Hi everyone, To prove the idea of GSoC project, I was working on some simple TPC-DS queries running with given generated data on direct runner. query example <https://gist.github.com/vectorijk/7c54f90aeebfd6fd9e9d2ee224bfed50>
The example is executed with TPC-DS query 9 <https://gist.github.com/vectorijk/7c54f90aeebfd6fd9e9d2ee224bfed50#file-tpcdssql-java-L176-L222>. Briefly, Query 9 uses case when clauses to select 5 counting numbers from store_sales (table 1). In order to show those result numbers, case when clause inside one select clause. In short, it looks like: SELECT CASE WHEN ( SELECT count(*) FROM table 1 WHERE..... ) THEN condition 1 ELSE condition 2, ..... CASE WHEN ..... FROM table 2 IIUC, this query doesn't need join operation on table 1 and table 2 since outside select clause doesn't need to interfere with table 1. But, the program shows it does and throws errors message said "java.lang.UnsupportedOperationException: CROSS JOIN is not supported". (error message detail <https://gist.github.com/vectorijk/5619a20485edc01113a56e348f87b0c3>) To make the query work, I am wondering where I can start with: 1. see logic plan? Will logic plan explain why the query need CROSS JOIN? 2. cross join support? I checked all queries in TPC-DS benchmark. Almost every query uses cross join. It is an important feature needs to implement. Unlike other join, it consumes a lot of computing resource. But, I think we need cross join in the future. and support both in join-library? I noticed James has open BEAM-2194 <https://issues.apache.org/jira/browse/BEAM-2194> for supporting cross join. Looking forward to comments! Best, Kai ᐧ
