druid/docs/querying/sql-functions.md

1326 lines
30 KiB
Markdown

---
id: sql-functions
title: "All Druid SQL functions"
sidebar_label: "All functions"
---
<!--
~ Licensed to the Apache Software Foundation (ASF) under one
~ or more contributor license agreements. See the NOTICE file
~ distributed with this work for additional information
~ regarding copyright ownership. The ASF licenses this file
~ to you under the Apache License, Version 2.0 (the
~ "License"); you may not use this file except in compliance
~ with the License. You may obtain a copy of the License at
~
~ http://www.apache.org/licenses/LICENSE-2.0
~
~ Unless required by applicable law or agreed to in writing,
~ software distributed under the License is distributed on an
~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
~ KIND, either express or implied. See the License for the
~ specific language governing permissions and limitations
~ under the License.
-->
> Apache Druid supports two query languages: Druid SQL and [native queries](querying.md).
> This document describes the SQL language.
This page provides a reference of all Druid SQL functions in alphabetical order.
Click the linked function type for documentation on a particular function.
## ABS
`ABS(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the absolute value of a numeric expression.
## ACOS
`ACOS(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the arc cosine of a numeric expression.
## ANY_VALUE
`ANY_VALUE(<NUMERIC>)`
`ANY_VALUE(<BOOLEAN>)`
`ANY_VALUE(<CHARACTER>, <NUMERIC>)`
**Function type:** [Aggregation](sql-aggregations.md)
Returns any value of the specified expression.
## APPROX_COUNT_DISTINCT
`APPROX_COUNT_DISTINCT(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Counts distinct values of a regular column or a prebuilt sketch column.
`APPROX_COUNT_DISTINCT_BUILTIN(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Counts distinct values of a string, numeric, or `hyperUnique` column using Druid's built-in `cardinality` or `hyperUnique` aggregators.
## APPROX_COUNT_DISTINCT_DS_HLL
`APPROX_COUNT_DISTINCT_DS_HLL(expr, [<NUMERIC>, <CHARACTER>])`
**Function type:** [Aggregation](sql-aggregations.md)
Counts distinct values of an HLL sketch column or a regular column.
## APPROX_COUNT_DISTINCT_DS_THETA
`APPROX_COUNT_DISTINCT_DS_THETA(expr, [<NUMERIC>])`
**Function type:** [Aggregation](sql-aggregations.md)
Counts distinct values of a Theta sketch column or a regular column.
## APPROX_QUANTILE
`APPROX_QUANTILE(expr, <NUMERIC>, [<NUMERIC>])`
**Function type:** [Aggregation](sql-aggregations.md)
Deprecated in favor of `APPROX_QUANTILE_DS`.
## APPROX_QUANTILE_DS
`APPROX_QUANTILE_DS(expr, <NUMERIC>, [<NUMERIC>])`
**Function type:** [Aggregation](sql-aggregations.md)
Computes approximate quantiles on a Quantiles sketch column or a regular numeric column.
## APPROX_QUANTILE_FIXED_BUCKETS
`APPROX_QUANTILE_FIXED_BUCKETS(expr, <NUMERIC>, <NUMERIC>, <NUMERIC>, <NUMERIC>, [<CHARACTER>])`
**Function type:** [Aggregation](sql-aggregations.md)
Computes approximate quantiles on fixed buckets histogram column or a regular numeric column.
## ARRAY[]
`ARRAY[expr1, expr2, ...]`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Constructs a SQL ARRAY literal from the expression arguments. The arguments must be of the same type.
## ARRAY_AGG
`ARRAY_AGG([DISTINCT] expr, [<NUMERIC>])`
**Function type:** [Aggregation](sql-aggregations.md)
Returns an array of all values of the specified expression.
## ARRAY_CONCAT_AGG
`ARRAY_CONCAT_AGG([DISTINCT] expr, [<NUMERIC>])`
**Function type:** [Aggregation](sql-aggregations.md)
Concatenates array inputs into a single array.
## ASIN
`ASIN(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the arc sine of a numeric expression.
## ATAN
`ATAN(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the arc tangent of a numeric expression.
## ATAN2
`ATAN2(<NUMERIC>, <NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the arc tangent of the two arguments.
## AVG
`AVG(<NUMERIC>)`
**Function type:** [Aggregation](sql-aggregations.md)
Calculates the average of a set of values.
