[fix](fe) Merge one row union outputs by slots

fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/MergeOneRowRelationIntoUnion.java

@@ -19,19 +19,20 @@
 
 import org.apache.doris.nereids.rules.Rule;
 import org.apache.doris.nereids.rules.RuleType;
+import org.apache.doris.nereids.trees.expressions.Expression;
 import org.apache.doris.nereids.trees.expressions.NamedExpression;
 import org.apache.doris.nereids.trees.expressions.SlotReference;
 import org.apache.doris.nereids.trees.plans.Plan;
 import org.apache.doris.nereids.trees.plans.logical.LogicalOneRowRelation;
-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.collect.ImmutableList;
 import com.google.common.collect.ImmutableList.Builder;
 import com.google.common.collect.Lists;
 
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 /**
  * merge one row relation into union, for easy to compute physical properties
@@ -56,15 +57,13 @@ public Rule build() {
                         } else {
                             ImmutableList.Builder<NamedExpression> constantExprs = new Builder<>();
                             List<NamedExpression> projects = ((LogicalOneRowRelation) child).getProjects();
-                            for (int j = 0; j < projects.size(); j++) {
-                                NamedExpression project = projects.get(j);
-                                DataType targetType = u.getOutput().get(j).getDataType();
-                                if (project.getDataType().equals(targetType)) {
-                                    constantExprs.add(project);
-                                } else {
-                                    constantExprs.add((NamedExpression) project.withChildren(
-                                            TypeCoercionUtils.castIfNotSameType(project.child(0), targetType)));
-                                }
+                            Map<Expression, Expression> replaceMap = new HashMap<>();
+                            for (NamedExpression expr : projects) {
+                                replaceMap.put(expr.toSlot(), expr);
+                            }
+                            for (Expression regularChildOutput : u.getRegularChildOutput(i)) {
+                                constantExprs.add((NamedExpression) ExpressionUtils.replace(
+                                        regularChildOutput, replaceMap));
                             }
                             constantExprsList.add(constantExprs.build());
                         }

fe/fe-core/src/test/java/org/apache/doris/nereids/rules/rewrite/MergeOneRowRelationIntoUnionTest.java

@@ -0,0 +1,74 @@
+// 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.rewrite;
+
+import org.apache.doris.nereids.trees.expressions.Alias;
+import org.apache.doris.nereids.trees.expressions.ExprId;
+import org.apache.doris.nereids.trees.expressions.NamedExpression;
+import org.apache.doris.nereids.trees.expressions.SlotReference;
+import org.apache.doris.nereids.trees.expressions.literal.IntegerLiteral;
+import org.apache.doris.nereids.trees.plans.Plan;
+import org.apache.doris.nereids.trees.plans.RelationId;
+import org.apache.doris.nereids.trees.plans.algebra.SetOperation.Qualifier;
+import org.apache.doris.nereids.trees.plans.logical.LogicalOneRowRelation;
+import org.apache.doris.nereids.trees.plans.logical.LogicalUnion;
+import org.apache.doris.nereids.types.IntegerType;
+import org.apache.doris.nereids.util.MemoTestUtils;
+import org.apache.doris.nereids.util.PlanChecker;
+
+import com.google.common.collect.ImmutableList;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+public class MergeOneRowRelationIntoUnionTest {
+
+    @Test
+    public void testMergeUsesRegularChildOutputToBuildConstantExprs() {
+        Alias firstProject = new Alias(new ExprId(1), new IntegerLiteral(10), "first_col");
+        Alias secondProject = new Alias(new ExprId(2), new IntegerLiteral(20), "second_col");
+        SlotReference secondProjectSlot = (SlotReference) secondProject.toSlot();
+        LogicalOneRowRelation oneRowRelation = new LogicalOneRowRelation(
+                new RelationId(1), ImmutableList.of(firstProject, secondProject));
+
+        SlotReference unionOutput = new SlotReference(new ExprId(10), "second_col",
+                IntegerType.INSTANCE, false, ImmutableList.of());
+        LogicalUnion union = new LogicalUnion(Qualifier.ALL,
+                ImmutableList.of(unionOutput),
+                ImmutableList.of(ImmutableList.of(secondProjectSlot)),
+                ImmutableList.of(),
+                false,
+                ImmutableList.of(oneRowRelation));
+
+        Plan rewritten = PlanChecker.from(MemoTestUtils.createConnectContext(), union)
+                .applyTopDown(new MergeOneRowRelationIntoUnion())
+                .getPlan();
+
+        Assertions.assertInstanceOf(LogicalUnion.class, rewritten);
+        LogicalUnion rewrittenUnion = (LogicalUnion) rewritten;
+        Assertions.assertEquals(0, rewrittenUnion.children().size());
+        Assertions.assertEquals(1, rewrittenUnion.getConstantExprsList().size());
+
+        List<NamedExpression> constantExprs = rewrittenUnion.getConstantExprsList().get(0);
+        Assertions.assertEquals(1, constantExprs.size());
+        Assertions.assertEquals(secondProject.getExprId(), constantExprs.get(0).getExprId());
+        Assertions.assertInstanceOf(IntegerLiteral.class, constantExprs.get(0).child(0));
+        Assertions.assertEquals(20, ((IntegerLiteral) constantExprs.get(0).child(0)).getValue());
+    }
+}

