Hi all, After reading http://carsabi.com/car-news/2012/03/23/optimizing-solr-7x-your-search-speed/ , I thought I'd do my own experiments. I used 2M docs from wikipedia, indexed in Solr 4.0 Beta on a standard EC2 large instance. I compared an unsharded and 2-shard configuration (the latter set up with SolrCloud following the http://wiki.apache.org/solr/SolrCloud example). I wrote a simple python script to randomly throw queries from a hand-compiled list at Solr. The only "extra" I had turned on was facets (on document category).
To my surprise, the performance of the 2-shard configuration is almost exactly half that of the unsharded index - unsharded 4983912891 results in 24920 searches; 0 errors 70.02 mean qps 0.35s mean query time, 2.25s max, 0.00s min 90% of qtimes <= 0.83s 99% of qtimes <= 1.42s 99.9% of qtimes <= 1.68s 2-shard 4990351660 results in 24501 searches; 0 errors 34.07 mean qps 0.66s mean query time, 694.20s max, 0.01s min 90% of qtimes <= 1.19s 99% of qtimes <= 2.12s 99.9% of qtimes <= 2.95s All caches were set to 4096 items, and performance looks ok in both cases (hit ratios close to 1.0, 0 evictions). I gave the single VM -Xmx1G and each shard VM -Xmx500M. I must be doing something stupid - surely this result is unexpected? Does anybody have any thoughts where it might be going wrong? cheers, Tom
