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1424 lines
55 KiB
Markdown
1424 lines
55 KiB
Markdown
---
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toc_priority: 50
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toc_title: Hash
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---
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# Hash Functions {#hash-functions}
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Hash functions can be used for the deterministic pseudo-random shuffling of elements.
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Simhash is a hash function, which returns close hash values for close (similar) arguments.
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## halfMD5 {#hash-functions-halfmd5}
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[Interprets](../../sql-reference/functions/type-conversion-functions.md#type_conversion_functions-reinterpretAsString) all the input parameters as strings and calculates the [MD5](https://en.wikipedia.org/wiki/MD5) hash value for each of them. Then combines hashes, takes the first 8 bytes of the hash of the resulting string, and interprets them as `UInt64` in big-endian byte order.
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``` sql
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halfMD5(par1, ...)
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```
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The function is relatively slow (5 million short strings per second per processor core).
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Consider using the [sipHash64](#hash_functions-siphash64) function instead.
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**Arguments**
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The function takes a variable number of input parameters. Arguments can be any of the [supported data types](../../sql-reference/data-types/index.md).
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**Returned Value**
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A [UInt64](../../sql-reference/data-types/int-uint.md) data type hash value.
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**Example**
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``` sql
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SELECT halfMD5(array('e','x','a'), 'mple', 10, toDateTime('2019-06-15 23:00:00')) AS halfMD5hash, toTypeName(halfMD5hash) AS type;
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```
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``` text
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┌────────halfMD5hash─┬─type───┐
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│ 186182704141653334 │ UInt64 │
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└────────────────────┴────────┘
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```
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## MD5 {#hash_functions-md5}
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Calculates the MD5 from a string and returns the resulting set of bytes as FixedString(16).
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If you do not need MD5 in particular, but you need a decent cryptographic 128-bit hash, use the ‘sipHash128’ function instead.
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If you want to get the same result as output by the md5sum utility, use lower(hex(MD5(s))).
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## sipHash64 {#hash_functions-siphash64}
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Produces a 64-bit [SipHash](https://131002.net/siphash/) hash value.
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``` sql
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sipHash64(par1,...)
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```
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This is a cryptographic hash function. It works at least three times faster than the [MD5](#hash_functions-md5) function.
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Function [interprets](../../sql-reference/functions/type-conversion-functions.md#type_conversion_functions-reinterpretAsString) all the input parameters as strings and calculates the hash value for each of them. Then combines hashes by the following algorithm:
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1. After hashing all the input parameters, the function gets the array of hashes.
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2. Function takes the first and the second elements and calculates a hash for the array of them.
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3. Then the function takes the hash value, calculated at the previous step, and the third element of the initial hash array, and calculates a hash for the array of them.
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4. The previous step is repeated for all the remaining elements of the initial hash array.
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**Arguments**
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The function takes a variable number of input parameters. Arguments can be any of the [supported data types](../../sql-reference/data-types/index.md).
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**Returned Value**
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A [UInt64](../../sql-reference/data-types/int-uint.md) data type hash value.
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**Example**
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``` sql
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SELECT sipHash64(array('e','x','a'), 'mple', 10, toDateTime('2019-06-15 23:00:00')) AS SipHash, toTypeName(SipHash) AS type;
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```
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``` text
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┌──────────────SipHash─┬─type───┐
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│ 13726873534472839665 │ UInt64 │
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└──────────────────────┴────────┘
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```
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## sipHash128 {#hash_functions-siphash128}
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Calculates SipHash from a string.
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Accepts a String-type argument. Returns FixedString(16).
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Differs from sipHash64 in that the final xor-folding state is only done up to 128 bits.
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## cityHash64 {#cityhash64}
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Produces a 64-bit [CityHash](https://github.com/google/cityhash) hash value.
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``` sql
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cityHash64(par1,...)
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```
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This is a fast non-cryptographic hash function. It uses the CityHash algorithm for string parameters and implementation-specific fast non-cryptographic hash function for parameters with other data types. The function uses the CityHash combinator to get the final results.
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**Arguments**
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The function takes a variable number of input parameters. Arguments can be any of the [supported data types](../../sql-reference/data-types/index.md).
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**Returned Value**
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A [UInt64](../../sql-reference/data-types/int-uint.md) data type hash value.