## BIT_AND
`BIT_AND(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Performs a bitwise AND operation on all input values.
## BIT_OR
`BIT_OR(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Performs a bitwise OR operation on all input values.
## BIT_XOR
`BIT_XOR(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Performs a bitwise XOR operation on all input values.
## BITWISE_AND
`BITWISE_AND(expr1, expr2)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Returns the bitwise AND between the two expressions, that is, `expr1 & expr2`.
## BITWISE_COMPLEMENT
`BITWISE_COMPLEMENT(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Returns the bitwise NOT for the expression, that is, `~expr`.
## BITWISE_CONVERT_DOUBLE_TO_LONG_BITS
`BITWISE_CONVERT_DOUBLE_TO_LONG_BITS(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Converts the bits of an IEEE 754 floating-point double value to a long.
## BITWISE_CONVERT_LONG_BITS_TO_DOUBLE
`BITWISE_CONVERT_LONG_BITS_TO_DOUBLE(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Converts a long to the IEEE 754 floating-point double specified by the bits stored in the long.
## BITWISE_OR
`BITWISE_OR(expr1, expr2)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Returns the bitwise OR between the two expressions, that is, `expr1 | expr2`.
## BITWISE_SHIFT_LEFT
`BITWISE_SHIFT_LEFT(expr1, expr2)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Returns a bitwise left shift of expr1, that is, `expr1 << expr2`.
## BITWISE_SHIFT_RIGHT
`BITWISE_SHIFT_RIGHT(expr1, expr2)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Returns a bitwise right shift of expr1, that is, `expr1 >> expr2`.
## BITWISE_XOR
`BITWISE_XOR(expr1, expr2)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Returns the bitwise exclusive OR between the two expressions, that is, `expr1 ^ expr2`.
## BLOOM_FILTER
`BLOOM_FILTER(expr, <NUMERIC>)`
**Function type:** [Aggregation](sql-aggregations.md)
Computes a Bloom filter from values produced by the specified expression.
## BLOOM_FILTER_TEST
`BLOOM_FILTER_TEST(expr, <STRING>)`
**Function type:** [Scalar, other](sql-scalar.md#other-scalar-functions)
Returns true if the expression is contained in a Base64-serialized Bloom filter.
## BTRIM
`BTRIM(<CHARACTER>, [<CHARACTER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Trims characters from both the leading and trailing ends of an expression.
## CASE
`CASE expr WHEN value1 THEN result1 \[ WHEN value2 THEN result2 ... \] \[ ELSE resultN \] END`
**Function type:** [Scalar, other](sql-scalar.md#other-scalar-functions)
Returns a result based on a given condition.
## CAST
`CAST(value AS TYPE)`
**Function type:** [Scalar, other](sql-scalar.md#other-scalar-functions)
Converts a value into the specified data type.
## CEIL (date and time)
`CEIL(<TIMESTAMP> TO <TIME_UNIT>)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Rounds up a timestamp by a given time unit.
## CEIL (numeric)
`CEIL(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the smallest integer value greater than or equal to the numeric expression.
## CHAR_LENGTH
`CHAR_LENGTH(expr)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Alias for [`LENGTH`](#length).
## CHARACTER_LENGTH
`CHARACTER_LENGTH(expr)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Alias for [`LENGTH`](#length).
## COALESCE
`COALESCE(expr, expr, ...)`
**Function type:** [Scalar, other](sql-scalar.md#other-scalar-functions)
Returns the first non-null value.
## CONCAT
`CONCAT(expr, expr...)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Concatenates a list of expressions.
## CONTAINS_STRING
`CONTAINS_STRING(<CHARACTER>, <CHARACTER>)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Finds whether a string is in a given expression, case-sensitive.
## COS
`COS(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the trigonometric cosine of an angle expressed in radians.
## COT
`COT(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the trigonometric cotangent of an angle expressed in radians.
## COUNT
`COUNT([DISTINCT] expr)`
`COUNT(*)`
**Function type:** [Aggregation](sql-aggregations.md)
Counts the number of rows.
## CURRENT_DATE
`CURRENT_DATE`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Returns the current date in the connection's time zone.
## CURRENT_TIMESTAMP
`CURRENT_TIMESTAMP`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Returns the current timestamp in the connection's time zone.
## DATE_TRUNC
`DATE_TRUNC(<CHARACTER>, <TIMESTAMP>)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Rounds down a timestamp by a given time unit.
