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303 lines
6.5 KiB
Markdown
303 lines
6.5 KiB
Markdown
---
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toc_priority: 48
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toc_title: Bit
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---
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# Bit Functions {#bit-functions}
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Bit functions work for any pair of types from UInt8, UInt16, UInt32, UInt64, Int8, Int16, Int32, Int64, Float32, or Float64.
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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.
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## bitAnd(a, b) {#bitanda-b}
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## bitOr(a, b) {#bitora-b}
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## bitXor(a, b) {#bitxora-b}
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## bitNot(a) {#bitnota}
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## bitShiftLeft(a, b) {#bitshiftlefta-b}
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## bitShiftRight(a, b) {#bitshiftrighta-b}
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## bitRotateLeft(a, b) {#bitrotatelefta-b}
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## bitRotateRight(a, b) {#bitrotaterighta-b}
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## bitTest {#bittest}
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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. The countdown starts from 0 from the right to the left.
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**Syntax**
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``` sql
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SELECT bitTest(number, index)
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```
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**Arguments**
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- `number` – Integer number.
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- `index` – Position of bit.
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**Returned values**
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Returns a value of bit at specified position.
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Type: `UInt8`.
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**Example**
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For example, the number 43 in base-2 (binary) numeral system is 101011.
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Query:
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``` sql
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SELECT bitTest(43, 1);
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```
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Result:
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``` text
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┌─bitTest(43, 1)─┐
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│ 1 │
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└────────────────┘
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```
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Another example:
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Query:
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``` sql
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SELECT bitTest(43, 2);
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```
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Result:
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``` text
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┌─bitTest(43, 2)─┐
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│ 0 │
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└────────────────┘
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```
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## bitTestAll {#bittestall}
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Returns result of [logical conjuction](https://en.wikipedia.org/wiki/Logical_conjunction) (AND operator) of all bits at given positions. The countdown starts from 0 from the right to the left.
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The conjuction for bitwise operations:
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0 AND 0 = 0
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0 AND 1 = 0
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1 AND 0 = 0
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1 AND 1 = 1
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**Syntax**
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``` sql
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SELECT bitTestAll(number, index1, index2, index3, index4, ...)
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```
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**Arguments**
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- `number` – Integer number.
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- `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`).
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**Returned values**
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Returns result of logical conjuction.
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Type: `UInt8`.
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**Example**
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For example, the number 43 in base-2 (binary) numeral system is 101011.
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Query:
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``` sql
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SELECT bitTestAll(43, 0, 1, 3, 5);
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```
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Result:
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``` text
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┌─bitTestAll(43, 0, 1, 3, 5)─┐
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│ 1 │
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└────────────────────────────┘
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```
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Another example:
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Query:
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``` sql
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SELECT bitTestAll(43, 0, 1, 3, 5, 2);
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```
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Result:
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``` text
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┌─bitTestAll(43, 0, 1, 3, 5, 2)─┐
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│ 0 │
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└───────────────────────────────┘
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```
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## bitTestAny {#bittestany}
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Returns result of [logical disjunction](https://en.wikipedia.org/wiki/Logical_disjunction) (OR operator) of all bits at given positions. The countdown starts from 0 from the right to the left.
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The disjunction for bitwise operations:
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0 OR 0 = 0
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0 OR 1 = 1
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1 OR 0 = 1
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1 OR 1 = 1
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**Syntax**
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``` sql
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SELECT bitTestAny(number, index1, index2, index3, index4, ...)
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```
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**Arguments**
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- `number` – Integer number.
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- `index1`, `index2`, `index3`, `index4` – Positions of bit.
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**Returned values**
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Returns result of logical disjuction.
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Type: `UInt8`.
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**Example**
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For example, the number 43 in base-2 (binary) numeral system is 101011.
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Query:
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``` sql
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SELECT bitTestAny(43, 0, 2);
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```
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Result:
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``` text
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┌─bitTestAny(43, 0, 2)─┐
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│ 1 │
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└──────────────────────┘
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```
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Another example:
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Query:
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``` sql
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SELECT bitTestAny(43, 4, 2);
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```
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Result:
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``` text
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┌─bitTestAny(43, 4, 2)─┐
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│ 0 │
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└──────────────────────┘
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```
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## bitCount {#bitcount}
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Calculates the number of bits set to one in the binary representation of a number.
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**Syntax**
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``` sql
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bitCount(x)
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```
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**Arguments**
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- `x` — [Integer](../../sql-reference/data-types/int-uint.md) or [floating-point](../../sql-reference/data-types/float.md) number. The function uses the value representation in memory. It allows supporting floating-point numbers.
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**Returned value**
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- Number of bits set to one in the input number.
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The function does not convert input value to a larger type ([sign extension](https://en.wikipedia.org/wiki/Sign_extension)). So, for example, `bitCount(toUInt8(-1)) = 8`.
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Type: `UInt8`.
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**Example**
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Take for example the number 333. Its binary representation: 0000000101001101.
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Query:
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``` sql
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SELECT bitCount(333);
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```
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Result:
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``` text
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┌─bitCount(333)─┐
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│ 5 │
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└───────────────┘
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```
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## bitHammingDistance {#bithammingdistance}
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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.
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**Syntax**
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``` sql
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bitHammingDistance(int1, int2)
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```
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**Arguments**
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- `int1` — First integer value. [Int64](../../sql-reference/data-types/int-uint.md).
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- `int2` — Second integer value. [Int64](../../sql-reference/data-types/int-uint.md).
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**Returned value**
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- The Hamming distance.
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Type: [UInt8](../../sql-reference/data-types/int-uint.md).
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**Examples**
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Query:
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``` sql
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SELECT bitHammingDistance(111, 121);
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```
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Result:
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``` text
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┌─bitHammingDistance(111, 121)─┐
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│ 3 │
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└──────────────────────────────┘
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```
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With [SimHash](../../sql-reference/functions/hash-functions.md#ngramsimhash):
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``` sql
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SELECT bitHammingDistance(ngramSimHash('cat ate rat'), ngramSimHash('rat ate cat'));
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```
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Result:
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``` text
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┌─bitHammingDistance(ngramSimHash('cat ate rat'), ngramSimHash('rat ate cat'))─┐
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│ 5 │
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└──────────────────────────────────────────────────────────────────────────────┘
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```
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