JavaScript user-defined aggregate functions (UDAFs) are in preview

## Feature [JavaScript user-defined aggregate functions (UDAFs)](https://cloud.google.com/bigquery/docs/user-defined-aggregates) are in [preview](https://cloud.google.com/products#product-launch-stages). You can create a JavaScript UDAF with the [CREATE AGGREGATE FUNCTION](https://cloud.google.com/bigquery/docs/reference/standard-sql/data-definition-language#javascript-create-udaf-function) statement. ## Feature You can now [store columns](https://cloud.google.com/bigquery/docs/vector-index#stored-columns) in your vector indexes and pre-filter data in your [vector searches](https://cloud.google.com/bigquery/docs/reference/standard-sql/search%5Ffunctions#vector%5Fsearch) to improve query efficiency. This feature is in [preview](https://cloud.google.com/products#product-launch-stages).