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<h1 id="apache-druid-incubating-expressions">Apache Druid (incubating) Expressions</h1>
<div class="note info">
This feature is still experimental. It has not been optimized for performance yet, and its implementation is known to have significant inefficiencies.
</div>
<p>This expression language supports the following operators (listed in decreasing order of precedence).</p>
<table><thead>
<tr>
<th>Operators</th>
<th>Description</th>
</tr>
</thead><tbody>
<tr>
<td>!, -</td>
<td>Unary NOT and Minus</td>
</tr>
<tr>
<td>^</td>
<td>Binary power op</td>
</tr>
<tr>
<td>*, /, %</td>
<td>Binary multiplicative</td>
</tr>
<tr>
<td>+, -</td>
<td>Binary additive</td>
</tr>
<tr>
<td>&lt;, &lt;=, &gt;, &gt;=, ==, !=</td>
<td>Binary Comparison</td>
</tr>
<tr>
<td>&amp;&amp;, &#124;</td>
<td>Binary Logical AND, OR</td>
</tr>
</tbody></table>
<p>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 &#39;.&#39; to your number if you want it interpreted as a double value. String literals should be quoted by single quotation marks.</p>
<p>Multi-value types are not fully supported yet. Expressions may behave inconsistently on multi-value types, and you
should not rely on the behavior in this case to stay the same in future releases.</p>
<p>Expressions can contain variables. Variable names may contain letters, digits, &#39;_&#39; and &#39;$&#39;. Variable names must not begin with a digit. To escape other special characters, you can quote it with double quotation marks.</p>
<p>For logical operators, a number is true if and only if it is positive (0 or negative value means false). For string type, it&#39;s the evaluation result of &#39;Boolean.valueOf(string)&#39;.</p>
<p>The following built-in functions are available.</p>
<h2 id="general-functions">General functions</h2>
<table><thead>
<tr>
<th>name</th>
<th>description</th>
</tr>
</thead><tbody>
<tr>
<td>cast</td>
<td>cast(expr,&#39;LONG&#39; or &#39;DOUBLE&#39; or &#39;STRING&#39;) returns expr with specified type. exception can be thrown</td>
</tr>
<tr>
<td>if</td>
<td>if(predicate,then,else) returns &#39;then&#39; if &#39;predicate&#39; evaluates to a positive number, otherwise it returns &#39;else&#39;</td>
</tr>
<tr>
<td>nvl</td>
<td>nvl(expr,expr-for-null) returns &#39;expr-for-null&#39; if &#39;expr&#39; is null (or empty string for string type)</td>
</tr>
<tr>
<td>like</td>
<td>like(expr, pattern[, escape]) is equivalent to SQL <code>expr LIKE pattern</code></td>
</tr>
<tr>
<td>case_searched</td>
<td>case_searched(expr1, result1, [[expr2, result2, ...], else-result])</td>
</tr>
<tr>
<td>case_simple</td>
<td>case_simple(expr, value1, result1, [[value2, result2, ...], else-result])</td>
</tr>
<tr>
<td>bloom_filter_test</td>
<td>bloom_filter_test(expr, filter) tests the value of &#39;expr&#39; against &#39;filter&#39;, a bloom filter serialized as a base64 string. See <a href="../development/extensions-core/bloom-filter.html">bloom filter extension</a> documentation for additional details.</td>
</tr>
</tbody></table>
<h2 id="string-functions">String functions</h2>
<table><thead>
<tr>
<th>name</th>
<th>description</th>
</tr>
</thead><tbody>
<tr>
<td>concat</td>
<td>concat(expr, expr...) concatenate a list of strings</td>
</tr>
<tr>
<td>like</td>
<td>like(expr, pattern[, escape]) is equivalent to SQL <code>expr LIKE pattern</code></td>
</tr>
<tr>
<td>lookup</td>
<td>lookup(expr, lookup-name) looks up expr in a registered <a href="../querying/lookups.html">query-time lookup</a></td>
</tr>
<tr>
<td>regexp_extract</td>
<td>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.</td>
</tr>
<tr>
<td>replace</td>
<td>replace(expr, pattern, replacement) replaces pattern with replacement</td>
</tr>
<tr>
<td>substring</td>
<td>substring(expr, index, length) behaves like java.lang.String&#39;s substring</td>
