Encoding functions - ClickHouse Documentation

bech32Decode

Introduced in: v25.6.0 Decodes a Bech32 address string generated by either the bech32 or bech32m algorithms.

Unlike the encode function, bech32Decode will automatically handle padded FixedStrings.

Syntax

bech32Decode(address[, 'raw'])

Arguments

address — A Bech32 string to decode. String or FixedString
mode — Optional. Pass 'raw' to decode without stripping the first byte as a witness version. Use this for non-SegWit addresses (e.g. Cosmos SDK). String

Returned value Returns a tuple consisting of (hrp, data) that was used to encode the string. The data is in binary format. Tuple(String, String) Examples Decode address

Query

SELECT tup.1 AS hrp, hex(tup.2) AS data FROM (SELECT bech32Decode('bc1w508d6qejxtdg4y5r3zarvary0c5xw7kj7gz7z') AS tup)

Response

bc   751E76E8199196D454941C45D1B3A323F1433BD6

Testnet address

Query

SELECT tup.1 AS hrp, hex(tup.2) AS data FROM (SELECT bech32Decode('tb1w508d6qejxtdg4y5r3zarvary0c5xw7kzp034v') AS tup)

Response

tb   751E76E8199196D454941C45D1B3A323F1433BD6

bech32Encode

Introduced in: v25.6.0 Encodes a binary data string, along with a human-readable part (HRP), using the Bech32 or Bech32m algorithms.

When using the FixedString data type, if a value does not fully fill the row it is padded with null characters. While the bech32Encode function will handle this automatically for the hrp argument, for the data argument the values must not be padded. For this reason it is not recommended to use the FixedString data type for your data values unless you are certain that they are all the same length and ensure that your FixedString column is set to that length as well.

Syntax

bech32Encode(hrp, data[, witver | 'bech32' | 'bech32m'])

Arguments

hrp — A String of 1 - 83 lowercase characters specifying the “human-readable part” of the code. Usually ‘bc’ or ‘tb’. String or FixedString
data — A String of binary data to encode. String or FixedString
witver_or_variant — Optional. Either a UInt* witness version (default = 1, 0 for Bech32, 1+ for Bech32m) or a String encoding variant: 'bech32' (BIP173) or 'bech32m' (BIP350). When a string variant is used, no witness version byte is prepended — this is needed for non-SegWit addresses such as Cosmos SDK. UInt* or String

Returned value Returns a Bech32 address string, consisting of the human-readable part, a separator character which is always ‘1’, and a data part. The length of the string will never exceed 90 characters. If the algorithm cannot generate a valid address from the input, it will return an empty string. String Examples Default Bech32m

Query

-- When no witness version is supplied, the default is 1, the updated Bech32m algorithm.
SELECT bech32Encode('bc', unhex('751e76e8199196d454941c45d1b3a323f1433bd6'))

Response

bc1w508d6qejxtdg4y5r3zarvary0c5xw7k8zcwmq

Bech32 algorithm

Query

-- A witness version of 0 will result in a different address string.
SELECT bech32Encode('bc', unhex('751e76e8199196d454941c45d1b3a323f1433bd6'), 0)

Response

bc1w508d6qejxtdg4y5r3zarvary0c5xw7kj7gz7z

Custom HRP

Query

-- While 'bc' (Mainnet) and 'tb' (Testnet) are the only allowed hrp values for the
-- SegWit address format, Bech32 allows any hrp that satisfies the above requirements.
SELECT bech32Encode('abcdefg', unhex('751e76e8199196d454941c45d1b3a323f1433bd6'), 10)

Response

abcdefg1w508d6qejxtdg4y5r3zarvary0c5xw7k9rp8r4

Cosmos SDK address (BIP173, no witness version)

Query

-- Using 'bech32' variant encodes raw data without a witness version byte,
-- compatible with Cosmos SDK, Injective, Osmosis, and other non-SegWit chains.
SELECT bech32Encode('inj', unhex('751e76e8199196d454941c45d1b3a323f1433bd6'), 'bech32')