## DEGREES
`DEGREES(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Converts an angle from radians to degrees.
## DIV
`DIV(x, y)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Returns the result of integer division of `x` by `y`.
## DS_CDF
`DS_CDF(expr, splitPoint0, splitPoint1, ...)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns a string representing an approximation to the Cumulative Distribution Function given the specified bin definition.
## DS_GET_QUANTILE
`DS_GET_QUANTILE(expr, fraction)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns the quantile estimate corresponding to `fraction` from a quantiles sketch.
## DS_GET_QUANTILES
`DS_GET_QUANTILES(expr, fraction0, fraction1, ...)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns a string representing an array of quantile estimates corresponding to a list of fractions from a quantiles sketch.
## DS_HISTOGRAM
`DS_HISTOGRAM(expr, splitPoint0, splitPoint1, ...)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns a string representing an approximation to the histogram given the specified bin definition.
## DS_HLL
`DS_HLL(expr, [lgK, tgtHllType])`
**Function type:** [Aggregation](sql-aggregations.md)
Creates an HLL sketch on a column containing HLL sketches or a regular column.
## DS_QUANTILE_SUMMARY
`DS_QUANTILE_SUMMARY(expr)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns a string summary of a quantiles sketch.
## DS_QUANTILES_SKETCH
`DS_QUANTILES_SKETCH(expr, [k])`
**Function type:** [Aggregation](sql-aggregations.md)
Creates a Quantiles sketch on a column containing Quantiles sketches or a regular column.
## DS_RANK
`DS_RANK(expr, value)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns an approximate rank between 0 and 1 of a given value, in which the rank signifies the fraction of the distribution less than the given value.
## DS_THETA
`DS_THETA(expr, [size])`
**Function type:** [Aggregation](sql-aggregations.md)
Creates a Theta sketch on a column containing Theta sketches or a regular column.
## EARLIEST
`EARLIEST(expr)`
`EARLIEST(expr, maxBytesPerString)`
**Function type:** [Aggregation](sql-aggregations.md)
Returns the value of a numeric or string expression corresponding to the earliest `__time` value.
## EARLIEST_BY
`EARLIEST_BY(expr, timestampExpr)`
`EARLIEST_BY(expr, timestampExpr, maxBytesPerString)`
**Function type:** [Aggregation](sql-aggregations.md)
Returns the value of a numeric or string expression corresponding to the earliest time value from `timestampExpr`.
## EXP
`EXP(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates _e_ raised to the power of the numeric expression.
## EXTRACT
`EXTRACT(<TIME_UNIT> FROM <TIMESTAMP>)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Extracts the value of some unit of the timestamp, optionally from a certain time zone, and returns the number.
## FLOOR (date and time)
`FLOOR(<TIMESTAMP> TO <TIME_UNIT>)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Rounds down a timestamp by a given time unit.
## FLOOR (numeric)
`FLOOR(<NUMERIC>)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the largest integer value less than or equal to the numeric expression.
## GREATEST
`GREATEST([expr1, ...])`
**Function type:** [Scalar, reduction](sql-scalar.md#reduction-functions)
Returns the maximum value from the provided arguments.
## GROUPING
`GROUPING(expr, expr...)`
**Function type:** [Aggregation](sql-aggregations.md)
Returns a number for each output row of a groupBy query, indicating whether the specified dimension is included for that row.
## HLL_SKETCH_ESTIMATE
`HLL_SKETCH_ESTIMATE(expr, [round])`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns the distinct count estimate from an HLL sketch.
## HLL_SKETCH_ESTIMATE_WITH_ERROR_BOUNDS
`HLL_SKETCH_ESTIMATE_WITH_ERROR_BOUNDS(expr, [numStdDev])`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns the distinct count estimate and error bounds from an HLL sketch.
## HLL_SKETCH_TO_STRING
`HLL_SKETCH_TO_STRING(expr)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns a human-readable string representation of an HLL sketch.
## HLL_SKETCH_UNION
`HLL_SKETCH_UNION([lgK, tgtHllType], expr0, expr1, ...)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns a union of HLL sketches.
## HUMAN_READABLE_BINARY_BYTE_FORMAT
`HUMAN_READABLE_BINARY_BYTE_FORMAT(value[, precision])`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Converts an integer byte size into human-readable IEC format.