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**Examples**
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Call example:
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``` sql
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SELECT cityHash64(array('e','x','a'), 'mple', 10, toDateTime('2019-06-15 23:00:00')) AS CityHash, toTypeName(CityHash) AS type;
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```
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``` text
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┌─────────────CityHash─┬─type───┐
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│ 12072650598913549138 │ UInt64 │
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└──────────────────────┴────────┘
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```
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The following example shows how to compute the checksum of the entire table with accuracy up to the row order:
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``` sql
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SELECT groupBitXor(cityHash64(*)) FROM table
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```
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## intHash32 {#inthash32}
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Calculates a 32-bit hash code from any type of integer.
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This is a relatively fast non-cryptographic hash function of average quality for numbers.
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## intHash64 {#inthash64}
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Calculates a 64-bit hash code from any type of integer.
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It works faster than intHash32. Average quality.
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## SHA1 {#sha1}
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## SHA224 {#sha224}
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## SHA256 {#sha256}
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## SHA512 {#sha512}
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Calculates SHA-1, SHA-224, SHA-256 or SHA-512 from a string and returns the resulting set of bytes as FixedString(20), FixedString(28), FixedString(32), or FixedString(64).
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The function works fairly slowly (SHA-1 processes about 5 million short strings per second per processor core, while SHA-224 and SHA-256 process about 2.2 million).
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We recommend using this function only in cases when you need a specific hash function and you can’t select it.
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Even in these cases, we recommend applying the function offline and pre-calculating values when inserting them into the table, instead of applying it in SELECTS.
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## URLHash(url\[, N\]) {#urlhashurl-n}
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A fast, decent-quality non-cryptographic hash function for a string obtained from a URL using some type of normalization.
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`URLHash(s)` – Calculates a hash from a string without one of the trailing symbols `/`,`?` or `#` at the end, if present.
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`URLHash(s, N)` – Calculates a hash from a string up to the N level in the URL hierarchy, without one of the trailing symbols `/`,`?` or `#` at the end, if present.
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Levels are the same as in URLHierarchy. This function is specific to Yandex.Metrica.
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## farmFingerprint64 {#farmfingerprint64}
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## farmHash64 {#farmhash64}
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Produces a 64-bit [FarmHash](https://github.com/google/farmhash) or Fingerprint value. `farmFingerprint64` is preferred for a stable and portable value.
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``` sql
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farmFingerprint64(par1, ...)
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farmHash64(par1, ...)
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```
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These functions use the `Fingerprint64` and `Hash64` methods respectively from all [available methods](https://github.com/google/farmhash/blob/master/src/farmhash.h).
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**Arguments**
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The function takes a variable number of input parameters. Arguments can be any of the [supported data types](../../sql-reference/data-types/index.md).
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**Returned Value**
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A [UInt64](../../sql-reference/data-types/int-uint.md) data type hash value.
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**Example**
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``` sql
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SELECT farmHash64(array('e','x','a'), 'mple', 10, toDateTime('2019-06-15 23:00:00')) AS FarmHash, toTypeName(FarmHash) AS type;
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```
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``` text
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┌─────────────FarmHash─┬─type───┐
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│ 17790458267262532859 │ UInt64 │
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└──────────────────────┴────────┘
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```
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## javaHash {#hash_functions-javahash}
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Calculates [JavaHash](http://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/478a4add975b/src/share/classes/java/lang/String.java#l1452) from a string. This hash function is neither fast nor having a good quality. The only reason to use it is when this algorithm is already used in another system and you have to calculate exactly the same result.
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**Syntax**
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``` sql
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SELECT javaHash('')
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```
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**Returned value**
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A `Int32` data type hash value.
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**Example**
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Query:
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``` sql
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SELECT javaHash('Hello, world!');
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```
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Result:
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``` text
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┌─javaHash('Hello, world!')─┐
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│ -1880044555 │
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└───────────────────────────┘
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```
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## javaHashUTF16LE {#javahashutf16le}
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Calculates [JavaHash](http://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/478a4add975b/src/share/classes/java/lang/String.java#l1452) from a string, assuming it contains bytes representing a string in UTF-16LE encoding.
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**Syntax**
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``` sql
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javaHashUTF16LE(stringUtf16le)
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```
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**Arguments**
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- `stringUtf16le` — a string in UTF-16LE encoding.
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**Returned value**
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A `Int32` data type hash value.
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**Example**
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Correct query with UTF-16LE encoded string.
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Query:
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``` sql
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SELECT javaHashUTF16LE(convertCharset('test', 'utf-8', 'utf-16le'));
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```
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Result:
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``` text
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┌─javaHashUTF16LE(convertCharset('test', 'utf-8', 'utf-16le'))─┐
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│ 3556498 │
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└──────────────────────────────────────────────────────────────┘
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```
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## hiveHash {#hash-functions-hivehash}
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Calculates `HiveHash` from a string.