</tr>
<tr>
<td>strlen</td>
<td>strlen(expr) returns length of a string in UTF-16 code units</td>
</tr>
<tr>
<td>strpos</td>
<td>strpos(haystack, needle[, fromIndex]) returns the position of the needle within the haystack, with indexes starting from 0. The search will begin at fromIndex, or 0 if fromIndex is not specified. If the needle is not found then the function returns -1.</td>
</tr>
<tr>
<td>trim</td>
<td>trim(expr[, chars]) remove leading and trailing characters from <code>expr</code> if they are present in <code>chars</code>. <code>chars</code> defaults to &#39; &#39; (space) if not provided.</td>
</tr>
<tr>
<td>ltrim</td>
<td>ltrim(expr[, chars]) remove leading characters from <code>expr</code> if they are present in <code>chars</code>. <code>chars</code> defaults to &#39; &#39; (space) if not provided.</td>
</tr>
<tr>
<td>rtrim</td>
<td>rtrim(expr[, chars]) remove trailing characters from <code>expr</code> if they are present in <code>chars</code>. <code>chars</code> defaults to &#39; &#39; (space) if not provided.</td>
</tr>
<tr>
<td>lower</td>
<td>lower(expr) converts a string to lowercase</td>
</tr>
<tr>
<td>upper</td>
<td>upper(expr) converts a string to uppercase</td>
</tr>
</tbody></table>
<h2 id="time-functions">Time functions</h2>
<table><thead>
<tr>
<th>name</th>
<th>description</th>
</tr>
</thead><tbody>
<tr>
<td>timestamp</td>
<td>timestamp(expr[,format-string]) parses string expr into date then returns milli-seconds from java epoch. without &#39;format-string&#39; it&#39;s regarded as ISO datetime format</td>
</tr>
<tr>
<td>unix_timestamp</td>
<td>same with &#39;timestamp&#39; function but returns seconds instead</td>
</tr>
<tr>
<td>timestamp_ceil</td>
<td>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 &quot;America/Los_Angeles&quot; or offset like &quot;-08:00&quot;.</td>
</tr>
<tr>
<td>timestamp_floor</td>
<td>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 &quot;America/Los_Angeles&quot; or offset like &quot;-08:00&quot;.</td>
</tr>
<tr>
<td>timestamp_shift</td>
<td>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 &quot;America/Los_Angeles&quot; or offset like &quot;-08:00&quot;.</td>
</tr>
<tr>
<td>timestamp_extract</td>
<td>timestamp_extract(expr, unit, [timezone]) extracts a time part from expr, returning it as a number. Unit can be EPOCH (number of seconds since 1970-01-01 00:00:00 UTC), SECOND, MINUTE, HOUR, DAY (day of month), DOW (day of week), DOY (day of year), WEEK (week of <a href="https://en.wikipedia.org/wiki/ISO_week_date">week year</a>), MONTH (1 through 12), QUARTER (1 through 4), or YEAR. The time zone, if provided, should be a time zone name like &quot;America/Los_Angeles&quot; or offset like &quot;-08:00&quot;</td>
</tr>
<tr>
<td>timestamp_parse</td>
<td>timestamp_parse(string expr, [pattern, [timezone]]) parses a string into a timestamp using a given <a href="http://www.joda.org/joda-time/apidocs/org/joda/time/format/DateTimeFormat.html">Joda DateTimeFormat pattern</a>. If the pattern is not provided, this parses time strings in either ISO8601 or SQL format. The time zone, if provided, should be a time zone name like &quot;America/Los_Angeles&quot; or offset like &quot;-08:00&quot;, 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.</td>
</tr>
<tr>
<td>timestamp_format</td>
<td>timestamp_format(expr, [pattern, [timezone]]) formats a timestamp as a string with a given <a href="http://www.joda.org/joda-time/apidocs/org/joda/time/format/DateTimeFormat.html">Joda DateTimeFormat pattern</a>, or ISO8601 if the pattern is not provided. The time zone, if provided, should be a time zone name like &quot;America/Los_Angeles&quot; or offset like &quot;-08:00&quot;. Pattern and time zone must be literals.</td>
</tr>
</tbody></table>
<h2 id="math-functions">Math functions</h2>
<p>See javadoc of java.lang.Math for detailed explanation for each function.</p>
