [Integer types](../data-types/int-uint.md), [String](../data-types/string.md) or [FixedString](../data-types/fixedstring.md).
|
||
- `b` — The number of shift positions. [Unsigned integer types](../data-types/int-uint.md), 64 bit types or less are allowed.
|
||
|
||
**Returned value**
|
||
|
||
- Shifted value.
|
||
|
||
The type of the returned value is the same as the type of the input value.
|
||
|
||
**Example**
|
||
|
||
In the following queries [bin](encoding-functions.md#bin) and [hex](encoding-functions.md#hex) functions are used to show bits of shifted values.
|
||
|
||
``` sql
|
||
SELECT 99 AS a, bin(a), bitShiftLeft(a, 2) AS a_shifted, bin(a_shifted);
|
||
SELECT 'abc' AS a, hex(a), bitShiftLeft(a, 4) AS a_shifted, hex(a_shifted);
|
||
SELECT toFixedString('abc', 3) AS a, hex(a), bitShiftLeft(a, 4) AS a_shifted, hex(a_shifted);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌──a─┬─bin(99)──┬─a_shifted─┬─bin(bitShiftLeft(99, 2))─┐
|
||
│ 99 │ 01100011 │ 140 │ 10001100 │
|
||
└────┴──────────┴───────────┴──────────────────────────┘
|
||
┌─a───┬─hex('abc')─┬─a_shifted─┬─hex(bitShiftLeft('abc', 4))─┐
|
||
│ abc │ 616263 │ &0 │ 06162630 │
|
||
└─────┴────────────┴───────────┴─────────────────────────────┘
|
||
┌─a───┬─hex(toFixedString('abc', 3))─┬─a_shifted─┬─hex(bitShiftLeft(toFixedString('abc', 3), 4))─┐
|
||
│ abc │ 616263 │ &0 │ 162630 │
|
||
└─────┴──────────────────────────────┴───────────┴───────────────────────────────────────────────┘
|
||
```
|
||
|
||
## bitShiftRight(a, b)
|
||
|
||
Shifts the binary representation of a value to the right by a specified number of bit positions.
|
||
|
||
A `FixedString` or a `String` is treated as a single multibyte value. Note that the length of a `String` value is reduced as bits are shifted out.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
bitShiftRight(a, b)
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `a` — A value to shift. [Integer types](../data-types/int-uint.md), [String](../data-types/string.md) or [FixedString](../data-types/fixedstring.md).
|
||
- `b` — The number of shift positions. [Unsigned integer types](../data-types/int-uint.md), 64 bit types or less are allowed.
|
||
|
||
**Returned value**
|
||
|
||
- Shifted value.
|
||
|
||
The type of the returned value is the same as the type of the input value.
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT 101 AS a, bin(a), bitShiftRight(a, 2) AS a_shifted, bin(a_shifted);
|
||
SELECT 'abc' AS a, hex(a), bitShiftRight(a, 12) AS a_shifted, hex(a_shifted);
|
||
SELECT toFixedString('abc', 3) AS a, hex(a), bitShiftRight(a, 12) AS a_shifted, hex(a_shifted);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌───a─┬─bin(101)─┬─a_shifted─┬─bin(bitShiftRight(101, 2))─┐
|
||
│ 101 │ 01100101 │ 25 │ 00011001 │
|
||
└─────┴──────────┴───────────┴────────────────────────────┘
|
||
┌─a───┬─hex('abc')─┬─a_shifted─┬─hex(bitShiftRight('abc', 12))─┐
|
||
│ abc │ 616263 │ │ 0616 │
|
||
└─────┴────────────┴───────────┴───────────────────────────────┘
|
||
┌─a───┬─hex(toFixedString('abc', 3))─┬─a_shifted─┬─hex(bitShiftRight(toFixedString('abc', 3), 12))─┐
|
||
│ abc │ 616263 │ │ 000616 │
|
||
└─────┴──────────────────────────────┴───────────┴─────────────────────────────────────────────────┘
|
||
```
|
||
|
||
## bitRotateLeft(a, b)
|
||
|
||
## bitRotateRight(a, b)
|
||
|
||
## bitSlice(s, offset, length)
|
||
|
||
Returns a substring starting with the bit from the ‘offset’ index that is ‘length’ bits long. bits indexing starts from
|
||
1
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
bitSlice(s, offset[, length])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `s` — s is [String](../data-types/string.md) or [FixedString](../data-types/fixedstring.md).
