Why Elasticsearch
Starting version 3.1, the default search engine used by CrafterCMS is Elasticsearch. The motivation for having Elasticsearch as the default search engine for CrafterCMS is the following:
Solr doesn’t cluster and scale as well as Elasticsearch and that would have held back CrafterCMS’s serverless mode
AWS doesn’t directly support Solr (AWS CloudSearch, while based on Solr, has an AWS specific API). Whereas Elasticsearch is the same on AWS or elsewhere.
CrafterCMS Search Architecture
With this arch update, users can now take advantage of Elasticsearch’s superior clustering capabilities, AWS ElasticSearch Service, and a direct/unabstracted interface to Elasticsearch.
We remain backward compatible with Crafter Search and Solr. You can choose to keep existing sites without changes on Crafter Search and Solr, by following this after upgrading.