Object Functions

This page covers functions for constructing and manipulating objects (string-keyed maps) in Rockset.

Note: All examples that use the collection data refer to

+-----------------------------------------------------+
| obj                                                 |
|-----------------------------------------------------|
| {"baz": [1, 2, 3], "bar": "hello world", "foo": 25} |
+-----------------------------------------------------+

OBJECT

OBJECT(keys, values) Construct an object from an array of keys and an array of values. keys must be an array of strings. values must be an arbitrary array of the same length as keys.

SELECT
      OBJECT(
          ARRAY_CREATE('foo', 'bar', 'baz'),
          ARRAY_CREATE(25, 'hello world', ARRAY_CREATE(1, 2, 3))
      )

SELECT
      OBJECT(
          KEYS(data.obj),
          VALUES(data.obj)
      )
  FROM
      data

You can also construct objects directly with curly brackets {}.

SELECT {'red': 'apples', 'yellow': 'banana'}

ZIP

ZIP(entries) Construct an object from an array of entries. Each entry in entry must itself be an array of size 2: the first element is the key (and must be a string), and the second element is the value.

SELECT
    ZIP(
        ARRAY_CREATE(
            ARRAY_CREATE('foo', 25),
            ARRAY_CREATE('bar', 'hello world'),
            ARRAY_CREATE('baz', ARRAY_CREATE(1, 2, 3))
        )
    )

ELEMENT_AT

ELEMENT_AT(array, val) Returns element of array at index val. If val < 0, this function accesses elements from the last to the first.

LENGTH

LENGTH(obj) Returns number of elements in obj.

KEYS

KEYS(obj) Return an array containing the keys of obj. The order is unspecified, but will be the same between KEYS(), VALUES(), and ITEMS().

VALUES

VALUES(obj) Return an array containing the values of obj. The order is unspecified, but will be the same between KEYS(), VALUES(), and ITEMS().

ITEMS

ITEMS(obj) Return an array containing the entries of obj. Each entry is a 2-element array; the first is the key, the second is the value. The order is unspecified, but will be the same between KEYS(), VALUES(), and ITEMS().

MERGE

MERGE(a, b) Return a new object containing the values from a and b. If the same key exists in both a and b, the value from b will overwrite the value from a. For example if collection X has the form

+----------------------+----------------------+
| a                    | b                    |
|----------------------+----------------------|
| {"baz": 2, "foo": 1} | {"baz": 4, "bar": 3} |
+----------------------+----------------------+

Then

ERASE

ERASE(obj, k) If k is a string, return a new object where the key k is erased. If k is an array of strings, return a new object where the keys in k are erased.

SELECT ERASE(data.obj, 'foo') FROM data

SELECT ERASE(data.obj, 'abc') FROM data

SELECT ERASE(data.obj, null) FROM data

SELECT
      ERASE(data.obj, ARRAY_CREATE('foo', 'bar'))
  FROM
      data

List of functions defined in this section: