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    MaxCompute:INDEX

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    MaxCompute:INDEX

    Last Updated:Aug 20, 2026

    Returns a value from an ARRAY or MAP parameter.

    Command format

    INDEX (<var1>[<var2>])

    Notes

    • If var1 is an array<T>, this function retrieves the element at index var2 from var1. Array elements are indexed starting from 0.

    • If var1 is a map<K, V>, this function retrieves the value for the key var2 from var1.

    Note

    • This operation does not use the INDEX keyword. Use the <var1>[<var2>] syntax directly. Otherwise, an error is returned.

    • If var1 is an array, var2 is the index. If var1 is a map, var2 is the key.

    Parameter description

    • var1: Required. An array<T> or map<K, V>. In array<T>, T specifies the data type of the array elements. T can be any data type. In map<K, V>, K and V represent the data types of the keys and values, respectively.

    • var2: Required.

      • If var1 is an array<T>, var2 must be a non-negative BIGINT value.

      • If var1 is a map<K, V>, var2 must have the same data type as K.

    Return value description

    • If var1 is an array<T>, the function returns a value of type T. The following rules apply:

      • If var2 is out of bounds for the var1 array, the function returns NULL.

      • If var1 is NULL, the function returns NULL.

    • If var1 is a map<K, V>, the function returns a value of type V. The following rules apply:

      • If the key var2 does not exist in the map<K, V>, the function returns NULL.

      • If var1 is NULL, the function returns NULL.

    Usage examples

    • Example 1: var1 is an array<T>.

      -- Returns c.
SELECT ARRAY('a','b','c')[2];

    • Example 2: var1 is a map<K, V>.

      -- Returns 1.
SELECT STR_TO_MAP("test1=1,test2=2")["test1"];

    Related functions

    INDEX is a complex type function. For more information about functions that process complex data types, such as ARRAY, MAP, STRUCT, and JSON, see Complex type functions.