Array values
An array is a structure that contains an ordered collection of data elements in which each element can be referenced by its index value in the collection.The cardinality of an array is the number of elements in the array. All elements in an array have the same data type.
An ordinary array has a defined upper bound on the number of elements, known as the maximum cardinality. Each element in the array is referenced by its ordinal position as the index value. If N is the number of elements in an ordinary array, the ordinal position associated with each element is an integer value greater than or equal to 1 and less than or equal to N.
An associative array has no specific upper bound on the number of elements. Each element is referenced by its associated index value. The data type of the index value can be an integer or a character string but is the same data type for the entire array.
The maximum cardinality of an ordinary array is not related to its physical representation, unlike the maximum cardinality of arrays in programming languages such as C. Instead, the maximum cardinality is used by the system at run time to ensure that subscripts are within bounds. The amount of memory required to represent an ordinary array value is not proportional to the maximum cardinality of its type.
The amount of memory required to represent an array value is usually proportional to its cardinality. When an array is being referenced, all of the values in the array are stored in main memory. Therefore, arrays that contain a large amount of data will consume large amounts of main memory.
The Array type is not supported for multi-row insert, update, or delete.