Fix channel mapping in createColumnValueAndRowIdChannels

Previously, createColumnValueAndRowIdChannels() iterated over all
variableReferenceExpressions and attempted to locate them in
columnValueAndRowIdSymbols, relying on the output order and performing
an incorrect size check.

This commit fixes the logic by iterating directly over
columnValueAndRowIdSymbols and verifying each one’s position in
variableReferenceExpressions. This removes the incorrect ordering
assumption and ensures accurate channel mapping when multiple
identical values or updates are involved.

Author: imjalpreet

presto-iceberg/src/test/java/com/facebook/presto/iceberg/IcebergDistributedTestBase.java

@@ -2439,6 +2439,18 @@ public void testInformationSchemaQueries()
         assertQuerySucceeds("DROP SCHEMA ICEBERG.TEST_SCHEMA2");
     }
 
+    @Test
+    public void testUpdateWithDuplicateValues()
+    {
+        String tableName = "test_update_duplicate_values_" + randomTableSuffix();
+        assertUpdate("CREATE TABLE " + tableName + "(id int, column1 varchar(10), column2 varchar(10), column3 int)");
+        assertUpdate("INSERT INTO " + tableName + " VALUES (1, 'a', 'a', 1), (2, 'b', 'b', 1), (3, 'c', 'c', 1)", 3);
+
+        // update single row with duplicate values
+        assertUpdate("UPDATE " + tableName + " SET column1 = CAST(1 as varchar), column2 = CAST(1 as varchar), column3 = 11 WHERE id = 1", 1);
+        assertQuery("SELECT id, column1, column2, column3 FROM " + tableName, "VALUES (1, '1', '1', 11), (2, 'b', 'b', 1), (3, 'c', 'c', 1)");
+    }
+
     @Test
     public void testUpdateWithPredicates()
     {

presto-main-base/src/main/java/com/facebook/presto/sql/planner/LocalExecutionPlanner.java

@@ -3008,16 +3008,15 @@ private List<Integer> createColumnValueAndRowIdChannels(List<VariableReferenceEx
         {
             Integer[] columnValueAndRowIdChannels = new Integer[columnValueAndRowIdSymbols.size()];
             int symbolCounter = 0;
-            // This depends on the outputSymbols being ordered as the blocks of the
-            // resulting page are ordered.
-            for (VariableReferenceExpression variableReferenceExpression : variableReferenceExpressions) {
-                int index = columnValueAndRowIdSymbols.indexOf(variableReferenceExpression);
-                if (index >= 0) {
-                    columnValueAndRowIdChannels[index] = symbolCounter;
-                }
+            for (VariableReferenceExpression columnValueAndRowIdSymbol : columnValueAndRowIdSymbols) {
+                int index = variableReferenceExpressions.indexOf(columnValueAndRowIdSymbol);
+
+                verify(index >= 0, "Could not find columnValueAndRowIdSymbol %s in the variableReferenceExpressions %s", columnValueAndRowIdSymbol, variableReferenceExpressions);
+                columnValueAndRowIdChannels[symbolCounter] = index;
+
                 symbolCounter++;
             }
-            checkArgument(symbolCounter == columnValueAndRowIdSymbols.size(), "symbolCounter %s should be columnValueAndRowIdChannels.size() %s", symbolCounter);
+
             return Arrays.asList(columnValueAndRowIdChannels);
         }