[jira] [Created] (CALCITE-1960) Duplicated mapping generated from RelMdPredicates

["Rheet Wong (JIRA)" <ji...@apache.org>]

Rheet Wong created CALCITE-1960:
-----------------------------------

             Summary: Duplicated mapping generated from RelMdPredicates
                 Key: CALCITE-1960
                 URL: https://issues.apache.org/jira/browse/CALCITE-1960
             Project: Calcite
          Issue Type: Bug
          Components: core
            Reporter: Rheet Wong
            Assignee: Julian Hyde


When inferring pulled up predicates, multiple mappings are generated to 
make sure equivalent expressions can be substitute. E.g., for an expression 
'a + b + c' and the following equivalences: 
{code:sql}
a : {a, b}
b : {a, b}
c : {c, e}
{code}

should generate:

{code:sql}
a + a + c
a + a + e
a + b + c
a + b + e
b + a + c
b + a + e
b + b + c
b + b + e
{code}

The mapping generation is a typical permutation generation process. However, 
the current code is not handling the permutation well, thus causing duplicated 
mappings.



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