Scalar functions

Numeric functions

ABS

ABS(col1)

Returns the absolute value of col1.

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ACOS

ACOS(col1)

Returns the inverse (arc) cosine of col1, in radians. Use the DEGREES function to convert the output to degrees.

This function returns NaN for any input outside [-1, 1].

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ASIN

ASIN(col1)

Returns the inverse (arc) sine of col1, in radians. Use the DEGREES function to convert the output to degrees.

This function returns NaN for any input outside [-1, 1].

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AS_VALUE

AS_VALUE(keyColumn)

Copies a row's key column into the row's value.

CREATE TABLE AGG AS
   SELECT 
     ID,                  -- this is the grouping column, which is stored in the message key.
     AS_VALUE(ID) AS ID2  -- this creates a copy of ID, named ID2, which is stored in the message value.
     COUNT(*) AS COUNT
   FROM S
   GROUP BY ID;

See AS_VALUE in action

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ATAN

ATAN(col1)

Returns the inverse (arc) tangent of col1, in radians. Use the DEGREES function to convert the output to degrees.

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ATAN2

ATAN2(y, x)

Returns the inverse (arc) tangent of y / x. This is equivalent to the angle theta when Cartesian coordinates (x, y) are converted to polar coordinates (radius, theta). The returned value is in radians. Use the DEGREES function to convert the output to degrees.

If x is zero, y / x is undefined, and this function returns the approximate value of a multiple of π/2.

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CAST

CAST(COL0 AS BIGINT)

Converts one type to another. The following casts are supported:

from	to	notes
any except BYTES	STRING	Converts the type to its string representation.
VARCHAR	BOOLEAN	Any string that exactly matches true, case-insensitive, is converted to true. Any other value is converted to false.
VARCHAR	INT, BIGINT, DECIMAL, DOUBLE	Converts string representation of numbers to number types. Conversion will fail if text does not contain a number or the number does not fit in the indicated type.
VARCHAR	TIME	Converts time strings to TIME. Conversion fails if text is not in HH:mm:ss format.
VARCHAR	DATE	Converts date strings to DATE. Conversion fails if text is not in yyyy-MM-dd format.
VARCHAR	TIMESTAMP	Converts datestrings to TIMESTAMP. Conversion fails if text is not in ISO-8601 format.
TIMESTAMP	TIME, DATE	Converts a TIMESTAMP to TIME or DATE by extracting the time or date portion of the TIMESTAMP.
DATE	TIMESTAMP	Converts a DATE to TIMESTAMP by setting the time portion to 00:00:00.000
INT, BIGINT, DECIMAL, DOUBLE	INT, BIGINT, DECIMAL, DOUBLE	Convert between numeric types. Conversion can result in rounding
ARRAY	ARRAY	(Since 0.14) Convert between arrays of different element types
MAP	MAP	(Since 0.14) Convert between maps of different key and value types
STRUCT	STRUCT	(Since 0.14) Convert between structs of different field types. Only fields that exist in the target STRUCT type are copied across. Any fields in the target type that don't exist in the source are set to NULL. Field name matching is case-sensitive.

See CAST in action

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CBRT

CBRT(col1)

Returns the cube root of col1.

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CEIL

CEIL(col1)

Returns the the smallest integer value that's greater than or equal to col1.

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COS

COS(col1)

Returns the cosine of col1. col1 is in radians. Use the RADIANS function to convert the input to radians, if necessary.

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COSH

COSH(col1)

Returns the hyperbolic cosine of col1. col1 is in radians. Use the RADIANS function to convert the input to radians, if necessary.

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COT

COT(col1)

Returns the cotangent of col1. col1 is in radians. Use the RADIANS function to convert the input to radians, if necessary.

This implementation returns a large value approaching positive or negative infinity near the asymptotes, because 2π and similar values cannot be represented exactly. At 0, it returns Infinity with the same sign as the input.

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DEGREES

DEGREES(col1)

Converts col1 from radians to degrees.

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ENTRIES

ENTRIES(map MAP, sorted BOOLEAN)

Creates an array of structs from the entries in a map. Each struct has a field named K containing the key, which is a string, and a field named V, which holds the value.

If sorted is true, the entries are sorted by key.

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EXP

EXP(col1)

Returns the exponential of col1, which is e raised to the power of col1.

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FLOOR

FLOOR(col1)

Returns the largest integer value that's less than or equal to col1.

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GENERATE_SERIES

GENERATE_SERIES(start, end)
GENERATE_SERIES(start, end, step)

Constructs an array of values between start and end, inclusive.

Parameters start and end can be an INT or BIGINT.

step, if supplied, specifies the step size. The step can be positive or negative. If not supplied, step defaults to 1. Parameter step must be an INT.

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GEO_DISTANCE

GEO_DISTANCE(lat1, lon1, lat2, lon2, unit)

The great-circle distance between two lat-long points, both specified in decimal degrees. An optional final parameter specifies KM (the default) or miles.

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GREATEST

GREATEST(col1, col2, …)

Returns the largest non-null value from a variable number of comparable columns.

If comparing columns of different numerical types, use CAST to first cast them to be of the same type.

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LEAST

LEAST(col1, col2, …)

Returns the smallest non-null value from a variable number of comparable columns.

If comparing columns of different numerical types, use CAST to first cast them to be of the same type.

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LN

LN(col1)

Returns the natural logarithm of col1, which is .

The value of col1 must be greater than 0.

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LOG

LOG(value)
LOG(base, value)

The single-parameter version of this method returns the base 10 logarithm of the value. The two-parameter version returns the logarithm with the given base of the value.

This function returns -Infinity for any base when the value is 0. It returns NaN when the value is negative, when the base is negative, when the base is 0, or when the base is 1.

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PI

PI()

Returns an approximate value of π.

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POWER

POWER(base, exponent)

Calculates the value of the base raised to the exponent.

This function returns Infinity when the result overflows the DOUBLE type.

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RADIANS

RADIANS(col1)

Converts col1 from degrees to radians.

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RANDOM

RANDOM()

Returns a random DOUBLE value between 0.0 and 1.0.