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``` sql
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SELECT hiveHash('')
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```
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This is just [JavaHash](#hash_functions-javahash) with zeroed out sign bit. This function is used in [Apache Hive](https://en.wikipedia.org/wiki/Apache_Hive) for versions before 3.0. This hash function is neither fast nor having a good quality. The only reason to use it is when this algorithm is already used in another system and you have to calculate exactly the same result.
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**Returned value**
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A `Int32` data type hash value.
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Type: `hiveHash`.
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**Example**
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Query:
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``` sql
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SELECT hiveHash('Hello, world!');
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```
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Result:
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``` text
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┌─hiveHash('Hello, world!')─┐
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│ 267439093 │
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└───────────────────────────┘
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```
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## metroHash64 {#metrohash64}
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Produces a 64-bit [MetroHash](http://www.jandrewrogers.com/2015/05/27/metrohash/) hash value.
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``` sql
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metroHash64(par1, ...)
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```
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**Arguments**
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The function takes a variable number of input parameters. Arguments can be any of the [supported data types](../../sql-reference/data-types/index.md).
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**Returned Value**
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A [UInt64](../../sql-reference/data-types/int-uint.md) data type hash value.
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**Example**
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``` sql
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SELECT metroHash64(array('e','x','a'), 'mple', 10, toDateTime('2019-06-15 23:00:00')) AS MetroHash, toTypeName(MetroHash) AS type;
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```
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``` text
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┌────────────MetroHash─┬─type───┐
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│ 14235658766382344533 │ UInt64 │
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└──────────────────────┴────────┘
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```
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## jumpConsistentHash {#jumpconsistenthash}
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Calculates JumpConsistentHash form a UInt64.
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Accepts two arguments: a UInt64-type key and the number of buckets. Returns Int32.
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For more information, see the link: [JumpConsistentHash](https://arxiv.org/pdf/1406.2294.pdf)
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## murmurHash2_32, murmurHash2_64 {#murmurhash2-32-murmurhash2-64}
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Produces a [MurmurHash2](https://github.com/aappleby/smhasher) hash value.
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``` sql
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murmurHash2_32(par1, ...)
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murmurHash2_64(par1, ...)
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```
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**Arguments**
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Both functions take a variable number of input parameters. Arguments can be any of the [supported data types](../../sql-reference/data-types/index.md).
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**Returned Value**
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- The `murmurHash2_32` function returns hash value having the [UInt32](../../sql-reference/data-types/int-uint.md) data type.
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- The `murmurHash2_64` function returns hash value having the [UInt64](../../sql-reference/data-types/int-uint.md) data type.
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**Example**
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``` sql
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SELECT murmurHash2_64(array('e','x','a'), 'mple', 10, toDateTime('2019-06-15 23:00:00')) AS MurmurHash2, toTypeName(MurmurHash2) AS type;
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```
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``` text
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┌──────────MurmurHash2─┬─type───┐
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│ 11832096901709403633 │ UInt64 │
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└──────────────────────┴────────┘
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```
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## gccMurmurHash {#gccmurmurhash}
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Calculates a 64-bit [MurmurHash2](https://github.com/aappleby/smhasher) hash value using the same hash seed as [gcc](https://github.com/gcc-mirror/gcc/blob/41d6b10e96a1de98e90a7c0378437c3255814b16/libstdc%2B%2B-v3/include/bits/functional_hash.h#L191). It is portable between CLang and GCC builds.
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**Syntax**
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``` sql
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gccMurmurHash(par1, ...)
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```
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**Arguments**
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- `par1, ...` — A variable number of parameters that can be any of the [supported data types](../../sql-reference/data-types/index.md#data_types).
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**Returned value**
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- Calculated hash value.
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Type: [UInt64](../../sql-reference/data-types/int-uint.md).
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**Example**
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Query:
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``` sql
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SELECT
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gccMurmurHash(1, 2, 3) AS res1,
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gccMurmurHash(('a', [1, 2, 3], 4, (4, ['foo', 'bar'], 1, (1, 2)))) AS res2
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```
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Result:
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``` text
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┌─────────────────res1─┬────────────────res2─┐
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│ 12384823029245979431 │ 1188926775431157506 │
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└──────────────────────┴─────────────────────┘
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```
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## murmurHash3_32, murmurHash3_64 {#murmurhash3-32-murmurhash3-64}
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Produces a [MurmurHash3](https://github.com/aappleby/smhasher) hash value.
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``` sql
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murmurHash3_32(par1, ...)
