Hans Zeller created TRAFODION-2349:
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Summary: Solve issue with mapping of value ids for statistics for
common subexpr
Key: TRAFODION-2349
URL: https://issues.apache.org/jira/browse/TRAFODION-2349
Project: Apache Trafodion
Issue Type: Sub-task
Components: sql-cmp
Affects Versions: 2.1-incubating
Reporter: Hans Zeller
Assignee: Hans Zeller
When we introduce a temp table, we want to "transplant" the statistics from the
original query tree representing the common subexpression to the new scan and
its ancestors. This requires two mappings, one from the original tree to the
temp table columns, the other from the temp table cols to the characteristic
outputs of the MapValueIds above the temp scan.
While most of these mappings are done in terms of VEGRefs, the statistics use
BaseColumns instead. Right now, we map the BaseColumns of single column stats
to VEGRefs in the new tree. We might be able to do the same for MC stats. Or,
alternatively, we may need to decided on specific BaseColumns to map to.
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