Anoop Sharma created TRAFODION-2683:
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             Summary: add a new explain option to mask variant fields in output
                 Key: TRAFODION-2683
                 URL: https://issues.apache.org/jira/browse/TRAFODION-2683
             Project: Apache Trafodion
          Issue Type: Improvement
            Reporter: Anoop Sharma
            Assignee: Anoop Sharma
            Priority: Minor


Full explain returns detailed information about a query plan which is very 
useful in
determining if the chosen plan is as expected and other details about it.

But returned output contains information that may vary from run to run, or from 
one
system to another, or may be data dependent, and so on.
Some examples are UIDs, or cost/memory estimates, or number of cpus/nodes, etc.

Currently these variations are handled by checking in the new expected files 
(bad idea),
or creating known diff files, or adding filters, or selecting specific fields 
from explain virtual
table, or just not using explain.

This jira proposes a new option which when specified, will filter and mask 
fields that
are variant and change.
The option is called 'c' (cleanse) and could be specified as part
of explain "options '<str>' " clause. It works with both full explain and 
formatted explain.
 
This option is useful when running regressions where one need to validate 
enhancements
and other changes that do not involve costing/estimates/dop etc related values.
This option should not be used when those values are important. 
For ex, if a scan is expected to return 100 rows and explain need to show that, 
or
if a query should use 4 esps, then using the 'c' option will mask it. 






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