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+
+# Functions
+
+PPL supports a wide range of built-in functions for data processing and analysis. These functions are organized into categories based on their functionality and can be used within PPL queries to manipulate and transform data.
+
+- [Aggregation Functions](aggregations.md)
+  - [COUNT](aggregations.md/#count)
+  - [SUM](aggregations.md/#sum)
+  - [AVG](aggregations.md/#avg)
+  - [MAX](aggregations.md/#max)
+  - [MIN](aggregations.md/#min)
+  - [VAR_SAMP](aggregations.md/#var_samp)
+  - [VAR_POP](aggregations.md/#var_pop)
+  - [STDDEV_SAMP](aggregations.md/#stddev_samp)
+  - [STDDEV_POP](aggregations.md/#stddev_pop)
+  - [DISTINCT_COUNT, DC](aggregations.md/#distinct_count-dc)
+  - [DISTINCT_COUNT_APPROX](aggregations.md/#distinct_count_approx)
+  - [EARLIEST](aggregations.md/#earliest)
+  - [LATEST](aggregations.md/#latest)
+  - [TAKE](aggregations.md/#take)
+  - [PERCENTILE, PERCENTILE_APPROX](aggregations.md/#percentile-or-percentile_approx)
+  - [MEDIAN](aggregations.md/#median)
+  - [FIRST](aggregations.md/#first)
+  - [LAST](aggregations.md/#last)
+  - [LIST](aggregations.md/#list)
+  - [VALUES](aggregations.md/#values)
+
+- [Collection Functions](collection.md)
+  - [ARRAY](collection.md/#array)
+  - [ARRAY_LENGTH](collection.md/#array_length)
+  - [FORALL](collection.md/#forall)
+  - [EXISTS](collection.md/#exists)
+  - [FILTER](collection.md/#filter)
+  - [TRANSFORM](collection.md/#transform)
+  - [REDUCE](collection.md/#reduce)
+  - [MVJOIN](collection.md/#mvjoin)
+  - [MVAPPEND](collection.md/#mvappend)
+  - [SPLIT](collection.md/#split)
+  - [MVDEDUP](collection.md/#mvdedup)
+  - [MVFIND](collection.md/#mvfind)
+  - [MVINDEX](collection.md/#mvindex)
+  - [MVMAP](collection.md/#mvmap)
+  - [MVZIP](collection.md/#mvzip)
+
+- [Condition Functions](condition.md)
+  - [ISNULL](condition.md/#isnull)
+  - [ISNOTNULL](condition.md/#isnotnull)
+  - [EXISTS](condition.md/#exists)
+  - [IFNULL](condition.md/#ifnull)
+  - [NULLIF](condition.md/#nullif)
+  - [IF](condition.md/#if)
+  - [CASE](condition.md/#case)
+  - [COALESCE](condition.md/#coalesce)
+  - [ISPRESENT](condition.md/#ispresent)
+  - [ISBLANK](condition.md/#isblank)
+  - [ISEMPTY](condition.md/#isempty)
+  - [EARLIEST](condition.md/#earliest)
+  - [LATEST](condition.md/#latest)
+  - [REGEXP_MATCH](condition.md/#regexp_match)
+
+- [Type Conversion Functions](conversion.md)
+  - [CAST](conversion.md/#cast)
+  - [TOSTRING](conversion.md/#tostring)
+  - [TONUMBER](conversion.md/#tonumber)
+
+- [Cryptographic Functions](cryptographic.md)
+  - [SHA1](cryptographic.md/#sha1)
+  - [SHA2](cryptographic.md/#sha2)
+
+- [Date and Time Functions](datetime.md)
+  - [ADDDATE](datetime.md/#adddate)
+  - [ADDTIME](datetime.md/#addtime)
+  - [CONVERT_TZ](datetime.md/#convert_tz)
+  - [CURDATE](datetime.md/#curdate)