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ROUND

ROUND(col1)
ROUND(col1, scale)

Rounds a value to the number of decimal places specified by scale.

If scale is negative, the value is rounded to the right of the decimal point.

Numbers equidistant to the nearest value are rounded up, in the positive direction.

If the number of decimal places is not provided, it defaults to zero.

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SIGN

SIGN(col1)

Returns the sign of col1 as an INTEGER:

• -1 if the argument is negative
• 0 if the argument is zero
• 1 if the argument is positive
• null argument is null

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SIN

SIN(col1)

Returns the sine of col1. col1 is in radians. Use the RADIANS function to convert the input to radians, if necessary.

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SINH

SINH(col1)

Returns the hyperbolic sine of col1. col1 is in radians. Use the RADIANS function to convert the input to radians, if necessary.

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SQRT

SQRT(col1)

Returns the square root of col.

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TAN

TAN(col1)

Returns the tangent of col1. col1 is in radians. Use the RADIANS function to convert the input to radians, if necessary.

This implementation returns a large value approaching positive or negative infinity near the asymptotes, because π/2 and similar values cannot be represented exactly.

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TANH

TANH(col1)

Returns the hyperbolic tangent of col1. col1 is in radians. Use the RADIANS function to convert the input to radians, if necessary.

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TRUNC

TRUNC(col1)
TRUNC(col1, scale)

Truncates (rounds toward zero) a value to the number of decimal places specified by scale.

If scale is negative, the value is truncated to the left of the decimal point. For example, TRUNC(12345.67, -3) returns 12000.

If the number of decimal places is not provided, it defaults to zero.

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Collections

ARRAY

ARRAY[exp1, exp2, …]

Constructs an array from a variable number of inputs.

All elements must be coercible to a common SQL type. For more information, see Implicit type coercion.

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ARRAY_CONCAT

ARRAY_CONCAT(array1, array2)

Returns an array representing the concatenation of both input arrays.

Returns NULL if both input arrays are NULL. If only one argument is NULL, the result is the other argument.

ARRAY_CONCAT(ARRAY[1, 2, 3, 1, 2], [4, 1])  => [1, 2, 3, 1, 2, 4, 1]
ARRAY_CONCAT(ARRAY['apple', 'apple', NULL, 'cherry'], ARRAY['cherry'])  => ['apple', 'apple', NULL, 'cherry', 'cherry']

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ARRAY_CONTAINS

ARRAY_CONTAINS(ARRAY[1, 2, 3], 3)

Given an array, checks if a search value is contained in the array.

Accepts any ARRAY type. The type of the second param must match the element type of the ARRAY.

See ARRAY_CONTAINS in action

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ARRAY_DISTINCT

ARRAY_DISTINCT([1, 2, 3])

Returns an array of all the distinct values, including NULL if present, from the input array.

The output array elements are in order of their first occurrence in the input.

Returns NULL if the input array is NULL.

ARRAY_DISTINCT(ARRAY[1, 1, 2, 3, 1, 2])  => [1, 2, 3]
ARRAY_DISTINCT(ARRAY['apple', 'apple', NULL, 'cherry'])  => ['apple', NULL, 'cherry']

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ARRAY_EXCEPT

ARRAY_EXCEPT(array1, array2)

Returns an array of all the distinct elements from an array, except for those also present in a second array.

The order of entries in the first array is preserved but duplicates are removed.

Returns NULL if either input is NULL.

ARRAY_EXCEPT(ARRAY[1, 2, 3, 1, 2], [2, 3])  => [1]
ARRAY_EXCEPT(ARRAY['apple', 'apple', NULL, 'cherry'], ARRAY['cherry'])  => ['apple', NULL]

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ARRAY_INTERSECT

ARRAY_INTERSECT(array1, array2)

Returns an array of all the distinct elements from the intersection of both input arrays.

The order of entries in the output is the same as in the first input array.

Returns NULL if either input array is NULL.

ARRAY_INTERSECT(ARRAY[1, 2, 3, 1, 2], [2, 1])  => [1, 2]
ARRAY_INTERSECT(ARRAY['apple', 'apple', NULL, 'cherry'], ARRAY['apple'])  => ['apple']

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ARRAY_JOIN

ARRAY_JOIN(col1, delimiter)

Creates a flat string representation of all the elements contained in an array.

The elements in the resulting string are separated by the chosen delimiter, which is an optional parameter. The default is the comma character, ,.

Array elements are limited to primitive ksqlDB types only.

See ARRAY_JOIN in action

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ARRAY_LENGTH

ARRAY_LENGTH(ARRAY[1, 2, 3])

Returns the number of elements in an array.

If the supplied parameter is NULL, the method returns NULL.

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ARRAY_MAX

ARRAY_MAX(['foo', 'bar', 'baz'])

Returns the maximum value from an array of primitive elements.

Arrays of other arrays, arrays of maps, arrays of structs, or combinations of these types aren't supported.

If the array field is NULL, or contains only NULL values, NULL is returned.

Array entries are compared according to their natural sort order, which sorts the various data types as shown in the following examples.

ARRAY_MAX[-1, 2, NULL, 0] => 2
ARRAY_MAX[false, NULL, true] => true
ARRAY_MAX['Foo', 'Bar', NULL, 'baz'] => 'baz' -- (lower-case characters are "greater" than upper-case characters)

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ARRAY_MIN

ARRAY_MIN(['foo', 'bar', 'baz'])

Returns the minimum value from an array of primitive elements.

Arrays of other arrays, arrays of maps, arrays of structs, or combinations of these types aren't supported.

If the array field is NULL, or contains only NULL values, NULL is returned.

Array entries are compared according to their natural sort order, which sorts the various data types as shown in the following examples.

ARRAY_MIN[-1, 2, NULL, 0] => -1
ARRAY_MIN[false, NULL, true] => false
ARRAY_MIN['Foo', 'Bar', NULL, 'baz'] => 'Bar'

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ARRAY_REMOVE

ARRAY_REMOVE(array, element)

Removes all elements from array that are equal to element.

