lgbo-ustc opened a new issue, #7986: URL: https://github.com/apache/incubator-gluten/issues/7986
### Backend CH (ClickHouse) ### Bug description Lazy expand(#7647) could work will on low cardinality group keys, but there is performance regression when there are high cardinality grouping keys. For example, tpcds q67 runs slower, since the `i_product_name` is a high cardinality column. It's a problem we have discuss in #7647, let's see what we could do to improve this cases. - disable lazy expand  - enable lazy expand  Obviously， with lazy expand enable, this first aggregate stage generates more rows. This increase the execution time of shuffle and the second aggregate stage. We use a simple algorithm to decide whether aggregate data from the expand operator, this cause there is no rows are aggregated from the expand operator. ### Spark version None ### Spark configurations _No response_ ### System information _No response_ ### Relevant logs _No response_ -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
