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# Hive Built-in Functions

This article lists all built-in functions supported by Hive 0.10.0 (CDH 4.3.1).

Get the extended Hive Guide as PDF.

## Mathematical Functions

Return Type Name(Signature) Description
double round(double a) Returns the rounded BIGINT value of the double
double round(double a, int d) Returns the double rounded to d decimal places
bigint floor(double a) Returns the maximum BIGINT value that is equal or less than the double
bigint ceil(double a), ceiling(double a) Returns the minimum BIGINT value that is equal or greater than the double
double rand(), rand(int seed) Returns a random number (that changes from row to row) that is distributed uniformly from 0 to 1. Specifiying the seed will make sure the generated random number sequence is deterministic.
double exp(double a) Returns ea where e is the base of the natural logarithm
double ln(double a) Returns the natural logarithm of the argument
double log10(double a) Returns the base-10 logarithm of the argument
double log2(double a) Returns the base-2 logarithm of the argument
double log(double base, double a) Return the base "base" logarithm of the argument
double pow(double a, double p), power(double a, double p) Return ap
double sqrt(double a) Returns the square root of a
string bin(bigint a) Returns the number in binary format (see http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_bin)
string hex(bigint a) hex(string a) If the argument is an int, hex returns the number as a string in hex format. Otherwise if the number is a string, it converts each character into its hex representation and returns the resulting string. (see http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_hex)
string unhex(string a) Inverse of hex. Interprets each pair of characters as a hexidecimal number and converts to the character represented by the number.
string conv(bigint num, int from_base, int to_base), conv(STRING num, int from_base, int to_base) Converts a number from a given base to another (see http://dev.mysql.com/doc/refman/5.0/en/mathematical-functions.html#function_conv)
double abs(double a) Returns the absolute value
int double pmod(int a, int b) pmod(double a, double b) Returns the positive value of a mod b
double sin(double a) Returns the sine of a (a is in radians)
double asin(double a) Returns the arc sin of x if -1<=a<=1 or null otherwise
double cos(double a) Returns the cosine of a (a is in radians)
double acos(double a) Returns the arc cosine of x if -1<=a<=1 or null otherwise
double tan(double a) Returns the tangent of a (a is in radians)
double atan(double a) Returns the arctangent of a
double degrees(double a) Converts value of a from radians to degrees
int double positive(int a), positive(double a) Returns a
int double negative(int a), negative(double a) Returns -a
float sign(double a) Returns the sign of a as '1.0' or '-1.0'
double e() Returns the value of e
double pi() Returns the value of pi

## Collection Functions

Return Type Name(Signature) Description
int size(Map<K.V>) Returns the number of elements in the map type
int size(Array<T>) Returns the number of elements in the array type
array<K> map_keys(Map<K.V>) Returns an unordered array containing the keys of the input map
array<V> map_values(Map<K.V>) Returns an unordered array containing the values of the input map
boolean array_contains(Array<T>, value) Returns TRUE if the array contains value
array<t> sort_array(Array<T>) Sorts the input array in ascending order according to the natural ordering of the array elements and returns it

## Type Conversion Functions

Return Type Name(Signature) Description
binary binary(string|binary) Casts the parameter into a binary
Expected "=" to follow "type" cast(expr as <type>) Converts the results of the expression expr to <type> e.g. cast('1' as BIGINT) will convert the string '1' to it integral representation. A null is returned if the conversion does not succeed.

