Apache Druid supports two query languages: Druid SQL and native queries. This document describes the SQL language.
Druid supports string dimensions containing multiple values. This page describes the operations you can perform on multi-value string dimensions using Druid SQL. See SQL multi-value strings and native Multi-value dimensions for more information.
All array references in the multi-value string function documentation can refer to multi-value string columns or ARRAY types. These functions are largely identical to the array functions, but use VARCHAR types and behavior. Multi-value strings can also be converted to ARRAY types using MV_TO_ARRAY. For additional details about ARRAY types, see ARRAY data type documentation.
| Function | Description |
|---|---|
MV_FILTER_ONLY(expr, arr) | Filters multi-value expr to include only values contained in array arr. |
MV_FILTER_NONE(expr, arr) | Filters multi-value expr to include no values contained in array arr. |
MV_LENGTH(arr) | Returns length of the array expression. |
MV_OFFSET(arr, long) | Returns the array element at the 0-based index supplied, or null for an out of range index. |
MV_ORDINAL(arr, long) | Returns the array element at the 1-based index supplied, or null for an out of range index. |
MV_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. |
MV_OVERLAP(arr1, arr2) | Returns 1 if arr1 and arr2 have any elements in common, else 0. |
MV_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. |
MV_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. |
MV_PREPEND(expr, arr) | Adds expr to arr at the beginning, the resulting array type determined by the type of the array. |
MV_APPEND(arr1, expr) | Appends expr to arr, the resulting array type determined by the type of the first array. |
MV_CONCAT(arr1, arr2) | Concatenates arr2 to arr1. The resulting array type is determined by the type of arr1. |
MV_SLICE(arr, start, end) | Returns the subarray of arr from the 0-based index start(inclusive) to end(exclusive), or null, if start is less than 0, greater than length of arr or greater than end. |
MV_TO_STRING(arr, str) | Joins all elements of arr by the delimiter specified by str. |
STRING_TO_MV(str1, str2) | Splits str1 into an array on the delimiter specified by str2, which is a regular expression. |
MV_TO_ARRAY(str) | Converts a multi-value string from a VARCHAR to a VARCHAR ARRAY. |