Topic on Help talk:CirrusSearch

The filters section says A namespace or a prefix term is not a filter because a namespace will not run standalone, and a prefix will not negate. This seems empirically untrue. On EnWP I get the following number of results for each of these queries, as expected:

• incategory:"LGBT-related musical films": 58
• incategory:"LGBT-related musical films" prefix:"Hello": 2
• incategory:"LGBT-related musical films" -prefix:"Hello": 56

So it seems like negating a prefix does work. Am I misunderstanding what this is trying to say? For now I added a {{dubious}} tag.

I took a long hard look at this and I'm confused, too. I'm not sure I understand the definition of "filter" being used. I don't know if the documentation is out of date or using some model that I'm not able to wrap my head around. Similarly, I don't get this: Insource ... is also a filter, but insource:/regexp/ is not a filter. insource:word and insource:/regex/ behave pretty much the same, other than the regex being much slower. Sounds like the documentation could use a thorough review to make sure all the advanced features and special cases are still described correctly.

A "filter" can reduce unwanted matches, providing refinement. Regex are special, catered for, terms that use filters. I made educated guesses at numerous terms, and even invented "greyspace". Just trying to help.

When I rewrote the help page to its current form, (years ago), there was neither documentation, nor discussion. So I would say prefixes can be negated now, but not then.

@Cpiral, thanks for the explanation. Also, I very much appreciate all the work you've put into these help pages! They definitely keep getting better.

So, I’m editing the page to indicate we can actually negate prefixes.

EDIT: since I’m not really sure what is true, I’ve only removed the concerned sentence. Feel free to explain what is possible and what is not.

It tested well. It is true that prefix is a filter. I added the sentence back, modified: A namespace is a specified search domain but not a filter because a namespace will not run standalone.  A ''prefix'' will negate so it is a filter.