Response

inj1w508d6qejxtdg4y5r3zarvary0c5xw7kgj5aqs

bin

Introduced in: v21.8.0 Returns a string containing the argument’s binary representation according to the following logic for different types:

Type	Description
`(U)Int*`	Prints bin digits from the most significant to least significant (big-endian or “human-readable” order). It starts with the most significant non-zero byte (leading zero bytes are omitted) but always prints eight digits of every byte if the leading digit is zero.
`Date` and `DateTime`	Formatted as corresponding integers (the number of days since epoch for Date and the value of unix timestamp for DateTime).
`String` and `FixedString`	All bytes are simply encoded as eight binary numbers. Zero bytes are not omitted.
`Float*` and `Decimal`	Encoded as their representation in memory. As we support little-endian architecture, they are encoded in little-endian. Zero leading/trailing bytes are not omitted.
`UUID`	Encoded as big-endian order string.

Syntax

bin(arg)

Arguments

arg — A value to convert to binary. String or FixedString or (U)Int* or Float* or Decimal or Date or DateTime

Returned value Returns a string with the binary representation of the argument. String Examples Simple integer

Query

SELECT bin(14)

Response

┌─bin(14)──┐
│ 00001110 │
└──────────┘

Float32 numbers

Query

SELECT bin(toFloat32(number)) AS bin_presentation FROM numbers(15, 2)

Response

┌─bin_presentation─────────────────┐
│ 00000000000000000111000001000001 │
│ 00000000000000001000000001000001 │
└──────────────────────────────────┘

Float64 numbers

Query

SELECT bin(toFloat64(number)) AS bin_presentation FROM numbers(15, 2)

Response

┌─bin_presentation─────────────────────────────────────────────────┐
│ 0000000000000000000000000000000000000000000000000010111001000000 │
│ 0000000000000000000000000000000000000000000000000011000001000000 │
└──────────────────────────────────────────────────────────────────┘

UUID conversion

Query

SELECT bin(toUUID('61f0c404-5cb3-11e7-907b-a6006ad3dba0')) AS bin_uuid

Response

┌─bin_uuid─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ 01100001111100001100010000000100010111001011001100010001111001111001000001111011101001100000000001101010110100111101101110100000 │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

bitPositionsToArray

Introduced in: v21.7.0 This function returns the positions (in ascending order) of the 1 bits in the binary representation of an unsigned integer. Signed input integers are first casted to an unsigned integer. Syntax

bitPositionsToArray(arg)

Arguments

arg — An integer value. (U)Int*

Returned value Returns an array with the ascendingly ordered positions of 1 bits in the binary representation of the input. Array(UInt64) Examples Single bit set

Query

SELECT bitPositionsToArray(toInt8(1)) AS bit_positions

Response

┌─bit_positions─┐
│ [0]           │
└───────────────┘

All bits set

Query

SELECT bitPositionsToArray(toInt8(-1)) AS bit_positions

Response

┌─bit_positions─────────────┐
│ [0, 1, 2, 3, 4, 5, 6, 7]  │
└───────────────────────────┘

bitmaskToArray

Introduced in: v1.1.0 This function decomposes an integer into a sum of powers of two. The powers of two are returned as an ascendingly ordered array. Syntax

bitmaskToArray(num)

Arguments

num — An integer value. (U)Int*

Returned value Returns an array with the ascendingly ordered powers of two which sum up to the input number. Array(UInt64) Examples Basic example

Query

SELECT bitmaskToArray(50) AS powers_of_two

Response

┌─powers_of_two───┐
│ [2, 16, 32]     │
└─────────────────┘

Single power of two

Query

SELECT bitmaskToArray(8) AS powers_of_two

Response

┌─powers_of_two─┐
│ [8]           │
└───────────────┘

bitmaskToList

Introduced in: v1.1.0 Like bitmaskToArray but returns the powers of two as a comma-separated string. Syntax

bitmaskToList(num)

Arguments

num — An integer value. (U)Int*

Returned value Returns a string containing comma-separated powers of two. String Examples Basic example

Query

SELECT bitmaskToList(50) AS powers_list

Response

┌─powers_list───┐
│ 2, 16, 32     │
└───────────────┘

char

Introduced in: v20.1.0 Returns a string with length equal to the number of arguments passed where each byte has the value of the corresponding argument. Accepts multiple arguments of numeric types. If the value of the argument is out of range of the UInt8 data type, then it is converted to UInt8 with potential rounding and overflow. Syntax

char(num1[, num2[, ...]])

