druid/docs/content/misc/math-expr.md

layout
doc_page

This expression language supports the following operators (listed in decreasing order of precedence).

Operators	Description
!, -	Unary NOT and Minus
^	Binary power op
*, /, %	Binary multiplicative
+, -	Binary additive
<, <=, >, >=, ==, !=	Binary Comparison
&&,||	Binary Logical AND, OR

Long, double and string data types are supported. If a number contains a dot, it is interpreted as a double, otherwise it is interpreted as a long. That means, always add a '.' to your number if you want it interpreted as a double value. String literal should be quoted by single quotation marks.

Expressions can contain variables. Variable names may contain letters, digits, '_' and '$'. Variable names must not begin with a digit. To escape other special characters, user can quote it with double quotation marks.

For logical operators, a number is true if and only if it is positive (0 or minus value means false). For string type, it's evaluation result of 'Boolean.valueOf(string)'.

Also, the following built-in functions are supported.

General functions

name	description
cast	cast(expr,'LONG' or 'DOUBLE' or 'STRING') returns expr with specified type. exception can be thrown
if	if(predicate,then,else) returns 'then' if 'predicate' evaluates to a positive number, otherwise it returns 'else'
nvl	nvl(expr,expr-for-null) returns 'expr-for-null' if 'expr' is null (or empty string for string type)
like	like(expr, pattern[, escape]) is equivalent to SQL expr LIKE pattern
case_searched	case_searched(expr1, result1, [[expr2, result2, ...], else-result])
case_simple	case_simple(expr, value1, result1, [[value2, result2, ...], else-result])

String functions

name	description
concat	concatenate a list of strings
like	like(expr, pattern[, escape]) is equivalent to SQL expr LIKE pattern
lookup	lookup(expr, lookup-name) looks up expr in a registered query-time lookup
regexp_extract	regexp_extract(expr, pattern[, index]) applies a regular expression pattern and extracts a capture group index, or null if there is no match. If index is unspecified or zero, returns the substring that matched the pattern.
replace	replace(expr, pattern, replacement) replaces pattern with replacement
substring	substring(expr, index, length) behaves like java.lang.String's substring
strlen	strlen(expr) returns length of a string in UTF-16 code units
trim	trim(expr[, chars]) remove leading and trailing characters from expr if they are present in chars. chars defaults to ' ' (space) if not provided.
ltrim	ltrim(expr[, chars]) remove leading characters from expr if they are present in chars. chars defaults to ' ' (space) if not provided.
rtrim	rtrim(expr[, chars]) remove trailing characters from expr if they are present in chars. chars defaults to ' ' (space) if not provided.
lower	lower(expr) converts a string to lowercase
upper	upper(expr) converts a string to uppercase

Time functions

name	description
timestamp	timestamp(expr[,format-string]) parses string expr into date then returns milli-seconds from java epoch. without 'format-string' it's regarded as ISO datetime format
unix_timestamp	same with 'timestamp' function but returns seconds instead
timestamp_ceil	timestamp_ceil(expr, period, [origin, [timezone]]) rounds up a timestamp, returning it as a new timestamp. Period can be any ISO8601 period, like P3M (quarters) or PT12H (half-days). The time zone, if provided, should be a time zone name like "America/Los_Angeles" or offset like "-08:00".
timestamp_floor	timestamp_floor(expr, period, [origin, [timezone]]) rounds down a timestamp, returning it as a new timestamp. Period can be any ISO8601 period, like P3M (quarters) or PT12H (half-days). The time zone, if provided, should be a time zone name like "America/Los_Angeles" or offset like "-08:00".
timestamp_shift	timestamp_shift(expr, period, step, [timezone]) shifts a timestamp by a period (step times), returning it as a new timestamp. Period can be any ISO8601 period. Step may be negative. The time zone, if provided, should be a time zone name like "America/Los_Angeles" or offset like "-08:00".
timestamp_extract	timestamp_extract(expr, unit, [timezone]) extracts a time part from expr, returning it as a number. Unit can be EPOCH, SECOND, MINUTE, HOUR, DAY (day of month), DOW (day of week), DOY (day of year), WEEK (week of week year), MONTH (1 through 12), QUARTER (1 through 4), or YEAR. The time zone, if provided, should be a time zone name like "America/Los_Angeles" or offset like "-08:00"
timestamp_parse	timestamp_parse(string expr, [pattern, [timezone]]) parses a string into a timestamp using a given Joda DateTimeFormat pattern, or ISO8601 if the pattern is not provided. The time zone, if provided, should be a time zone name like "America/Los_Angeles" or offset like "-08:00", and will be used as the time zone for strings that do not include a time zone offset. Pattern and time zone must be literals. Strings that cannot be parsed as timestamps will be returned as nulls.
timestamp_format	timestamp_format(expr, [pattern, [timezone]]) formats a timestamp as a string with a given Joda DateTimeFormat pattern, or ISO8601 if the pattern is not provided. The time zone, if provided, should be a time zone name like "America/Los_Angeles" or offset like "-08:00". Pattern and time zone must be literals.

