druid/docs/querying/sql-array-functions.md

id	title	sidebar_label
sql-array-functions	SQL ARRAY functions	Array functions

Apache Druid supports two query languages: Druid SQL and native queries. This document describes the SQL language.

This page describes the operations you can perform on arrays using Druid SQL. See ARRAY data type documentation for additional details.

All array references in the array function documentation can refer to multi-value string columns or ARRAY literals. These functions are largely identical to the multi-value string functions, but use ARRAY types and behavior. Multi-value string VARCHAR columns can be converted to VARCHAR ARRAY to use with these functions using MV_TO_ARRAY, and ARRAY types can be converted to multi-value string VARCHAR with ARRAY_TO_MV.

Function	Description
ARRAY[expr1, expr2, ...]	Constructs a SQL ARRAY literal from the expression arguments, using the type of the first argument as the output array type.
ARRAY_LENGTH(arr)	Returns length of the array expression.
ARRAY_OFFSET(arr, long)	Returns the array element at the 0-based index supplied, or null for an out of range index.
ARRAY_ORDINAL(arr, long)	Returns the array element at the 1-based index supplied, or null for an out of range index.
ARRAY_CONTAINS(arr, expr)	If expr is a scalar type, returns 1 if arr contains expr. If expr is an array, returns 1 if arr contains all elements of expr. Otherwise returns 0.
ARRAY_OVERLAP(arr1, arr2)	Returns 1 if arr1 and arr2 have any elements in common, else 0.
ARRAY_OFFSET_OF(arr, expr)	Returns the 0-based index of the first occurrence of expr in the array. If no matching elements exist in the array, returns -1 or null if druid.generic.useDefaultValueForNull=false.
ARRAY_ORDINAL_OF(arr, expr)	Returns the 1-based index of the first occurrence of expr in the array. If no matching elements exist in the array, returns -1 or null if druid.generic.useDefaultValueForNull=false.
ARRAY_PREPEND(expr, arr)	Prepends expr to arr at the beginning, the resulting array type determined by the type of arr.
ARRAY_APPEND(arr1, expr)	Appends expr to arr, the resulting array type determined by the type of arr1.
ARRAY_CONCAT(arr1, arr2)	Concatenates arr2 to arr1. The resulting array type is determined by the type of arr1.
ARRAY_SLICE(arr, start, end)	Returns the subarray of arr from the 0-based index start (inclusive) to end (exclusive). Returns null, if start is less than 0, greater than length of arr, or greater than end.
ARRAY_TO_STRING(arr, str)	Joins all elements of arr by the delimiter specified by str.
STRING_TO_ARRAY(str1, str2)	Splits str1 into an array on the delimiter specified by str2.
ARRAY_TO_MV(arr)	Converts an ARRAY of any type into a multi-value string VARCHAR.