taobupt opened a new issue, #9109: URL: https://github.com/apache/pinot/issues/9109
### Background For use case like the dashboard, we have the requirements to precompute metrics for several years so we can enable the year_over_year comparison. One of the biggest challenges for the metric precomputation is precompute non-rollup metrics. Sometimes we can use the hyperloglog to get the estimated number, but here we want to discuss how to support precise non-rollup metric calculation. e.g. count(distinct) using the bitmap. (Apache Kylin also has similar [implementation](https://kylin.apache.org/blog/2016/08/01/count-distinct-in-kylin/#:~:text=Apache%20Kylin%20implements%20approximately%20count,max%20error%20rate%20is%201.22%25.)) ### Problem statement Currently the Pinot already provide the [bitmap way](https://docs.pinot.apache.org/configuration-reference/functions/distinctcountbitmap) for count(distinct), but it does not support: 1. stored the query result as the bitmap (binary data type) for further aggregation. 2. calculate the cardinality of bitmap (stored as binary data type). 3. bitmap aggregation: merge two bitmap into new a bitmap when we roll up the metric for finest granularity to higher granularity -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