If the array field is NULL, NULL is returned.

ARRAY_REMOVE([1, 2, 3, 2, 1], 2) => [1, 3, 1]
ARRAY_REMOVE([false, NULL, true, true], false) => [NULL, true, true]
ARRAY_REMOVE(['Foo', 'Bar', NULL, 'baz'], null) => ['Foo', 'Bar', 'baz']

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ARRAY_SORT

ARRAY_SORT(['foo', 'bar', 'baz'], 'ASC|DESC')

Given an array of primitive elements, returns an array of the same elements sorted according to their natural sort order.

Arrays of other arrays, arrays of maps, arrays of structs, or combinations of these types aren't supported.

Any NULL values in the array are moved to the end.

If the array field is NULL, NULL is returned.

The optional second parameter specifies whether to sort the elements in ascending (ASC) or descending (DESC) order. If neither is specified, the default is ascending order.

ARRAY_SORT[-1, 2, NULL, 0] -> [-1, 0, 2, NULL]
ARRAY_SORT[false, NULL, true] -> [false, true, NULL]
ARRAY_SORT['Foo', 'Bar', NULL, 'baz'] -> ['Bar', 'Foo', 'baz', NULL]

See ARRAY_SORT in action

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ARRAY_UNION

ARRAY_UNION(array1, array2)

Returns an array of all the distinct elements from both input arrays, in the order they're encountered.

Returns NULL if either input array is NULL.

ARRAY_UNION(ARRAY[1, 2, 3, 1, 2], [4, 1])  => [1, 2, 3, 4]
ARRAY_UNION(ARRAY['apple', 'apple', NULL, 'cherry'], ARRAY['cherry'])  => ['apple', NULL, 'cherry']

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AS_MAP

AS_MAP(keys, vals)

Constructs a map from a list of keys and a list of values.

See AS_MAP in action

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ELT

ELT(n INTEGER, args VARCHAR[])

Returns element n in the args list of strings, or NULL if n is less than 1 or greater than the number of arguments.

The ELT function is 1-indexed.

ELT is the complement to the FIELD function.

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FIELD

FIELD(str VARCHAR, args VARCHAR[])

Returns the 1-indexed position of str in args, or 0 if not found.

If str is NULL, the return value is 0, because NULL isn't considered to be equal to any value.

FIELD is the complement to the ELT function.

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JSON_ARRAY_CONTAINS

JSON_ARRAY_CONTAINS('[1, 2, 3]', 3)

Given a STRING containing a JSON array, checks if a search value is contained in the array.

Returns false if the first parameter doesn't contain a JSON array.

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MAP

MAP(key VARCHAR := value, …)

Constructs a map from specific key-value tuples.

All values must be coercible to a common SQL type.

For more information, see Implicit type coercion.

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MAP_KEYS

MAP_KEYS(a_map)

Returns an array that contains all keys from the specified map.

Returns NULL if the input map is NULL.

map_keys( map('apple' := 10, 'banana' := 20) )  => ['apple', 'banana'] 

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MAP_VALUES

MAP_VALUES(a_map)

Returns an array that contains all values from the specified map.

Returns NULL if the input map is NULL.

map_values( map('apple' := 10, 'banana' := 20) )  => [10, 20] 

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MAP_UNION

MAP_UNION(map1, map2)

Returns a new map containing the union of all entries from both input maps.

If a key is present in both input maps, the corresponding value from map2 is returned.

Returns NULL if all input maps are NULL.

MAP_UNION( MAP('apple' := 10, 'banana' := 20), MAP('cherry' := 99) )  => ['apple': 10, 'banana': 20, 'cherry': 99] 
MAP_UNION( MAP('apple' := 10, 'banana' := 20), MAP('apple' := 50) )  => ['apple': 50, 'banana': 20] 

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SLICE

SLICE(col1, from, to)

Slices a list based on the supplied indices.

The indices start at 1 and include both endpoints.

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Invocation Functions

Apply lambda functions to collections.

FILTER

FILTER(array, x => …)
FILTER(map, (k,v) => …)

Filters a collection with a lambda function.

If the collection is an array, the lambda function must have one input argument.

If the collection is a map, the lambda function must have two input arguments.

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REDUCE

REDUCE(array, state, (s, x) => …)
REDUCE(map, state, (s, k, v) => …)

Reduces a collection starting from an initial state.

If the collection is an array, the lambda function must have two input arguments.

If the collection is a map, the lambda function must have three input arguments.

If the state is NULL, the result is NULL.

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TRANSFORM

TRANSFORM(array, x => …)
TRANSFORM(map, (k,v) => …, (k,v) => …)

Transforms a collection by using a lambda function.

If the collection is an array, the lambda function must have one input argument.

If the collection is a map, two lambda functions must be provided, and both lambdas must have two arguments: a map entry key and a map entry value.

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Strings

CHR

CHR(decimal_code | utf_string)

Returns a single-character string representing the Unicode code-point described by the input.

The input parameter can be either a decimal character code or a string representation of a UTF code.

Returns NULL if the input is NULL or doesn't represent a valid code-point.

Commonly used to insert control characters such as Tab (9), Line Feed (10), or Carriage Return (13) into strings.

CHR(75)        => 'K'
CHR('\u004b')  => 'K'
CHR(22909)     => '好'
CHR('\u597d')  => '好'

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CONCAT

CONCAT(col1, col2, 'hello', …, col-n)
CONCAT(bytes1, bytes2, …, bytes-n)

Concatenates two or more string or bytes expressions.

Any inputs which evaluate to NULL are replaced with an empty string or bytes in the output.

See CONCAT in action

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CONCAT_WS

CONCAT_WS(separator, expr1, expr2, …)

Concatenates two or more string or bytes expressions, inserting a separator string or bytes between each.

If the separator is NULL, this function returns NULL.

Any expressions which evaluate to NULL are skipped.

CONCAT_WS(', ', 'apple', 'banana', NULL, 'date')  ->  'apple, banana, date'

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ENCODE

ENCODE(col1, input_encoding, output_encoding)

Given a STRING that is encoded as input_encoding, encode it using the output_encoding.

