agg_count, go back to ExAliyunOts.Search module for more information.
Calculate the count of the assigned field by aggregation in the nested
:aggs option of
import MyApp.TableStore search "table", "index_name", search_query: [ query: ..., aggs: [ agg_sum("agg_name", "score") ] ]
aggregation_name can be any business description string, when get the calculated results, we need to use
it to fetch them.
If the field is not existed in a row of data, then this row does not participate in the statistics of count.