DaveBirdsall opened a new pull request #1855: [TRAFODION-3325] Enable index access for non-VEG equality join predicates URL: https://github.com/apache/trafodion/pull/1855 The problem is that sometimes join equality predicates are not converted into VEGs, and therefore do not get pushed down to their children. That prevents Scan::addIndexInfo from considering indexes when there are column references in the join predicate. That can result in missed opportunities to use efficient index plans and instead doing full table scans + hash joins. The fix is to look for equality predicates that didn't get pushed down, and if we find one and it has a child that is covered, we create an IS NOT NULL predicate on that child and push that down. That allows Scan::addIndexInfo to notice that an index might be useful. Later, if the join is converted to a TSJ, the equality predicate will be pushed down and the Optimizer can make use of the index. An example of a join equality predicate that is not converted to a VEG is a join predicate involving a tuple list. I added a CQD, COMP_BOOL_194, which if set to 'OFF' turns off this fix. The default is 'ON'. When unit testing this fix, I noticed a bug in some of the optimizer debugging code that caused a core. I fixed that too (optimizer/opt.cpp).
---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
