ARRAY Operators
Milvus provides powerful operators to query array fields, allowing you to filter and retrieve entities based on the contents of arrays.
All elements within an array must be the same type, and nested structures within arrays are treated as plain strings. Therefore, when working with ARRAY fields, it is advisable to avoid excessively deep nesting and ensure that your data structures are as flat as possible for optimal performance.
Available ARRAY Operators
The ARRAY operators allow for fine-grained querying of array fields in Milvus. These operators are:
ARRAY_CONTAINS(identifier, expr): checks if a specific element exists in an array field.ARRAY_CONTAINS_ALL(identifier, expr): ensures that all elements of the specified list are present in the array field.ARRAY_CONTAINS_ANY(identifier, expr): checks if any of the elements from the specified list are present in the array field.ARRAY_LENGTH(identifier, expr): allows you to filter entities based on the number of elements in an array field.
ARRAY_CONTAINS
The ARRAY_CONTAINS operator checks if a specific element exists in an array field. It’s useful when you want to find entities where a given element is present in the array.
Example
Suppose you have an array field history_temperatures, which contains the recorded lowest temperatures for different years. To find all entities where the array contains the value 23, you can use the following filter expression:
filter = 'ARRAY_CONTAINS(history_temperatures, 23)'
This will return all entities where the history_temperatures array contains the value 23.
ARRAY_CONTAINS_ALL
The ARRAY_CONTAINS_ALL operator ensures that all elements of the specified list are present in the array field. This operator is useful when you want to match entities that contain multiple values in the array.
Example
If you want to find all entities where the history_temperatures array contains both 23 and 24, you can use:
filter = 'ARRAY_CONTAINS_ALL(history_temperatures, [23, 24])'
This will return all entities where the history_temperatures array contains both of the specified values.
ARRAY_CONTAINS_ANY
The ARRAY_CONTAINS_ANY operator checks if any of the elements from the specified list are present in the array field. This is useful when you want to match entities that contain at least one of the specified values in the array.
Example
To find all entities where the history_temperatures array contains either 23 or 24, you can use:
filter = 'ARRAY_CONTAINS_ANY(history_temperatures, [23, 24])'
This will return all entities where the history_temperatures array contains at least one of the values 23 or 24.
ARRAY_LENGTH
The ARRAY_LENGTH operator allows you to filter entities based on the number of elements in an array field. This is useful when you need to find entities with arrays of a certain length.
Example
If you want to find all entities where the history_temperatures array has fewer than 10 elements, you can use:
filter = 'ARRAY_LENGTH(history_temperatures) < 10'
This will return all entities where the history_temperatures array has fewer than 10 elements.