not 100% sure if this is a Kibana and/or Elasticsearch issue but I have to start somewhere...
We use Elastic Stack for centralized logging. I'm migrating from Elastic Stack 5.6.5 to Elastic Stack 6.3.2. At the moment I ship all our logs to both Elasticsearch clusters. Because Elasticsearch version 6 can only have one type of document per index I have sharded what used to be in 3 or 4 daily indices with 5 shards and one replica in Elasticsearch 5 to 12 daily indices with 2 shards and one replica. In the end the amount of shards is fairly similar per day.
The underlying hardware is very similar and the amount of ES and Kibana nodes is pretty much the same.
Discover in Kibana 6.3.2 (searching ES 6.3.2) is very slow compared to Kibana 5.6.5 (searching ES 5.6.5).
In Kibana Monitoring I can see much higher Search Rate in Kibana 6 (30-50x compared to Kibana 5). Also search latency is much higher...
In Kibana 6 the Index pattern will match many more indices but around the same amount of shards.
Is the amount of indices a likely reason to the slow Kibana Discover in version 6.3.2? Any tips on what I can look at to find what is the root cause?