hive常見內置函數
摘要php
Hive內部提供了不少函數給開發者使用，包括數學函數，類型轉換函數，條件函數，字符函數，聚合函數，表生成函數等等，這些函數都統稱爲內置函數。html
目錄java
數學函數mysql
| Return Type正則表達式 |
Name (Signature)sql |
Descriptionexpress |
|---|---|---|
| DOUBLEapache |
round(DOUBLE a)json |
Returns the rounded 返回對a四捨五入的BIGINT值 |
| DOUBLE |
round(DOUBLE a, INT d) |
Returns 返回DOUBLE型d的保留n位小數的DOUBLW型的近似值 |
| DOUBLE | bround(DOUBLE a) | Returns the rounded BIGINT value of a using HALF_EVEN rounding mode (as of Hive 1.3.0, 2.0.0). Also known as Gaussian rounding or bankers' rounding. Example: bround(2.5) = 2, bround(3.5) = 4.銀行家舍入法（1~4：舍，6~9：進，5->前位數是偶：舍，5->前位數是奇：進） |
| DOUBLE | bround(DOUBLE a, INT d) | Returns a rounded to d decimal places using HALF_EVEN rounding mode (as of Hive 1.3.0, 2.0.0). Example: bround(8.25, 1) = 8.2, bround(8.35, 1) = 8.4.銀行家舍入法,保留d位小數 |
| BIGINT |
floor(DOUBLE a) |
Returns the maximum 向下取整，最數軸上最接近要求的值的左邊的值 如：6.10->6 -3.4->-4 |
| BIGINT |
ceil(DOUBLE a), ceiling(DOUBLE a) |
Returns the minimum BIGINT value that is equal to or greater than 求其不小於小給定實數的最小整數如：ceil(6) = ceil(6.1)= ceil(6.9) = 6 |
| DOUBLE |
rand(), rand(INT seed) |
Returns a random number (that changes from row to row) that is distributed uniformly from 0 to 1. Specifying the seed will make sure the generated random number sequence is deterministic. 每行返回一個DOUBLE型隨機數seed是隨機因子 |
| DOUBLE |
exp(DOUBLE a), exp(DECIMAL a) |
Returns 返回e的a冪次方， a可爲小數 |
| DOUBLE |
ln(DOUBLE a), ln(DECIMAL a) |
Returns the natural logarithm of the argument 以天然數爲底d的對數，a可爲小數 |
| DOUBLE |
log10(DOUBLE a), log10(DECIMAL a) |
Returns the base-10 logarithm of the argument 以10爲底d的對數，a可爲小數 |
| DOUBLE |
log2(DOUBLE a), log2(DECIMAL a) |
Returns the base-2 logarithm of the argument 以2爲底數d的對數，a可爲小數 |
| DOUBLE |
log(DOUBLE base, DOUBLE a) log(DECIMAL base, DECIMAL a) |
Returns the base- 以base爲底的對數，base 與 a都是DOUBLE類型 |
| DOUBLE |
pow(DOUBLE a, DOUBLE p), power(DOUBLE a, DOUBLE p) |
Returns 計算a的p次冪 |
| DOUBLE |
sqrt(DOUBLE a), sqrt(DECIMAL a) |
Returns the square root of 計算a的平方根 |
| 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). 計算二進制a的STRING類型，a爲BIGINT類型 |
| STRING |
hex(BIGINT a) hex(STRING a) hex(BINARY a) |
If the argument is an 計算十六進制a的STRING類型，若是a爲STRING類型就轉換成字符相對應的十六進制 |
| BINARY |
unhex(STRING a) |
Inverse of hex. Interprets each pair of characters as a hexadecimal number and converts to the byte representation of the number. ( hex的逆方法 |
| 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). 將GIGINT/STRING類型的num從from_base進制轉換成to_base進制 |
| DOUBLE |
abs(DOUBLE a) |
Returns the absolute value. 計算a的絕對值 |
| INT or DOUBLE |
pmod(INT a, INT b), pmod(DOUBLE a, DOUBLE b) |
Returns the positive value of a對b取模 |
| DOUBLE |
sin(DOUBLE a), sin(DECIMAL a) |
Returns the sine of 求a的正弦值 |
| DOUBLE |
asin(DOUBLE a), asin(DECIMAL a) |
Returns the arc sin of 求d的反正弦值 |
| DOUBLE |
cos(DOUBLE a), cos(DECIMAL a) |
Returns the cosine of 求餘弦值 |
| DOUBLE |
acos(DOUBLE a), acos(DECIMAL a) |
Returns the arccosine of 求反餘弦值 |
| DOUBLE |
tan(DOUBLE a), tan(DECIMAL a) |
Returns the tangent of 求正切值 |
| DOUBLE |
atan(DOUBLE a), atan(DECIMAL a) |
Returns the arctangent of 求反正切值 |
| DOUBLE |
degrees(DOUBLE a), degrees(DECIMAL a) |
Converts value of 獎弧度值轉換角度值 |
| DOUBLE |
radians(DOUBLE a), radians(DOUBLE a) |
