Esper - concatenate values from multiple rows to a list

Question

I have an Esper query that returns multiple rows, but I'd like to instead get one row, where that row has a list (or concatenated string) of all of the values from the (corresponding columns of the) matching rows that my current query returns.

For example:

SELECT Name, avg(latency) as avgLatency
FROM MyStream.win:time(5 min)
GROUP BY Name
HAVING avgLatency / 1000 > 60
OUTPUT last every 5 min

Returns:

Name    avgLatency
----    ----------
A       65
B       70
C       75

What I'd really like:

Name
----
{A, B, C}

Is this possible to do via the query itself? I tried to make this work using subqueries, but I'm not working with multiple streams. I can't find any aggregation functions or enumeration functions in the Esper documentation that fits what I'm trying to do either.

Thanks to anybody that has any insight or direction for me here.

EDIT: If this can't be done via the query, I'm open to changing the subscriber, or anything else, if necessary.

Answer 1

You can have a subscriber or listener do the concat. There is a "Multi-Row Delivery" for subscribers. Or use a table like below.

// create table to hold aggregation result
create table LatencyTable(name string primary key, avgLatency avg(double));

// update aggregations in table from events coming in
into LatencyTable select name, avg(latency) as avgLatency from MyStream#time(5 min) group by name;

// do a select with the "aggregate" enumeration method 
select (select * from LatencyTable where avgLatency > x).aggregate(....) from pattern[every timer:interval(5 min)]