The accepted input and output encodings are:

• hex
• utf8
• ascii
• base64

Throws an exception if the provided encodings are not supported.

The following example encodes a hex representation of a string to a utf8 representation.

ENCODE(string, 'hex', 'utf8')

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EXTRACTJSONFIELD

EXTRACTJSONFIELD(message, '$.log.cloud')

Given a STRING that contains JSON data, extracts the value at the specified JSONPath.

For example, given a STRING containing the following JSON:

{
   "log": {
      "cloud": "gcp836Csd",
      "app": "ksProcessor",
      "instance": 4
   }
}

EXTRACTJSONFIELD(message, '$.log.cloud') returns the STRING gcp836Csd.

If the requested JSONPath does not exist, the function returns NULL.

The result of EXTRACTJSONFIELD is always a STRING. Use CAST to convert the result to another type.

For example, CAST(EXTRACTJSONFIELD(message, '$.log.instance') AS INT) extracts the instance number from the previous JSON object as a INT.

The return type of EXTRACTJSONFIELD is STRING, so JSONPaths that select multiple elements, like those containing wildcards, aren't supported.

Note

EXTRACTJSONFIELD is useful for extracting data from JSON when either the schema of the JSON data isn't static or the JSON data is embedded in a row that's encoded using a different format, for example, a JSON field within an Avro-encoded message.

If the whole row is encoded as JSON with a known schema or structure, use the JSON format and define the structure as the source's columns.

For example, a stream of JSON objects similar to the previous example could be defined using a statement similar to the following:

CREATE STREAM LOGS (LOG STRUCT<CLOUD STRING, APP STRING, INSTANCE INT>, …)
  WITH (VALUE_FORMAT='JSON', …)

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FROM_BYTES

FROM_BYTES(bytes, encoding)

Converts a BYTES column to a STRING in the specified encoding type.

The following list shows the supported encoding types.

• hex
• utf8
• ascii
• base64

IS_JSON_STRING

IS_JSON_STRING(json_string) => Boolean

Returns true if json_string can be parsed as a valid JSON value; otherwise, false .

IS_JSON_STRING('[1, 2, 3]') => true
IS_JSON_STRING('{}') => true
IS_JSON_STRING('1') => true
IS_JSON_STRING('\"abc\"') => true
IS_JSON_STRING('null') => true
IS_JSON_STRING('') => false
IS_JSON_STRING('abc') => false
IS_JSON_STRING(NULL) => false

JSON_ARRAY_LENGTH

JSON_ARRAY_LENGTH(json_string) => Integer

Parses json_string as a JSON value and returns the length of the top-level array.

Returns NULL if the string can't be interpreted as a JSON array, for example, when the string is NULL or it doesn't contain valid JSON, or the JSON value is not an array.

JSON_ARRAY_LENGTH('[1, 2, 3]') => 3
JSON_ARRAY_LENGTH('[1, [1, [2]], 3]') =>  3
JSON_ARRAY_LENGTH('[]') => 0
JSON_ARRAY_LENGTH('{}') => NULL
JSON_ARRAY_LENGTH('123') => NULL
JSON_ARRAY_LENGTH(NULL) => NULL
JSON_ARRAY_LENGTH('abc') => returns NULL and logs an "Invalid JSON format" exception in server log

JSON_CONCAT

JSON_CONCAT(json_string1, json_string2, ...) => String

Given N strings, parses them as JSON values and returns a string representing their concatenation.

Concatenation rules are identical to PostgreSQL's || operator:

• If all strings deserialize into JSON objects, return an object with a union of the input keys. If there are duplicate objects, take values from the last object.
• If all strings deserialize into JSON arrays, return the result of array concatenation.
• If at least one of the deserialized values is not an object, convert non-array inputs to a single-element array and return the result of array concatenation.
• If at least one of the input strings is NULL or can't be deserialized as JSON, return NULL.

Similar to PostgreSQL's || operator, this function merges only top-level object keys or arrays.

Examples:

JSON_CONCAT('{\"a\": 1}', '{\"b\": 2}') => '{"a":1,"b":2}'
JSON_CONCAT('{\"a\": {\"5\": 6}}', '{\"a\": {\"3\": 4}}') => '{"a":{"3":4}}'
JSON_CONCAT('{}', '{}') => '{}'
JSON_CONCAT('[1, 2]', '[3, 4]') => '[1,2,3,4]'
JSON_CONCAT('[1, [2]]', '[[[3]], [[[4]]]]') => '[ 1, [2], [[3]], [[[4]]] ]'
JSON_CONCAT('null', 'null') => '[null, null]'
JSON_CONCAT('[1, 2]', '{\"a\": 1}') => '[1,2,{"a":1}]'
JSON_CONCAT('[1, 2]', '3') => '[1, 2, 3]'
JSON_CONCAT('1', '2') => '[1, 2]'
JSON_CONCAT('[]', '[]') => '[]'
JSON_CONCAT('abc', '[1]') => NULL
JSON_CONCAT(NULL, '[1]') => NULL

JSON_KEYS

JSON_KEYS(json_string) => Array<String>

Parses json_string as a JSON object and returns an array of strings representing the top-level keys.

Returns NULL if the string can't be interpreted as a JSON object, for example, when the string is NULL or it does not contain valid JSON, or the JSON value is not an object.

JSON_KEYS('{\"a\": \"abc\", \"b\": { \"c\": \"a\" }, \"d\": 1}') => ['a', 'b', 'd']
JSON_KEYS('{}') => []
JSON_KEYS('[]') => NULL
JSON_KEYS('123') => NULL
JSON_KEYS(NULL) => NULL
JSON_KEYS('') => NULL

JSON_RECORDS

JSON_RECORDS(json_string) => Map<String, String>

Parses json_string as a JSON object and returns a map representing the top-level keys and values.

Returns NULL if the string can't be interpreted as a JSON object, for example, when the string is NULL or it does not contain valid JSON, or the JSON value is not an object.