Converts value of 將角度值轉換成弧度值 |
| INT or DOUBLE |
positive(INT a), positive(DOUBLE a) |
Returns 返回a |
| INT or DOUBLE |
negative(INT a), negative(DOUBLE a) |
Returns 返回a的相反數 |
| DOUBLE or INT |
sign(DOUBLE a), sign(DECIMAL a) |
Returns the sign of 若是a是正數則返回1.0，是負數則返回-1.0，不然返回0.0 |
| DOUBLE |
e() |
Returns the value of 數學常數e |
| DOUBLE |
pi() |
Returns the value of 數學常數pi |
| BIGINT | factorial(INT a) | Returns the factorial of a (as of Hive 1.2.0). Valid a is [0..20].求a的階乘 |
| DOUBLE | cbrt(DOUBLE a) | Returns the cube root of a double value (as of Hive 1.2.0).求a的立方根 |
|
INT BIGINT |
shiftleft(TINYINT|SMALLINT|INT a, INT b) shiftleft(BIGINT a, INT b) |
Bitwise left shift (as of Hive 1.2.0). Shifts Returns int for tinyint, smallint and int 按位左移 |
| INT BIGINT |
shiftright(TINYINT|SMALLINT|INT a, INTb) shiftright(BIGINT a, INT b) |
Bitwise right shift (as of Hive 1.2.0). Shifts Returns int for tinyint, smallint and int 按拉右移 |
| INT BIGINT |
shiftrightunsigned(TINYINT|SMALLINT|INTa, INT b), shiftrightunsigned(BIGINT a, INT b) |
Bitwise unsigned right shift (as of Hive 1.2.0). Shifts Returns int for tinyint, smallint and int 無符號按位右移（<<<） |
| T | greatest(T v1, T v2, ...) | Returns the greatest value of the list of values (as of Hive 1.1.0). Fixed to return NULL when one or more arguments are NULL, and strict type restriction relaxed, consistent with ">" operator (as of Hive 2.0.0). 求最大值 |
| T | least(T v1, T v2, ...) | Returns the least value of the list of values (as of Hive 1.1.0). Fixed to return NULL when one or more arguments are NULL, and strict type restriction relaxed, consistent with "<" operator (as of Hive 2.0.0). 求最小值 |
集合函數
| Return Type |
Name(Signature) |
Description |
|---|---|---|
| int |
size(Map<K.V>) |
Returns the number of elements in the map type. 求map的長度 |
| int |
size(Array<T>) |
Returns the number of elements in the array type. 求數組的長度 |
| array<K> |
map_keys(Map<K.V>) |
Returns an unordered array containing the keys of the input map. 返回map中的全部key |
| array<V> |
map_values(Map<K.V>) |
Returns an unordered array containing the values of the input map. 返回map中的全部value |
| boolean |
array_contains(Array<T>, value) |
Returns TRUE if the array contains value. 如該數組Array<T>包含value返回true。，不然返回false |
| array |
sort_array(Array<T>) |
Sorts the input array in ascending order according to the natural ordering of the array elements and returns it (as of version 0.9.0). 按天然順序對數組進行排序並返回 |
類型轉換函數
| Return Type |
Name(Signature) |
Description |
|---|---|---|
| binary |
binary(string|binary) |
Casts the parameter into a binary. 將輸入的值轉換成二進制 |
| Expected "=" to follow "type" |
cast(expr as <type>) |
Converts the results of the expression expr to <type>. For example, cast('1' as BIGINT) will convert the string '1' to its integral representation. A null is returned if the conversion does not succeed. If cast(expr as boolean) Hive returns true for a non-empty string. 將expr轉換成type類型 如：cast("1" as BIGINT) 將字符串1轉換成了BIGINT類型，若是轉換失敗將返回NULL |
日期函數
| 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". 將時間的秒值轉換成format格式（format可爲「yyyy-MM-dd hh:mm:ss」,「yyyy-MM-dd hh」,「yyyy-MM-dd hh:mm」等等）如from_unixtime(1250111000,"yyyy-MM-dd") 獲得2009-03-12 |
| bigint |
unix_timestamp() |