## Date Functions

Return Type Name(Signature) Description
string from_unixtime(bigint unixtime[, string format]) Converts the number of seconds from unix epoch (1970-01-01 00:00:00 UTC) to a string representing the timestamp of that moment in the current system time zone in the format of "1970-01-01 00:00:00"
bigint unix_timestamp() Gets current time stamp using the default time zone.
bigint unix_timestamp(string date) Converts time string in format yyyy-MM-dd HH:mm:ss to Unix time stamp, return 0 if fail: unix_timestamp('2009-03-20 11:30:01') = 1237573801
bigint unix_timestamp(string date, string pattern) Convert time string with given pattern (see here) to Unix time stamp, return 0 if fail: unix_timestamp('2009-03-20', 'yyyy-MM-dd') = 1237532400
string to_date(string timestamp) Returns the date part of a timestamp string: to_date("1970-01-01 00:00:00") = "1970-01-01"
int year(string date) Returns the year part of a date or a timestamp string: year("1970-01-01 00:00:00") = 1970, year("1970-01-01") = 1970
int month(string date) Returns the month part of a date or a timestamp string: month("1970-11-01 00:00:00") = 11, month("1970-11-01") = 11
int day(string date) dayofmonth(date) Return the day part of a date or a timestamp string: day("1970-11-01 00:00:00") = 1, day("1970-11-01") = 1
int hour(string date) Returns the hour of the timestamp: hour('2009-07-30 12:58:59') = 12, hour('12:58:59') = 12
int minute(string date) Returns the minute of the timestamp
int second(string date) Returns the second of the timestamp
int weekofyear(string date) Return the week number of a timestamp string: weekofyear("1970-11-01 00:00:00") = 44, weekofyear("1970-11-01") = 44
int datediff(string enddate, string startdate) Return the number of days from startdate to enddate: datediff('2009-03-01', '2009-02-27') = 2
string date_sub(string startdate, int days) Subtract a number of days to startdate: date_sub('2008-12-31', 1) = '2008-12-30'
timestamp from_utc_timestamp(timestamp, string timezone) Assumes given timestamp ist UTC and converts to given timezone
timestamp to_utc_timestamp(timestamp, string timezone) Assumes given timestamp is in given timezone and converts to UTC

## Conditional Functions

Return Type Name(Signature) Description
T if(boolean testCondition, T valueTrue, T valueFalseOrNull) Return valueTrue when testCondition is true, returns valueFalseOrNull otherwise
T COALESCE(T v1, T v2, ...) Return the first v that is not NULL, or NULL if all v's are NULL
T CASE a WHEN b THEN c [WHEN d THEN e]* [ELSE f] END When a = b, returns c; when a = d, return e; else return f
T CASE WHEN a THEN b [WHEN c THEN d]* [ELSE e] END When a = true, returns b; when c = true, return d; else return e