|
||
- `offset` — The start index with bit, A positive value indicates an offset on the left, and a negative value is an indent on the right. Numbering of the bits begins with 1.
|
||
- `length` — The length of substring with bit. If you specify a negative value, the function returns an open substring \[offset, array_length - length\]. If you omit the value, the function returns the substring \[offset, the_end_string\]. If length exceeds s, it will be truncate.If length isn't multiple of 8, will fill 0 on the right.
|
||
|
||
**Returned value**
|
||
|
||
- The substring. [String](../data-types/string.md)
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
select bin('Hello'), bin(bitSlice('Hello', 1, 8))
|
||
select bin('Hello'), bin(bitSlice('Hello', 1, 2))
|
||
select bin('Hello'), bin(bitSlice('Hello', 1, 9))
|
||
select bin('Hello'), bin(bitSlice('Hello', -4, 8))
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bin('Hello')─────────────────────────────┬─bin(bitSlice('Hello', 1, 8))─┐
|
||
│ 0100100001100101011011000110110001101111 │ 01001000 │
|
||
└──────────────────────────────────────────┴──────────────────────────────┘
|
||
┌─bin('Hello')─────────────────────────────┬─bin(bitSlice('Hello', 1, 2))─┐
|
||
│ 0100100001100101011011000110110001101111 │ 01000000 │
|
||
└──────────────────────────────────────────┴──────────────────────────────┘
|
||
┌─bin('Hello')─────────────────────────────┬─bin(bitSlice('Hello', 1, 9))─┐
|
||
│ 0100100001100101011011000110110001101111 │ 0100100000000000 │
|
||
└──────────────────────────────────────────┴──────────────────────────────┘
|
||
┌─bin('Hello')─────────────────────────────┬─bin(bitSlice('Hello', -4, 8))─┐
|
||
│ 0100100001100101011011000110110001101111 │ 11110000 │
|
||
└──────────────────────────────────────────┴───────────────────────────────┘
|
||
```
|
||
|
||
## byteSlice(s, offset, length)
|
||
|
||
See function [substring](string-functions.md#substring).
|
||
|
||
## bitTest
|
||
|
||
Takes any integer and converts it into [binary form](https://en.wikipedia.org/wiki/Binary_number), returns the value of a bit at specified position. Counting is right-to-left, starting at 0.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
SELECT bitTest(number, index)
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `number` – Integer number.
|
||
- `index` – Position of bit.
|
||
|
||
**Returned value**
|
||
|
||
- Value of the bit at the specified position. [UInt8](../data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
For example, the number 43 in base-2 (binary) numeral system is 101011.
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT bitTest(43, 1);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitTest(43, 1)─┐
|
||
│ 1 │
|
||
└────────────────┘
|
||
```
|
||
|
||
Another example:
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT bitTest(43, 2);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitTest(43, 2)─┐
|
||
│ 0 │
|
||
└────────────────┘
|
||
```
|
||
|
||
## bitTestAll
|
||
|
||
Returns result of [logical conjunction](https://en.wikipedia.org/wiki/Logical_conjunction) (AND operator) of all bits at given positions. Counting is right-to-left, starting at 0.
|
||
|
||
The conjunction for bit-wise operations:
|
||
|
||
0 AND 0 = 0
|
||
|
||
0 AND 1 = 0
|
||
|
||
1 AND 0 = 0
|
||
|
||
1 AND 1 = 1
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
SELECT bitTestAll(number, index1, index2, index3, index4, ...)
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `number` – Integer number.
|
||
- `index1`, `index2`, `index3`, `index4` – Positions of bit. For example, for set of positions (`index1`, `index2`, `index3`, `index4`) is true if and only if all of its positions are true (`index1` ⋀ `index2`, ⋀ `index3` ⋀ `index4`).
|
||
|
||
**Returned value**
|
||
|
||
- Result of the logical conjunction. [UInt8](../data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
For example, the number 43 in base-2 (binary) numeral system is 101011.