JSON_RECORDS('{\"a\": \"abc\", \"b\": { \"c\": \"a\" }, \"d\": 1}') => {d=1, a="abc", b={"c":"a"}}
JSON_RECORDS('{}') => {}
JSON_RECORDS('[]') => NULL
JSON_RECORDS('123') => NULL
JSON_RECORDS(NULL) => NULL
JSON_RECORDS('abc') => NULL

JSON_ITEMS

JSON_ITEMS(json_string) => Array<String>

Given a string with JSON array, converts it to a ksqlDB array of JSON strings.

Returns NULL if the string can't be interpreted as a JSON array, for example, when the string is NULL or it does not contain valid JSON, or the JSON value is not an array.

JSON_ITEMS('[{\"type\": \"A\", \"ts\": \"2022-01-27\"}, {\"type\": \"B\", \"ts\": \"2022-05-18\"}]') => ["{\"type\": \"A\", \"ts\": \"2022-01-27\"}", "{\"type\": \"B\", \"ts\": \"2022-05-18\"}"]
JSON_ITEMS('[]') => []
JSON_ITEMS('[1, 2, 3]') => ["1","2","3"]
JSON_ITEMS(NULL) => NULL
JSON_ITEMS('abc') => NULL

TO_JSON_STRING

TO_JSON_STRING(val) => String

Given any ksqlDB type, returns the equivalent JSON string.

TO_JSON_STRING(1) => '1'
TO_JSON_STRING(15.3) => '15.3'
TO_JSON_STRING('abc') => '"abc"'
TO_JSON_STRING(true) => 'true'
TO_JSON_STRING(PARSE_DATE('2021-10-11', 'yyyy-MM-dd')) => '"2021-10-11"'
TO_JSON_STRING(PARSE_TIME('13:25', 'HH:mm')) => '"13:25"'
TO_JSON_STRING(PARSE_TIMESTAMP('2021-06-31 12:18:39.446', 'yyyy-MM-dd HH:mm:ss.SSS')) => '"2021-06-30T12:18:39.446"'
TO_JSON_STRING(NULL) => 'null'

TO_JSON_STRING(Array[1, 2, 3]) => '[1, 2, 3]'
TO_JSON_STRING(Struct(id := 1, name := 'A')) => '{"ID":1,"NAME":"A"}'
TO_JSON_STRING(Map('c' := 2, 'd' := 4)) => '{"c": 2, "d": 4}'
TO_JSON_STRING(Array[Struct(json_key := 1, json_value := Map('c' := 2, 'd' := 3))]) => '[{"JSON_KEY": 1, "JSON_VALUE": {"c": 2, "d": 3}}]'

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INITCAP

INITCAP(col1)

Capitalizes the first letter in each word and converts all other letters to lowercase.

Words are delimited by whitespace.

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INSTR

INSTR(string, substring, [position], [occurrence])

Returns the position of substring in string.

The first character is at position 1.

If position is provided, search starts from the specified position.

A negative value for position causes the search to work from the end to the start of string.

If occurrence is provided, the position of the n-th occurrence is returned.

If substring is not found, the return value is 0.

INSTR('CORPORATE FLOOR', 'OR') -> 2
INSTR('CORPORATE FLOOR', 'OR', 3) -> 5
INSTR('CORPORATE FLOOR', 'OR', 3, 2) -> 14
INSTR('CORPORATE FLOOR', 'OR', -3) -> 5
INSTR('CORPORATE FLOOR', 'OR', -3, 2) -> 2b
INSTR('CORPORATE FLOOR', 'MISSING') -> 0

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LCASE

LCASE(col1)

Converts a string to lowercase.

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LEN

LEN(string)
LEN(bytes)

Returns the length of a STRING or the number of bytes in a BYTES value.

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LPAD

LPAD(input, length, padding)

Pads the input string or bytes, beginning from the left, with the specified padding of the same type, until the target length is reached.

If the input is longer than length, it is truncated.

If the padding string or byte array is empty or NULL, or the target length is negative, NULL is returned.

LPAD('Foo', 7, 'Bar')  =>  'BarBFoo'
LPAD('Foo', 2, 'Bar')  =>  'Fo'
LPAD('', 2, 'Bar')  =>  'Ba'
LPAD('123', 5, '0')  => '00123'

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MASK

MASK(col1, 'X', 'x', 'n', '-')

Convert a string to a masked or obfuscated version of itself.

The optional arguments following the input string to be masked are the characters to be substituted for upper-case, lower-case, numeric, and other characters of the input, respectively.

If the mask characters are omitted, the default values are applied, as shown in the following example.

MASK("My Test $123") => "Xx-Xxxx--nnn"

Set a given mask character to NULL to prevent any masking of that character type.

MASK("My Test $123", '*', NULL, '1', NULL) => "*y *est $111" 

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MASK_KEEP_LEFT

MASK_KEEP_LEFT(col1, numChars, 'X', 'x', 'n', '-')

Similar to the MASK function, except that the first or left-most numChars characters aren't masked in any way.

MASK_KEEP_LEFT("My Test $123", 4) => "My Txxx--nnn"

---

MASK_KEEP_RIGHT

MASK_KEEP_RIGHT(col1, numChars, 'X', 'x', 'n', '-')

Similar to the MASK function, except that the last or right-most numChars characters aren't masked in any way.

MASK_KEEP_RIGHT("My Test $123", 4) => "Xx-Xxxx-$123"

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MASK_LEFT

MASK_LEFT(col1, numChars, 'X', 'x', 'n', '-')

Similar to the MASK function, except that only the first or left-most numChars characters have any masking applied to them.

MASK_LEFT("My Test $123", 4) => "Xx-Xest $123"

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MASK_RIGHT

MASK_RIGHT(col1, numChars, 'X', 'x', 'n', '-')

Similar to the MASK function, except that only the last or right-most numChars characters have any masking applied to them.

MASK_RIGHT("My Test $123", 4) => "My Test -nnn"

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REPLACE

REPLACE(col1, 'foo', 'bar')

Replaces all instances of a substring in a string with a new string.