Arguments

num1[, num2[, num3 ...]] — Numerical arguments interpreted as integers. (U)Int8/16/32/64 or Float*

Returned value Returns a string of the given bytes. String Examples Basic example

Query

SELECT char(104.1, 101, 108.9, 108.9, 111) AS hello;

Response

┌─hello─┐
│ hello │
└───────┘

Constructing arbitrary encodings

Query

-- You can construct a string of arbitrary encoding by passing the corresponding bytes.
-- for example UTF8
SELECT char(0xD0, 0xBF, 0xD1, 0x80, 0xD0, 0xB8, 0xD0, 0xB2, 0xD0, 0xB5, 0xD1, 0x82) AS hello;

Response

┌─hello──┐
│ привет │
└────────┘

hex

Introduced in: v1.1.0 Returns a string containing the argument’s hexadecimal representation according to the following logic for different types:

Type	Description
`(U)Int*`	Prints hex digits (“nibbles”) from the most significant to least significant (big-endian or “human-readable” order). It starts with the most significant non-zero byte (leading zero bytes are omitted) but always prints both digits of every byte even if the leading digit is zero.
`Date` and `DateTime`	Formatted as corresponding integers (the number of days since epoch for Date and the value of unix timestamp for DateTime).
`String` and `FixedString`	All bytes are simply encoded as two hexadecimal numbers. Zero bytes are not omitted.
`Float*` and `Decimal`	Encoded as their representation in memory. ClickHouse represents the values internally always as little endian, therefore they are encoded as such. Zero leading/trailing bytes are not omitted.
`UUID`	Encoded as big-endian order string.

The function uses uppercase letters A-F and not using any prefixes (like 0x) or suffixes (like h). Syntax

hex(arg)

Arguments

arg — A value to convert to hexadecimal. String or (U)Int* or Float* or Decimal or Date or DateTime

Returned value Returns a string with the hexadecimal representation of the argument. String Examples Simple integer

Query

SELECT hex(1)

Response

Float32 numbers

Query

SELECT hex(toFloat32(number)) AS hex_presentation FROM numbers(15, 2)

Response

┌─hex_presentation─┐
│ 00007041         │
│ 00008041         │
└──────────────────┘

Float64 numbers

Query

SELECT hex(toFloat64(number)) AS hex_presentation FROM numbers(15, 2)

Response

┌─hex_presentation─┐
│ 0000000000002E40 │
│ 0000000000003040 │
└──────────────────┘

UUID conversion

Query

SELECT lower(hex(toUUID('61f0c404-5cb3-11e7-907b-a6006ad3dba0'))) AS uuid_hex

Response

┌─uuid_hex─────────────────────────┐
│ 61f0c4045cb311e7907ba6006ad3dba0 │
└──────────────────────────────────┘

hilbertDecode

Introduced in: v24.6.0 Decodes a Hilbert curve index back into a tuple of unsigned integers, representing coordinates in multi-dimensional space. As with the hilbertEncode function, this function has two modes of operation:

Simple
Expanded

Simple mode Accepts up to 2 unsigned integers as arguments and produces a UInt64 code. Expanded mode Accepts a range mask (tuple) as a first argument and up to 2 unsigned integers as other arguments. Each number in the mask configures the number of bits by which the corresponding argument will be shifted left, effectively scaling the argument within its range. Range expansion can be beneficial when you need a similar distribution for arguments with wildly different ranges (or cardinality) For example: ‘IP Address’ (0...FFFFFFFF) and ‘Country code’ (0...FF). As with the encode function, this is limited to 8 numbers at most. Syntax

hilbertDecode(tuple_size, code)

