SQL: Consider adding support for multiple fields and indices

[gufeng20081010]

At the moment, ES SQL supports group by only one field and search one indices. Would be helpful to also support multiple fields and indices .
Like this： select count (*) from index1, index2 group by field1, field2

[elasticmachine]

Pinging @elastic/es-search-aggs

[astefan]

Grouping by multiple fields is possible and the change was merged quite recently: #31818

But, when it comes to searching multiple indices, you can do this by defining an alias in Elasticsearch that will include those indices, but with the restriction of indices having identical mappings. There is an issue already created for improving this: #31837. Closing as duplicate.