See REPLACE in action

• Detect and analyze SSH attacks

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REGEXP_EXTRACT

REGEXP_EXTRACT('.*', col1)
REGEXP_EXTRACT('(([AEIOU]).)', col1, 2)

Extracts the first substring matched by the regular expression pattern from the input.

You can specify a capturing group number to return that specific group. If a number isn't specified, the entire substring is returned by default.

REGEXP_EXTRACT("(.*) (.*)", 'hello there', 2) => "there"

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REGEXP_EXTRACT_ALL

REGEXP_EXTRACT_ALL('.*', col1)
REGEXP_EXTRACT_ALL('(([AEIOU]).)', col1, 2)

Extracts all subtrings matched by the regular expression pattern from the input.

You can specify a capturing group number to return that specific group. If a number isn't specified, the entire substring is returned by default.

REGEXP_EXTRACT("(\\w+) (\\w+)", "hello there nice day", 2) => ["there", "day"]

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REGEXP_REPLACE

REGEXP_REPLACE(col1, 'a.b+', 'bar')

Replaces all matches of a regular expression in an input string with a new string.

If either the input string, the regular expression, or the new string is NULL, the result is NULL.

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REGEXP_SPLIT_TO_ARRAY

REGEXP_SPLIT_TO_ARRAY(col1, 'a.b+')

Splits a string into an array of substrings based on a regular expression.

If there is no match, the original string is returned as the only element in the array.

If the regular expression is empty, all characters in the string are split.

If either the string or the regular expression is NULL, a NULL value is returned.

If the regular expression is found at the beginning or end of the string, or there are contiguous matches, an empty element is added to the array.

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RPAD

RPAD(input, length, padding)

Pads the input string or bytes, starting from the end, with the specified padding of the same type, until the target length is reached.

If the input is longer than the specified target length, it is truncated.

If the padding string or byte array is empty or NULL, or the target length is negative, NULL is returned.

RPAD('Foo', 7, 'Bar')  =>  'FooBarB'
RPAD('Foo', 2, 'Bar')  =>  'Fo'
RPAD('', 2, 'Bar')  =>  'Ba'

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SPLIT

SPLIT(col1, delimiter)

Splits a string into an array of substrings, or bytes into an array of subarrays, based on a delimiter.

If the delimiter isn't found, the original string or byte array is returned as the only element in the array.

If the delimiter is empty, every character in the string or byte in the array is split.

If the delimiter is found at the beginning or end of the string or bytes, or there are contiguous delimiters, an empty space is added to the array.

Returns NULL if either parameter is NULL.

See SPLIT in action

• Detect and analyze SSH attacks

---

SPLIT_TO_MAP

SPLIT_TO_MAP(input, entryDelimiter, kvDelimiter)

Splits a string into key-value pairs and creates a map from them.

The entryDelimiter splits the string into key-value pairs which are then split by kvDelimiter.

If the same key is present multiple times in the input, the latest value for the key is returned.

Returns NULL if the input text is NULL.

Returns NULL if either of the delimiters is NULL or an empty string.

SPLIT_TO_MAP('apple':='green'/'cherry':='red', '/', ':=')  => { 'apple':'green', 'cherry':'red'}

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SUBSTRING

SUBSTRING(str, pos, [len])
SUBSTRING(bytes, pos, [len])

Returns the portion of str or bytes that starts at pos and has length len, or continues to the end of the string or bytes.

The first character or byte is at position 1.

SUBSTRING("stream", 1, 4)  => "stre"

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TO_BYTES

TO_BYTES(string, encoding)

Converts a STRING column in the specified encoding type to a BYTES column.

The following list shows the supported encoding types.

• hex
• utf8
• ascii
• base64

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TRIM

TRIM(col1)

Removes the spaces from the beginning and end of a string.

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UCASE

UCASE(col1)

Converts a string to uppercase.

See UCASE in action

• Handle corrupted data from Salesforce

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UUID

UUID()
UUID(bytes)

Creates a Universally Unique Identifier (UUID) generated according to RFC 4122.

A call to UUID() returns a value conforming to UUID version 4, sometimes called "random UUID", as described in RFC 4122.

A call to UUID(bytes) returns a value conforming to UUID.

The value is a 128-bit number represented as a string of five hexadecimal numbers, aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee, for example, 237e9877-e79b-12d4-a765-321741963000.

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Bytes

BIGINT_FROM_BYTES

BIGINT_FROM_BYTES(col1, [byteOrder])

Converts a BYTES value to a BIGINT value according to the specified byte order.

BYTES must be 8 bytes long, or a NULL value is returned.

Byte order values must be BIG_ENDIAN or LITTLE_ENDIAN. If omitted, BIG_ENDIAN is used.

A NULL value is returned if an invalid byte order value is provided.

Example, where b is a BYTES value represented as a base64 string AAAAASoF8gA=:

BIGINT_FROM_BYTES(b, 'BIG_ENDIAN') => 5000000000

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DOUBLE_FROM_BYTES

DOUBLE_FROM_BYTES(col1, [byteOrder])

Converts a BYTES value to a DOUBLE value according to the specified byte order.

BYTES must be 8 bytes long, or a NULL value is returned.

Byte order values must be BIG_ENDIAN or LITTLE_ENDIAN. If omitted, BIG_ENDIAN is used.

A NULL value is returned if an invalid byte order value is provided.

Example, where b is a BYTES value represented as a base64 string QICm/ZvJ9YI=:

DOUBLE_FROM_BYTES(b, 'BIG_ENDIAN') => 532.8738323

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INT_FROM_BYTES

INT_FROM_BYTES(col1, [byteOrder])

Converts a BYTES value to an INT value according to the specified byte order.

BYTES must be 4 bytes long, or a NULL value is returned.

Byte order values must be BIG_ENDIAN or LITTLE_ENDIAN. If omitted, BIG_ENDIAN is used.

A NULL value is returned if an invalid byte order value is provided.

