I could see such solutions used in cases where:
1. you are already using Redis for some other part of the application
2. you don't want yet to have Lucene/Solr/ElasticSearch
3. you don't need to support too advanced searches
On the other hand while building such a library could be a good learning exercise, I think that before using it in an application you should look for other already existing libraries and try to collaborate with the original authors.
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