Steven Phillips created DRILL-3477:
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Summary: Using IntVector for null expressions causes problems with
implicit cast
Key: DRILL-3477
URL: https://issues.apache.org/jira/browse/DRILL-3477
Project: Apache Drill
Issue Type: Bug
Reporter: Steven Phillips
Assignee: Steven Phillips
See DRILL-3353, for example.
A simple example is this:
{code}
select * from t where a = 's';
{code}
If the first batch scanned from table t does not contain the column a, the
expression materializer in Project defaults to Nullable Int as the type. The
Filter then sees an Equals expression between a VarChar and an Int type, so it
does an implicit cast. Implicit cast rules give Int higher precedence, so the
literal 's' is cast to Int, which ends up throwing a NumberFormatException.
In the class ResolverTypePrecedence, we see that Null type has the lowest
precedence, which makes sense. But since we don't actually currently have an
implementation for NullVector, we should materialize the Null type as the
Vector with the lowest possible precedence, which is VarBinary.
My suggestion is that we should use VarBinary as the default type in
ExpressionMaterializer instead of Int.
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