avamingli commented on PR #670:
URL: https://github.com/apache/cloudberry/pull/670#issuecomment-2499736143

   > > Do we have a **Parallel Plan** test(ex: cbdb_parallel.sql) to ensure the 
output is as expected?
   > 
   > I'm not sure what we need **Parallel Plan** test, but I expanded 
`gp_explain.sql` test
   
   In GPDB, there is one process executed the Slice on each segments. And 
explain use the statistic of that gang of QEs to compute the results.
   In CBDB, we have Parallel feature. For a parallel plan, there may be 
multiple QEs execute the same Slice on each segments.
   We call them parallel workers.
   
   See CBDB style README 
https://github.com/apache/cloudberry/blob/11333c0b4d3a4962b0a6610ceb5b6d7a12e45ec4/src/backend/optimizer/README.cbdb.parallel
 for more details.
   And most cases could be found in 
https://github.com/apache/cloudberry/blob/11333c0b4d3a4962b0a6610ceb5b6d7a12e45ec4/src/test/regress/sql/cbdb_parallel.sql
   
   This is a significant difference between CBDB and GPDB.
   
   In parallel plan cases, what do the statistic results should be? Do current 
codes compute results right or it's already expected?
   Maybe the current codes don't need to do anything else more, but we should 
be clear about that.
   In any cases, there should be test cases to verify the explain output.
   
   
   
   


-- 
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]

Reply via email to