## HUMAN_READABLE_DECIMAL_BYTE_FORMAT
`HUMAN_READABLE_DECIMAL_BYTE_FORMAT(value[, precision])`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Converts a byte size into human-readable SI format.
## HUMAN_READABLE_DECIMAL_FORMAT
`HUMAN_READABLE_DECIMAL_FORMAT(value[, precision])`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Converts a byte size into human-readable SI format with single-character units.
## ICONTAINS_STRING
`ICONTAINS_STRING(<expr>, str)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Finds whether a string is in a given expression, case-insensitive.
## IPV4_MATCH
`IPV4_MATCH(address, subnet)`
**Function type:** [Scalar, IP address](sql-scalar.md#ip-address-functions)
Returns true if the `address` belongs to the `subnet` literal, else false.
## IPV4_PARSE
`IPV4_PARSE(address)`
**Function type:** [Scalar, IP address](sql-scalar.md#ip-address-functions)
Parses `address` into an IPv4 address stored as an integer.
## IPV4_STRINGIFY
`IPV4_STRINGIFY(address)`
**Function type:** [Scalar, IP address](sql-scalar.md#ip-address-functions)
Converts `address` into an IPv4 address in dot-decimal notation.
## LATEST
`LATEST(expr)`
`LATEST(expr, maxBytesPerString)`
**Function type:** [Aggregation](sql-aggregations.md)
Returns the value of a numeric or string expression corresponding to the latest `__time` value.
## LATEST_BY
`LATEST_BY(expr, timestampExpr)`
`LATEST_BY(expr, timestampExpr, maxBytesPerString)`
**Function type:** [Aggregation](sql-aggregations.md)
Returns the value of a numeric or string expression corresponding to the latest time value from `timestampExpr`.
## LEAST
`LEAST([expr1, ...])`
**Function type:** [Scalar, reduction](sql-scalar.md#reduction-functions)
Returns the minimum value from the provided arguments.
## LEFT
`LEFT(expr, [length])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the leftmost number of characters from an expression.
## LENGTH
`LENGTH(expr)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the length of the expression in UTF-16 encoding.
## LN
`LN(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the natural logarithm of the numeric expression.
## LOG10
`LOG10(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the base-10 of the numeric expression.
## LOOKUP
`LOOKUP(<CHARACTER>, <CHARACTER>)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Looks up the expression in a registered query-time lookup table.
## LOWER
`LOWER(expr)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the expression in lowercase.
## LPAD
`LPAD(<CHARACTER>, <INTEGER>, [<CHARACTER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the leftmost number of characters from an expression, optionally padded with the given characters.
## LTRIM
`LTRIM(<CHARACTER>, [<CHARACTER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Trims characters from the leading end of an expression.
## MAX
`MAX(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Returns the maximum value of a set of values.
## MILLIS_TO_TIMESTAMP
`MILLIS_TO_TIMESTAMP(millis_expr)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Converts a number of milliseconds since epoch into a timestamp.
## MIN
`MIN(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Returns the minimum value of a set of values.
## MOD
`MOD(x, y)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates x modulo y, or the remainder of x divided by y.
## MV_APPEND
`MV_APPEND(arr1, expr)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Adds the expression to the end of the array.
## MV_CONCAT
`MV_CONCAT(arr1, arr2)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Concatenates two arrays.
## MV_CONTAINS
`MV_CONTAINS(arr, expr)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Returns true if the expression is in the array, false otherwise.
## MV_FILTER_NONE
`MV_FILTER_NONE(expr, arr)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Filters a multi-value expression to include no values contained in the array.
## MV_FILTER_ONLY
`MV_FILTER_ONLY(expr, arr)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Filters a multi-value expression to include only values contained in the array.
## MV_LENGTH
`MV_LENGTH(arr)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Returns the length of an array expression.
## MV_OFFSET
`MV_OFFSET(arr, long)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Returns the array element at the given zero-based index.
## MV_OFFSET_OF
`MV_OFFSET_OF(arr, expr)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Returns the zero-based index of the first occurrence of a given expression in the array.
## MV_ORDINAL
`MV_ORDINAL(arr, long)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Returns the array element at the given one-based index.
## MV_ORDINAL_OF
`MV_ORDINAL_OF(arr, expr)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Returns the one-based index of the first occurrence of a given expression.