+  - [CURRENT_DATE](datetime.md/#current_date)
+  - [CURRENT_TIME](datetime.md/#current_time)
+  - [CURRENT_TIMESTAMP](datetime.md/#current_timestamp)
+  - [CURTIME](datetime.md/#curtime)
+  - [DATE](datetime.md/#date)
+  - [DATE_ADD](datetime.md/#date_add)
+  - [DATE_FORMAT](datetime.md/#date_format)
+  - [DATETIME](datetime.md/#datetime)
+  - [DATE_SUB](datetime.md/#date_sub)
+  - [DATEDIFF](datetime.md/#datediff)
+  - [DAY](datetime.md/#day)
+  - [DAYNAME](datetime.md/#dayname)
+  - [DAYOFMONTH](datetime.md/#dayofmonth)
+  - [DAY_OF_MONTH](datetime.md/#day_of_month)
+  - [DAYOFWEEK](datetime.md/#dayofweek)
+  - [DAY_OF_WEEK](datetime.md/#day_of_week)
+  - [DAYOFYEAR](datetime.md/#dayofyear)
+  - [DAY_OF_YEAR](datetime.md/#day_of_year)
+  - [EXTRACT](datetime.md/#extract)
+  - [FROM_DAYS](datetime.md/#from_days)
+  - [FROM_UNIXTIME](datetime.md/#from_unixtime)
+  - [GET_FORMAT](datetime.md/#get_format)
+  - [HOUR](datetime.md/#hour)
+  - [HOUR_OF_DAY](datetime.md/#hour_of_day)
+  - [LAST_DAY](datetime.md/#last_day)
+  - [LOCALTIMESTAMP](datetime.md/#localtimestamp)
+  - [LOCALTIME](datetime.md/#localtime)
+  - [MAKEDATE](datetime.md/#makedate)
+  - [MAKETIME](datetime.md/#maketime)
+  - [MICROSECOND](datetime.md/#microsecond)
+  - [MINUTE](datetime.md/#minute)
+  - [MINUTE_OF_HOUR](datetime.md/#minute_of_hour)
+  - [MONTH](datetime.md/#month)
+  - [MONTH_OF_YEAR](datetime.md/#month_of_year)
+  - [MONTHNAME](datetime.md/#monthname)
+  - [NOW](datetime.md/#now)
+  - [PERIOD_ADD](datetime.md/#period_add)
+  - [PERIOD_DIFF](datetime.md/#period_diff)
+  - [QUARTER](datetime.md/#quarter)
+  - [SEC_TO_TIME](datetime.md/#sec_to_time)
+  - [SECOND](datetime.md/#second)
+  - [SECOND_OF_MINUTE](datetime.md/#second_of_minute)
+  - [STRFTIME](datetime.md/#strftime)
+  - [STR_TO_DATE](datetime.md/#str_to_date)
+  - [SUBDATE](datetime.md/#subdate)
+  - [SUBTIME](datetime.md/#subtime)
+  - [SYSDATE](datetime.md/#sysdate)
+  - [TIME](datetime.md/#time)
+  - [TIME_FORMAT](datetime.md/#time_format)
+  - [TIME_TO_SEC](datetime.md/#time_to_sec)
+  - [TIMEDIFF](datetime.md/#timediff)
+  - [TIMESTAMP](datetime.md/#timestamp)
+  - [TIMESTAMPADD](datetime.md/#timestampadd)
+  - [TIMESTAMPDIFF](datetime.md/#timestampdiff)
+  - [TO_DAYS](datetime.md/#to_days)
+  - [TO_SECONDS](datetime.md/#to_seconds)
+  - [UNIX_TIMESTAMP](datetime.md/#unix_timestamp)
+  - [UTC_DATE](datetime.md/#utc_date)
+  - [UTC_TIME](datetime.md/#utc_time)
+  - [UTC_TIMESTAMP](datetime.md/#utc_timestamp)
+  - [WEEK](datetime.md/#week)
+  - [WEEKDAY](datetime.md/#weekday)
+  - [WEEK_OF_YEAR](datetime.md/#week_of_year)
+  - [YEAR](datetime.md/#year)
+  - [YEARWEEK](datetime.md/#yearweek)
+
+- [Expressions](expressions.md)
+  - [Arithmetic Operators](expressions.md#arithmetic-operators)
+  - [Predicate Operators](expressions.md/#predicate-operators)
+
+- [IP Address Functions](ip.md)
+  - [CIDRMATCH](ip.md/#cidrmatch)
