Julian Hyde created CALCITE-1290:
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             Summary: When converting to CNF, fail if the expression exceeds a 
threshold
                 Key: CALCITE-1290
                 URL: https://issues.apache.org/jira/browse/CALCITE-1290
             Project: Calcite
          Issue Type: Bug
            Reporter: Julian Hyde
            Assignee: Julian Hyde


When converting to conjunctive normal form (CNF), fail if the expression 
exceeds a threshold. CNF can explode exponentially in the size of the input 
expression, but rarely does so in practice. Add a {{maxNodeCount}} parameter to 
{{RexUtil.toCnf}} and throw or return null if it is exceeded.

I don't believe it is possible to predict the size of the CNF from the input 
expression (especially if there are duplicate terms) but I might be wrong.



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