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murmurHash3_64(par1, ...)
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```
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**Arguments**
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Both functions take a variable number of input parameters. Arguments can be any of the [supported data types](../../sql-reference/data-types/index.md).
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**Returned Value**
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- The `murmurHash3_32` function returns a [UInt32](../../sql-reference/data-types/int-uint.md) data type hash value.
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- The `murmurHash3_64` function returns a [UInt64](../../sql-reference/data-types/int-uint.md) data type hash value.
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**Example**
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``` sql
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SELECT murmurHash3_32(array('e','x','a'), 'mple', 10, toDateTime('2019-06-15 23:00:00')) AS MurmurHash3, toTypeName(MurmurHash3) AS type;
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```
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``` text
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┌─MurmurHash3─┬─type───┐
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│ 2152717 │ UInt32 │
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└─────────────┴────────┘
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```
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## murmurHash3_128 {#murmurhash3-128}
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Produces a 128-bit [MurmurHash3](https://github.com/aappleby/smhasher) hash value.
|
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``` sql
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murmurHash3_128( expr )
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```
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**Arguments**
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- `expr` — [Expressions](../../sql-reference/syntax.md#syntax-expressions) returning a [String](../../sql-reference/data-types/string.md)-type value.
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||
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**Returned Value**
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||
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A [FixedString(16)](../../sql-reference/data-types/fixedstring.md) data type hash value.
|
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**Example**
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``` sql
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SELECT hex(murmurHash3_128('example_string')) AS MurmurHash3, toTypeName(MurmurHash3) AS type;
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```
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``` text
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┌─MurmurHash3──────────────────────┬─type───┐
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│ 368A1A311CB7342253354B548E7E7E71 │ String │
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└──────────────────────────────────┴────────┘
|
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```
|
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## xxHash32, xxHash64 {#hash-functions-xxhash32}
|
||
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Calculates `xxHash` from a string. It is proposed in two flavors, 32 and 64 bits.
|
||
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``` sql
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SELECT xxHash32('')
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OR
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SELECT xxHash64('')
|
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```
|
||
|
||
**Returned value**
|
||
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||
A `Uint32` or `Uint64` data type hash value.
|
||
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||
Type: `xxHash`.
|
||
|
||
**Example**
|
||
|
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Query:
|
||
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``` sql
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SELECT xxHash32('Hello, world!');
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```
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Result:
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||
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||
``` text
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┌─xxHash32('Hello, world!')─┐
|
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│ 834093149 │
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└───────────────────────────┘
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```
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**See Also**
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- [xxHash](http://cyan4973.github.io/xxHash/).
|
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## ngramSimHash {#ngramsimhash}
|
||
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Splits a ASCII string into n-grams of `ngramsize` symbols and returns the n-gram `simhash`. Is case sensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [bitHammingDistance](../../sql-reference/functions/bit-functions.md#bithammingdistance). The smaller is the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) of the calculated `simhashes` of two strings, the more likely these strings are the same.
|
||
|
||
**Syntax**
|
||
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||
``` sql
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ngramSimHash(string[, ngramsize])
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```
|
||
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**Arguments**
|
||
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||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
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||
**Returned value**
|
||
|
||
- Hash value.
|
||
|
||
Type: [UInt64](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramSimHash('ClickHouse') AS Hash;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌───────Hash─┐
|
||
│ 1627567969 │
|
||
└────────────┘
|
||
```
|
||
|
||
## ngramSimHashCaseInsensitive {#ngramsimhashcaseinsensitive}
|
||
|
||
Splits a ASCII string into n-grams of `ngramsize` symbols and returns the n-gram `simhash`. Is case insensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [bitHammingDistance](../../sql-reference/functions/bit-functions.md#bithammingdistance). The smaller is the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) of the calculated `simhashes` of two strings, the more likely these strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramSimHashCaseInsensitive(string[, ngramsize])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Hash value.
|
||
|
||
Type: [UInt64](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramSimHashCaseInsensitive('ClickHouse') AS Hash;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌──────Hash─┐
|
||
│ 562180645 │
|
||
└───────────┘
|
||
```
|
||
|
||
## ngramSimHashUTF8 {#ngramsimhashutf8}
|
||
|
||
Splits a UTF-8 string into n-grams of `ngramsize` symbols and returns the n-gram `simhash`. Is case sensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [bitHammingDistance](../../sql-reference/functions/bit-functions.md#bithammingdistance). The smaller is the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) of the calculated `simhashes` of two strings, the more likely these strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramSimHashUTF8(string[, ngramsize])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Hash value.
