After some work with the DokuWiki, I've looked into it's fulltext search index, and found out that it counts my three (3)-letter russian words as six (6)-letter. This is known problem with PHP, because it isn't aware internally about multi-byte characters, and cyrillic letters in the UTF-8 encoding are two bytes long each.
So, I've used an mbstring extension, and turn full function overload on (to use multibyte-aware functions instead of built-in ones, without rewriting the code), adding the following line into .htaccess file:
php_value mbstring.func_overload 7
Then, I simply rebuilt an index, and I was satisfied with this.
After some time, I've noticed, that javascript in the DokuWiki is not working at all, and even Internet Explorer throws an error message: "This page contains errors!" (It always throws unusable error messages).
Then, after some test reinstalls, I've found a regularity.
If I do a cache clear (using the cacherevisionseraser plugin) with an mbstring turned ON, I've got garbaged javascript, which is not working. Then I edit .htaccess and comment out that line, and do a cache clear again. JS is working now! After that, I can turn mbstring back on, and work normally until next cache clear.
Firefox's 'error console' shows all range of errors, when I try to edit a page just after a cache clear with mbstring on:
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Error: invalid XML attribute value
Source:
http://www.merlin-ru.homelinux.net/wiki/lib/exe/js.php?edit=1&write=1
Line 1, character 12
Source code:
<font color=#880000><br />
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Error: missing ; before statement
Source:
http://www.merlin-ru.homelinux.net/wiki/lib/exe/js.php?edit=1&write=1
Line 1, character 33
Source code:
ar notSavedYet=ar reallyDel = 'Вы на самом деле желаете удалить выбранное?';LANG = {"keepopen":"\u041d\u0435 \u0437\u0430\u043a\u0440\u044b\u0432\u0430\u0442;var reallyDel=\u043d","hidedetails":"\u0421\u043a\u0440\u044b\u0442\u044c "};
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etc.
So, I address the problem to an javascript generation code.