apache · github-actions · Jan 23, 2026
@@ -1631,6 +1631,7 @@ primaryExpression
     | CASE value=expression whenClause+ (ELSE elseExpression=expression)? END                  #simpleCase
     | name=CAST LEFT_PAREN expression AS castDataType RIGHT_PAREN                              #cast
     | name=TRY_CAST LEFT_PAREN expression AS castDataType RIGHT_PAREN                           #tryCast
+    | DEFAULT LEFT_PAREN qualifiedName RIGHT_PAREN                                                 #defaultValue
     | constant                                                                                 #constantDefault
     | interval                                                                                 #intervalLiteral
     | ASTERISK (exceptOrReplace)*                                                              #star

@@ -525,6 +525,7 @@
 import org.apache.doris.nereids.trees.expressions.BitXor;
 import org.apache.doris.nereids.trees.expressions.CaseWhen;
 import org.apache.doris.nereids.trees.expressions.Cast;
+import org.apache.doris.nereids.trees.expressions.Default;
 import org.apache.doris.nereids.trees.expressions.DefaultValueSlot;
 import org.apache.doris.nereids.trees.expressions.DereferenceExpression;
 import org.apache.doris.nereids.trees.expressions.Divide;
@@ -3124,6 +3125,17 @@ public Expression visitTryCast(DorisParser.TryCastContext ctx) {
         return ParserUtils.withOrigin(ctx, () -> processTryCast(getExpression(ctx.expression()), ctx.castDataType()));
     }
 
+    @Override
+    public Expression visitDefaultValue(DorisParser.DefaultValueContext ctx) {
+        return ParserUtils.withOrigin(ctx, () -> {
+            List<String> nameParts = ctx.qualifiedName().identifier()
+                    .stream()
+                    .map(RuleContext::getText)
+                    .collect(ImmutableList.toImmutableList());
+            return new Default(new UnboundSlot(nameParts));
+        });
+    }
+
     @Override
     public UnboundFunction visitExtract(DorisParser.ExtractContext ctx) {
         return ParserUtils.withOrigin(ctx, () -> {

@@ -30,6 +30,7 @@
 import org.apache.doris.nereids.rules.expression.rules.MergeDateTrunc;
 import org.apache.doris.nereids.rules.expression.rules.NormalizeBinaryPredicatesRule;
 import org.apache.doris.nereids.rules.expression.rules.NormalizeStructElement;
+import org.apache.doris.nereids.rules.expression.rules.RewriteDefaultExpression;
 import org.apache.doris.nereids.rules.expression.rules.SimplifyArithmeticComparisonRule;
 import org.apache.doris.nereids.rules.expression.rules.SimplifyArithmeticRule;
 import org.apache.doris.nereids.rules.expression.rules.SimplifyCastRule;
@@ -54,6 +55,7 @@ public class ExpressionNormalization extends ExpressionRewrite {
     public static final List<ExpressionRewriteRule<ExpressionRewriteContext>> NORMALIZE_REWRITE_RULES
                 = ImmutableList.of(
             bottomUp(
+                RewriteDefaultExpression.INSTANCE,
                 SupportJavaDateFormatter.INSTANCE,
                 NormalizeBinaryPredicatesRule.INSTANCE,
                 InPredicateDedup.INSTANCE,

@@ -60,6 +60,7 @@ public enum ExpressionRuleType {
     NORMALIZE_STRUCT_ELEMENT,
     TIMESTAMP_TO_ADD_TIME,
     TOPN_TO_MAX,
+    REWRITE_DEFAULT_EXPRESSION,
     ADD_SESSION_VAR_GUARD;
 