Example, where b_big is a BYTES value represented as a base64 string AAAH5Q==:

INT_FROM_BYTES(b, 'BIG_ENDIAN') -> 2021

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TO_BYTES

TO_BYTES(col1, encoding)

Converts a STRING value in the specified encoding to BYTES.

The following list shows the supported encoding types.

• hex
• utf8
• ascii
• base64

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Nulls

COALESCE

COALESCE(a, b, c, d)

Returns the first parameter that is not NULL. All parameters must be of the same type.

If the parameter is a complex type, for example, ARRAY or STRUCT, the contents of the complex type are not inspected. The behaviour is the same: the first NOT NULL element is returned.

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IFNULL

IFNULL(expression, altValue)

If expression is NULL, returns altValue; otherwise, returns expression.

If expression evaluates to a complex type, for example, ARRAY or STRUCT, the contents of the complex type are not inspected.

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NULLIF

NULLIF(expression1, expression2)

Returns NULL if expression1 is equal to expression2; otherwise, returns expression1.

If expression evaluates to a complex type, for example, ARRAY or STRUCT, the contents of the complex type are not inspected.

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Date and time

CONVERT_TZ

CONVERT_TZ(col1, 'from_timezone', 'to_timezone')

Converts a TIMESTAMP value from from_timezone to to_timezone.

The from_timezone and to_timezone parameters are java.util.TimeZone ID formats, for example:

• "UTC"
• "America/Los_Angeles"
• "PDT"
• "Europe/London"

For more information on timestamp formats, see DateTimeFormatter.

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DATEADD

DATEADD(unit, interval, col0)

Adds an interval to a date.

Intervals are defined by an integer value and a supported time unit.

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DATESUB

DATESUB(unit, interval, col0)

Subtracts an interval from a date.

Intervals are defined by an integer value and a supported time unit.

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FORMAT_DATE

FORMAT_DATE(date, 'yyyy-MM-dd')

Converts a DATE value into a string that represents the date in the specified format.

You can escape single-quote characters in the timestamp format by using two successive single quotes, '', for example: 'yyyy-MM-dd''T'''.

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FORMAT_TIME

FORMAT_TIME(time, 'HH:mm:ss.SSS')

Converts a TIME value into the string representation of the time in the given format.

You can escape single-quote characters in the time format by using two successive single quotes, '', for example: '''T''HH:mm:ssX'.

For more information on time formats, see DateTimeFormatter.

---

FORMAT_TIMESTAMP

FORMAT_TIMESTAMP(timestamp, 'yyyy-MM-dd HH:mm:ss.SSS' [, TIMEZONE])

Converts a TIMESTAMP value into the string representation of the timestamp in the specified format.

You can escape single-quote characters in the timestamp format by using two successive single quotes, '', for example: 'yyyy-MM-dd''T''HH:mm:ssX'.

The optional TIMEZONE parameter is a java.util.TimeZone ID format, for example:

• "UTC"
• "America/Los_Angeles"
• "PDT"
• "Europe/London"

Note

To use the FORMAT_TIMESTAMP function with a BIGINT millisecond timestamp parameter, convert the millisecond value to a TIMESTAMP by using the FROM_UNIXTIME function, for example:

FORMAT_TIMESTAMP(FROM_UNIXTIME(unix_timestamp))

For more information on timestamp formats, see DateTimeFormatter.

See FORMAT_TIMESTAMP in action

• Analyze datacenter power usage
• Detect and analyze SSH attacks

---

FROM_DAYS

FROM_DAYS(days)

Converts an INT number of days since epoch to a DATE value.

---

FROM_UNIXTIME

FROM_UNIXTIME(milliseconds)

Converts a BIGINT millisecond timestamp value into a TIMESTAMP value.

See FROM_UNIXTIME in action

• Analyze datacenter power usage

---

PARSE_DATE

PARSE_DATE(col1, 'yyyy-MM-dd')

Converts a string representation of a date in the specified format into a DATE value.

You can escape single-quote characters in the timestamp format by using two successive single quotes, '', for example: 'yyyy-MM-dd''T'''.

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PARSE_TIME

PARSE_TIME(col1, 'HH:mm:ss.SSS')

Converts a string value in the specified format into a TIME value.

You can escape single-quote characters in the time format by using successive single quotes, '', for example: '''T''HH:mm:ssX'.

For more information on time formats, see DateTimeFormatter.

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PARSE_TIMESTAMP

PARSE_TIMESTAMP(col1, 'yyyy-MM-dd HH:mm:ss.SSS' [, TIMEZONE])

Converts a string value in the given format into the TIMESTAMP value.

You can escape single-quote characters in the timestamp format by using successive single quotes, '', for example: 'yyyy-MM-dd''T''HH:mm:ssX'.

The optional TIMEZONE parameter is a java.util.TimeZone ID format, for example:

• "UTC"
• "America/Los_Angeles"
• "PDT"
• "Europe/London"

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TIMEADD

TIMEADD(unit, interval, COL0)

Adds an interval to a TIME.

Intervals are defined by an integer value and a supported time unit.

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TIMESUB

TIMESUB(unit, interval, COL0)

Subtracts an interval from a TIME.

Intervals are defined by an integer value and a supported time unit.

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TIMESTAMPADD

TIMESTAMPADD(unit, interval, COL0)

Adds an interval to a TIMESTAMP.

Intervals are defined by an integer value and a supported time unit.

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TIMESTAMPSUB

TIMESTAMPSUB(unit, interval, COL0)

Subtracts an interval from a TIMESTAMP.

Intervals are defined by an integer value and a supported time unit.

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UNIX_DATE

UNIX_DATE([date])

If UNIX_DATE is called with the date parameter, the function returns the DATE value as an INTEGER value representing the number of days since 1970-01-01.

If the date parameter is not provided, the function returns an integer representing days since 1970-01-01.

Important

The returned integer may differ depending on the local time of different ksqlDB Server instances.

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UNIX_TIMESTAMP

UNIX_TIMESTAMP([timestamp])

If UNIX_TIMESTAMP is called with the timestamp parameter, the function returns the TIMESTAMP value as a BIGINT value representing the number of milliseconds since 1970-01-01T00:00:00 UTC.

