Re: Database madness

Raymond Toy <[email protected]> Sun, 26 Jul 2026 15:00:35 -0700
Newsgroups	gmane.comp.mathematics.maxima.general
Message-ID	<[email protected]>
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On 7/26/26 2:29 PM, David Scherfgen via Maxima-discuss wrote:

> Hi all,
>
> Something funny to try:
>
> run_testsuite(tests=[rtest_limit_extra]);
> for i : 1 thru 10000 do is(f(x) > i);
> run_testsuite(tests=[rtest_limit_extra]);
>
> The second test run takes about 15 times as much time as the first one.
>
> Why? Because when asking is(f(x) > i), a database node for the number 
> i is created (if there's none yet) in the variable *NOBJECTS*. This 
> slows down subsequent sign queries, because Maxima has to search in a 
> list that gets longer and longer.
Kinda funny, but certainly a rather pathological case. This doesn’t seem 
like something anyone would do on purpose. (Maybe I lack imagination.)

Could it be replaced by a hash table? I suppose that might break lots of 
code?

&#8203;
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    <div class=3D"markdown-here-wrapper">
      <p style=3D"margin-bottom: 19.2px; margin-top: 0px;">On 7/26/26 2:2=
9
        PM, David Scherfgen via Maxima-discuss wrote:<br>
      </p>
      <blockquote type=3D"cite"
style=3D"border-block-color: rgb(119, 119, 119); border-bottom-color: rgb=
(119, 119, 119); border-inline-color: rgb(114, 159, 207) rgb(119, 119, 11=
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rgb(119, 119, 119);">
        <div dir=3D"auto">Hi all,
          <div dir=3D"auto"><br>
          </div>
          <div dir=3D"auto">Something funny to try:</div>
          <div dir=3D"auto"><br>
          </div>
          <div dir=3D"auto">run_testsuite(tests=3D[rtest_limit_extra]);</=
div>
          <div dir=3D"auto">for i : 1 thru 10000 do is(f(x) &gt; i);</div=
>
          <div dir=3D"auto">run_testsuite(tests=3D[rtest_limit_extra]);</=
div>
          <div dir=3D"auto"><br>
          </div>
          <div dir=3D"auto">The second test run takes about 15 times as
            much time as the first one.</div>
          <div dir=3D"auto"><br>
          </div>
          <div dir=3D"auto">Why? Because when asking is(f(x) &gt; i), a
            database node for the number i is created (if there's none
            yet) in the variable *NOBJECTS*. This slows down subsequent
            sign queries, because Maxima has to search in a list that
            gets longer and longer.</div>
        </div>
      </blockquote>
      Kinda funny, but certainly a rather pathological case. This
      doesn=E2=80=99t seem like something anyone would do on purpose. (Ma=
ybe I
      lack imagination.)
      <p style=3D"margin-bottom: 19.2px; margin-top: 0px;">Could it be
        replaced by a hash table? I suppose that might break lots of
        code?</p>
    </div>
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