With using search API query for interwiki search (&srinterwiki=1 option) we saw pageid="0" for all results from projects that are different from the initial one.
Steps to Reproduce:
As example, requested from en-wikipedia:
https://en.wikipedia.org/w/api.php?action=query&list=search&format=xml&redirects=resolve&srlimit=1&srenablerewrites=1&&srprop=snippet&srinterwiki=1&srsearch=Tolstoy
Actual Results:
<api batchcomplete=""> <continue sroffset="1" continue="-||"/> <query> <searchinfo totalhits="4331"/> <search> <p ns="0" title="Leo Tolstoy" pageid="18622119" snippet="Count Lev Nikolayevich <span class="searchmatch">Tolstoy</span> (/ˈtoʊlstɔɪ, ˈtɒl-/; Russian: Лев Николаевич Толстой, tr. Lev Nikoláyevich <span class="searchmatch">Tolstóy</span>; [lʲef nʲɪkɐˈlaɪvʲɪtɕ tɐlˈstoj] (listen);"/> </search> <interwikisearch> <wikt> <_v ns="0" title="Tolstoy" pageid="0" snippet="From Russian Толсто́й (Tolstój), from a stress variant of the ancestor of то́лстый (tólstyj, “stout”). <span class="searchmatch">Tolstoy</span> A surname." namespace="" url="https://en.wiktionary.org/wiki/Tolstoy"/> </wikt> <s> <_v ns="0" title="A Confession (Tolstoy)" pageid="0" snippet="of Исповедь (A Confession) by Leo <span class="searchmatch">Tolstoy</span> 1996511English-language translations of Исповедь (A Confession)Leo <span class="searchmatch">Tolstoy</span> English-language translations of Исповедь" namespace="" url="https://en.wikisource.org/wiki/A_Confession_(Tolstoy)"/> </s> <q> <_v ns="0" title="Leo Tolstoy" pageid="0" snippet="Lev Nikolayevitch <span class="searchmatch">Tolstoy</span> [Ле́в Никола́евич Толсто́й, usually rendered Leo <span class="searchmatch">Tolstoy</span>, or sometimes Tolstoi] (9 September 1828 – 20 November 1910) was a Russian" namespace="" url="https://en.wikiquote.org/wiki/Leo_Tolstoy"/> </q> <b> <_v ns="0" title="Anarchist FAQ/What is Anarchism?/3.7" pageid="0" snippet="anarchist movement with the work of the famous Russian author Leo <span class="searchmatch">Tolstoy</span>. <span class="searchmatch">Tolstoy</span> took the message of the Bible seriously and came to consider that a" namespace="" url="https://en.wikibooks.org/wiki/Anarchist_FAQ/What_is_Anarchism%3F/3.7"/> </b> </interwikisearch> <interwikisearchinfo totalhits="1855"/> </query> </api>
Expected Results:
<api batchcomplete=""> <continue sroffset="1" continue="-||"/> <query> <searchinfo totalhits="4331"/> <search> <p ns="0" title="Leo Tolstoy" pageid="18622119" snippet="Count Lev Nikolayevich <span class="searchmatch">Tolstoy</span> (/ˈtoʊlstɔɪ, ˈtɒl-/; Russian: Лев Николаевич Толстой, tr. Lev Nikoláyevich <span class="searchmatch">Tolstóy</span>; [lʲef nʲɪkɐˈlaɪvʲɪtɕ tɐlˈstoj] (listen);"/> </search> <interwikisearch> <wikt> <_v ns="0" title="Tolstoy" pageid="6592235" snippet="From Russian Толсто́й (Tolstój), from a stress variant of the ancestor of то́лстый (tólstyj, “stout”). <span class="searchmatch">Tolstoy</span> A surname." namespace="" url="https://en.wiktionary.org/wiki/Tolstoy"/> </wikt> <s> <_v ns="0" title="A Confession (Tolstoy)" pageid="1996511" snippet="of Исповедь (A Confession) by Leo <span class="searchmatch">Tolstoy</span> 1996511English-language translations of Исповедь (A Confession)Leo <span class="searchmatch">Tolstoy</span> English-language translations of Исповедь" namespace="" url="https://en.wikisource.org/wiki/A_Confession_(Tolstoy)"/> </s> <q> <_v ns="0" title="Leo Tolstoy" pageid="143" snippet="Lev Nikolayevitch <span class="searchmatch">Tolstoy</span> [Ле́в Никола́евич Толсто́й, usually rendered Leo <span class="searchmatch">Tolstoy</span>, or sometimes Tolstoi] (9 September 1828 – 20 November 1910) was a Russian" namespace="" url="https://en.wikiquote.org/wiki/Leo_Tolstoy"/> </q> <b> <_v ns="0" title="Anarchist FAQ/What is Anarchism?/3.7" pageid="219749" snippet="anarchist movement with the work of the famous Russian author Leo <span class="searchmatch">Tolstoy</span>. <span class="searchmatch">Tolstoy</span> took the message of the Bible seriously and came to consider that a" namespace="" url="https://en.wikibooks.org/wiki/Anarchist_FAQ/What_is_Anarchism%3F/3.7"/> </b> </interwikisearch> <interwikisearchinfo totalhits="1855"/> </query> </api>