     public int type() {

@@ -0,0 +1,104 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.apache.doris.nereids.rules.expression.rules;
+
+import org.apache.doris.catalog.Column;
+import org.apache.doris.nereids.CascadesContext;
+import org.apache.doris.nereids.analyzer.UnboundFunction;
+import org.apache.doris.nereids.exceptions.AnalysisException;
+import org.apache.doris.nereids.parser.NereidsParser;
+import org.apache.doris.nereids.rules.analysis.ExpressionAnalyzer;
+import org.apache.doris.nereids.rules.expression.ExpressionMatchingContext;
+import org.apache.doris.nereids.rules.expression.ExpressionPatternMatcher;
+import org.apache.doris.nereids.rules.expression.ExpressionPatternRuleFactory;
+import org.apache.doris.nereids.rules.expression.ExpressionRuleType;
+import org.apache.doris.nereids.trees.expressions.Default;
+import org.apache.doris.nereids.trees.expressions.Expression;
+import org.apache.doris.nereids.trees.expressions.SlotReference;
+import org.apache.doris.nereids.trees.expressions.literal.NullLiteral;
+import org.apache.doris.nereids.trees.plans.logical.LogicalPlan;
+import org.apache.doris.nereids.types.DataType;
+import org.apache.doris.nereids.util.TypeCoercionUtils;
+
+import com.google.common.collect.ImmutableList;
+
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Rewrite DEFAULT(column) expression to the actual default value of the column.
+ * This rule transforms:
+ * 1. DEFAULT(column) with default value -> the actual default value expression
+ * 2. DEFAULT(column) with no default value but nullable -> NULL
+ * 3. DEFAULT(column) with no default value and not nullable -> error
+ */
+public class RewriteDefaultExpression implements ExpressionPatternRuleFactory {
+
+    public static final RewriteDefaultExpression INSTANCE = new RewriteDefaultExpression();
+
+    @Override
+    public List<ExpressionPatternMatcher<? extends Expression>> buildRules() {
+        return ImmutableList.of(
+                matchesType(Default.class)
+                        .thenApply(RewriteDefaultExpression::rewrite)
+                        .toRule(ExpressionRuleType.REWRITE_DEFAULT_EXPRESSION)
+        );
+    }
+
+    private static Expression rewrite(ExpressionMatchingContext<Default> context) {
+        Default defaultExpr = context.expr;
+        Expression child = defaultExpr.child();
+
+        if (!(child instanceof SlotReference)) {
+            throw new AnalysisException("DEFAULT requires a column reference, but got: " + child.toSql());
+        }
+
+        SlotReference slotRef = (SlotReference) child;
+        Optional<Column> columnOpt = slotRef.getOriginalColumn();
+        if (!columnOpt.isPresent()) {
+            throw new AnalysisException("Cannot find column information for DEFAULT("
+                    + slotRef.getName() + ")");
+        }
+
+        Column column = columnOpt.get();
+        DataType targetType = DataType.fromCatalogType(column.getType());
+        if (column.isGeneratedColumn()) {
+            throw new AnalysisException("DEFAULT cannot be used on generated column '"
+                    + column.getName() + "'");
+        }
+
+        String defaultValueSql = column.getDefaultValueSql();
+        if (defaultValueSql == null) {
+            if (column.isAllowNull()) {
+                return new NullLiteral(targetType);
+            } else {
+                throw new AnalysisException("Column '" + column.getName()
+                        + "' has no default value and does not allow NULL or column is auto-increment");
+            }
+        }
+
+        Expression defaultValueExpr = new NereidsParser().parseExpression(defaultValueSql);
+        if (defaultValueExpr instanceof UnboundFunction) {
+            CascadesContext cascadesContext = context.cascadesContext;
+            LogicalPlan plan = (LogicalPlan) context.rewriteContext.plan.orElse(null);
+            defaultValueExpr = ExpressionAnalyzer.analyzeFunction(plan, cascadesContext, defaultValueExpr);
+        }
+
+        return TypeCoercionUtils.castIfNotSameType(defaultValueExpr, targetType);
+    }
+}
@@ -0,0 +1,76 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.apache.doris.nereids.trees.expressions;
+
+import org.apache.doris.nereids.exceptions.AnalysisException;
+import org.apache.doris.nereids.trees.expressions.functions.AlwaysNullable;
+import org.apache.doris.nereids.trees.expressions.shape.UnaryExpression;
+import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
+import org.apache.doris.nereids.types.DataType;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+
+import java.util.List;
+
+/**
+ * Default value expression.
+ */
+public class Default extends Expression
+        implements UnaryExpression, AlwaysNullable {
+
+    public Default(Expression child) {
+        super(ImmutableList.of(child));
+    }
+
+    /**
+     * constructor with 1 argument.
+     */
+    public Default(Expression arg, DataType targetType) {
+        super(ImmutableList.of(arg));
+    }
+
+    @Override
+    public Default withChildren(List<Expression> children) {
+        Preconditions.checkArgument(children.size() == 1);
+        return new Default(children.get(0));
+    }
+
+    @Override
+    public DataType getDataType() {
+        return child().getDataType();
+    }
+
+    @Override
+    public void checkLegalityBeforeTypeCoercion() {
+        Expression arg = child();
+        if (!(arg instanceof SlotReference)) {
+            throw new AnalysisException("DEFAULT requires a column reference");
+        }
+    }
+
+    @Override
+    public void checkLegalityAfterRewrite() {
+        checkLegalityBeforeTypeCoercion();
+    }
+
+    @Override
+    public <R, C> R accept(ExpressionVisitor<R, C> visitor, C context) {
+        return visitor.visitDefault(this, context);
+    }
+}
@@ -40,6 +40,7 @@
 import org.apache.doris.nereids.trees.expressions.Cast;
 import org.apache.doris.nereids.trees.expressions.ComparisonPredicate;
 import org.apache.doris.nereids.trees.expressions.CompoundPredicate;
+import org.apache.doris.nereids.trees.expressions.Default;
 import org.apache.doris.nereids.trees.expressions.DefaultValueSlot;
 import org.apache.doris.nereids.trees.expressions.DereferenceExpression;
 import org.apache.doris.nereids.trees.expressions.Divide;
@@ -239,6 +240,10 @@ public R visitSlotReference(SlotReference slotReference, C context) {
         return visitSlot(slotReference, context);
     }
 