Arguments

tuple_size — Integer value of no more than 2. UInt8/16/32/64 or Tuple(UInt8/16/32/64)
code — UInt64 code. UInt64

Returned value Returns a tuple of the specified size. Tuple(UInt64) Examples Simple mode

Query

SELECT hilbertDecode(2, 31)

Response

["3", "4"]

Single argument

Query

-- Hilbert code for one argument is always the argument itself (as a tuple).
SELECT hilbertDecode(1, 1)

Response

["1"]

Expanded mode

Query

-- A single argument with a tuple specifying bit shifts will be right-shifted accordingly.
SELECT hilbertDecode(tuple(2), 32768)

Response

["128"]

Column usage

Query

-- First create the table and insert some data
CREATE TABLE hilbert_numbers(
    n1 UInt32,
    n2 UInt32
)
ENGINE=MergeTree()
ORDER BY n1 SETTINGS index_granularity_bytes = '10Mi';
insert into hilbert_numbers (*) values(1,2);

-- Use column names instead of constants as function arguments
SELECT untuple(hilbertDecode(2, hilbertEncode(n1, n2))) FROM hilbert_numbers;

Response

1    2

hilbertEncode

Introduced in: v24.6.0 Calculates code for Hilbert Curve for a list of unsigned integers. The function has two modes of operation:

Simple
Expanded

Simple mode Accepts up to 2 unsigned integers as arguments and produces a UInt64 code. Expanded mode Accepts a range mask (Tuple) as the first argument and up to 2 unsigned integers as other arguments. Each number in the mask configures the number of bits by which the corresponding argument will be shifted left, effectively scaling the argument within its range. Syntax

-- Simplified mode
hilbertEncode(args)

-- Expanded mode
hilbertEncode(range_mask, args)

Arguments

args — Up to two UInt values or columns of type UInt. UInt8/16/32/64
range_mask — For the expanded mode, up to two UInt values or columns of type UInt. UInt8/16/32/64

Returned value Returns a UInt64 code. UInt64 Examples Simple mode

Query

SELECT hilbertEncode(3, 4)

Response

Expanded mode

Query

-- Range expansion can be beneficial when you need a similar distribution for
-- arguments with wildly different ranges (or cardinality).
-- For example: 'IP Address' (0...FFFFFFFF) and 'Country code' (0...FF).
-- Note: tuple size must be equal to the number of the other arguments.
SELECT hilbertEncode((10, 6), 1024, 16)

Response

4031541586602

Single argument

Query

-- For a single argument without a tuple, the function returns the argument
-- itself as the Hilbert index, since no dimensional mapping is needed.
SELECT hilbertEncode(1)

Response

Expanded single argument

Query

-- If a single argument is provided with a tuple specifying bit shifts, the function
-- shifts the argument left by the specified number of bits.
SELECT hilbertEncode(tuple(2), 128)

Response

Column usage

Query

-- First create the table and insert some data
CREATE TABLE hilbert_numbers(
    n1 UInt32,
    n2 UInt32
)
ENGINE=MergeTree()
ORDER BY n1;
insert into hilbert_numbers (*) values(1, 2);

-- Use column names instead of constants as function arguments
SELECT hilbertEncode(n1, n2) FROM hilbert_numbers;

Response

mortonDecode

Introduced in: v24.6.0 Decodes a Morton encoding (ZCurve) into the corresponding unsigned integer tuple. As with the mortonEncode function, this function has two modes of operation:

Simple
Expanded

Simple mode Accepts a resulting tuple size as the first argument and the code as the second argument. Expanded mode Accepts a range mask (tuple) as the first argument and the code as the second argument. Each number in the mask configures the amount of range shrink:

1 - no shrink
2 - 2x shrink
3 - 3x shrink ⋮
Up to 8x shrink.