|
||
|
||
Type: [UInt64](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramSimHashUTF8('ClickHouse') AS Hash;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌───────Hash─┐
|
||
│ 1628157797 │
|
||
└────────────┘
|
||
```
|
||
|
||
## ngramSimHashCaseInsensitiveUTF8 {#ngramsimhashcaseinsensitiveutf8}
|
||
|
||
Splits a UTF-8 string into n-grams of `ngramsize` symbols and returns the n-gram `simhash`. Is case insensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [bitHammingDistance](../../sql-reference/functions/bit-functions.md#bithammingdistance). The smaller is the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) of the calculated `simhashes` of two strings, the more likely these strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramSimHashCaseInsensitiveUTF8(string[, ngramsize])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Hash value.
|
||
|
||
Type: [UInt64](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramSimHashCaseInsensitiveUTF8('ClickHouse') AS Hash;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌───────Hash─┐
|
||
│ 1636742693 │
|
||
└────────────┘
|
||
```
|
||
|
||
## wordShingleSimHash {#wordshinglesimhash}
|
||
|
||
Splits a ASCII string into parts (shingles) of `shinglesize` words and returns the word shingle `simhash`. Is case sensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [bitHammingDistance](../../sql-reference/functions/bit-functions.md#bithammingdistance). The smaller is the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) of the calculated `simhashes` of two strings, the more likely these strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleSimHash(string[, shinglesize])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Hash value.
|
||
|
||
Type: [UInt64](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleSimHash('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).') AS Hash;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌───────Hash─┐
|
||
│ 2328277067 │
|
||
└────────────┘
|
||
```
|
||
|
||
## wordShingleSimHashCaseInsensitive {#wordshinglesimhashcaseinsensitive}
|
||
|
||
Splits a ASCII string into parts (shingles) of `shinglesize` words and returns the word shingle `simhash`. Is case insensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [bitHammingDistance](../../sql-reference/functions/bit-functions.md#bithammingdistance). The smaller is the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) of the calculated `simhashes` of two strings, the more likely these strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleSimHashCaseInsensitive(string[, shinglesize])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Hash value.
|
||
|
||
Type: [UInt64](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleSimHashCaseInsensitive('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).') AS Hash;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌───────Hash─┐
|
||
│ 2194812424 │
|
||
└────────────┘
|
||
```
|
||
|
||
## wordShingleSimHashUTF8 {#wordshinglesimhashutf8}
|
||
|
||
Splits a UTF-8 string into parts (shingles) of `shinglesize` words and returns the word shingle `simhash`. Is case sensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [bitHammingDistance](../../sql-reference/functions/bit-functions.md#bithammingdistance). The smaller is the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) of the calculated `simhashes` of two strings, the more likely these strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleSimHashUTF8(string[, shinglesize])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optinal. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Hash value.
|
||
|
||
Type: [UInt64](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleSimHashUTF8('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).') AS Hash;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌───────Hash─┐
|
||
│ 2328277067 │
|
||
└────────────┘
|
||
```
|
||
|
||
## wordShingleSimHashCaseInsensitiveUTF8 {#wordshinglesimhashcaseinsensitiveutf8}
|
||
|
||
Splits a UTF-8 string into parts (shingles) of `shinglesize` words and returns the word shingle `simhash`. Is case insensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [bitHammingDistance](../../sql-reference/functions/bit-functions.md#bithammingdistance). The smaller is the [Hamming Distance](https://en.wikipedia.org/wiki/Hamming_distance) of the calculated `simhashes` of two strings, the more likely these strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleSimHashCaseInsensitiveUTF8(string[, shinglesize])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Hash value.