If the timestamp parameter is not provided, the function returns the current UNIX timestamp in milliseconds, represented as a BIGINT.

Important

The returned BIGINT may differ depending on the local time of different ksqlDB Server instances.

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URLs

All ksqlDB URL functions assume URI syntax defined in RFC 39386. For more information on the structure of a URI, including definitions of the various components, see Section 3 of the RFC.

For encoding and decoding, ksqlDB uses the application/x-www-form-urlencoded convention.

URL_DECODE_PARAM

URL_DECODE_PARAM(col1)

Unescapes the URL-param-encoded_ value in col1.

This is the inverse of the URL_ENCODE_PARAM function.

URL_DECODE_PARAM("url%20encoded") => "url encoded"

---

URL_ENCODE_PARAM

URL_ENCODE_PARAM(col1)

Escapes the value of col1 such that it can safely be used in URL query parameters.

Note

URL_ENCODE_PARAM is not the same as encoding a value for use in the path portion of a URL.

URL_ENCODE_PARAM("url encoded") => "url%20encoded"

---

URL_EXTRACT_FRAGMENT

URL_EXTRACT_FRAGMENT(url)

Extracts the fragment portion of the specified value.

Returns NULL if url is not a valid URL or if the fragment doesn't exist.

All encoded values are decoded.

URL_EXTRACT_FRAGMENT("http://test.com#frag") => "frag"
URL_EXTRACT_FRAGMENT("http://test.com#frag%20space") => "frag space"

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URL_EXTRACT_HOST

URL_EXTRACT_HOST(url)

Extracts the host-name portion of the specified value.

Returns NULL if url is not a valid URI according to RFC-2396.

URL_EXTRACT_HOST("http://test.com:8080/path") => "test.com"

---

URL_EXTRACT_PARAMETER

URL_EXTRACT_PARAMETER(url, parameter_name)

Extracts the value of the requested parameter from the query-string of url.

Returns NULL if the parameter is not present, has no value specified for it in the query string, or url is not a valid URI.

The function encodes the parameter and decodes the output.

To get all parameter values from a URL as a single string, use URL_EXTRACT_QUERY.

URL_EXTRACT_PARAMETER("http://test.com?a%20b=c%20d", "a b") => "c d"
URL_EXTRACT_PARAMETER("http://test.com?a=foo&b=bar", "b") => "bar"

---

URL_EXTRACT_PATH

URL_EXTRACT_PATH(url)

Extracts the path from url.

Returns NULL if url is not a valid URI but returns an empty string if the path is empty.

URL_EXTRACT_PATH("http://test.com/path/to#a") => "path/to"

---

URL_EXTRACT_PORT

URL_EXTRACT_PORT(url)

Extracts the port number from url.

Returns NULL if url is not a valid URI or does not contain an explicit port number.

URL_EXTRACT_PORT("http://localhost:8080/path") => "8080"

---

URL_EXTRACT_PROTOCOL

URL_EXTRACT_PROTOCOL(url)

Extracts the protocol from url.

Returns NULL if url is an invalid URI or has no protocol.

URL_EXTRACT_PROTOCOL("http://test.com?a=foo&b=bar") => "http"

---

URL_EXTRACT_QUERY

URL_EXTRACT_QUERY(url)

Extracts the decoded query-string portion of url.

Returns NULL if no query-string is present or url is not a valid URI.

URL_EXTRACT_QUERY("http://test.com?a=foo%20bar&b=baz") => "a=foo bar&b=baz"

---

Deprecated

DATETOSTRING

Since: 0.7.1

Deprecated since 0.20.0 (use FORMAT_DATE)

DATETOSTRING(START_DATE, 'yyyy-MM-dd')

Converts an integer representation of a date into a string representing the date in the given format. Single quotes in the timestamp format can be escaped with two successive single quotes, '', for example: 'yyyy-MM-dd''T'''. The integer represents days since epoch matching the encoding used by Connect dates.

STRINGTODATE

Since: 0.7.1

Deprecated since 0.20.0 (use PARSE_DATE)

STRINGTODATE(col1, 'yyyy-MM-dd')

Converts a string representation of a date in the given format into an integer representing days since epoch. Single quotes in the timestamp format can be escaped with two successive single quotes, '', for example: 'yyyy-MM-dd''T'''.

STRINGTOTIMESTAMP

Since: 0.7.1

Deprecated since 0.17.0 (use PARSE_TIMESTAMP)

STRINGTOTIMESTAMP(col1, 'yyyy-MM-dd HH:mm:ss.SSS' [, TIMEZONE])

Converts a string value in the given format into the BIGINT value
that represents the millisecond timestamp. Single quotes in the timestamp format can be escaped with two successive single quotes, '', for example: 'yyyy-MM-dd''T''HH:mm:ssX'.

TIMEZONE is an optional parameter and it is a java.util.TimeZone ID format, for example: "UTC", "America/Los_Angeles", "PDT", "Europe/London". For more information on timestamp formats, see DateTimeFormatter.

TIMESTAMPTOSTRING

Since: 0.7.1

Deprecated since 0.17.0 (use FORMAT_TIMESTAMP)

TIMESTAMPTOSTRING(ROWTIME, 'yyyy-MM-dd HH:mm:ss.SSS' [, TIMEZONE])

Converts a BIGINT millisecond timestamp value into the string representation of the timestamp in the given format. Single quotes in the timestamp format can be escaped with two successive single quotes, '', for example: 'yyyy-MM-dd''T''HH:mm:ssX'.

TIMEZONE is an optional parameter, and it is a java.util.TimeZone ID format, for example, "UTC", "America/Los_Angeles", "PDT", or "Europe/London". For more information on timestamp formats, see DateTimeFormatter.

Note

To use the FORMAT_TIMESTAMP function with a BIGINT millisecond timestamp parameter, convert the millisecond value to a TIMESTAMP by using the FROM_UNIXTIME function, for example:

FORMAT_TIMESTAMP(FROM_UNIXTIME(unix_timestamp))

---

Last update: 2024-10-28