Range expansion can be beneficial when you need a similar distribution for arguments with wildly different ranges (or cardinality). For example: ‘IP Address’ (0...FFFFFFFF) and ‘Country code’ (0...FF). As with the encode function, this is limited to 8 numbers at most. Syntax

-- Simple mode
mortonDecode(tuple_size, code)

-- Expanded mode
mortonDecode(range_mask, code)

Arguments

tuple_size — Integer value no more than 8. UInt8/16/32/64
range_mask — For the expanded mode, the mask for each argument. The mask is a tuple of unsigned integers. Each number in the mask configures the amount of range shrink. Tuple(UInt8/16/32/64)
code — UInt64 code. UInt64

Returned value Returns a tuple of the specified size. Tuple(UInt64) Examples Simple mode

Query

SELECT mortonDecode(3, 53)

Response

["1", "2", "3"]

Single argument

Query

SELECT mortonDecode(1, 1)

Response

["1"]

Expanded mode, shrinking one argument

Query

SELECT mortonDecode(tuple(2), 32768)

Response

["128"]

Column usage

Query

-- First create the table and insert some data
CREATE TABLE morton_numbers(
    n1 UInt32,
    n2 UInt32,
    n3 UInt16,
    n4 UInt16,
    n5 UInt8,
    n6 UInt8,
    n7 UInt8,
    n8 UInt8
)
ENGINE=MergeTree()
ORDER BY n1;
INSERT INTO morton_numbers (*) values(1, 2, 3, 4, 5, 6, 7, 8);

-- Use column names instead of constants as function arguments
SELECT untuple(mortonDecode(8, mortonEncode(n1, n2, n3, n4, n5, n6, n7, n8))) FROM morton_numbers;

Response

1 2 3 4 5 6 7 8

mortonEncode

Introduced in: v24.6.0 Calculates the Morton encoding (ZCurve) for a list of unsigned integers. The function has two modes of operation:

Simple
Expanded*

Simple mode Accepts up to 8 unsigned integers as arguments and produces a UInt64 code. Expanded mode Accepts a range mask (Tuple) as the first argument and up to 8 unsigned integers as other arguments. Each number in the mask configures the amount of range expansion:

1 - no expansion
2 - 2x expansion
3 - 3x expansion ⋮
Up to 8x expansion.

Syntax

-- Simplified mode
mortonEncode(args)

-- Expanded mode
mortonEncode(range_mask, args)

Arguments

args — Up to 8 unsigned integers or columns of the aforementioned type. UInt8/16/32/64
range_mask — For the expanded mode, the mask for each argument. The mask is a tuple of unsigned integers from 1 - 8. Each number in the mask configures the amount of range shrink. Tuple(UInt8/16/32/64)

Returned value Returns a UInt64 code. UInt64 Examples Simple mode

Query

SELECT mortonEncode(1, 2, 3)

Response

Expanded mode

Query

-- Range expansion can be beneficial when you need a similar distribution for
-- arguments with wildly different ranges (or cardinality)
-- For example: 'IP Address' (0...FFFFFFFF) and 'Country code' (0...FF).
-- Note: the Tuple size must be equal to the number of the other arguments.
SELECT mortonEncode((1,2), 1024, 16)

Response

Single argument

Query

-- Morton encoding for one argument is always the argument itself
SELECT mortonEncode(1)

Response

Expanded single argument

Query

SELECT mortonEncode(tuple(2), 128)

Response

Column usage

Query

-- First create the table and insert some data
CREATE TABLE morton_numbers(
    n1 UInt32,
    n2 UInt32,
    n3 UInt16,
    n4 UInt16,
    n5 UInt8,
    n6 UInt8,
    n7 UInt8,
    n8 UInt8
)
ENGINE=MergeTree()
ORDER BY n1;
INSERT INTO morton_numbers (*) values(1, 2, 3, 4, 5, 6, 7, 8);

-- Use column names instead of constants as function arguments
SELECT mortonEncode(n1, n2, n3, n4, n5, n6, n7, n8) FROM morton_numbers;

Response

2155374165

sqidDecode

Introduced in: v24.1.0 Transforms a sqid back into an array of numbers. Syntax

sqidDecode(sqid)

Arguments

sqid — The sqid to decode. String

Returned value Returns an array of numbers from sqid. Array(UInt64) Examples Usage example

Query

SELECT sqidDecode('gXHfJ1C6dN');

Response

┌─sqidDecode('gXHfJ1C6dN')─────┐
│ [1, 2, 3, 4, 5]              │
└──────────────────────────────┘

sqidEncode

Introduced in: v24.1.0 Transforms numbers into a sqid, a Youtube-like ID string. Syntax

sqidEncode(n1[, n2, ...])

