_get_term_hierarchy( string $taxonomy ): array
- Since
- 2.3.0
- Source
wp-includes/taxonomy.php:3966
Compatibility
- WordPress
- since 2.3.0
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.
Parameters
$taxonomystring- Taxonomy name.
Return value
array- Empty if $taxonomy isn't hierarchical or returns children as term IDs.
Performance profile
How much work a call to _get_term_hierarchy() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Heavy
- Scaling
- Scales with input
- Instructions
- 6–31
- Plugin surface
- None
- Called by
- 8
Reaches the database via get_terms().
The body loops, so the work grows with what you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 40.
Nothing here hands control to plugin code.
8 places in core call this, so the cost is paid more often than your own code shows.
What it touches
- optionoption read or write
get_option()called directly - querycontent query
get_terms()called directly - hookthird-party callbacks
apply_filters()one call below _get_term_hierarchy() - cacheobject cache
wp_cache_get()one call below _get_term_hierarchy() - serializeserialisation
maybe_unserialize()one call below _get_term_hierarchy()
Further down the call graph this can also reach transient. That is the worst case, several calls deep and usually down an error path, not what a normal call pays.
What one call costs · 3 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost _get_term_hierarchy() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
!is_taxonomy_hierarchical() | 6 | is_taxonomy_hierarchical() |
is_taxonomy_hierarchical() && is_array($children) | 13 | is_taxonomy_hierarchical(), get_option() |
is_taxonomy_hierarchical() && !is_array($children) | 30–31 | is_taxonomy_hierarchical(), get_option(), taxonomy(), update_option() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 40 instructions, 6–31 executed per call, 5 branches. The work does not change between versions.
An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.
Uses · 4
- is_taxonomy_hierarchical()Determines whether the taxonomy object is hierarchical.
- get_option()Retrieves an option value based on an option name.
- get_terms()Retrieves the terms in a given taxonomy or list of taxonomies.
- update_option()Updates the value of an option that was already added.
Used by · 8
- WP_Term_Query::get_terms()Retrieves the query results.
- WP_Terms_List_Table::display_rows_or_placeholder()
- _get_term_children()Gets the subset of $terms that are descendants of $term_id.
- _pad_term_counts()Adds count of children to parent count.
- _wp_batch_split_terms()Splits a batch of shared taxonomy terms.
- _wp_menu_item_classes_by_context()Adds the class property classes for the current context, if applicable.
- clean_taxonomy_cache()Cleans the caches for a taxonomy.
- get_term_children()Merges all term children into a single array of their IDs.
Source code
function _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;}Changelog
Introduced in 2.3.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
About this page
- Parsed data
- Generated from the wordpress-develop 7.1.0 tag, from
src/wp-includes/taxonomy.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it. - Corrections
- Something wrong on this page? Report it and it gets fixed in the next regeneration.