Hi, community.
Recently, when I tried to fix bugs in Elasticsearch Adapter, I’ve found that some new features in released Elasticsearch cannot be applied in Calcite, since the Elasticsearch version in Calcite is 7.0.1. For instance, as CALCITE-4868 mentioned, I want to sort aggregation results by multi_terms(supported after ES 7.1.11) as it’s more suitable under such circumstances than terms aggregation, however the DSL is not supported in Calcite currently. Moreover, I've browsed Elasticsearch's release notes roughly, and there are many new SQL features were added from 7.0.1 to 7.15.2, and lots of bugs were fixed meanwhile(if needed, I will spend some time to collect such info that benefits Calcite users). Since we use RestClient in Elasticsearch Adapter, there are still some cons about upgrading ES version, like new DSL couldn’t be used in old version Elasticsearch cluster, current use case might need to be adjusted. Nevertheless, I’m still wondering if we can upgrade the Elasticsearch version to 7.15, which could enrich ES Adapter's ablility as much as possible. Best regards, Zhe Hu
