Tree reorder slow in CakePHP - cakephp

Question

I'm using Tree Behavior to store a ordered list of items.
When I add new elements to the tree I reorder it calling to the "reorder()" function. It is very slow. I've been trying a lot of things. My last test was a single table with 70 elements (1 parent and 69 childs). The time used for the reorder() function, was 1 minute & 20 seconds. I'm using MySQL and I have indexes in id, parent_id, rght and lft fields.
What could I be doing wrong?
Thanks

Answer 1

I've spent some time investigating this one as well.
It turns out that the reorder function is very inefficient. Basically it sets the left and right fields on the first item to high values, and then reorders the rest of the fields. Then it does the same for the second item, etc. You end up with tens of thousands of queries being run, for a tree with only a hundred items.
I sorted it out with the following code. What this does is only update each record once, and it preserves the gap between left and right values. It recursively goes through the items and reorders them properly.
Create a new file in app/Model/Behavior called "BRTreeBehavior.php", and then modify your model's $actsAs field to use BRTree instead of Tree.
<?php
/**
* Copyright 2015, Perthweb Pty Ltd
*
*/
App::uses('TreeBehavior', 'Model/Behavior');
/**
* BetterReorderTree Behavior.
*
* Improves reorder of tree behavior
*
*/
class BRTreeBehavior extends TreeBehavior {
/**
* Reorder method.
*
* Reorders the nodes (and child nodes) of the tree according to the field and direction specified in the parameters.
* This method does not change the parent of any node.
*
* Requires a valid tree, by default it verifies the tree before beginning.
*
* Options:
*
* - 'id' id of record to use as top node for reordering
* - 'field' Which field to use in reordering defaults to displayField
* - 'order' Direction to order either DESC or ASC (defaults to ASC)
* - 'verify' Whether or not to verify the tree before reorder. defaults to true.
*
* #param Model $Model Model instance
* #param array $options array of options to use in reordering.
* #return boolean true on success, false on failure
* #link http://book.cakephp.org/2.0/en/core-libraries/behaviors/tree.html#TreeBehavior::reorder
*/
public function reorder(Model $Model, $options = array()) {
$options = array_merge(array('id' => null, 'field' => $Model->displayField, 'order' => 'ASC', 'verify' => true, 'startIndex' => null), $options);
extract($options);
if ($verify && !$this->verify($Model)) {
return false;
}
$verify = false;
extract($this->settings[$Model->alias]);
$fields = array($Model->primaryKey, $field, $left, $right);
$sort = $field . ' ' . $order;
$nodes = $this->children($Model, $id, true, $fields, $sort, null, null, $recursive);
$cacheQueries = $Model->cacheQueries;
$Model->cacheQueries = false;
if ($nodes) {
if($id == null){
$index = 1;
}
else if($startIndex == null){
$index = $nodes[0][$Model->alias][$left];
}
else {
$index = $startIndex;
}
foreach ($nodes as $node) {
$id = $node[$Model->alias][$Model->primaryKey];
$difference = $node[$Model->alias][$right] - $node[$Model->alias][$left];
$nodeData = array(
$Model->alias => array(
$Model->primaryKey => $id,
$left => $index,
$right => $index + $difference
)
);
$Model->create();
$Model->save($nodeData, array('validate' => false, 'callbacks' => false, 'fieldList' => array($left, $right)));
$Model->clear();
$startIndex = $index + 1;
if ($difference != 1) {
$this->reorder($Model, compact('id', 'field', 'order', 'verify', 'startIndex'));
}
$index += $difference + 1;
}
}
$Model->cacheQueries = $cacheQueries;
return true;
}
}