|
||
|
||
Type: [UInt64](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleSimHashCaseInsensitiveUTF8('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).') AS Hash;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌───────Hash─┐
|
||
│ 2194812424 │
|
||
└────────────┘
|
||
```
|
||
|
||
## ngramMinHash {#ngramminhash}
|
||
|
||
Splits a ASCII string into n-grams of `ngramsize` symbols and calculates hash values for each n-gram. Uses `hashnum` minimum hashes to calculate the minimum hash and `hashnum` maximum hashes to calculate the maximum hash. Returns a tuple with these hashes. Is case sensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [tupleHammingDistance](../../sql-reference/functions/tuple-functions.md#tuplehammingdistance). For two strings: if one of the returned hashes is the same for both strings, we think that those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramMinHash(string[, ngramsize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two hashes — the minimum and the maximum.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([UInt64](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md)).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramMinHash('ClickHouse') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple──────────────────────────────────────┐
|
||
│ (18333312859352735453,9054248444481805918) │
|
||
└────────────────────────────────────────────┘
|
||
```
|
||
|
||
## ngramMinHashCaseInsensitive {#ngramminhashcaseinsensitive}
|
||
|
||
Splits a ASCII string into n-grams of `ngramsize` symbols and calculates hash values for each n-gram. Uses `hashnum` minimum hashes to calculate the minimum hash and `hashnum` maximum hashes to calculate the maximum hash. Returns a tuple with these hashes. Is case insensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [tupleHammingDistance](../../sql-reference/functions/tuple-functions.md#tuplehammingdistance). For two strings: if one of the returned hashes is the same for both strings, we think that those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramMinHashCaseInsensitive(string[, ngramsize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two hashes — the minimum and the maximum.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([UInt64](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md)).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramMinHashCaseInsensitive('ClickHouse') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple──────────────────────────────────────┐
|
||
│ (2106263556442004574,13203602793651726206) │
|
||
└────────────────────────────────────────────┘
|
||
```
|
||
|
||
## ngramMinHashUTF8 {#ngramminhashutf8}
|
||
|
||
Splits a UTF-8 string into n-grams of `ngramsize` symbols and calculates hash values for each n-gram. Uses `hashnum` minimum hashes to calculate the minimum hash and `hashnum` maximum hashes to calculate the maximum hash. Returns a tuple with these hashes. Is case sensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [tupleHammingDistance](../../sql-reference/functions/tuple-functions.md#tuplehammingdistance). For two strings: if one of the returned hashes is the same for both strings, we think that those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramMinHashUTF8(string[, ngramsize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two hashes — the minimum and the maximum.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([UInt64](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md)).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramMinHashUTF8('ClickHouse') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple──────────────────────────────────────┐
|
||
│ (18333312859352735453,6742163577938632877) │
|
||
└────────────────────────────────────────────┘
|
||
```
|
||
|
||
## ngramMinHashCaseInsensitiveUTF8 {#ngramminhashcaseinsensitiveutf8}
|
||
|
||
Splits a UTF-8 string into n-grams of `ngramsize` symbols and calculates hash values for each n-gram. Uses `hashnum` minimum hashes to calculate the minimum hash and `hashnum` maximum hashes to calculate the maximum hash. Returns a tuple with these hashes. Is case insensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [tupleHammingDistance](../../sql-reference/functions/tuple-functions.md#tuplehammingdistance). For two strings: if one of the returned hashes is the same for both strings, we think that those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramMinHashCaseInsensitiveUTF8(string [, ngramsize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two hashes — the minimum and the maximum.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([UInt64](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md)).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramMinHashCaseInsensitiveUTF8('ClickHouse') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple───────────────────────────────────────┐
|
||
│ (12493625717655877135,13203602793651726206) │
|
||
└─────────────────────────────────────────────┘
|
||
```
|
||
|
||
## ngramMinHashArg {#ngramminhasharg}
|
||
|
||
Splits a ASCII string into n-grams of `ngramsize` symbols and returns the n-grams with minimum and maximum hashes, calculated by the [ngramMinHash](#ngramminhash) function with the same input. Is case sensitive.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramMinHashArg(string[, ngramsize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two tuples with `hashnum` n-grams each.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md)), [Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md))).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramMinHashArg('ClickHouse') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple─────────────────────────────────────────────────────────────────────────┐
|
||
│ (('ous','ick','lic','Hou','kHo','use'),('Hou','lic','ick','ous','ckH','Cli')) │
|
||
└───────────────────────────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
## ngramMinHashArgCaseInsensitive {#ngramminhashargcaseinsensitive}
|
||
|
||
Splits a ASCII string into n-grams of `ngramsize` symbols and returns the n-grams with minimum and maximum hashes, calculated by the [ngramMinHashCaseInsensitive](#ngramminhashcaseinsensitive) function with the same input. Is case insensitive.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramMinHashArgCaseInsensitive(string[, ngramsize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two tuples with `hashnum` n-grams each.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md)), [Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md))).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramMinHashArgCaseInsensitive('ClickHouse') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple─────────────────────────────────────────────────────────────────────────┐
