Mihai Budiu created CALCITE-7451:
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Summary: REINTERPRET should not be used in logical plans
Key: CALCITE-7451
URL: https://issues.apache.org/jira/browse/CALCITE-7451
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.41.0
Reporter: Mihai Budiu
This one may not be easy to fix.
Calcite has a version of a cast named REINTERPRET.
Here is the documentation from SqlStdOperatorTable:
{code:java}
/**
* An <code>REINTERPRET</code> operator is internal to the planner. When the
* physical storage of two types is the same, this operator may be used to
* reinterpret values of one type as the other. This operator is similar to
* a cast, except that it does not alter the data value. Like a regular cast
* it accepts one operand and stores the target type as the return type. It
* performs an overflow check if it has <i>any</i> second operand, whether
* true or not.
*/
public static final SqlSpecialOperator REINTERPRET =
new SqlSpecialOperator("Reinterpret", SqlKind.REINTERPRET) {
@Override public SqlOperandCountRange getOperandCountRange() {
return SqlOperandCountRanges.between(1, 2);
}
};{code}
As the documentation says, this should only be used when the physical size is
known. However, in logical plans the physical size is not known.
This cast is introduced by RexBuilder in the conversion from Sql to Rel, via
the SqlRexConvertletTable. That is very early in the compilation process, in a
layer which should know nothing about physical sizes.
I have seen this cast used mostly for converting intervals to integers; this
assumes that the cast knows the representation of intervals. But this layer has
no business assuming a representation for the intervals, that's for much later
in the compilation process. Intervals could be represented, for example, as
DECIMAL values, or perhaps as a long number of nanoseconds.
This code seems to be there since 2012.
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