Hi. team. https://docs.pinot.apache.org/basics/components/table#pre-aggregation I'm looking at this article to check the pre-aggregation feature. How do i verify that metrics is pre-aggregated.

i’ve done it 2 ways 1. look for this log line in your logs. but in general search for

Metrics aggregation

because there are several other logs that will tell you why it wasn’t able to be turned on that are not immediately apparent (like not specifying noDictionaryColumns) 2. run a query like

SELECT $segmentName, all_time_columns, all_dimension_columns, count(*) from your_table group by $segmentName, all_time_columns, all_dimensions_columns having count(*) > 1

. that should return nothing since everything in the segment is aggregated

Thanks Johan Adami. I was able to verify that the pre-aggregation was done using the SQL you provided. one question is, the document say as 'We sum the metric column values of all rows that have the same dimensions and create a single row in the segment.' In my test case, the 'segmentsConfig > timeColumnName' field had to have the same value as well. The query you provided is also grouping the time column, is the documentation wrong?

Not wrong, but maybe under specified. My understanding is all columns except for metrics are used for grouping. And all metrics are summed. @User does that sound right to you

Yes, it is dimensions + time. I’ll update the doc to reflect that.