## MV_OVERLAP
`MV_OVERLAP(arr1, arr2)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Returns true if the two arrays have any elements in common, false otherwise.
## MV_PREPEND
`MV_PREPEND(expr, arr)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Adds the expression to the beginning of the array.
## MV_SLICE
`MV_SLICE(arr, start, end)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Returns a slice of the array from the zero-based start and end indexes.
## MV_TO_STRING
`MV_TO_STRING(arr, str)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Joins all elements of the array together by the given delimiter.
## NULLIF
`NULLIF(value1, value2)`
**Function type:** [Scalar, other](sql-scalar.md#other-scalar-functions)
Returns NULL if two values are equal, else returns the first value.
## NVL
`NVL(e1, e2)`
**Function type:** [Scalar, other](sql-scalar.md#other-scalar-functions)
Returns `e2` if `e1` is null, else returns `e1`.
## PARSE_LONG
`PARSE_LONG(<CHARACTER>, [<INTEGER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Converts a string into a BIGINT with the given base or into a DECIMAL data type if the base is not specified.
## POSITION
`POSITION(<CHARACTER> IN <CHARACTER> [FROM <INTEGER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the one-based index position of a substring within an expression, optionally starting from a given one-based index.
## POWER
`POWER(expr, power)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates a numerical expression raised to the specified power.
## RADIANS
`RADIANS(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Converts an angle from degrees to radians.
## REGEXP_EXTRACT
`REGEXP_EXTRACT(<CHARACTER>, <CHARACTER>, [<INTEGER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Applies a regular expression to the string expression and returns the _n_th match.
## REGEXP_LIKE
`REGEXP_LIKE(<CHARACTER>, <CHARACTER>)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns true or false signifying whether the regular expression finds a match in the string expression.
## REPEAT
`REPEAT(<CHARACTER>, [<INTEGER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Repeats the string expression an integer number of times.
## REPLACE
`REPLACE(expr, pattern, replacement)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Replaces a pattern with another string in the given expression.
## REVERSE
`REVERSE(expr)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Reverses the given expression.
## RIGHT
`RIGHT(expr, [length])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the rightmost number of characters from an expression.
## ROUND
`ROUND(expr[, digits])`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the rounded value for a numerical expression.
## RPAD
`RPAD(<CHARACTER>, <INTEGER>, [<CHARACTER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the rightmost number of characters from an expression, optionally padded with the given characters.
## RTRIM
`RTRIM(<CHARACTER>, [<CHARACTER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Trims characters from the trailing end of an expression.
## SAFE_DIVIDE
`SAFE_DIVIDE(x, y)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Returns `x` divided by `y`, guarded on division by 0.
## SIN
`SIN(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the trigonometric sine of an angle expressed in radians.
## SQRT
`SQRT(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the square root of a numeric expression.
## STDDEV
`STDDEV(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Alias for [`STDDEV_SAMP`](#stddev_samp).
## STDDEV_POP
`STDDEV_POP(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Calculates the population standard deviation of a set of values.
## STDDEV_SAMP
`STDDEV_SAMP(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Calculates the sample standard deviation of a set of values.
## STRING_AGG
`STRING_AGG(expr, separator, [size])`
**Function type:** [Aggregation](sql-aggregations.md)
Collects all values of an expression into a single string.
## STRING_FORMAT
`STRING_FORMAT(pattern[, args...])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns a string formatted in accordance to Java's String.format method.
## STRING_TO_MV
`STRING_TO_MV(str1, str2)`
**Function type:** [Multi-value string](sql-multivalue-string-functions.md)
Converts a string into an array, split by the given delimiter.
## STRLEN
`STRLEN(expr)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Alias for [`LENGTH`](#length).
## STRPOS
`STRPOS(<CHARACTER>, <CHARACTER>)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the one-based index position of a substring within an expression.
## SUBSTR
`SUBSTR(<CHARACTER>, <INTEGER>, [<INTEGER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Alias for [`SUBSTRING`](#substring).
## SUBSTRING
`SUBSTRING(<CHARACTER>, <INTEGER>, [<INTEGER>])`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns a substring of the expression starting at a given one-based index.
## SUM
`SUM(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Calculates the sum of a set of values.
## TAN
`TAN(expr)`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Calculates the trigonometric tangent of an angle expressed in radians.
## TDIGEST_GENERATE_SKETCH
`TDIGEST_GENERATE_SKETCH(expr, [compression])`
**Function type:** [Aggregation](sql-aggregations.md)
Generates a T-digest sketch from values of the specified expression.
