How to set max bucket in canvas?

i want to show max tps(count per seconds).
In present i show tps in Metric(visualize).
like below...

how to set max bucket in canvas?

Hey @Yungyoung_Ok, you can use the "Elasticsearch SQL" data-source with Canvas and then use the Max aggregate function: https://www.elastic.co/guide/en/elasticsearch/reference/current/sql-functions-aggs.html#sql-functions-aggs-max

I want to count the number every second to get the maximum count.
So i'm trying to group by my_date_field.

SELECT SUBSTR(CONCAT(TO_CHAR(my_date_field)),4), COUNT(*) FROM "my_index_name" GROUP BY SUBSTR(CONCAT(TO_CHAR(my_date_field)),4)

but TO_CHAR is unknown function...
and i show like this..

my_date_field format is strict_date_time(yyy-MM-dd'T'HH:mm:ss.SSSZZ).

how can i set to get max records?