|
||
│ (('ous','ick','lic','kHo','use','Cli'),('kHo','lic','ick','ous','ckH','Hou')) │
|
||
└───────────────────────────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
## ngramMinHashArgUTF8 {#ngramminhashargutf8}
|
||
|
||
Splits a UTF-8 string into n-grams of `ngramsize` symbols and returns the n-grams with minimum and maximum hashes, calculated by the [ngramMinHashUTF8](#ngramminhashutf8) function with the same input. Is case sensitive.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramMinHashArgUTF8(string[, ngramsize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two tuples with `hashnum` n-grams each.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md)), [Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md))).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramMinHashArgUTF8('ClickHouse') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple─────────────────────────────────────────────────────────────────────────┐
|
||
│ (('ous','ick','lic','Hou','kHo','use'),('kHo','Hou','lic','ick','ous','ckH')) │
|
||
└───────────────────────────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
## ngramMinHashArgCaseInsensitiveUTF8 {#ngramminhashargcaseinsensitiveutf8}
|
||
|
||
Splits a UTF-8 string into n-grams of `ngramsize` symbols and returns the n-grams with minimum and maximum hashes, calculated by the [ngramMinHashCaseInsensitiveUTF8](#ngramminhashcaseinsensitiveutf8) function with the same input. Is case insensitive.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
ngramMinHashArgCaseInsensitiveUTF8(string[, ngramsize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `ngramsize` — The size of an n-gram. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two tuples with `hashnum` n-grams each.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md)), [Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md))).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT ngramMinHashArgCaseInsensitiveUTF8('ClickHouse') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple─────────────────────────────────────────────────────────────────────────┐
|
||
│ (('ckH','ous','ick','lic','kHo','use'),('kHo','lic','ick','ous','ckH','Hou')) │
|
||
└───────────────────────────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
## wordShingleMinHash {#wordshingleminhash}
|
||
|
||
Splits a ASCII string into parts (shingles) of `shinglesize` words and calculates hash values for each word shingle. Uses `hashnum` minimum hashes to calculate the minimum hash and `hashnum` maximum hashes to calculate the maximum hash. Returns a tuple with these hashes. Is case sensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [tupleHammingDistance](../../sql-reference/functions/tuple-functions.md#tuplehammingdistance). For two strings: if one of the returned hashes is the same for both strings, we think that those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleMinHash(string[, shinglesize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two hashes — the minimum and the maximum.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([UInt64](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md)).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleMinHash('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple──────────────────────────────────────┐
|
||
│ (16452112859864147620,5844417301642981317) │
|
||
└────────────────────────────────────────────┘
|
||
```
|
||
|
||
## wordShingleMinHashCaseInsensitive {#wordshingleminhashcaseinsensitive}
|
||
|
||
Splits a ASCII string into parts (shingles) of `shinglesize` words and calculates hash values for each word shingle. Uses `hashnum` minimum hashes to calculate the minimum hash and `hashnum` maximum hashes to calculate the maximum hash. Returns a tuple with these hashes. Is case insensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [tupleHammingDistance](../../sql-reference/functions/tuple-functions.md#tuplehammingdistance). For two strings: if one of the returned hashes is the same for both strings, we think that those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleMinHashCaseInsensitive(string[, shinglesize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two hashes — the minimum and the maximum.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([UInt64](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md)).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleMinHashCaseInsensitive('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple─────────────────────────────────────┐
|
||
│ (3065874883688416519,1634050779997673240) │
|
||
└───────────────────────────────────────────┘
|
||
```
|
||
|
||
## wordShingleMinHashUTF8 {#wordshingleminhashutf8}
|
||
|
||
Splits a UTF-8 string into parts (shingles) of `shinglesize` words and calculates hash values for each word shingle. Uses `hashnum` minimum hashes to calculate the minimum hash and `hashnum` maximum hashes to calculate the maximum hash. Returns a tuple with these hashes. Is case sensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [tupleHammingDistance](../../sql-reference/functions/tuple-functions.md#tuplehammingdistance). For two strings: if one of the returned hashes is the same for both strings, we think that those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleMinHashUTF8(string[, shinglesize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two hashes — the minimum and the maximum.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([UInt64](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md)).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleMinHashUTF8('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple──────────────────────────────────────┐
|
||
│ (16452112859864147620,5844417301642981317) │
|
||
└────────────────────────────────────────────┘
|
||
```
|
||
|
||
## wordShingleMinHashCaseInsensitiveUTF8 {#wordshingleminhashcaseinsensitiveutf8}
|
||
|
||
Splits a UTF-8 string into parts (shingles) of `shinglesize` words and calculates hash values for each word shingle. Uses `hashnum` minimum hashes to calculate the minimum hash and `hashnum` maximum hashes to calculate the maximum hash. Returns a tuple with these hashes. Is case insensitive.
