Item12618: Search ordering is not predictable on Perl 5.18.1 and later

The Fn_SEARCH::topicOrder tests give very inconsistent results on Perl 5.18.1.

It's specifically the following two tests:

    #order=modified
    $result =
      $this->{test_topicObject}->expandMacros( $search . 'order="modified"}%' );

    $this->assert_str_equals(
"QueryTopicThree,QueryTopicTwo,QueryTopic,WebPreferences,TestTopicSEARCH,OkTopic,OkATopic,OkBTopic",
        $result
    );

    $result =
      $this->{test_topicObject}->expandMacros(
        $search . 'order="modified" reverse="on" format="$topic"}%' );

#be very careful with this test and the one above - the change in order between QueryTopicTwo,QueryTopic is due to them having the same date, so its sorting by topicname
    $this->assert_str_equals(
"OkBTopic,OkATopic,OkTopic,TestTopicSEARCH,WebPreferences,QueryTopicTwo,QueryTopic,QueryTopicThree",
        $result
    );

The comment says it all. The order of the two topics with the same date seem to exchange position. The assumption that there is a secondary sort ordering of Topic name does not appear to be true. And there is nothing in the Foswiki::Search::InfoCache code that I can find that would apply a secondary sort order.

Debug statements in InfoCache shows that the raw list of files returned by the ListIterator changes order for every %SEARCH execution. And the sort of the results set seems to assume that the topics were in topic name order.

Running on 5.16.1, the topic list is exactly the same for each run, and the resulting searches are consistent and all tests pass.

I'm making this a blocker, %SEARCH should return the same results for each search if everything else remains constant.

-- GeorgeClark - 29 Oct 2013

I can't find where this apparent randomization happens. Store eachTopic returns a sorted list of topic names, So how it becomes un-sorted ... That's for another day.

-- GeorgeClark - 29 Oct 2013

Defer to Foswiki 1.2

-- GeorgeClark - 05 Nov 2013

I don't have anything to add beyond what I discussed with George on IRC, so taking myself off the WaitingFor and deferring to 1.2

-- CrawfordCurrie - 07 Nov 2013

Perl has changed by design: see here (Hash Order Randomization)

-- OliverKrueger - 13 Mar 2014

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