mihaibudiu commented on code in PR #4353:
URL: https://github.com/apache/calcite/pull/4353#discussion_r2072480416
##########
core/src/main/java/org/apache/calcite/sql/validate/implicit/TypeCoercionImpl.java:
##########
@@ -422,6 +439,34 @@ protected boolean booleanEquality(SqlCallBinding binding,
return false;
}
+ /**
+ * COALESCE type coercion, collect all the branches types to find a common
type,
+ * then cast the operands to the common type when needed.
+ */
+ private boolean coalesceCoercion(SqlCallBinding callBinding) {
+ List<RelDataType> argTypes = new ArrayList<>();
+ SqlValidatorScope scope = getScope(callBinding);
+ for (SqlNode node : callBinding.operands()) {
+ argTypes.add(validator.deriveType(scope, node));
+ }
+ RelDataType widerType = getWiderTypeFor(argTypes, true);
+ if (null != widerType) {
+ return coerceOperandsType(scope, callBinding.getCall(), widerType);
+ }
+ return false;
+ }
+
+ /**
+ * NULLIF type coercion, cast the second operand type to the first operand
type when needed.
Review Comment:
Are you sure this is right?
When you translate this to a CASE statement the wider type will be used by
coercion.
You have to preserve this behavior.
##########
core/src/main/java/org/apache/calcite/sql/validate/implicit/TypeCoercionImpl.java:
##########
@@ -383,11 +383,28 @@ protected boolean booleanEquality(SqlCallBinding binding,
}
/**
- * CASE and COALESCE type coercion, collect all the branches types including
then
- * operands and else operands to find a common type, then cast the operands
to the common type
- * when needed.
+ * Coerces CASE WHEN, COALESCE and NULLIF statement branches to a unified
type.
+ *
+ * @deprecated Use {@link #caseOrEquivalentCoercion} instead.
+ */
+ @Deprecated @Override public boolean caseWhenCoercion(SqlCallBinding
callBinding) {
+ return caseOrEquivalentCoercion(callBinding);
+ }
+
+ /**
+ * Coerces CASE WHEN, COALESCE and NULLIF statement branches to a unified
type.
*/
- @Override public boolean caseWhenCoercion(SqlCallBinding callBinding) {
+ @Override public boolean caseOrEquivalentCoercion(SqlCallBinding
callBinding) {
+ if (callBinding.getCall().getKind() == SqlKind.COALESCE) {
+ // For sql statement like: `coalesce(a, b, c)`
+ return coalesceCoercion(callBinding);
+ }
+
+ if (callBinding.getCall().getKind() == SqlKind.NULLIF) {
+ // For sql statement like: `nullif(a, b)`
+ return nullifCoercion(callBinding);
+ }
+
Review Comment:
can you also add an assertion here that the remaining call is CASE?
##########
core/src/main/java/org/apache/calcite/sql/validate/implicit/TypeCoercionImpl.java:
##########
@@ -382,12 +383,22 @@ protected boolean booleanEquality(SqlCallBinding binding,
return false;
}
+ @Deprecated @Override public boolean caseWhenCoercion(SqlCallBinding
callBinding) {
+ return caseOrEquivalentCoercion(callBinding);
Review Comment:
I don't think we promise to preserve the original functionality for
deprecated methods, just their signature.
But there is an argument to be made for preserving the original
functionality too.
##########
core/src/main/java/org/apache/calcite/sql/validate/implicit/TypeCoercionImpl.java:
##########
@@ -383,11 +383,28 @@ protected boolean booleanEquality(SqlCallBinding binding,
}
/**
- * CASE and COALESCE type coercion, collect all the branches types including
then
- * operands and else operands to find a common type, then cast the operands
to the common type
- * when needed.
+ * Coerces CASE WHEN, COALESCE and NULLIF statement branches to a unified
type.
+ *
+ * @deprecated Use {@link #caseOrEquivalentCoercion} instead.
+ */
+ @Deprecated @Override public boolean caseWhenCoercion(SqlCallBinding
callBinding) {
+ return caseOrEquivalentCoercion(callBinding);
+ }
+
+ /**
+ * Coerces CASE WHEN, COALESCE and NULLIF statement branches to a unified
type.
*/
- @Override public boolean caseWhenCoercion(SqlCallBinding callBinding) {
+ @Override public boolean caseOrEquivalentCoercion(SqlCallBinding
callBinding) {
+ if (callBinding.getCall().getKind() == SqlKind.COALESCE) {
+ // For sql statement like: `coalesce(a, b, c)`
+ return coalesceCoercion(callBinding);
+ }
+
+ if (callBinding.getCall().getKind() == SqlKind.NULLIF) {
+ // For sql statement like: `nullif(a, b)`
+ return nullifCoercion(callBinding);
+ }
+
Review Comment:
for symmetry you may also want to move this code into a separate private
function
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