Sean Broeder created CALCITE-7827:
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Summary: commonTypeForBinaryComparison narrows DECIMAL vs.
FLOAT/REAL comparisons
Key: CALCITE-7827
URL: https://issues.apache.org/jira/browse/CALCITE-7827
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.42.0
Reporter: Sean Broeder
Assignee: Sean Broeder
AbstractTypeCoercion#commonTypeForBinaryComparison picks the approximate
numeric operand's own type (FLOAT/REAL) as the common type for a comparison
between an exact numeric DECIMAL and an approximate numeric operand, resulting
in a loss of precision.
A 32-bit FLOAT/REAL carries only ~7 significant decimal digits. When the
validator uses this common type to insert an implicit CAST on the DECIMAL
operand, two genuinely different DECIMAL values can collapse onto the same
float value and incorrectly compare equal.
commonTypeForBinaryComparison should consider the exact numeric's type before
blindly returning the approximate numeric's type.
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