PQL UNION()

Union() takes one or more arguments – each a row call – and unions them. You can think of Union() as OR in set theory. It returns the set of record IDs / keys that is in the first set of record IDs / keys OR is in the second set of record IDs / keys OR so on and so forth.

Union() is a row call.

Call Definition

Union(ROW_CALL, ... )

Mandatory Arguments

• ROW_CALL : the output of any row call (set of record IDs / keys)

Optional Arguments

• ... : Any number of additional row call separated by commas

Returns

• list of record IDs or record keys

Examples

Data:

Index: customer (non keyed index)

 _id | age (Int) | has_purchased (Set) | last_purchase (Timestamp)
-----+-----------+---------------------+---------------------------
 0   |    23     | ["brand1","brand2"] | 2021-01-05T08:30:00Z
 1   |    31     | ["brand1","brand3"] | 2020-09-12T12:30:00Z
 2   |    28     | ["brand1","brand3"] | 2021-08-06T16:15:00Z
 3   |    19     | []                  | null
 4   |    25     | ["brand1","brand4"] | 2021-10-01T20:45:00Z
 5   |    40     | ["brand4"]          | 2022-01-13T11:00:00Z

Example 1

What is the set of customers / records who’s age is over 35 or who have made a purchase prior to 2021?

Query

[customer]Union(
  Row(age > 35),
  Row(last_purchase < '2021-01-01T00:00:00Z')
)

Tabular Response

 _id
-----
 1
 5

HTTP Response

{
  "results": [
    {
      "columns": [
        1,
        5
      ]
    }
  ]
}

Explanation

Row(age > 35) returns [5] and Row(last_purchase < '2021-01-01T00:00:00Z') returns [1]. Union() does a set union on these two sets which is [1,5].

Example 2

What is the set of customers / records who’s age is over 30, has purchased from brand1, or has purchased from brand3?

[customer]Union(
  Row(has_purchased = brand1),
  Row(has_purchased = brand2),
  Row(has_purchased = brand3)
)

Tabular Response

 _id
-----
 0
 1
 2
 4

HTTP Response

"results": [
    {
       "columns": [
         0,
         1,
         2,
         5
       ]
    }
]

Explanation

Row(has_purchased = brand1) returns [0,1,2,5], Row(has_purchased = brand2) returns [0], and Row(has_purchased = brand3) returns [1,2]. Union() does a set union of these three sets which is [0,1,2,5].