Math functions

See javadoc of java.lang.Math for detailed explanation for each function.

name	description
abs	abs(x) would return the absolute value of x
acos	acos(x) would return the arc cosine of x
asin	asin(x) would return the arc sine of x
atan	atan(x) would return the arc tangent of x
atan2	atan2(y, x) would return the angle theta from the conversion of rectangular coordinates (x, y) to polar * coordinates (r, theta)
cbrt	cbrt(x) would return the cube root of x
ceil	ceil(x) would return the smallest (closest to negative infinity) double value that is greater than or equal to x and is equal to a mathematical integer
copysign	copysign(x) would return the first floating-point argument with the sign of the second floating-point argument
cos	cos(x) would return the trigonometric cosine of x
cosh	cosh(x) would return the hyperbolic cosine of x
div	div(x,y) is integer division of x by y
exp	exp(x) would return Euler's number raised to the power of x
expm1	expm1(x) would return e^x-1
floor	floor(x) would return the largest (closest to positive infinity) double value that is less than or equal to x and is equal to a mathematical integer
getExponent	getExponent(x) would return the unbiased exponent used in the representation of x
hypot	hypot(x, y) would return sqrt(x^2+y^2) without intermediate overflow or underflow
log	log(x) would return the natural logarithm of x
log10	log10(x) would return the base 10 logarithm of x
log1p	log1p(x) would the natural logarithm of x + 1
max	max(x, y) would return the greater of two values
min	min(x, y) would return the smaller of two values
nextafter	nextafter(x, y) would return the floating-point number adjacent to the x in the direction of the y
nextUp	nextUp(x) would return the floating-point value adjacent to x in the direction of positive infinity
pow	pow(x, y) would return the value of the x raised to the power of y
remainder	remainder(x, y) would return the remainder operation on two arguments as prescribed by the IEEE 754 standard
rint	rint(x) would return value that is closest in value to x and is equal to a mathematical integer
round	round(x) would return the closest long value to x, with ties rounding up
scalb	scalb(d, sf) would return d * 2^sf rounded as if performed by a single correctly rounded floating-point multiply to a member of the double value set
signum	signum(x) would return the signum function of the argument x
sin	sin(x) would return the trigonometric sine of an angle x
sinh	sinh(x) would return the hyperbolic sine of x
sqrt	sqrt(x) would return the correctly rounded positive square root of x
tan	tan(x) would return the trigonometric tangent of an angle x
tanh	tanh(x) would return the hyperbolic tangent of x
todegrees	todegrees(x) converts an angle measured in radians to an approximately equivalent angle measured in degrees
toradians	toradians(x) converts an angle measured in degrees to an approximately equivalent angle measured in radians
ulp	ulp(x) would return the size of an ulp of the argument x