wp-includes/taxonomy.php:3912Retrieves children of taxonomy as term IDs.
$taxonomystringarrayfunction _get_term_hierarchy( $taxonomy ) { if ( ! is_taxonomy_hierarchical( $taxonomy ) ) { return array(); } $children = get_option( "{$taxonomy}_children" ); if ( is_array( $children ) ) { return $children; } $children = array(); $terms = get_terms( array( 'taxonomy' => $taxonomy, 'get' => 'all', 'orderby' => 'id', 'fields' => 'id=>parent', 'update_term_meta_cache' => false, ) ); foreach ( $terms as $term_id => $parent ) { if ( $parent > 0 ) { $children[ $parent ][] = $term_id; } } update_option( "{$taxonomy}_children", $children ); return $children;}Introduced in 2.3.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/taxonomy.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.