Aliases: sqid Arguments

n1[, n2, ...] — Arbitrarily many numbers. UInt8/16/32/64

Returned value Returns a hash ID String Examples Usage example

Query

SELECT sqidEncode(1, 2, 3, 4, 5);

Response

┌─sqidEncode(1, 2, 3, 4, 5)─┐
│ gXHfJ1C6dN                │
└───────────────────────────┘

unbin

Introduced in: v21.8.0 Interprets each pair of binary digits (in the argument) as a number and converts it to the byte represented by the number. The functions performs the opposite operation to bin. For a numeric argument unbin() does not return the inverse of bin(). If you want to convert the result to a number, you can use the reverse and reinterpretAs<Type> functions.

If unbin is invoked from within the clickhouse-client, binary strings are displayed using UTF-8.

Supports binary digits 0 and 1. The number of binary digits does not have to be multiples of eight. If the argument string contains anything other than binary digits, the result is undefined (no exception is thrown). Syntax

unbin(arg)

Arguments

arg — A string containing any number of binary digits. String

Returned value Returns a binary string (BLOB). String Examples Basic usage

Query

SELECT UNBIN('001100000011000100110010'), UNBIN('0100110101111001010100110101000101001100')

Response

┌─unbin('001100000011000100110010')─┬─unbin('0100110101111001010100110101000101001100')─┐
│ 012                               │ MySQL                                             │
└───────────────────────────────────┴───────────────────────────────────────────────────┘

Convert to number

Query

SELECT reinterpretAsUInt64(reverse(unbin('1110'))) AS num

Response

┌─num─┐
│  14 │
└─────┘

unhex

Introduced in: v1.1.0 Performs the opposite operation of hex. It interprets each pair of hexadecimal digits (in the argument) as a number and converts it to the byte represented by the number. The returned value is a binary string (BLOB). If you want to convert the result to a number, you can use the reverse and reinterpretAs<Type> functions.

clickhouse-client interprets strings as UTF-8. This may cause that values returned by hex to be displayed surprisingly.

Supports both uppercase and lowercase letters A-F. The number of hexadecimal digits does not have to be even. If it is odd, the last digit is interpreted as the least significant half of the 00-0F byte. If the argument string contains anything other than hexadecimal digits, some implementation-defined result is returned (an exception isn’t thrown). For a numeric argument the inverse of hex(N) is not performed by unhex(). Syntax

unhex(arg)

Arguments

arg — A string containing any number of hexadecimal digits. String or FixedString

Returned value Returns a binary string (BLOB). String Examples Basic usage

Query

SELECT unhex('303132'), UNHEX('4D7953514C')

Response

┌─unhex('303132')─┬─unhex('4D7953514C')─┐
│ 012             │ MySQL               │
└─────────────────┴─────────────────────┘

Convert to number

Query

SELECT reinterpretAsUInt64(reverse(unhex('FFF'))) AS num

Response

┌──num─┐
│ 4095 │
└──────┘

SQL Reference

Documentation Index

​bech32Decode

​bech32Encode

​bin

​bitPositionsToArray

​bitmaskToArray

​bitmaskToList

​char

​hex

​hilbertDecode

​hilbertEncode

​mortonDecode

​mortonEncode

​sqidDecode

​sqidEncode

​unbin

​unhex

bech32Decode

bech32Encode

bin

bitPositionsToArray

bitmaskToArray

bitmaskToList

char

hex

hilbertDecode

hilbertEncode

mortonDecode

mortonEncode

sqidDecode

sqidEncode

unbin

unhex