|
||
|
||
Can be used for detection of semi-duplicate strings with [tupleHammingDistance](../../sql-reference/functions/tuple-functions.md#tuplehammingdistance). For two strings: if one of the returned hashes is the same for both strings, we think that those strings are the same.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleMinHashCaseInsensitiveUTF8(string[, shinglesize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two hashes — the minimum and the maximum.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([UInt64](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md)).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleMinHashCaseInsensitiveUTF8('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).') AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple─────────────────────────────────────┐
|
||
│ (3065874883688416519,1634050779997673240) │
|
||
└───────────────────────────────────────────┘
|
||
```
|
||
|
||
## wordShingleMinHashArg {#wordshingleminhasharg}
|
||
|
||
Splits a ASCII string into parts (shingles) of `shinglesize` words each and returns the shingles with minimum and maximum word hashes, calculated by the [wordshingleMinHash](#wordshingleminhash) function with the same input. Is case sensitive.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleMinHashArg(string[, shinglesize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two tuples with `hashnum` word shingles each.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md)), [Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md))).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleMinHashArg('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).', 1, 3) AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple─────────────────────────────────────────────────────────────────┐
|
||
│ (('OLAP','database','analytical'),('online','oriented','processing')) │
|
||
└───────────────────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
## wordShingleMinHashArgCaseInsensitive {#wordshingleminhashargcaseinsensitive}
|
||
|
||
Splits a ASCII string into parts (shingles) of `shinglesize` words each and returns the shingles with minimum and maximum word hashes, calculated by the [wordShingleMinHashCaseInsensitive](#wordshingleminhashcaseinsensitive) function with the same input. Is case insensitive.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleMinHashArgCaseInsensitive(string[, shinglesize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two tuples with `hashnum` word shingles each.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md)), [Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md))).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleMinHashArgCaseInsensitive('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).', 1, 3) AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple──────────────────────────────────────────────────────────────────┐
|
||
│ (('queries','database','analytical'),('oriented','processing','DBMS')) │
|
||
└────────────────────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
## wordShingleMinHashArgUTF8 {#wordshingleminhashargutf8}
|
||
|
||
Splits a UTF-8 string into parts (shingles) of `shinglesize` words each and returns the shingles with minimum and maximum word hashes, calculated by the [wordShingleMinHashUTF8](#wordshingleminhashutf8) function with the same input. Is case sensitive.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleMinHashArgUTF8(string[, shinglesize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two tuples with `hashnum` word shingles each.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md)), [Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md))).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleMinHashArgUTF8('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).', 1, 3) AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple─────────────────────────────────────────────────────────────────┐
|
||
│ (('OLAP','database','analytical'),('online','oriented','processing')) │
|
||
└───────────────────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
## wordShingleMinHashArgCaseInsensitiveUTF8 {#wordshingleminhashargcaseinsensitiveutf8}
|
||
|
||
Splits a UTF-8 string into parts (shingles) of `shinglesize` words each and returns the shingles with minimum and maximum word hashes, calculated by the [wordShingleMinHashCaseInsensitiveUTF8](#wordshingleminhashcaseinsensitiveutf8) function with the same input. Is case insensitive.
|
||
|
||
**Syntax**
|
||
|
||
``` sql
|
||
wordShingleMinHashArgCaseInsensitiveUTF8(string[, shinglesize, hashnum])
|
||
```
|
||
|
||
**Arguments**
|
||
|
||
- `string` — String. [String](../../sql-reference/data-types/string.md).
|
||
- `shinglesize` — The size of a word shingle. Optional. Possible values: any number from `1` to `25`. Default value: `3`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
- `hashnum` — The number of minimum and maximum hashes used to calculate the result. Optional. Possible values: any number from `1` to `25`. Default value: `6`. [UInt8](../../sql-reference/data-types/int-uint.md).
|
||
|
||
**Returned value**
|
||
|
||
- Tuple with two tuples with `hashnum` word shingles each.
|
||
|
||
Type: [Tuple](../../sql-reference/data-types/tuple.md)([Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md)), [Tuple](../../sql-reference/data-types/tuple.md)([String](../../sql-reference/data-types/string.md))).
|
||
|
||
**Example**
|
||
|
||
Query:
|
||
|
||
``` sql
|
||
SELECT wordShingleMinHashArgCaseInsensitiveUTF8('ClickHouse® is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).', 1, 3) AS Tuple;
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─Tuple──────────────────────────────────────────────────────────────────┐
|
||
│ (('queries','database','analytical'),('oriented','processing','DBMS')) │
|
||
└────────────────────────────────────────────────────────────────────────┘
|
||
```
|