Stamatis Zampetakis created CALCITE-3541:
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Summary: Avoid transformations to Enumerable nodes for custom
SqlOperators
Key: CALCITE-3541
URL: https://issues.apache.org/jira/browse/CALCITE-3541
Project: Calcite
Issue Type: Improvement
Components: core
Affects Versions: 1.21.0
Reporter: Stamatis Zampetakis
Assignee: Stamatis Zampetakis
Fix For: 1.22.0
Most Enumerable converter rules apply a transformation as soon as the
{{RelNode}} class and its convention match those defined by the rule. However,
there are use-cases that we would like to restrict the matches even further to
avoid generating unimplementable plans that will fail at runtime.
The most prominent example comes from extending the standard operator set with
new {{SqlOperator}}s that appear in filters and projections as part of a row
expression ({{RexNode}}). If we use the default instance of the
{{EnumerableCalcRule}} we might end-up with a plan that will fail at runtime
since the new operator is not handled by the Enumerable convention. Most likely
there is a {{RelNode}} in another convention that can handle this new operator.
We could avoid such undesirable transformations by allowing instantiations of
the Enumerable converter rules with user-defined predicates. This also means
adding public constructors to the rules that currently they do not have one.
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