Categories:

Aggregate functions (Semi-structured Data) , Window functions (General) , Semi-structured and structured data functions (Array/Object)

OBJECT_AGG¶

Returns one OBJECT per group. For each (key, value) input pair, where key must be a VARCHAR and value must be a VARIANT, the resulting OBJECT contains a key:value field.

Aliases:

OBJECTAGG

Syntax¶

Aggregate function

OBJECT_AGG(<key>, <value>)

Window function

OBJECT_AGG(<key>, <value>) OVER ( [ PARTITION BY <expr2> ] )

Usage notes¶

• Input tuples with NULL key and/or value are ignored.
• Duplicate keys within a group result in a Duplicate field key 'key' error.
• The DISTINCT keyword is supported, but it only filters out duplicate rows where both key and value are equal.

Examples¶

These examples build a table of key-value pairs, then use OBJECT_AGG to collect the pairs in each group into a single OBJECT (for example, gathering a person’s attributes into one object per person).

First, create and populate a table. The value column is typed as VARIANT because the value argument of OBJECT_AGG must be a VARIANT, so each inserted value is cast with ::VARIANT:

CREATE OR REPLACE TABLE objectagg_example(g NUMBER, k VARCHAR(30), v VARIANT);
INSERT INTO objectagg_example SELECT 0, 'name', 'Joe'::VARIANT;
INSERT INTO objectagg_example SELECT 0, 'age', 21::VARIANT;
INSERT INTO objectagg_example SELECT 1, 'name', 'Sue'::VARIANT;
INSERT INTO objectagg_example SELECT 1, 'zip', 94401::VARIANT;

SELECT * FROM objectagg_example;

+---+------+-------+
| G |  K   |   V   |
|---+------+-------|
| 0 | name | "Joe" |
| 0 | age  | 21    |
| 1 | name | "Sue" |
| 1 | zip  | 94401 |
+---+------+-------+

This example uses OBJECT_AGG as an aggregate function. Grouping by g produces one OBJECT per group, where each k value becomes a key and its v value becomes the corresponding value:

SELECT OBJECT_AGG(k, v) FROM objectagg_example GROUP BY g;

+-------------------+
| OBJECT_AGG(K, V)  |
|-------------------|
| {                 |
|  "name": "Sue",   |
|   "zip": 94401    |
| }                 |
| {                 |
|  "age": 21,       |
|  "name": "Joe"    |
| }                 |
+-------------------+

The following example is optional and shows how to expand the aggregated objects back into rows. It passes the OBJECT produced by OBJECT_AGG to FLATTEN, which returns one row for each key-value pair in each object:

SELECT seq, key, value
  FROM (SELECT object_agg(k, v) o FROM objectagg_example GROUP BY g),
    LATERAL FLATTEN(input => o);

+-----+------+-------+
| SEQ | KEY  | VALUE |
|-----+------+-------|
|   1 | name | "Sue" |
|   1 | zip  | 94401 |
|   2 | age  | 21    |
|   2 | name | "Joe" |
+-----+------+-------+