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT bitTestAll(43, 0, 1, 3, 5);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitTestAll(43, 0, 1, 3, 5)─┐
|
||
│ 1 │
|
||
└────────────────────────────┘
|
||
```
|
||
|
||
Another example:
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT bitTestAll(43, 0, 1, 3, 5, 2);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitTestAll(43, 0, 1, 3, 5, 2)─┐
|
||
│ 0 │
|
||
└───────────────────────────────┘
|
||
```
|
||
|
||
## bitTestAny
|
||
|
||
Returns result of [logical disjunction](https://en.wikipedia.org/wiki/Logical_disjunction) (OR operator) of all bits at given positions. Counting is right-to-left, starting at 0.
|
||
|
||
The disjunction for bit-wise operations:
|
||
|
||
0 OR 0 = 0
|
||
|
||
0 OR 1 = 1
|
||
|
||
1 OR 0 = 1
|
||
|
||
1 OR 1 = 1
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
SELECT bitTestAny(number, index1, index2, index3, index4, ...)
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `number` – Integer number.
|
||
- `index1`, `index2`, `index3`, `index4` – Positions of bit.
|
||
|
||
**Returned value**
|
||
|
||
- Result of the logical disjunction. [UInt8](../data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
For example, the number 43 in base-2 (binary) numeral system is 101011.
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT bitTestAny(43, 0, 2);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitTestAny(43, 0, 2)─┐
|
||
│ 1 │
|
||
└──────────────────────┘
|
||
```
|
||
|
||
Another example:
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT bitTestAny(43, 4, 2);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitTestAny(43, 4, 2)─┐
|
||
│ 0 │
|
||
└──────────────────────┘
|
||
```
|
||
|
||
## bitCount
|
||
|
||
Calculates the number of bits set to one in the binary representation of a number.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
bitCount(x)
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `x` — [Integer](../data-types/int-uint.md) or [floating-point](../data-types/float.md) number. The function uses the value representation in memory. It allows supporting floating-point numbers.
|
||
|
||
**Returned value**
|
||
|
||
- Number of bits set to one in the input number. [UInt8](../data-types/int-uint.md).
|
||
|
||
:::note
|
||
The function does not convert the input value to a larger type ([sign extension](https://en.wikipedia.org/wiki/Sign_extension)). So, for example, `bitCount(toUInt8(-1)) = 8`.
|
||
:::
|
||
|
||
**Example**
|
||
|
||
Take for example the number 333. Its binary representation: 0000000101001101.
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT bitCount(333);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitCount(333)─┐
|
||
│ 5 │
|
||
└───────────────┘
|
||
```
|
||
|
||
## bitHammingDistance
|
||
|
||
Returns the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) between the bit representations of two integer values. Can be used with [SimHash](../../sql-reference/functions/hash-functions.md#ngramsimhash) functions for detection of semi-duplicate strings. The smaller is the distance, the more likely those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
bitHammingDistance(int1, int2)
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `int1` — First integer value. [Int64](../data-types/int-uint.md).
|
||
- `int2` — Second integer value. [Int64](../data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- The Hamming distance. [UInt8](../data-types/int-uint.md).
|
||
|
||
**Examples**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT bitHammingDistance(111, 121);
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitHammingDistance(111, 121)─┐
|
||
│ 3 │
|
||
└──────────────────────────────┘
|
||
```
|
||
|
||
With [SimHash](../../sql-reference/functions/hash-functions.md#ngramsimhash):
|
||
|
||
``` sql
|
||
SELECT bitHammingDistance(ngramSimHash('cat ate rat'), ngramSimHash('rat ate cat'));
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─bitHammingDistance(ngramSimHash('cat ate rat'), ngramSimHash('rat ate cat'))─┐
|
||
│ 5 │
|
||
└──────────────────────────────────────────────────────────────────────────────┘
|
||
```
|