The story so far:
Decided to go with Xapian as search backend because it has all search-engine features I was looking for, knows about Unicode, stemming, has few dependencies and requires no bloated app-server installation on top of it.
Tried Django and Haystack (plus xapian-haystack, the backend glue code to tie Haystack to Xapian) because it was advertised on quite some blogs as "working". Did not work. Neither django-haystack nor the xapian-haystack project provide a version combination that actually works together. MASTER from both projects yields an error from Xapian, so it's not stable at all. Haystack 1.0.1 and xapian-haystack 1.0.x/1.1.0 are not API-compatible. Plus, in a minimally working installation of Haystack 1.0.1 and xapian-haystack MASTER, any complex query yields zero results due to errors in either django-haystack or xapian-haystack (I double-verified this), maybe because the unit-tests actually test very simple cases, and no edge-cases at all.
Tried Djapian. The source-code is riddled with spelling errors (mind you, in variable names, not comments), documentation is also riddled with ambiguities and outdated information that will never lead to a working installation. Not surprisingly, users rarely ask for features but how to get it working in the first place.
Next on the plate: exploring Solr (installing a Java environment plus Tomcat gives me headaches, the machine is RAM- and CPU-constrained), or Lucene (slightly less headaches, but still).
Before I proceed spending more time with a solution that might or might not work as advertised, I'd like to know: Did anyone ever get an actual, real-world search solution working in Django? I'm serious. I find it really frustrating reading about "large problems mostly solved", and then realizing that you will never get a working installation from the source-code because, actually, all bloggers dealing with those "mostly solved problems" never went past basic installation and copy-pasting the official tutorials.
So here are the requirements:
must be able to search for 10-100 terms in one query
must handle + (term must be present) and - (term must not be present), AND/OR
must handle arbitrary grouping (i.e. parentheses around AND/OR)
must allow for Django-ORM filtering before or after fulltext-search (i.e. pre-/post-processing of results with the full set of filters that Django knows about)
alternatively, there must be a facility to bulk-fetch the result set and transform it into a QuerySet
should be light on the machine, so preferably no humongous JVM and Java-based app-server installation
Is there anything out there that does this? I'm not interested in anecdotal evidence, or references to some blog posts that claim it should be working. I'd like to hear from someone who actually has a fully-functional setup working in the real world, under real conditions, with real queries.
EDIT:
Let me repeat again that I'm not so much interested in anecdotal evidence that someone, somewhere has a somewhat running installation working with unspecified properties. I already went there, I read all the blog posts, mailing lists, I contacted the authors, but when it came to actual implementation of real-world scenarios, nothing ever worked as advertised.
Also, and a user below brought that point up as well, considering the TCO of any project, I'm definitely not interested in hearing that someone, somewhere was able to pull it off once a vendor parachuted in an unknown number of specialists to monkey-patch the whole installation with specific domain-knowledge that's documented nowhere.
So, please, if you claim you have a working installation that actually satisfies minimum requirements for a full-fledged search (see requirements above), please provide the following so that we can all benefit from a search solution for Django that actually solves the problem:
exact Linux distribution, release version,
exact release version of Haystack (or equivalent) and release version of search backend,
exact release version of the search engine
publicly (!) available documentation how to set up all components exactly in the way that your installation was set up such that the minimal requirements above are met.
Thank you.