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I’m really curious about this. Are you able to share a bit about your use case and how you use roaring bitmaps outright (vs. through search infra like Solr or ElasticSearch)?

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Well the replacement of this code base uses Solr. But when legacy started we where on lucene 1x that over the years upgraded to lucene 9x. So one of the things we used our bitmaps for was for a number extensions to pure lucene. So like facets, but also inter index joins. And then preserving résultats for fast faceting that remained part of the query.

E.g. a thing that legacy can but the new www (Solr) currently can't is allow downloads in a streaming fashion of more than 5million documents. As maintaing a roaringbitmap cost very little memory but depends on docid to key/value store mapping. Our extensions allowed this and gave us a very easy to use rest API.

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