Sorry it took me so long to triage this but I'm not really sure what you want. A few points:

1. The default query operator is AND so you can get no results even though all the terms in the search provided results.
2. Queries support somewhat complicated sets of operators many of which see active use which complicates this further. It is possible for the user to search for foo OR bar for example.
3. We can certainly log searches and how many results they returned.

Gerard.meijssen wrote:

Hoi,

I am looking for the 404 results for finding a label in Wikidata or an article in Wikipedia. I need a number per language for the failures that is the accumulation for the period of say one month.

These numbers help us identify what the most looked after failures are to provide information. They will include spelling errors, they will include words as spelled in a different language.. Triaging this stuff will help us provide better results.

I am not particularly interested in complicated use with operators. I am looking for straight forward searches.

What is relevant here is that Wikidata will provides substantially more simple results than Wikipedia does.. http://ultimategerardm.blogspot.nl/2013/11/divcon-search-beyond-tail.html The objective is to provide information when we have it. This can be done by combining Wikipedia with the labels available at Wikidata. http://ultimategerardm.blogspot.nl/2013/11/divcon-valerie-sutton-found-on-occitan.html for the proof of the pudding that we can do this.
Thanks,

GerardM

This sounds like a duplicate of bug 3437.

Some sort of list of redlinks hits/search queries with no results to find the most common wanted articles/missing articles has been requested multiple times, also in the form of logs, especially by Wiktionary, but I can't find a link handy.

Related/complement proposal about search queries with results: http://lists.wikimedia.org/pipermail/analytics/2013-December/001378.html

Ah right, and of course also https://blog.wikimedia.org/2012/09/19/what-are-readers-looking-for-wikipedia-search-data-now-available/

Gerard.meijssen wrote:

Magnus is asking for access to the search logs.. He is waiting for access so that he can adapt the existing software that provides the most searched NOT FOUND for the English Wikipedai.

What Magnus will do is provide a quantified list per language of not find items...
Thanks,

GerardM

PS so far there has been no reply