SQL 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.
The following table describes array functions. To learn more about array aggregation functions, see SQL aggregation functions.
| 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 null or -1 if druid.generic.useDefaultValueForNull=true (deprecated legacy mode). |
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 null or -1 if druid.generic.useDefaultValueForNull=true (deprecated legacy mode). |
ARRAY_PREPEND(expr, arr) | Adds expr to the beginning of arr, the resulting array type determined by the type of arr. |
ARRAY_APPEND(arr, expr) | Appends expr to arr, the resulting array type determined by the type of arr. |
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, which is a regular expression. |
ARRAY_TO_MV(arr) | Converts an ARRAY of any type into a multi-value string VARCHAR. |