Gets current Unix timestamp in seconds. 獲取本地時區下的時間戳 |
| bigint |
unix_timestamp(string date) |
Converts time string in format 將格式爲yyyy-MM-dd HH:mm:ss的時間字符串轉換成時間戳 如unix_timestamp('2009-03-20 11:30:01') = 1237573801 |
| bigint |
unix_timestamp(string date, string pattern) |
Convert time string with given pattern (see [http://docs.oracle.com/javase/tutorial/i18n/format/simpleDateFormat.html]) to Unix time stamp (in seconds), return 0 if fail: unix_timestamp('2009-03-20', 'yyyy-MM-dd') = 1237532400. 將指定時間字符串格式字符串轉換成Unix時間戳，若是格式不對返回0 如：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". 返回時間字符串的日期部分 |
| 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. 返回時間字符串的年份部分 |
| int | quarter(date/timestamp/string) | Returns the quarter of the year for a date, timestamp, or string in the range 1 to 4 (as of Hive 1.3.0). Example: quarter('2015-04-08') = 2. 返回當前時間屬性哪一個季度 如quarter('2015-04-08') = 2 |
| 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. 返回時間字符串的月份部分 |
| int |
day(string date) dayofmonth(date) |
Returns the day part of a date or a timestamp string: day("1970-11-01 00:00:00") = 1, day("1970-11-01") = 1. 返回時間字符串的天 |
| int |
hour(string date) |
Returns the hour of the timestamp: hour('2009-07-30 12:58:59') = 12, hour('12:58:59') = 12. 返回時間字符串的小時 |
| int |
minute(string date) |
Returns the minute of the timestamp. 返回時間字符串的分鐘 |
| int |
second(string date) |
Returns the second of the timestamp. 返回時間字符串的秒 |
| int |
weekofyear(string date) |
Returns the week number of a timestamp string: weekofyear("1970-11-01 00:00:00") = 44, weekofyear("1970-11-01") = 44. 返回時間字符串位於一年中的第幾個周內 如weekofyear("1970-11-01 00:00:00") = 44, weekofyear("1970-11-01") = 44 |
| int |
datediff(string enddate, string startdate) |
Returns the number of days from startdate to enddate: datediff('2009-03-01', '2009-02-27') = 2. 計算開始時間startdate到結束時間enddate相差的天數 |
| string |
date_add(string startdate, int days) |
Adds a number of days to startdate: date_add('2008-12-31', 1) = '2009-01-01'. 從開始時間startdate加上days |
| string |
date_sub(string startdate, int days) |
Subtracts a number of days to startdate: date_sub('2008-12-31', 1) = '2008-12-30'. 從開始時間startdate減去days |
| timestamp |
from_utc_timestamp(timestamp, string timezone) |
Assumes given timestamp is UTC and converts to given timezone (as of Hive 0.8.0). For example, from_utc_timestamp('1970-01-01 08:00:00','PST') returns 1970-01-01 00:00:00. 若是給定的時間戳並不是UTC，則將其轉化成指定的時區下時間戳 |
| timestamp |
to_utc_timestamp(timestamp, string timezone) |
Assumes given timestamp is in given timezone and converts to UTC (as of Hive 0.8.0). For example, to_utc_timestamp('1970-01-01 00:00:00','PST') returns 1970-01-01 08:00:00. 若是給定的時間戳指定的時區下時間戳，則將其轉化成UTC下的時間戳 |
| date | current_date | Returns the current date at the start of query evaluation (as of Hive 1.2.0). All calls of current_date within the same query return the same value. 返回當前時間日期 |
| timestamp | current_timestamp | Returns the current timestamp at the start of query evaluation (as of Hive 1.2.0). All calls of current_timestamp within the same query return the same value. 返回當前時間戳 |
