mirror of https://github.com/apache/druid.git
72 lines
4.7 KiB
Markdown
72 lines
4.7 KiB
Markdown
---
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layout: doc_page
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---
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This expression language supports the following operators (listed in decreasing order of precedence).
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|Operators|Description|
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|---------|-----------|
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|!, -|Unary NOT and Minus|
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|^|Binary power op|
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|*, /, %|Binary multiplicative|
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|+, -|Binary additive|
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|<, <=, >, >=, ==, !=|Binary Comparison|
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|&&,\|\||Binary Logical AND, OR|
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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.
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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.
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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)'.
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Also, the following built-in functions are supported.
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|name|description|
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|----|-----------|
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|cast|cast(expr,'LONG' or 'DOUBLE' or 'STRING') returns expr with specified type. exception can be thrown |
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|if|if(predicate,then,else) returns 'then' if 'predicate' evaluates to a positive number, otherwise it returns 'else' |
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|nvl|nvl(expr,expr-for-null) returns 'expr-for-null' if 'expr' is null (or empty string for string type) |
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|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 |
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|unix_timestamp|same with 'timestamp' function but returns seconds instead |
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And built-in math functions. See javadoc of java.lang.Math for detailed explanation for each function.
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|name|description|
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|----|-----------|
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|abs|abs(x) would return the absolute value of x|
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|acos|acos(x) would return the arc cosine of x|
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|asin|asin(x) would return the arc sine of x|
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|atan|atan(x) would return the arc tangent of x|
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|atan2|atan2(y, x) would return the angle theta from the conversion of rectangular coordinates (x, y) to polar * coordinates (r, theta)|
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|cbrt|cbrt(x) would return the cube root of x|
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|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|
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|copysign|copysign(x) would return the first floating-point argument with the sign of the second floating-point argument|
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|cos|cos(x) would return the trigonometric cosine of x|
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|cosh|cosh(x) would return the hyperbolic cosine of x|
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|exp|exp(x) would return Euler's number raised to the power of x|
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|expm1|expm1(x) would return e^x-1|
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|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|
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|getExponent|getExponent(x) would return the unbiased exponent used in the representation of x|
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|hypot|hypot(x, y) would return sqrt(x^2+y^2) without intermediate overflow or underflow|
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|log|log(x) would return the natural logarithm of x|
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|log10|log10(x) would return the base 10 logarithm of x|
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|log1p|log1p(x) would the natural logarithm of x + 1|
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|max|max(x, y) would return the greater of two values|
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|min|min(x, y) would return the smaller of two values|
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|nextafter|nextafter(x, y) would return the floating-point number adjacent to the x in the direction of the y|
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|nextUp|nextUp(x) would return the floating-point value adjacent to x in the direction of positive infinity|
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|pow|pow(x, y) would return the value of the x raised to the power of y|
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|remainder|remainder(x, y) would return the remainder operation on two arguments as prescribed by the IEEE 754 standard|
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|rint|rint(x) would return value that is closest in value to x and is equal to a mathematical integer|
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|round|round(x) would return the closest long value to x, with ties rounding up|
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|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|
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|signum|signum(x) would return the signum function of the argument x|
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|sin|sin(x) would return the trigonometric sine of an angle x|
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|sinh|sinh(x) would return the hyperbolic sine of x|
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|sqrt|sqrt(x) would return the correctly rounded positive square root of x|
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|tan|tan(x) would return the trigonometric tangent of an angle x|
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|tanh|tanh(x) would return the hyperbolic tangent of x|
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|todegrees|todegrees(x) converts an angle measured in radians to an approximately equivalent angle measured in degrees|
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|toradians|toradians(x) converts an angle measured in degrees to an approximately equivalent angle measured in radians|
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|ulp|ulp(x) would return the size of an ulp of the argument x|
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