Nested Data Functions (Reference)

Nested data helpers build and inspect row-level arrays, maps, and structs. They are scalar expressions: every helper returns one value for each input row and does not change relation cardinality.

Generator or table-valued operations such as row-expanding explode(...) are separate from this page.

Arrays

Function	Meaning
array(values)	Build an array expression from one or more scalar expressions.
cardinality(value)	Return the size of an array or map.
array_contains(array_expr, value)	Return whether an array contains a value.
arrays_overlap(left, right)	Return whether two arrays have any elements in common.
array_position(array_expr, value)	Return the one-based position of a value.
element_at(array_expr, index)	Return an array element by one-based index.
array_sort(array_expr)	Sort one array value.
array_distinct(array_expr)	Remove duplicate elements from one array value.
array_except(left, right)	Return elements from left that are not in right.
array_intersect(left, right)	Return elements shared by both arrays.
array_union(left, right)	Return the union of both arrays.
array_join(array_expr, delimiter)	Join a string array into one string.
array_range(start, stop)	Build a row-level integer array from start inclusive to stop exclusive.
array_slice(array_expr, start, stop)	Return a one-based array slice using the backend adapter's slice contract.
array_reverse(array_expr)	Reverse one array value.
array_flatten(array_expr)	Flatten an array-of-arrays into one row-level array value.

Maps And Structs

Function	Meaning
map_from_arrays(keys, values)	Build a map from key and value arrays.
map_extract(map_expr, key)	Return the values associated with a key.
map_contains_key(map_expr, key)	Return whether map_extract(...) finds at least one value for the key.
map_keys(map_expr)	Return the map's keys as an array.
map_values(map_expr)	Return the map's values as an array.
map_entries(map_expr)	Return map entries.
named_struct(field_names, values)	Build a struct expression with explicit field names.

Semantics

• Array indexing is one-based for element_at(...), array_position(...), and array_slice(...).
• element_at(...) currently maps to the portable array-element adapter path. Out-of-range behavior follows the current backend adapter's recoverable result until IncQL has a richer static/runtime error-policy split for strict versus try-style element access.
• array_flatten(...) is intentionally named to stay distinct from the relation-shaping generator flatten(...).
• Grouping or ordering by nested values is not documented as portable until equality and ordering semantics for arrays, maps, and structs are specified.
• For task-oriented usage, see Work with nested row values.