| string | add_months(string start_date, int num_months) | Returns the date that is num_months after start_date (as of Hive 1.1.0). start_date is a string, date or timestamp. num_months is an integer. The time part of start_date is ignored. If start_date is the last day of the month or if the resulting month has fewer days than the day component of start_date, then the result is the last day of the resulting month. Otherwise, the result has the same day component as start_date. 返回當前時間下再增長num_months個月的日期 |
| string | last_day(string date) | Returns the last day of the month which the date belongs to (as of Hive 1.1.0). date is a string in the format 'yyyy-MM-dd HH:mm:ss' or 'yyyy-MM-dd'. The time part of date is ignored. 返回這個月的最後一天的日期，忽略時分秒部分（HH:mm:ss） |
| string | next_day(string start_date, string day_of_week) | Returns the first date which is later than start_date and named as day_of_week (as of Hive1.2.0). start_date is a string/date/timestamp. day_of_week is 2 letters, 3 letters or full name of the day of the week (e.g. Mo, tue, FRIDAY). The time part of start_date is ignored. Example: next_day('2015-01-14', 'TU') = 2015-01-20. 返回當前時間的下一個星期X所對應的日期 如：next_day('2015-01-14', 'TU') = 2015-01-20 以2015-01-14爲開始時間，其下一個星期二所對應的日期爲2015-01-20 |
| string | trunc(string date, string format) | Returns date truncated to the unit specified by the format (as of Hive 1.2.0). Supported formats: MONTH/MON/MM, YEAR/YYYY/YY. Example: trunc('2015-03-17', 'MM') = 2015-03-01. 返回時間的最開始年份或月份 如trunc("2016-06-26",「MM」)=2016-06-01 trunc("2016-06-26",「YY」)=2016-01-01 注意所支持的格式爲MONTH/MON/MM, YEAR/YYYY/YY |
| double | months_between(date1, date2) | Returns number of months between dates date1 and date2 (as of Hive 1.2.0). If date1 is later than date2, then the result is positive. If date1 is earlier than date2, then the result is negative. If date1 and date2 are either the same days of the month or both last days of months, then the result is always an integer. Otherwise the UDF calculates the fractional portion of the result based on a 31-day month and considers the difference in time components date1 and date2. date1 and date2 type can be date, timestamp or string in the format 'yyyy-MM-dd' or 'yyyy-MM-dd HH:mm:ss'. The result is rounded to 8 decimal places. Example: months_between('1997-02-28 10:30:00', '1996-10-30') = 3.94959677 返回date1與date2之間相差的月份，如date1>date2，則返回正，若是date1<date2,則返回負，不然返回0.0 如：months_between('1997-02-28 10:30:00', '1996-10-30') = 3.94959677 1997-02-28 10:30:00與1996-10-30相差3.94959677個月 |
| string | date_format(date/timestamp/string ts, string fmt) | Converts a date/timestamp/string to a value of string in the format specified by the date format fmt (as of Hive 1.2.0). Supported formats are Java SimpleDateFormat formats –https://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html. The second argument fmt should be constant. Example: date_format('2015-04-08', 'y') = '2015'. date_format can be used to implement other UDFs, e.g.:
|
條件函數
| Return Type |
Name(Signature) |
Description |
|---|---|---|
| T |
if(boolean testCondition, T valueTrue, T valueFalseOrNull) |
Returns valueTrue when testCondition is true, returns valueFalseOrNull otherwise. 若是testCondition 爲true就返回valueTrue,不然返回valueFalseOrNull ，（valueTrue，valueFalseOrNull爲泛型） |
| T | nvl(T value, T default_value) | Returns default value if value is null else returns value (as of HIve 0.11). 若是value值爲NULL就返回default_value,不然返回value |