<table><thead>
<tr>
<th>name</th>
<th>description</th>
</tr>
</thead><tbody>
<tr>
<td>abs</td>
<td>abs(x) would return the absolute value of x</td>
</tr>
<tr>
<td>acos</td>
<td>acos(x) would return the arc cosine of x</td>
</tr>
<tr>
<td>asin</td>
<td>asin(x) would return the arc sine of x</td>
</tr>
<tr>
<td>atan</td>
<td>atan(x) would return the arc tangent of x</td>
</tr>
<tr>
<td>atan2</td>
<td>atan2(y, x) would return the angle theta from the conversion of rectangular coordinates (x, y) to polar * coordinates (r, theta)</td>
</tr>
<tr>
<td>cbrt</td>
<td>cbrt(x) would return the cube root of x</td>
</tr>
<tr>
<td>ceil</td>
<td>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</td>
</tr>
<tr>
<td>copysign</td>
<td>copysign(x) would return the first floating-point argument with the sign of the second floating-point argument</td>
</tr>
<tr>
<td>cos</td>
<td>cos(x) would return the trigonometric cosine of x</td>
</tr>
<tr>
<td>cosh</td>
<td>cosh(x) would return the hyperbolic cosine of x</td>
</tr>
<tr>
<td>div</td>
<td>div(x,y) is integer division of x by y</td>
</tr>
<tr>
<td>exp</td>
<td>exp(x) would return Euler&#39;s number raised to the power of x</td>
</tr>
<tr>
<td>expm1</td>
<td>expm1(x) would return e^x-1</td>
</tr>
<tr>
<td>floor</td>
<td>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</td>
</tr>
<tr>
<td>getExponent</td>
<td>getExponent(x) would return the unbiased exponent used in the representation of x</td>
</tr>
<tr>
<td>hypot</td>
<td>hypot(x, y) would return sqrt(x^2+y^2) without intermediate overflow or underflow</td>
</tr>
<tr>
<td>log</td>
<td>log(x) would return the natural logarithm of x</td>
</tr>
<tr>
<td>log10</td>
<td>log10(x) would return the base 10 logarithm of x</td>
</tr>
<tr>
<td>log1p</td>
<td>log1p(x) would the natural logarithm of x + 1</td>
</tr>
<tr>
<td>max</td>
<td>max(x, y) would return the greater of two values</td>
</tr>
<tr>
<td>min</td>
<td>min(x, y) would return the smaller of two values</td>
</tr>
<tr>
<td>nextafter</td>
<td>nextafter(x, y) would return the floating-point number adjacent to the x in the direction of the y</td>
</tr>
<tr>
<td>nextUp</td>
<td>nextUp(x) would return the floating-point value adjacent to x in the direction of positive infinity</td>
</tr>
<tr>
<td>pow</td>
<td>pow(x, y) would return the value of the x raised to the power of y</td>
</tr>
<tr>
<td>remainder</td>
<td>remainder(x, y) would return the remainder operation on two arguments as prescribed by the IEEE 754 standard</td>
</tr>
<tr>
<td>rint</td>
<td>rint(x) would return value that is closest in value to x and is equal to a mathematical integer</td>
</tr>
<tr>
<td>round</td>
<td>round(x) would return the closest long value to x, with ties rounding up</td>
</tr>
<tr>
<td>scalb</td>
<td>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</td>
</tr>
<tr>
<td>signum</td>
<td>signum(x) would return the signum function of the argument x</td>
</tr>
<tr>
<td>sin</td>
<td>sin(x) would return the trigonometric sine of an angle x</td>
</tr>
<tr>
<td>sinh</td>
<td>sinh(x) would return the hyperbolic sine of x</td>
</tr>
<tr>
<td>sqrt</td>
<td>sqrt(x) would return the correctly rounded positive square root of x</td>
</tr>
<tr>
<td>tan</td>
<td>tan(x) would return the trigonometric tangent of an angle x</td>
</tr>
<tr>
<td>tanh</td>
<td>tanh(x) would return the hyperbolic tangent of x</td>
</tr>
<tr>
<td>todegrees</td>
<td>todegrees(x) converts an angle measured in radians to an approximately equivalent angle measured in degrees</td>
</tr>
<tr>
<td>toradians</td>
<td>toradians(x) converts an angle measured in degrees to an approximately equivalent angle measured in radians</td>
</tr>
<tr>
<td>ulp</td>
<td>ulp(x) would return the size of an ulp of the argument x</td>
</tr>
</tbody></table>
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