I'm considering patching Moodle to support pluggable search engines for searching content. This is largely inspired by customisations I've previously worked on using the GSOC Global Search plugin. I envisage two stock search plugins, a purely SQL based one that will run in a standard Moodle environment, and a SOLR plugin that will require a connection to a SOLR instance/master-slave setup.
To keep my life simple, and release code to the community in a reasonable timeframe, I'd like to incrementally patch different search functions in moodle core, starting with course descriptions, then moving on to other content at a later date. Would people find it useful/desirable to merge a partial implementation as a base for future development, or is the preference for a fully complete feature?
A key part of this implementation would be providing a standard mechanism to add custom metadata to indexed resources, to allow drill-down by these additional criteria in large catalogues, in a similar way to many e-commerce sites (e.g. e-Bay, Amazon, etc.)
Note that I'm likely to largely ignore the current SOLR global search plugin (possibly using it as a reference in some instances), as there are quite a few limitations I'd like to get away from - not least is the requirement for a PHP plugin when talking XML to a SOLR instance would work just as well.