| T |
COALESCE(T v1, T v2, ...) |
Returns the first v that is not NULL, or NULL if all v's are NULL. 返回第一非null的值，若是所有都爲NULL就返回NULL 如：COALESCE (NULL,44,55)=44/strong> |
| T |
CASE a WHEN b THEN c [WHEN d THEN e]* [ELSE f] END |
When a = b, returns c; when a = d, returns e; else returns f. 若是a=b就返回c,a=d就返回e，不然返回f 如CASE 4 WHEN 5 THEN 5 WHEN 4 THEN 4 ELSE 3 END 將返回4 |
| T |
CASE WHEN a THEN b [WHEN c THEN d]* [ELSE e] END |
When a = true, returns b; when c = true, returns d; else returns e. 若是a=ture就返回b,c= ture就返回d，不然返回e 如：CASE WHEN 5>0 THEN 5 WHEN 4>0 THEN 4 ELSE 0 END 將返回5；CASE WHEN 5<0 THEN 5 WHEN 4<0 THEN 4 ELSE 0 END 將返回0 |
| boolean | isnull( a ) | Returns true if a is NULL and false otherwise. 若是a爲null就返回true，不然返回false |
| boolean | isnotnull ( a ) | Returns true if a is not NULL and false otherwise. 若是a爲非null就返回true，不然返回false |
字符函數
| Return Type |
Name(Signature) |
Description |
|---|---|---|
| int |
ascii(string str) |
Returns the numeric value of the first character of str. 返回str中首個ASCII字符串的整數值 |
| string |
base64(binary bin) |
Converts the argument from binary to a base 64 string (as of Hive 0.12.0).. 將二進制bin轉換成64位的字符串 |
| 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. For example, concat('foo', 'bar') results in 'foobar'. Note that this function can take any number of input strings.. 對二進制字節碼或字符串按次序進行拼接 |
| 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.. 與ngram相似，但context_ngram()容許你預算指定上下文(數組)來去查找子序列，具體看StatisticsAndDataMining(這裏的解釋更易懂) |
| string |
concat_ws(string SEP, string A, string B...) |
Like concat() above, but with custom separator SEP.. 與concat()相似，但使用指定的分隔符喜進行分隔 |
| string |
concat_ws(string SEP, array<string>) |
Like concat_ws() above, but taking an array of strings. (as of Hive 0.9.0). 拼接Array中的元素並用指定分隔符進行分隔 |
| string |
decode(binary bin, string charset) |
Decodes 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.). 使用指定的字符集charset將二進制值bin解碼成字符串，支持的字符集有：'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'，若是任意輸入參數爲NULL都將返回NULL |
| binary |
encode(string src, string charset) |
Encodes 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.). 使用指定的字符集charset將字符串編碼成二進制值，支持的字符集有：'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16'，若是任一輸入參數爲NULL都將返回NULL |
| 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. For example, find_in_set('ab', 'abc,b,ab,c,def') returns 3.. 返回以逗號分隔的字符串中str出現的位置，若是參數str爲逗號或查找失敗將返回0，若是任一參數爲NULL將返回NULL回 |
| 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; bug with float types fixed in Hive 0.14.0, decimal type support added in Hive 0.14.0). 將數值X轉換成"#,###,###.##"格式字符串，並保留d位小數，若是d爲0，將進行四捨五入且不保留小數 |
| string |
get_json_object(string json_string, string path) |
Extracts json object from a json string based on json path specified, and returns 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.. 從指定路徑上的JSON字符串抽取出JSON對象，並返回這個對象的JSON格式，若是輸入的JSON是非法的將返回NULL,注意此路徑上JSON字符串只能由數字 字母 下劃線組成且不能有大寫字母和特殊字符，且key不能由數字開頭，這是因爲Hive對列名的限制 |
| boolean |
in_file(string str, string filename) |
Returns true if the string str appears as an entire line in filename.. 若是文件名爲filename的文件中有一行數據與字符串str匹配成功就返回true |
| int |
instr(string str, string substr) |
