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There are some opportunities to reduce the overhead load created by SOLR. It is for example not required to run SOLR on the same server as DSpace. It is possible to create a separate SOLR server. Another way of reducing the load is by creating a charted sharded SOLR core (for example per year). One third party service uses a SOLR caching mechanism to balance the load SOLR puts on DSpace's performance, this way there should not be a noticeable difference.
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