[GitHub] [calcite] twdsilva commented on pull request #2876: [CALCITE-5240] Enhance MaterializedViewRule so that it applies to rol…

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twdsilva commented on PR #2876:
URL: https://github.com/apache/calcite/pull/2876#issuecomment-1336037626

   > @twdsilva thanks for the PR, I think it's a very useful feature, I still share the doubts that @julianhyde raised in a [jira comment](https://issues.apache.org/jira/browse/CALCITE-5240?focusedCommentId=17598705&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-17598705) (copying a filter into the view seems hacky and does not always seem safe) and that @zabetak raised [in the ML](https://lists.apache.org/thread/6c1x985qrzjvd1tc38kmcj56hs9q43bw) (isn't there a way to modify the query to match the view, instead of changing the view and making view matching more complex?).
   > 
   > In the same ML discussion, you have raised a question on this point, I don't have an answer to that myself, but I feel that the we all need to agree that we are going into the right direction before being able to merge the PR.
   
   Thank you @asolimando for the review. 
   We have a use case where we maintain materialized preaggregated cubes that store data rolled up to the UTC day or hour. The queries in our system always have a time range predicate that doesn't neccesarily align on the UTC day or boundary. We would like to use the materialized cube table whenever possible. Here is an [example](https://github.com/twilio/calcite-kudu/blob/30c0d4e7b1d15288f7c30cdfda885c0c3a4666bf/adapter/src/test/java/com/twilio/kudu/sql/ScenarioIT.java#L278).
   I could not figure how to get `MaterializedViewAggregateRule`  to handle the case when a view contains a rollup (has a group by with a `FLOOR(col)`) other than rewriting the view to include a predicate based on the query predicate. The existing code that uses the union operator works if we include this generated predicate. The other main change is to map `FLOOR(col)` to col which is valid because the predicate added to the view is aligned on the floored value of the query predicate. If there is a cleaner way to make this work I would appreciate any pointers. 
   


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