Returns the position of the first occurrence of 查找字符串str中子字符串substr出現的位置，若是查找失敗將返回0，若是任一參數爲Null將返回null，注意位置爲從1開始的 |
| int |
length(string A) |
Returns the length of the string.. 返回字符串的長度 |
| int |
locate(string substr, string str[, int pos]) |
Returns the position of the first occurrence of substr in str after position pos.. 查找字符串str中的pos位置後字符串substr第一次出現的位置 |
| string |
lower(string A) lcase(string A) |
Returns the string resulting from converting all characters of B to lower case. For example, lower('fOoBaR') results in 'foobar'.. 將字符串A的全部字母轉換成小寫字母 |
| string |
lpad(string str, int len, string pad) |
Returns str, left-padded with pad to a length of len.. 從左邊開始對字符串str使用字符串pad填充，最終len長度爲止，若是字符串str自己長度比len大的話，將去掉多餘的部分 |
| string |
ltrim(string A) |
Returns the string resulting from trimming spaces from the beginning(left hand side) of A. For example, ltrim(' foobar ') results in 'foobar '.. 去掉字符串A前面的空格 |
| 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.. 返回出現次數TOP K的的子序列,n表示子序列的長度，具體看StatisticsAndDataMining (這裏的解釋更易懂) |
| 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. For example, 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, for example, parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'QUERY', 'k1') returns 'v1'.. 返回從URL中抽取指定部分的內容，參數url是URL字符串，而參數partToExtract是要抽取的部分，這個參數包含(HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, and USERINFO,例如：parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'HOST') ='facebook.com'，若是參數partToExtract值爲QUERY則必須指定第三個參數key 如：parse_url('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1', 'QUERY', 'k1') =‘v1’ |
| string |
printf(String format, Obj... args) |
Returns the input formatted according do printf-style format strings (as of Hive0.9.0).. 按照printf風格格式輸出字符串 |
| string |
regexp_extract(string subject, string pattern, int index) |
Returns the string extracted using the pattern. For example, 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.. 抽取字符串subject中符合正則表達式pattern的第index個部分的子字符串，注意些預約義字符的使用，如第二個參數若是使用'\s'將被匹配到s,'\\s'纔是匹配空格 |
| 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. For example, 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.. 按照Java正則表達式PATTERN將字符串INTIAL_STRING中符合條件的部分紅REPLACEMENT所指定的字符串，如裏REPLACEMENT這空的話，抽符合正則的部分將被去掉 如：regexp_replace("foobar", "oo|ar", "") = 'fb.' 注意些預約義字符的使用，如第二個參數若是使用'\s'將被匹配到s,'\\s'纔是匹配空格 |
| string |
repeat(string str, int n) |
Repeats str n times.. 重複輸出n次字符串str |
| string |
reverse(string A) |
Returns the reversed string.. 反轉字符串 |
| string |
rpad(string str, int len, string pad) |
Returns str, right-padded with pad to a length of len.. 從右邊開始對字符串str使用字符串pad填充，最終len長度爲止，若是字符串str自己長度比len大的話，將去掉多餘的部分 |
| string |
rtrim(string A) |
Returns the string resulting from trimming spaces from the end(right hand side) of A. For example, rtrim(' foobar ') results in ' foobar'.. 去掉字符串後面出現的空格 |
| 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. For example, sentences('Hello there! How are you?') returns ( ("Hello", "there"), ("How", "are", "you") ).. 字符串str將被轉換成單詞數組，如：sentences('Hello there! How are you?') =( ("Hello", "there"), ("How", "are", "you") ) |
| string |
space(int n) |
Returns a string of n spaces.. 返回n個空格 |
| array |
split(string str, string pat) |
