I need to optimize some code. Would it be faster to read in the elements of a DBI select all at once in to hash and work with them or is it best to get them one by one through fetchrow_hashref as the code below does? Is there any difference? 
#(This section uses String::Similarity)

 <while ($items = $sth->fetchrow_hashref)
    
    {
       $foundblock = $items->{'Block'};
       $founditem=$items->{'itemID'};
        
       $similarity = similarity $foundblock,$block);
               
        #checking for duplicate blocks
        
        select(undef,undef,undef,0.005);
        if ($similarity*100 > 85)
        {
        
            #duplicate found
        
            $duplicate = 1;
            last;
        
        }
    }

[download]

In reply to Is a hash faster? by rkac

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.