Functions/Lists & arrays/list_reduce
Lists & arrays Scalar

list_reduce()

Returns a single value that is the result of applying the lambda function to each element of the input list, starting with the first element and then repeatedly applying the lambda function to the result of the previous application and the next element of the list. When an initial value is provided, it is used as the first argument to the lambda function

Arguments & returns

2 overloads

list_reduce(list, lambda[)

Scalar
Overload link listlambda[ Returns
#01 ANY[]LAMBDA ANY

list_reduce(list, lambda[, initial])

Scalar
Overload link listlambda[initial] Returns
#02 ANY[]LAMBDAANY ANY

Example

list_reduce example
SQL
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Engine example · Run to view results.

Catalog examples

SELECT
  list_reduce([1, 2, 3], (x, y) -> x + y);

In other engines

Used in larger rewrites 1

These examples use list_reduce as one part of a larger SQL translation.

Snowflakebitmap_construct_agg()

SELECT BITMAP_CONSTRUCT_AGG(v) FROM t
In DuckDB
SELECT (SELECT CASE WHEN l IS NULL OR LENGTH(l) = 0 THEN NULL WHEN LENGTH(l) <> LENGTH(LIST_FILTER(l, __v -> __v BETWEEN 0 AND 32767)) THEN NULL WHEN LENGTH(l) < 5 THEN UNHEX(PRINTF('%04X', LENGTH(l)) || h || REPEAT('00', GREATEST(0, 4 - LENGTH(l)) * 2)) ELSE UNHEX('08000000000000000000' || h) END FROM (SELECT l, COALESCE(LIST_REDUCE(LIST_TRANSFORM(l, __x -> PRINTF('%02X%02X', CAST(__x AS INT) & 255, (CAST(__x AS INT) >> 8) & 255)), (__a, __b) -> __a || __b, ''), '') AS h FROM (SELECT LIST_SORT(LIST_DISTINCT(LIST(v) FILTER(WHERE NOT v IS NULL))) AS l))) FROM t

SQLGlot example ↗