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POHow can I optimize my array_join (simulates a LEFT JOIN) function?
 

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  1. POHow can I optimize my array_join (simulates a LEFT JOIN) function?
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    <p>I wrote the following code to take arrays in PHP and "join" them together the way that a LEFT JOIN would in MySQL. For my sake I wrote the function using foreach and passed the arrays in and returned a new array... I feel like it's pretty readable, but I also know that it's inefficient.</p> <p>Ideally, I'd like this function to handle upwards of 10,000 rows per array, and I suspect that means: 1) passing $original by reference (to save memory), and 2) using one of PHP iterative array function rather than a foreach (to save processing time).</p> <p>Usually I don't post these sort of "quiz" like questions, but I feel like the answer to this will benefit the community. (Like this guy: <a href="https://stackoverflow.com/questions/8833522/join-2-multidimensional-array">Join 2 multidimensional array</a>)</p> <p>May the 1) fastest, and 2) lowest memory consuming answer win! :P</p> <pre><code>&lt;?php // Join Arrays on Keys (**updated with knittl's suggestion**) function array_join($original, $merge, $on) { if (!is_array($on)) $on = array($on); foreach ($merge as $remove =&gt; $right) { foreach ($original as $index =&gt; $left) { foreach ($on as $from_key =&gt; $to_key) { if (!isset($original[$index][$from_key]) || !isset($right[$to_key]) || $original[$index][$from_key] != $right[$to_key]) continue 2; } $original[$index] = array_merge($left, $right); unset($merge[$remove]); } } return array_merge($original, $merge); } // Test Arrays $data1 = array( array( 'productId' =&gt; '822335', 'dateHour' =&gt; '2011-11-17 06:00:00', 'qtySold' =&gt; '200', 'qtyCanceled' =&gt; '10', ), array( 'productId' =&gt; '822335', 'dateHour' =&gt; '2011-11-17 07:00:00', 'qtySold' =&gt; '100', 'qtyCanceled' =&gt; '20', ), array( 'productId' =&gt; '822336', 'dateHour' =&gt; '2011-11-17 06:00:00', 'qtySold' =&gt; '0', 'qtyCanceled' =&gt; '30', ), array( 'productId' =&gt; '822336', 'dateHour' =&gt; '2011-11-17 07:00:00', 'qtySold' =&gt; '50', 'qtyCanceled' =&gt; '40', ), ); $data2 = array( array( 'entity_id' =&gt; '822335', 'dateHour' =&gt; '2011-11-17 06:00:00', 'productInventory' =&gt; '300', ), array( 'entity_id' =&gt; '822335', 'dateHour' =&gt; '2011-11-17 07:00:00', 'productInventory' =&gt; '200', ), array( 'entity_id' =&gt; '822336', 'dateHour' =&gt; '2011-11-17 06:00:00', 'productInventory' =&gt; '100', ), array( 'entity_id' =&gt; '822336', 'dateHour' =&gt; '2011-11-17 07:00:00', 'productInventory' =&gt; '50', ), ); // Usage $result = array_join($data1, $data2, array( 'productId' =&gt; 'entity_id', 'dateHour' =&gt; 'dateHour' )); print_r($result); </code></pre>
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    1. USCaleb Gray
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    2. VO
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      1. POHow can I optimize my array_join (simulates a LEFT JOIN) function?
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    1. COHere are the three "basic" kinds of join techniques: `LOOP`, `HASH`, `MERGE`. Which one is the above? How would the others work? What is the Big-O of each?
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      1. POHow can I optimize my array_join (simulates a LEFT JOIN) function?
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    2. COAdd a `break` to your innermost foreach+if … this should speed up execution tremendously.
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      1. POHow can I optimize my array_join (simulates a LEFT JOIN) function?
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    3. CO@knittl: Unfortunately breaking out of any of the foreach's would prevent the multi-key matching to work.
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      1. POHow can I optimize my array_join (simulates a LEFT JOIN) function?
      1. USCaleb Gray
 

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