# Apache Hive Built-In Functions | Hive Functions

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Basically, to perform several operations there are some functions available. Similarly, in Hive also there are some built-in functions available. Such as Hive Collection Functions, Hive Date Functions, Hive Mathematical Functions, Hive Conditional Functions and Hive String Functions.

So, this blog contains the whole concept of Hive Built-In Functions. At first, we will understand what are Hive functions actually mean. Afterward, we will learn the whole concept of Hive Built-in Functions. Also, we will cover the description of each function in detail.

## Hive Functions

So, to perform several operations there are some functions built for a specific purpose. Such as Mathematical, arithmetic, logical and relational on the operands of table column names.

## Introduction to Hive Built-In Functions

In Hive, there are some built-in functions available. Basically, to use Hive built-in functions in our applications first we need to check the application requirement. However, it is possible to call these functions directly in our application.

In addition, there are several types of Hive Built-in Functions available.

Now, let’s describe Hive Built-in Functions in detail:

### a. Collection Functions

Basically, as par its name we use “Collection Functions” for collections.

Here, collections are nothing but defined as a grouping of elements and returning single or array of elements depends on return type mentioned in the function name. Let’s discuss each Collection Functions- Hive Built-in functions in below table:

 Return Type Function Name Description INT size(Map) It will fetch and give the components number in the map type INT size(Array) It will fetch and give the elements number in the array type Array Map_keys(Map) It will fetch and gives an array containing the keys of the input map. Here array is in unordered Array Map_values(Map) It will fetch and gives an array containing the values of the input map. Here array is in unordered Array Sort_array(Array) sorts the input array in ascending order of array and elements and returns it

### b. Hive Date Functions

However, to perform date manipulations and conversion of date types from one type to another type we use Hive date Functions. Let’s discuss each Date Function – Hive Built-in Functions in below table:

 Function Name Return Type Description Unix_Timestamp() Unix_Timestamp() We will get current Unix timestamp in seconds To_date(string timestamp) string It will fetch and give the date part of a timestamp string: year(string date) INT It will fetch and give the year part of a date or a timestamp string quarter(date/timestamp/string) INT It will fetch and give the quarter of the year for a date, timestamp, or string in the range 1 to 4 month(string date) INT It will give the month part of a date or a timestamp string hour(string date) INT It will fetch and gives the hour of the timestamp minute(string date) INT It will fetch and gives the minute of the timestamp Date_sub(string starting date, int days) string It will fetch and gives Subtraction of number of days to starting date Current_date date It will fetch and gives the current date at the start of query evaluation LAST _day(string date) string It will fetch and gives the last day of the month which the date belongs to trunc(string date, string format) string It will fetch and gives date truncated to the unit specified by the format. Supported formats in this : MONTH/MON/MM, YEAR/YYYY/YY.

### c. Mathematical Functions

Technology is evolving rapidly!

For Mathematical Operations in Hive, we use “Mathematical Functions”. Though, we have some inbuilt mathematical functions in Hive despite creating UDFs. Let’s discuss each Mathematical Function- Hive Built-in Functions in below table:

 Function Name Return Type Description round(DOUBLE X) DOUBLE It will fetch and returns the rounded BIGINT value of X round(DOUBLE X, INT d) DOUBLE It will fetch and returns X rounded to d decimal places bound(DOUBLE X) DOUBLE It will fetch and returns the rounded BIGINT value of X using HALF_EVEN rounding mode floor(DOUBLE X) BIGINT It will fetch and returns the maximum BIGINT value that is equal to or less than X value ceil(DOUBLE a), ceiling(DOUBLE a) BIGINT It will fetch and returns the minimum BIGINT value that is equal to or greater than X value rand(), rand(INT seed) DOUBLE It will fetch and returns a random number that is distributed uniformly from 0 to 1

### d. Conditional Functions

While it comes to conditional values checks in Hive, we use “Conditional Functions”. Let’s discuss each Conditional Function- Hive Built-In Functions in below table:

 Function Name Return Type Description if(Boolean testCondition, T valueTrue, T valueFalseOrNull) T It will fetch and gives value True when Test Condition is of true, gives value False Or Null otherwise. ISNULL( X) Boolean It will fetch and gives true if X is NULL and false otherwise. ISNOTNULL(X ) Boolean It will fetch and gives true if X is not NULL and false otherwise.

### e. Hive String Functions

For String manipulations and string operations in Hive, we call Hive String Functions. Let’s discuss each String Function- Hive Built-In Functions in below table:

 Function Name Return Type Description reverse(string X) string It will give the reversed string of X rpad(string str, int length, string pad) string It will fetch and gives str, which is right-padded with the pad to a length of length(integer value) rtrim(string X) string It will fetch and returns the string resulting from trimming spaces from the end (right-hand side) of X For example, rtrim(‘ results ‘) results in ‘ results’ space(INT n) string It will fetch and gives a string of n spaces. split(STRING str, STRING pat) array Splits str around pat (pat is a regular expression). Str_to_map(text[, delimiter1, delimiter2]) map It will split text into key-value pairs using two delimiters.

## Conclusion

As a result, in this blog, we have learned all the possible Hive Built-in Functions. Also, we have described types of Hive Built-In Functions, Hive Date Functions, Hive Mathematical Functions, Hive Conditional Functions and Hive String Functions in detail along with their return type.

Still, if any doubt occurs regarding Hive Built-in Functions, feel free to ask in the comment section.

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