Sphinx randomly fails to combine subqueries - php

Question

I have this sphinx search engine that I use through Zend using sphinxapi.php . It works fantastic. Really really great.
However, there is one problem: It randomly fails.
// Prepare Sphinx search
$sphinxClient = new SphinxClient();
$sphinxClient->SetServer($ip, $port);
$sphinxClient->SetConnectTimeout( 10 );
$sphinxClient->SetMatchMode( SPH_MATCH_ANY );
$sphinxClient->SetLimits( $resultsPerPage * ($nPage - 1), $resultsPerPage );
$sphinxClient->SetArrayResult( true );
$query = array();
$query['lang'] = '#lang "lang' . $language . '"';
if (isset($params)) {
foreach ($params as $param) {
$query['tags'] = '#tags "' . $param . '"';
}
}
// Make the Sphinx search
$sphinxClient->SetMatchMode(SPH_MATCH_EXTENDED);
$sphinxResult = $sphinxClient->Query(implode(' ', $query), '*');
As seen here, I search for a language and an arbitrary amount of tags, imploded into a single query string in the end (instead of making a battleload of subqueries).
So, normally, this works like a charm, but occassionally sphinx returns that it found 2000 entries in English and, say, 1000 entries with the tag "pictures" (or some other purely english word) but ZERO hits that fit both results, which is purely false. In fact, refreshing the page everything returns to normal with something like 800 real results.
My question is why does it do this and how do I make it stop?
Any ideas?
:Edit: Added shortened output log
[error] =>
[warning] =>
...
[total] => 0
[total_found] => 0
[time] => 0.000
[words] => Array (
[langen] => Array (
[docs] => 2700
[hits] => 2701 )
[picture] => Array (
[docs] => 829
[hits] => 1571 ) ) )

Answer 1

have you checked to see if the sphinx client is giving you any error or warning messages that may describe the failure?
if($sphinxResult === false) {
print "Query failed: " . $sphinxClient->GetLastError();
} else {
if($sphinxClient->GetLastWarning()) {
print "WARNING: " . $sphinxClient->GetLastWarning();
}
// process results
}

Answer 2

This issue has been solved completely a few months after the original post. The issue is that our service providers in the umbrella corporation har mistakenly assigned the wrong root values to the sphinx commands. The problem above was actually running on Sphinx 0.9.8 and was obviously buggy. My advice, if you ever experience similar problems is to double-tripple-check the version you use both to index and to query.
It feels like one of those times your math calculation doesn't roll out because you forgot a minus on the first row. Thanks to everyone that have tried to help in this and related threads.