Dear all,
Just a status update, in case this can help others.
We went forward and disabled the position information indexing and the re-indexed of our mail data (over a couple of days to avoid overloading the systems). Before the re-indexing we had 1.33 TiB in our Solr Indexes. After re-indexation, we had only 542 GiB, that's a 60% of our storage requirements for our FTS indexes :)
So far, we haven't been reported any issue or measurable differences by
our users concerning the quality of the FTS. From further debugging, as
discussed on the solr-user mailing list
(https://lists.apache.org/thread.html/rcdf8bb97be0839e57928ad5fa34501ec8a7339...),
I've come to the conclusion that, with the current integration between
Dovecot and Solr (esp the fact that " is escaped), it's impossible to
trigger phrase queries from user queries as long as
autoGeneratePhraseQueries is false.
I've attached the schema.xml and solrconfig.xml we are now using with Solr 8.6.0, in case there is any interest from others. Let me know if you prefer a MR to update the xmls present in https://github.com/dovecot/core/tree/master/doc.
Cheers, Vincent