来源：https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF
Complex Type Constructors
The following functions construct instances of complex types.
|
Constructor Function |
Operands |
Description |
|---|---|---|
|
map |
(key1, value1, key2, value2, ...) |
Creates a map with the given key/value pairs |
|
struct |
(val1, val2, val3, ...) |
Creates a struct with the given field values. Struct field names will be col1, col2, ... |
|
named_struct |
(name1, val1, name2, val2, ...) |
Creates a struct with the given field names and values. (as of Hive 0.8.0) |
|
array |
(val1, val2, ...) |
Creates an array with the given elements |
|
create_union |
(tag, val1, val2, ...) |
Creates a union type with the value that is being pointed to by the tag parameter |
Date Functions
The following built-in date functions are supported in hive:
|
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 Unix timestamp in seconds |
|
bigint |
unix_timestamp(string date) |
Converts time string in format |
|
bigint |
unix_timestamp(string date, string pattern) |
Convert time string with given pattern (see [http://java.sun.com/j2se/1.4.2/docs/api/java/text/SimpleDateFormat.html]) to Unix time stamp (in seconds), 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_add(string startdate, int days) |
Add a number of days to startdate: date_add('2008-12-31', 1) = '2009-01-01' |
|
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 is UTC and converts to given timezone (as of Hive 0.8.0) |
|
timestamp |
to_utc_timestamp(timestamp, string timezone) |
Assumes given timestamp is in given timezone and converts to UTC (as of Hive 0.8.0) |
String Functions
The following built-in String functions are supported in hive:
|
Return Type |
Name(Signature) |
Description |
|---|---|---|
|
int |
ascii(string str) |
Returns the numeric value of the first character of str |
|
string |
base64(binary bin) |
Convert the argument from binary to a base 64 string (as of Hive 0.12.0) |
|
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. (as of Hive 0.9.0) |
|
string |
decode(binary bin, string charset) |
Decode the first argument into a String using the provided character set (one of 'US_ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'). If either argument is null, the result will also be null. (as of Hive 0.12.0) |
|
binary |
encode(string src, string charset) |
Encode the first argument into a BINARY using the provided character set (one of 'US_ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'). If either argument is null, the result will also be null. (as of Hive 0.12.0) |
|
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. (as of Hive 0.10.0) |
|
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. NOTE: 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 occurrence of |
|
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 |
lpad(string str, int len, string pad) |
Returns str, left-padded with pad to a length of len |
|
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 (as of Hive 0.9.0) |
|
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; ' |
|
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; ' |
|
string |
repeat(string str, int n) |
Repeat str n times |
|
string |
reverse(string A) |
Returns the reversed string |
|
string |
rpad(string str, int len, string pad) |
Returns str, right-padded with pad to a length of len |
|
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 |
|
string |
trim(string A) |
Returns the string resulting from trimming spaces from both ends of A e.g. trim(' foobar ') results in 'foobar' |
|
binary |
unbase64(string str) |
Convert the argument from a base 64 string to BINARY (as of Hive 0.12.0) |
|
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' |