Splits str around pat (pat is a regular expression).. 按照正則表達式pat來分割字符串str,並將分割後的數組字符串的形式返回 |
| 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.. 將字符串str按照指定分隔符轉換成Map，第一個參數是須要轉換字符串，第二個參數是鍵值對之間的分隔符，默認爲逗號;第三個參數是鍵值之間的分隔符，默認爲"=" |
| 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. For example, substr('foobar', 4) results in 'bar' (see [http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_substr]).. 對於字符串A,從start位置開始截取字符串並返回 |
| 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. For example, substr('foobar', 4, 1) results in 'b' (see [http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_substr]).. 對於二進制/字符串A,從start位置開始截取長度爲length的字符串並返回 |
| string | substring_index(string A, string delim, int count) | Returns the substring from string A before count occurrences of the delimiter delim (as of Hive 1.3.0). If count is positive, everything to the left of the final delimiter (counting from the left) is returned. If count is negative, everything to the right of the final delimiter (counting from the right) is returned. Substring_index performs a case-sensitive match when searching for delim. Example: substring_index('www.apache.org', '.', 2) = 'www.apache'.. 截取第count分隔符以前的字符串，如count爲正則從左邊開始截取，若是爲負則從右邊開始截取 |
| string |
translate(string|char|varchar input, string|char|varchar from, string|char|varchar to) |
Translates the input string by replacing the characters present in the Char/varchar support added as of Hive 0.14.0.. 將input出如今from中的字符串替換成to中的字符串 如：translate("MOBIN","BIN","M")="MOM" |
| string |
trim(string A) |
Returns the string resulting from trimming spaces from both ends of A. For example, trim(' foobar ') results in 'foobar'. 將字符串A先後出現的空格去掉 |
| binary |
unbase64(string str) |
Converts the argument from a base 64 string to BINARY. (As of Hive 0.12.0.). 將64位的字符串轉換二進制值 |
| string |
upper(string A) ucase(string A) |
Returns the string resulting from converting all characters of A to upper case. For example, upper('fOoBaR') results in 'FOOBAR'.. 將字符串A中的字母轉換成大寫字母 |
| string | initcap(string A) | Returns string, with the first letter of each word in uppercase, all other letters in lowercase. Words are delimited by whitespace. (As of Hive 1.1.0.). 將字符串A轉換第一個字母大寫其他字母的字符串 |
| int | levenshtein(string A, string B) | Returns the Levenshtein distance between two strings (as of Hive 1.2.0). For example, levenshtein('kitten', 'sitting') results in 3.. 計算兩個字符串之間的差別大小 如：levenshtein('kitten', 'sitting') = 3 |
| string | soundex(string A) | Returns soundex code of the string (as of Hive 1.2.0). For example, soundex('Miller') results in M460.. 將普通字符串轉換成soundex字符串 |
聚合函數
| Return Type |
Name(Signature) |
Description |
|---|---|---|
| BIGINT |
count(*), count(expr), count(DISTINCT expr[, expr...]) |
count(*) - Returns the total number of retrieved rows, including rows containing NULL values. 統計總行數，包括含有NULL值的行 count(expr) - Returns the number of rows for which the supplied expression is non-NULL. 統計提供非NULL的expr表達式值的行數 count(DISTINCT expr[, expr]) - Returns the number of rows for which the supplied expression(s) are unique and non-NULL. Execution of this can be optimized with hive.optimize.distinct.rewrite. 統計提供非NULL且去重後的expr表達式值的行數 |
| DOUBLE |
sum(col), sum(DISTINCT col) |
