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[opt](coercion) change the coercion behavior for coalesce #59679

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a06d6d0
[opt](coercion) change the coercion behavior for coalesce
Jan 8, 2026
55d5bad
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Jan 15, 2026
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85 changes: 38 additions & 47 deletions ...e/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/Coalesce.java
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Original file line number Diff line number Diff line change
Expand Up @@ -19,61 +19,27 @@

import org.apache.doris.catalog.FunctionSignature;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.functions.CustomSignature;
import org.apache.doris.nereids.trees.expressions.functions.ExpressionTrait;
import org.apache.doris.nereids.trees.expressions.functions.SearchSignature;
import org.apache.doris.nereids.trees.expressions.literal.Literal;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.nereids.types.BigIntType;
import org.apache.doris.nereids.types.BitmapType;
import org.apache.doris.nereids.types.BooleanType;
import org.apache.doris.nereids.types.DateTimeType;
import org.apache.doris.nereids.types.DateTimeV2Type;
import org.apache.doris.nereids.types.DateType;
import org.apache.doris.nereids.types.DateV2Type;
import org.apache.doris.nereids.types.DecimalV2Type;
import org.apache.doris.nereids.types.DecimalV3Type;
import org.apache.doris.nereids.types.DoubleType;
import org.apache.doris.nereids.types.FloatType;
import org.apache.doris.nereids.types.IntegerType;
import org.apache.doris.nereids.types.LargeIntType;
import org.apache.doris.nereids.types.SmallIntType;
import org.apache.doris.nereids.types.StringType;
import org.apache.doris.nereids.types.TimeType;
import org.apache.doris.nereids.types.TimeV2Type;
import org.apache.doris.nereids.types.TinyIntType;
import org.apache.doris.nereids.types.VarcharType;
import org.apache.doris.nereids.types.DataType;
import org.apache.doris.nereids.util.ExpressionUtils;
import org.apache.doris.nereids.util.TypeCoercionUtils;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;

import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.stream.Collectors;

/**
* ScalarFunction 'coalesce'. This class is generated by GenerateFunction.
*/
public class Coalesce extends ScalarFunction
implements ExplicitlyCastableSignature {

public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
FunctionSignature.ret(BooleanType.INSTANCE).varArgs(BooleanType.INSTANCE),
FunctionSignature.ret(TinyIntType.INSTANCE).varArgs(TinyIntType.INSTANCE),
FunctionSignature.ret(SmallIntType.INSTANCE).varArgs(SmallIntType.INSTANCE),
FunctionSignature.ret(IntegerType.INSTANCE).varArgs(IntegerType.INSTANCE),
FunctionSignature.ret(BigIntType.INSTANCE).varArgs(BigIntType.INSTANCE),
FunctionSignature.ret(LargeIntType.INSTANCE).varArgs(LargeIntType.INSTANCE),
FunctionSignature.ret(DoubleType.INSTANCE).varArgs(DoubleType.INSTANCE),
FunctionSignature.ret(FloatType.INSTANCE).varArgs(FloatType.INSTANCE),
FunctionSignature.ret(DateTimeV2Type.SYSTEM_DEFAULT).varArgs(DateTimeV2Type.SYSTEM_DEFAULT),
FunctionSignature.ret(DateTimeType.INSTANCE).varArgs(DateTimeType.INSTANCE),
FunctionSignature.ret(DateV2Type.INSTANCE).varArgs(DateV2Type.INSTANCE),
FunctionSignature.ret(DateType.INSTANCE).varArgs(DateType.INSTANCE),
FunctionSignature.ret(TimeType.INSTANCE).varArgs(TimeType.INSTANCE),
FunctionSignature.ret(TimeV2Type.INSTANCE).varArgs(TimeV2Type.INSTANCE),
FunctionSignature.ret(DecimalV3Type.WILDCARD).varArgs(DecimalV3Type.WILDCARD),
FunctionSignature.ret(DecimalV2Type.SYSTEM_DEFAULT).varArgs(DecimalV2Type.SYSTEM_DEFAULT),
FunctionSignature.ret(BitmapType.INSTANCE).varArgs(BitmapType.INSTANCE),
FunctionSignature.ret(VarcharType.SYSTEM_DEFAULT).varArgs(VarcharType.SYSTEM_DEFAULT),
FunctionSignature.ret(StringType.INSTANCE).varArgs(StringType.INSTANCE)
);
public class Coalesce extends ScalarFunction implements CustomSignature {

/**
* constructor with 1 or more arguments.
Expand Down Expand Up @@ -106,8 +72,33 @@ public Coalesce withChildren(List<Expression> children) {
}

@Override
public List<FunctionSignature> getSignatures() {
return SIGNATURES;
public FunctionSignature customSignature() {
Map<Boolean, List<Expression>> partitioned = getArguments().stream()
.collect(Collectors.partitioningBy(
e -> (e instanceof Literal && ((Literal) e).isStringLikeLiteral())));
List<DataType> forFindCommon = partitioned.get(false).stream()
.map(ExpressionTrait::getDataType)
.collect(Collectors.toList());
Optional<DataType> commonType = TypeCoercionUtils.findWiderCommonTypeForCaseWhen(forFindCommon);
if (!commonType.isPresent()) {
SearchSignature.throwCanNotFoundFunctionException(this.getName(), getArguments());
return null;
} else {
for (Expression stringLiteral : partitioned.get(true)) {
Optional<Expression> option = TypeCoercionUtils.characterLiteralTypeCoercion(
((Literal) stringLiteral).getStringValue(), commonType.get());
if (!option.isPresent()) {
List<DataType> commonTypes = Lists.newArrayList(commonType.get(), stringLiteral.getDataType());
commonType = TypeCoercionUtils.findWiderCommonTypeForCaseWhen(commonTypes);
if (!commonType.isPresent()) {
SearchSignature.throwCanNotFoundFunctionException(this.getName(), getArguments());
} else {
break;
}
}
}
return FunctionSignature.ret(commonType.get()).varArgs(commonType.get());
}
}

@Override
Expand Down
4 changes: 2 additions & 2 deletions ...java/org/apache/doris/nereids/rules/expression/rules/SimplifyConditionalFunctionTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -60,10 +60,10 @@ public void testCoalesce() {
assertRewrite(new Coalesce(slot, nonNullableSlot), new Coalesce(slot, nonNullableSlot));

// coalesce(null, null) -> null
assertRewrite(new Coalesce(NullLiteral.INSTANCE, NullLiteral.INSTANCE), new NullLiteral(BooleanType.INSTANCE));
assertRewrite(new Coalesce(NullLiteral.INSTANCE, NullLiteral.INSTANCE), NullLiteral.INSTANCE);

// coalesce(null) -> null
assertRewrite(new Coalesce(NullLiteral.INSTANCE), new NullLiteral(BooleanType.INSTANCE));
assertRewrite(new Coalesce(NullLiteral.INSTANCE), NullLiteral.INSTANCE);

// coalesce(non-nullable_slot) -> non-nullable_slot
assertRewrite(new Coalesce(nonNullableSlot), nonNullableSlot);
Expand Down