## TDIGEST_QUANTILE
`TDIGEST_QUANTILE(expr, quantileFraction, [compression])`
**Function type:** [Aggregation](sql-aggregations.md)
Returns the quantile for the specified fraction from a T-Digest sketch constructed from values of the expression.
## TEXTCAT
`TEXTCAT(<CHARACTER>, <CHARACTER>)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Concatenates two string expressions.
## THETA_SKETCH_ESTIMATE
`THETA_SKETCH_ESTIMATE(expr)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns the distinct count estimate from a Theta sketch.
## THETA_SKETCH_ESTIMATE_WITH_ERROR_BOUNDS
`THETA_SKETCH_ESTIMATE_WITH_ERROR_BOUNDS(expr, errorBoundsStdDev)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns the distinct count estimate and error bounds from a Theta sketch.
## THETA_SKETCH_INTERSECT
`THETA_SKETCH_INTERSECT([size], expr0, expr1, ...)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns an intersection of Theta sketches.
## THETA_SKETCH_NOT
`THETA_SKETCH_NOT([size], expr0, expr1, ...)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns a set difference of Theta sketches.
## THETA_SKETCH_UNION
`THETA_SKETCH_UNION([size], expr0, expr1, ...)`
**Function type:** [Scalar, sketch](sql-scalar.md#sketch-functions)
Returns a union of Theta sketches.
## TIME_CEIL
`TIME_CEIL(<TIMESTAMP>, <period>, [<origin>, [<timezone>]])`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Rounds up a timestamp by a given time period, optionally from some reference time or timezone.
## TIME_EXTRACT
`TIME_EXTRACT(<TIMESTAMP>, [<unit>, [<timezone>]])`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Extracts the value of some unit of the timestamp and returns the number.
## TIME_FLOOR
`TIME_FLOOR(<TIMESTAMP>, <period>, [<origin>, [<timezone>]])`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Rounds down a timestamp by a given time period, optionally from some reference time or timezone.
## TIME_FORMAT
`TIME_FORMAT(<TIMESTAMP>, [<pattern>, [<timezone>]])`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Formats a timestamp as a string.
## TIME_IN_INTERVAL
`TIME_IN_INTERVAL(<TIMESTAMP>, <CHARACTER>)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Returns whether a timestamp is contained within a particular interval, formatted as a string.
## TIME_PARSE
`TIME_PARSE(<string_expr>, [<pattern>, [<timezone>]])`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Parses a string into a timestamp.
## TIME_SHIFT
`TIME_SHIFT(<TIMESTAMP>, <period>, <step>, [<timezone>])`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Shifts a timestamp forwards or backwards by a given number of time units.
## TIMESTAMP_TO_MILLIS
`TIMESTAMP_TO_MILLIS(<TIMESTAMP>)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Returns the number of milliseconds since epoch for the given timestamp.
## TIMESTAMPADD
`TIMESTAMPADD(<unit>, <count>, <TIMESTAMP>)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Adds a certain amount of time to a given timestamp.
## TIMESTAMPDIFF
`TIMESTAMPDIFF(<unit>, <TIMESTAMP>, <TIMESTAMP>)`
**Function type:** [Scalar, date and time](sql-scalar.md#date-and-time-functions)
Takes the difference between two timestamps, returning the results in the given units.
## TRIM
`TRIM([BOTH|LEADING|TRAILING] [<chars> FROM] expr)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Trims the leading or trailing characters of an expression.
## TRUNC
`TRUNC(expr[, digits])`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Alias for [`TRUNCATE`](#truncate).
## TRUNCATE
`TRUNCATE(expr[, digits])`
**Function type:** [Scalar, numeric](sql-scalar.md#numeric-functions)
Truncates a numerical expression to a specific number of decimal digits.
## UPPER
`UPPER(expr)`
**Function type:** [Scalar, string](sql-scalar.md#string-functions)
Returns the expression in uppercase.
## VAR_POP
`VAR_POP(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Calculates the population variance of a set of values.
## VAR_SAMP
`VAR_SAMP(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Calculates the sample variance of a set of values.
## VARIANCE
`VARIANCE(expr)`
**Function type:** [Aggregation](sql-aggregations.md)
Alias for [`VAR_SAMP`](#var_samp).