regression-test/data/query_p0/compress_materialize/compress_materialize.out

@@ -53,21 +53,11 @@ a	1
 中	8
 bb	3
 
--- !explain_sort_agg --
-cost = 19.563333333333333
-PhysicalResultSink[294] ( outputExprs=[v1#1] )
-+--PhysicalProject[289]@5 ( stats=1, projects=[v1#1] )
-   +--PhysicalQuickSort[284]@4 ( stats=1, orderKeys=[encode_as_bigint(v1)#4 asc null first], phase=MERGE_SORT )
-      +--PhysicalDistribute[279]@7 ( stats=1, distributionSpec=DistributionSpecGather )
-         +--PhysicalQuickSort[274]@7 ( stats=1, orderKeys=[encode_as_bigint(v1)#4 asc null first], phase=LOCAL_SORT )
-            +--PhysicalProject[269]@3 ( stats=1, projects=[decode_as_varchar(encode_as_bigint(v1)#3) AS `v1`#1, encode_as_bigint(decode_as_varchar(encode_as_bigint(v1)#3)) AS `encode_as_bigint(decode_as_varchar(encode_as_bigint(v1)))`#4], multi_proj=l0([encode_as_bigint(v1)#3, decode_as_varchar(encode_as_bigint(v1)#3) AS `decode_as_varchar(encode_as_bigint(v1))`#5])l1([decode_as_varchar(encode_as_bigint(v1))#5 AS `v1`#1, encode_as_bigint(decode_as_varchar(encode_as_bigint(v1))#5) AS `encode_as_bigint(decode_as_varchar(encode_as_bigint(v1)))`#4]) )
-               +--PhysicalHashAggregate[264]@2 ( stats=1, aggPhase=GLOBAL, aggMode=BUFFER_TO_RESULT, maybeUseStreaming=false, groupByExpr=[encode_as_bigint(v1)#3], outputExpr=[encode_as_bigint(v1)#3], partitionExpr=Optional[[encode_as_bigint(v1)#3]], topnFilter=false, topnPushDown=false )
-                  +--PhysicalDistribute[259]@8 ( stats=1, distributionSpec=DistributionSpecHash ( orderedShuffledColumns=[3], shuffleType=EXECUTION_BUCKETED, tableId=-1, selectedIndexId=-1, partitionIds=[], equivalenceExprIds=[[3]], exprIdToEquivalenceSet={3=0} ) )
-                     +--PhysicalHashAggregate[254]@8 ( stats=1, aggPhase=LOCAL, aggMode=INPUT_TO_BUFFER, maybeUseStreaming=true, groupByExpr=[encode_as_bigint(v1)#3], outputExpr=[encode_as_bigint(v1)#3], partitionExpr=Optional[[encode_as_bigint(v1)#3]], topnFilter=false, topnPushDown=false )
-                        +--PhysicalProject[249]@1 ( stats=1, projects=[encode_as_bigint(v1#1) AS `encode_as_bigint(v1)`#3] )
-                           +--PhysicalOlapScan[t1]@0 ( stats=1 )
+-- !const_union_group_by --
+alpha	1
+beta	1
 
--- !exec_sort_agg --
-a
-b
+-- !const_union_project_order --
+alpha
+beta
 

regression-test/suites/query_p0/compress_materialize/compress_materialize.groovy

@@ -194,5 +194,26 @@ suite("compress_materialize") {
     qt_sort "select * from compressSort order by k desc, v";
     qt_sort "select * from compressSort order by k desc nulls last";
     qt_sort "select * from compressSort order by k desc nulls last, v limit 3";
-}
 
+    order_qt_const_union_group_by """
+        SELECT /*+ SET_VAR(enable_compress_materialize=true) */
+               v,
+               COUNT(*) AS c
+        FROM (
+            SELECT CAST('alpha' AS CHAR(6)) AS v
+            UNION ALL
+            SELECT CAST('beta' AS CHAR(6))
+        ) u
+        GROUP BY v
+    """
+
+    order_qt_const_union_project_order """
+        SELECT v
+        FROM (
+            SELECT CAST('unused' AS CHAR(6)) AS k, CAST('alpha' AS CHAR(6)) AS v
+            UNION ALL
+            SELECT CAST('unused' AS CHAR(6)), CAST('beta' AS CHAR(6))
+        ) u
+        GROUP BY v
+    """
+}