Query Optimization: Which SELECT syntax is faster?

Question

Given the 5000 identifiers of records in the database, which query, in your opinion, is faster?

• Scroll through 5000 identifiers with php and execute a SELECT query for each of them,

  foreach($ids as $id){
    // do the query 
    $r = mysql_query("SELECT * FROM TABLE WHERE ID = {$id}");
  }
  

• Or collect all identifiers in an array and use SELECT * FROM TABLE WHERE ID IN (from 1 to 5000)

  //assuming $ids = array(1,2 ---- up to 5000);
  $r = mysql_query("SELECT * FROM TABLE WHERE ID IN (".join(",",$ids).")");
  

Answer 1

Without a shadow of a doubt, downloading them all at once will be faster. Running 5,000 requests will be much slower, as each request will incur a certain amount of overhead.

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Answer 2

2 . 5000 db .

Answer 3

- 5000 .
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Answer 4

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Answer 5

Loop , . ; .

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Answer 6

2 . 1 roundtrim .

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Answer 7

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<?php
    $start = getmicrotime();
    for ($i=0;$i<100000;$i++)
    {
            foreach($ids as $id){
              // do the query 
              $r = mysql_query("SELECT * FROM TABLE WHERE ID = {$id}");
            }

    }
    $end = getmicrotime();
    echo 'Time (1): '.($end- $start).' sec';



    $start = getmicrotime();
    for ($i=0;$i<100000;$i++)
    {
            //assuming $ids = array(1,2 ---- up to 5000);
            $r = mysql_query("SELECT * FROM TABLE WHERE ID IN (".join(",",$ids).")");
    }
    $end = getmicrotime();
    echo 'Time (2): '.($end- $start).' sec';
?>