I wrote a perl script that uses Perl DBI to connect and query an Oracle 9.2 database. I prepared a statement handle outside of a loop that is a select statement with 3 placeholder in the WHERE part of the statement. The statement will be executed approximately 800 times in the loop. e.g. 
      my $sth = $dbh->prepare("select ... where fld1 = ? and
                                                fld2 = ? and       
                                                fld3 = ?");
      for ($i=0; $i<800; $i++0){
       ...
       $sth->execute($var2, $var2, $var4);
       ...
      }

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Ran some test and it takes almost 2 min to execute the loop 4 times. I rewrote the script and prepared the statement inside the loop by concatenating a string with variable values. e.g. 
     for ($i=0; $i<800; $i++){
       ...
      my $sql = "select ... where fld1=" . $var1 . 
                            " and fld2=" .$var2 .  
                            " and fld3=" . $var3;
      my $sth=$dbh->prepare($sql);
      $sth->execute();
       ...
     }

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Same loop executes in less than 10 seconds. All the documentation I can find says the placeholder code should be more efficient and run faster than the concatenated code. Any idea what's going on?

In reply to DBI placeholders less efficient? by rbuckner

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