+    public R visitDefault(Default defaultExpr, C context) {
+        return visit(defaultExpr, context);
+    }
+
     public R visitDefaultValue(DefaultValueSlot defaultValueSlot, C context) {
         return visitSlot(defaultValueSlot, context);
     }

@@ -0,0 +1,32 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !scalar_defaults --
+true	7	32000	2147483647	9223372036854775807	170141183460469231731687303715884105727	3.125	2.718281828	123456789.123456789	99999.1234	charDemo		plain string	2025-10-25 11:22:33.666777+08:00	2025-10-25T11:22:33	2025-10-31	\N	192.168.1.1	2001:db8::1	[]	\N	\N	\N	\N
+
+-- !null_column_default --
+\N
+
+-- !boundary_defaults --
+-128	127	-32768	32767	-2147483648	2147483647	-9223372036854775808	9223372036854775807	0.0	0	0.00		\N
+
+-- !complex_defaults --
+[]	\N	\N	\N	\N	\N
+
+-- !datetime_format_defaults --
+2025-01-01	2025-01-01T12:30:45
+
+-- !ip_defaults --
+127.0.0.1	10.0.0.1	::1	2001:db8:85a3::8a2e:370:7334
+
+-- !string_defaults --
+fixed	variable length string	very long string that can be much longer than varchar		
+
+-- !pi_e_defaults --
+3.141592653589793	2.718281828459045
+
+-- !empty_table_defaults --
+
+-- !same_col_name --
+hello	2026-01-13	3.141592653589793	2023-12-31T23:59:59
+hello	2026-01-13	3.141592653589793	2023-12-31T23:59:59
+hello	2026-01-13	3.141592653589793	2023-12-31T23:59:59
+