Hi Wei, Hard commits are about data durability. It will roll over transaction logs and create index new index segment. If configured with openSearcher=false, they do not affect query performance much (other then taking some resources) since they do not invalidate caches. If you have transaction logs enabled, without hard commits it would grow infinitely and can result in full disk. In case of heavy indexing, even rare hard commits can result in large transaction logs causing Solr restart after crash to take a while because transaction logs are replayed. Soft commits are the one that are affecting query performance and should be as rare as your requirements allow. They invalidate caches causing cold searches or if you have warming set up, take resources to do the warming.
I would recommend to keep hard commits, set to every 20-60 seconds (depending on indexing volume) and make sure openSearcher is set to false. HTH, Emir > On 29 Sep 2017, at 06:55, Wei <weiwan...@gmail.com> wrote: > > Hello All, > > What are the impacts if solr cloud is configured to have only soft commits > but no hard commits? In this way if a non-leader node crashes, will it > still be able to recover from the leader? Basically we are wondering in a > read heavy & write heavy scenario, whether taking hard commit out could > help to improve query performance and what are the consequences. > > Thanks, > Wei
