Thanks for showing your comparison of the unzip pipeline vs. reading uncompressed text. I had said that the former would be faster (because of less reading from disk), but without actually testing it. (I think I must have encountered at least a couple situations in the past where some process finished more quickly if I read compressed data from disk, rather than uncompressed, but I don't know what may have been different in those cases.)

Having now tested it for this situation (multiple times in quick succession to check for consistency), the difference in timing was negligible or slightly favoring reading the uncompressed file, so it seems my initial idea about the role of disk access was wrong: either it really doesn't make any difference, or else whatever difference it makes is washed out by the added overhead of the extra unzip process and/or the pipeline itself.

(The perl one-liner was still faster than the compiled "grep" utility on my machine, but YMMV - different machines will have different versions / compilations of both Perl and grep.)

In reply to Re^3: How to optimize a regex on a large file read line by line ? by graff
in thread How to optimize a regex on a large file read line by line ? by John FENDER

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.