WordPress at a glance
function is not described

update_postmeta_cache() WP 2.1.0

Updates metadata cache for list of post IDs.

Performs SQL query to retrieve the metadata for the post IDs and updates the metadata cache for the posts. Therefore, the functions, which call this function, do not need to perform SQL queries on their own.

No Hooks.

Return

Array/false. Returns false if there is nothing to update or an array of metadata.

Usage

update_postmeta_cache( $post_ids );
$post_ids(array) (required)
List of post IDs.

Code of update postmeta cache: wp-includes/post.php VER 5.0.3

<?php
function update_postmeta_cache( $post_ids ) {
	return update_meta_cache('post', $post_ids);
}