+  - [GEOIP](ip.md/#geoip)
+
+- [JSON Functions](json.md)
+  - [JSON](json.md/#json)
+  - [JSON_VALID](json.md/#json_valid)
+  - [JSON_OBJECT](json.md/#json_object)
+  - [JSON_ARRAY](json.md/#json_array)
+  - [JSON_ARRAY_LENGTH](json.md/#json_array_length)
+  - [JSON_EXTRACT](json.md/#json_extract)
+  - [JSON_DELETE](json.md/#json_delete)
+  - [JSON_SET](json.md/#json_set)
+  - [JSON_APPEND](json.md/#json_append)
+  - [JSON_EXTEND](json.md/#json_extend)
+  - [JSON_KEYS](json.md/#json_keys)
+
+- [Mathematical Functions](math.md)
+  - [ADD](math.md/#add)
+  - [SUBTRACT](math.md/#subtract)
+  - [MULTIPLY](math.md/#multiply)
+  - [DIVIDE](math.md/#divide)
+  - [SUM](math.md/#sum)
+  - [AVG](math.md/#avg)
+  - [ACOS](math.md/#acos)
+  - [ASIN](math.md/#asin)
+  - [ATAN](math.md/#atan)
+  - [ATAN2](math.md/#atan2)
+  - [CEIL](math.md/#ceil)
+  - [CEILING](math.md/#ceiling)
+  - [CONV](math.md/#conv)
+  - [COS](math.md/#cos)
+  - [COSH](math.md/#cosh)
+  - [COT](math.md/#cot)
+  - [CRC32](math.md/#crc32)
+  - [DEGREES](math.md/#degrees)
+  - [E](math.md/#e)
+  - [EXP](math.md/#exp)
+  - [EXPM1](math.md/#expm1)
+  - [FLOOR](math.md/#floor)
+  - [LN](math.md/#ln)
+  - [LOG](math.md/#log)
+  - [LOG2](math.md/#log2)
+  - [LOG10](math.md/#log10)
+  - [MOD](math.md/#mod)
+  - [MODULUS](math.md/#modulus)
+  - [PI](math.md/#pi)
+  - [POW](math.md/#pow)
+  - [POWER](math.md/#power)
+  - [RADIANS](math.md/#radians)
+  - [RAND](math.md/#rand)
+  - [ROUND](math.md/#round)
+  - [SIGN](math.md/#sign)
+  - [SIGNUM](math.md/#signum)
+  - [SIN](math.md/#sin)
+  - [SINH](math.md/#sinh)
+  - [SQRT](math.md/#sqrt)
+  - [CBRT](math.md/#cbrt)
+  - [RINT](math.md/#rint)
+
+- [Relevance Functions](relevance.md)
+  - [MATCH](relevance.md/#match)
+  - [MATCH_PHRASE](relevance.md/#match_phrase)
+  - [MATCH_PHRASE_PREFIX](relevance.md/#match_phrase_prefix)
+  - [MULTI_MATCH](relevance.md/#multi_match)
+  - [SIMPLE_QUERY_STRING](relevance.md/#simple_query_string)
+  - [MATCH_BOOL_PREFIX](relevance.md/#match_bool_prefix)
+  - [QUERY_STRING](relevance.md/#query_string)
+
+- [Statistical Functions](statistical.md)
+  - [MAX](statistical.md/#max)
+  - [MIN](statistical.md/#min)
+
+- [String Functions](string.md)
+  - [CONCAT](string.md/#concat)
+  - [CONCAT_WS](string.md/#concat_ws)
+  - [LENGTH](string.md/#length)
+  - [LIKE](string.md/#like)
+  - [ILIKE](string.md/#ilike)
+  - [LOCATE](string.md/#locate)
+  - [LOWER](string.md/#lower)
+  - [LTRIM](string.md/#ltrim)
+  - [POSITION](string.md/#position)
+  - [REPLACE](string.md/#replace)
+  - [REVERSE](string.md/#reverse)
+  - [RIGHT](string.md/#right)
+  - [RTRIM](string.md/#rtrim)
+  - [SUBSTRING](string.md/#substring)
+  - [TRIM](string.md/#trim)
+  - [UPPER](string.md/#upper)
+  - [REGEXP_REPLACE](string.md/#regexp_replace)
+
+- [System Functions](system.md)
+  - [TYPEOF](system.md/#typeof)
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