SetUnion / List Layer

Compute the set union between two variable-length lists. Returns a list containing all unique elements from both lists. Similar to Python's set union operation or SQL's UNION.

Mathematical definition: For sets A and B, the union A ∪ B is defined as: $A \cup B = {x ∣ x \in A or x \in B}$ In other words, elements that are in either A or B (or both).

Example transformation:

left_list	right_list	union
[1, 2, 3]	[2, 4, 5]	[1, 2, 3, 4, 5]
[a, b, c]	[b, d]	[a, b, c, d]
[1, 1, 2]	[2, 3]	[1, 2, 3]
[x, y]	[]	[x, y]
[1, null, 3]	[1, 2]	[1, 2, 3]

Properties:

Commutative: $A \cup B = B \cup A$
Associative: $(A \cup B) \cup C = A \cup (B \cup C)$
Identity: $A \cup \emptyset = A$
Idempotent: $A \cup A = A$

Common applications:

Combining feature sets
Merging permission lists
Aggregating categories
Consolidating tag sets
Building complete catalogs
Creating comprehensive listings

Note: Duplicates in input lists are removed (set semantics). Null values are ignored. Order of elements in result is not guaranteed. Lists can have different lengths.

Table

SelectLeft

column

The first list column (SelectLeft) for union. Examples:

Basic features: [search, filter, sort]
Group A permissions: [read, write]
Primary categories: [books, music] Lists can have different lengths. Duplicates allowed but treated as single elements.

SelectRight

column

The second list column (SelectRight) for union. Examples:

Premium features: [export, import, sync]
Group B permissions: [execute, delete]
Secondary categories: [movies, games] Lists can have different lengths. Duplicates allowed but treated as single elements.

Name for the new column. If not provided, the system generates a unique name. If AsColumn matches an existing column, the existing column is replaced. The name should follow valid column naming conventions.