## String Functions

Return Type Name(Signature) Description
int ascii(string str) Returns the numeric value of the first character of str
string concat(string|binary A, string|binary B...) Returns the string or bytes resulting from concatenating the strings or bytes passed in as parameters in order. e.g. concat('foo', 'bar') results in 'foobar'. Note that this function can take any number of input strings.
array<struct<string,double>> context_ngrams(array<array<string>>, array<string>, int K, int pf) Returns the top-k contextual N-grams from a set of tokenized sentences, given a string of "context". See StatisticsAndDataMining for more information.
string concat_ws(string SEP, string A, string B...) Like concat() above, but with custom separator SEP.
string concat_ws(string SEP, array<string>) Like concat_ws() above, but taking an array of strings.
int find_in_set(string str, string strList) Returns the first occurance of str in strList where strList is a comma-delimited string. Returns null if either argument is null. Returns 0 if the first argument contains any commas. e.g. find_in_set('ab', 'abc,b,ab,c,def') returns 3
string format_number(number x, int d) Formats the number X to a format like '#,###,###.##', rounded to D decimal places, and returns the result as a string. If D is 0, the result has no decimal point or fractional part.
string get_json_object(string json_string, string path) Extract json object from a json string based on json path specified, and return json string of the extracted json object. It will return null if the input json string is invalid. The json path can only have the characters [0-9a-z_], i.e., no upper-case or special characters. Also, the keys *cannot start with numbers.* This is due to restrictions on Hive column names.
boolean in_file(string str, string filename) Returns true if the string str appears as an entire line in filename.
int instr(string str, string substr) Returns the position of the first occurence of substr in str
int length(string A) Returns the length of the string
int locate(string substr, string str[, int pos]) Returns the position of the first occurrence of substr in str after position pos
string lower(string A) lcase(string A) Returns the string resulting from converting all characters of B to lower case e.g. lower('fOoBaR') results in 'foobar'
string ltrim(string A) Returns the string resulting from trimming spaces from the beginning(left hand side) of A e.g. ltrim(' foobar ') results in 'foobar '
array<struct<string,double>> ngrams(array<array<string>>, int N, int K, int pf) Returns the top-k N-grams from a set of tokenized sentences, such as those returned by the sentences() UDAF. See StatisticsAndDataMining for more information.
string parse_url(string urlString, string partToExtract [, string keyToExtract]) Returns the specified part from the URL. Valid values for partToExtract include HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, and USERINFO. e.g. parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'HOST') returns 'facebook.com'. Also a value of a particular key in QUERY can be extracted by providing the key as the third argument, e.g. parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'QUERY', 'k1') returns 'v1'.
string printf(String format, Obj... args) Returns the input formatted according do printf-style format strings
string regexp_extract(string subject, string pattern, int index) Returns the string extracted using the pattern. e.g. regexp_extract('foothebar', 'foo(.*?)(bar)', 2) returns 'bar.' Note that some care is necessary in using predefined character classes: using '\s' as the second argument will match the letter s; '
s' is necessary to match whitespace, etc. The 'index' parameter is the Java regex Matcher group() method index. See docs/api/java/util/regex/Matcher.html for more information on the 'index' or Java regex group() method.
string regexp_replace(string INITIAL_STRING, string PATTERN, string REPLACEMENT) Returns the string resulting from replacing all substrings in INITIAL_STRING that match the java regular expression syntax defined in PATTERN with instances of REPLACEMENT, e.g. regexp_replace("foobar", "oo|ar", "") returns 'fb.' Note that some care is necessary in using predefined character classes: using '\s' as the second argument will match the letter s; '
s' is necessary to match whitespace, etc.
string repeat(string str, int n) Repeat str n times
string reverse(string A) Returns the reversed string
string rtrim(string A) Returns the string resulting from trimming spaces from the end(right hand side) of A e.g. rtrim(' foobar ') results in ' foobar'
array<array<string>> sentences(string str, string lang, string locale) Tokenizes a string of natural language text into words and sentences, where each sentence is broken at the appropriate sentence boundary and returned as an array of words. The 'lang' and 'locale' are optional arguments. e.g. sentences('Hello there! How are you?') returns ( ("Hello", "there"), ("How", "are", "you") )
string space(int n) Return a string of n spaces
array split(string str, string pat) Split str around pat (pat is a regular expression)
map<string,string> str_to_map(text[, delimiter1, delimiter2]) Splits text into key-value pairs using two delimiters. Delimiter1 separates text into K-V pairs, and Delimiter2 splits each K-V pair. Default delimiters are ',' for delimiter1 and '=' for delimiter2.
string substr(string|binary A, int start) substring(string|binary A, int start) Returns the substring or slice of the byte array of A starting from start position till the end of string A e.g. substr('foobar', 4) results in 'bar' (see http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_substr)
string substr(string|binary A, int start, int len) substring(string|binary A, int start, int len) Returns the substring or slice of the byte array of A starting from start position with length len e.g. substr('foobar', 4, 1) results in 'b' (see http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_substr)
string translate(string input, string from, string to) Translates the input string by replacing the characters present in the from string with the corresponding characters in the to string. This is similar to the translate function in PostgreSQL. If any of the parameters to this UDF are NULL, the result is NULL as well
string trim(string A) Returns the string resulting from trimming spaces from both ends of A e.g. trim(' foobar ') results in 'foobar'
string upper(string A) ucase(string A) Returns the string resulting from converting all characters of A to upper case e.g. upper('fOoBaR') results in 'FOOBAR'

## Misc Functions

Return Type Name(Signature) Description
int hash(a1[, a2...]) Returns a hash value of the arguments