FILTER and REDUCE

Array manipulation goes beyond reading elements. You can filter, reduce, and aggregate array contents directly in SQL. FILTER for Conditional Rows FILTER with CARDINALITY A common pattern counts how many elements match a condition: This filters the reviews array to include only ratings of 4 or higher, then counts the result. The original reviews array is unchanged. REDUCE for Aggregation REDUCE has four components: the array, an initial accumulator value, a function that combines each element with the accumulator, and a final output function. Calculating Weighted Avg REDUCE enables complex aggregations like weighted averages: The accumulator is a struct with sum and count fields. Each iteration updates both fields. The output function divides sum by count to produce the average.