Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

I do not have the answer for you, but if i had your problem, then i would try to identify the cause through benchmarking the code with Devel::NYTProf. Seeing which line of code consumes most time, might help you in identifying the root cause, and as such fixing it.

Some random thought based on your description (might not apply):

"Perl takes several seconds may return no rows, even where there are matching candidates."
From the behaviour this makes me think of a locking/timeout issue. E.g. the file is locked through another process, and your call times out, while trying to acquire a lock. Googling i stumbled across which mentions locking in combination with sqlite_busy_timeout. One thing contradicting this theory however is, that you use
RaiseError => 1
, and as such you should get an exception when you fail to acquire the lock. An empty result, where there should be a result, is however many times the symptom of an unhandled exception or timeout.

Update: Googling further i also stumbled over the following article which mentions that in certain circumstances sqlite might sleep for whole seconds instead of microseconds when trying to acquire a lock. If you have concurrent processes/threads accessing the same sqlite file, then this might be another possible theory. Can you reproduce your issue with a copy of the sqlite database, with no other process accessing the file?

In reply to Re: DBD::Sqlite queries slow - and gives wrong results by rminner
in thread DBD::Sqlite queries slow - and gives wrong results by astroboy

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, 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, 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.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others perusing the Monastery: (7)
    As of 2021-03-01 15:54 GMT
    Find Nodes?
      Voting Booth?
      My favorite kind of desktop background is:

      Results (12 votes). Check out past polls.