Returns the sum of the elements in the group or the sum of the distinct values of the column in the group. sum(col),表示求指定列的和，sum(DISTINCT col)表示求去重後的列的和 |
| DOUBLE |
avg(col), avg(DISTINCT col) |
Returns the average of the elements in the group or the average of the distinct values of the column in the group. avg(col),表示求指定列的平均值，avg(DISTINCT col)表示求去重後的列的平均值 |
| DOUBLE |
min(col) |
Returns the minimum of the column in the group. 求指定列的最小值 |
| DOUBLE |
max(col) |
Returns the maximum value of the column in the group. 求指定列的最大值 |
| DOUBLE |
variance(col), var_pop(col) |
Returns the variance of a numeric column in the group. 求指定列數值的方差 |
| DOUBLE |
var_samp(col) |
Returns the unbiased sample variance of a numeric column in the group. 求指定列數值的樣本方差 |
| DOUBLE |
stddev_pop(col) |
Returns the standard deviation of a numeric column in the group. 求指定列數值的標準誤差 |
| DOUBLE |
stddev_samp(col) |
Returns the unbiased sample standard deviation of a numeric column in the group. 求指定列數值的樣本標準誤差 |
| DOUBLE |
covar_pop(col1, col2) |
Returns the population covariance of a pair of numeric columns in the group. 求指定列數值的協方差 |
| DOUBLE |
covar_samp(col1, col2) |
Returns the sample covariance of a pair of a numeric columns in the group. 求指定列數值的樣本協方差 |
| DOUBLE |
corr(col1, col2) |
Returns the Pearson coefficient of correlation of a pair of a numeric columns in the group. 返回兩列數值的相關係數 |
| DOUBLE |
percentile(BIGINT col, p) |
Returns the exact pth percentile of a column in the group (does not work with floating point types). p must be between 0 and 1. NOTE: A true percentile can only be computed for integer values. Use PERCENTILE_APPROX if your input is non-integral. 返回col的p%分位數 |
表生成函數
| Return Type |
Name(Signature) |
Description |
|---|---|---|
| Array Type |
explode(array<TYPE> a) |
For each element in a, generates a row containing that element. 對於a中的每一個元素，將生成一行且包含該元素 |
| N rows |
explode(ARRAY) |
Returns one row for each element from the array.. 每行對應數組中的一個元素 |
| N rows |
explode(MAP) |
Returns one row for each key-value pair from the input map with two columns in each row: one for the key and another for the value. (As of Hive 0.8.0.). 每行對應每一個map鍵-值，其中一個字段是map的鍵，另外一個字段是map的值 |
| N rows |
posexplode(ARRAY) |
Behaves like 與explode相似，不一樣的是還返回各元素在數組中的位置 |
| N rows |
stack(INT n, v_1, v_2, ..., v_k) |
Breaks up v_1, ..., v_k into n rows. Each row will have k/n columns. n must be constant.. 把M列轉換成N行，每行有M/N個字段，其中n必須是個常數 |
| tuple |
json_tuple(jsonStr, k1, k2, ...) |
Takes a set of names (keys) and a JSON string, and returns a tuple of values. This is a more efficient version of the 從一個JSON字符串中獲取多個鍵並做爲一個元組返回，與get_json_object不一樣的是此函數能一次獲取多個鍵值 |
| tuple |
parse_url_tuple(url, p1, p2, ...) |
This is similar to the 返回從URL中抽取指定N部分的內容，參數url是URL字符串，而參數p1,p2,....是要抽取的部分，這個參數包含HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, USERINFO, QUERY:<KEY> |
|
|
inline(ARRAY<STRUCT[,STRUCT]>) |
Explodes an array of structs into a table. (As of Hive 0.10.). 將結構體數組提取出來並插入到表中 |
參考：https://www.cnblogs.com/MOBIN/p/5618747.html#6
http://blog.csdn.net/scgaliguodong123_/article/details/46954009
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- 4. hive 內置函數
- 5. Hive 內置函數
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