Paul Rogers created IMPALA-7818:
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Summary: Standardize use of Expr predicates
Key: IMPALA-7818
URL: https://issues.apache.org/jira/browse/IMPALA-7818
Project: IMPALA
Issue Type: Improvement
Components: Frontend
Affects Versions: Impala 3.0
Reporter: Paul Rogers
Assignee: Paul Rogers
The {{Expr}} (expression) class in the frontend has many handy predicates such
as {{IS_BINARY_PREDICATE}} and so on. (Note the confusing terminology: there
are subclasses of {{Expr}} which are SQL predicates. The predicates discussed
here are those based on the Guava {{Predicate}} class.)
The class also has predicate-like methods: {{isLiteral()}} and
{{isNullLiteral()}}. As it has evolved, {{isNullLiteral()}} checks not only for
a null literal, but also a cast of a null to some type. These functions are in
the base class, but do their work by checking the type of the expression.
It would be cleaner to make these methods into predicates with names that
follow their function: {{IS_LITERAL}}, and {{IS_NULL_VALUE}}.
Further, there are a few places in the code that check for a non-null literal
using an and of conditions, This would be cleaner using a new
{{IS_NON_NULL_LITERAL}} predicate.
These changes put us in position to add new predicates as a result of work in
the pipeline; this refactoring is done as a separate change to keep the other
commit smaller.
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