druid/docs/querying/sql-multivalue-string-functions.md

id	title	sidebar_label
sql-multivalue-string-functions	SQL multi-value string functions	Multi-value string functions

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, and ARRAY into multi-value strings via ARRAY_TO_MV. 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.