Hmmm. Good catch, although I thought I had a test case to ensure that was handled correctly. I'll check that :) You seem to know more about regexes than I do. Why would you guess this particular regex is slow? Line-by-line profiling proves that it is consuming the vast majority of the time. It consumes almost 300 CPU seconds, and the next most expensive line in this code consumes 89 seconds, on an 8GB file.

The next-most-worst offender is

$query =~ s/(?<=\w_)\d+(_\d+)?\b/$1 ? "N_N" : "N"/eg;

followed by

$query =~ s/\s{2,}/ /g;

In reply to Re^2: In search of an efficient query abstractor by xaprb
in thread In search of an efficient query abstractor by xaprb

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.