Remove restriction for presense of columns in ON clause of MERGE USING

h2/src/docsrc/html/changelog.html

@@ -23,6 +23,8 @@ Change Log
 <ul>
 <li>Issue #1493: MERGE statement fails when it updates more than one row
 </li>
+<li>Issue #1492: Unnecessary restriction on MERGE USING statement when ON clause doesn't reference any target table columns
+</li>
 <li>Issue #1491: Unnecessary restriction on MERGE USING statement when ON predicate doesn't match inserted row
 </li>
 <li>Issue #1490: NullPointerException when running invalid MERGE statement

h2/src/main/org/h2/command/dml/MergeUsing.java

@@ -7,7 +7,6 @@ package org.h2.command.dml;
 
 import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.HashSet;
 
 import org.h2.api.ErrorCode;
 import org.h2.api.Trigger;
@@ -18,7 +17,6 @@ import org.h2.engine.Session;
 import org.h2.expression.ConditionAndOr;
 import org.h2.expression.Expression;
 import org.h2.expression.ExpressionColumn;
-import org.h2.expression.ExpressionVisitor;
 import org.h2.message.DbException;
 import org.h2.result.ResultInterface;
 import org.h2.result.Row;
@@ -102,7 +100,6 @@ public class MergeUsing extends Prepared {
     private Table targetTable;
     private TableFilter targetTableFilter;
     private Column[] columns;
-    private Column[] keys;
     private final ArrayList<Expression[]> valuesExpressionList = Utils.newSmallArrayList();
     private Query query;
 
@@ -253,17 +250,7 @@ public class MergeUsing extends Prepared {
             buff.appendExceptFirst(", ");
             buff.append(c.getSQL());
         }
-        buff.append(')');
-        if (keys != null) {
-            buff.append(" KEY(");
-            buff.resetCount();
-            for (Column c : keys) {
-                buff.appendExceptFirst(", ");
-                buff.append(c.getSQL());
-            }
-            buff.append(')');
-        }
-        buff.append('\n');
+        buff.append(')').append('\n');
         if (!valuesExpressionList.isEmpty()) {
             buff.append("VALUES ");
             int row = 0;
@@ -297,15 +284,6 @@ public class MergeUsing extends Prepared {
         onCondition.mapColumns(sourceTableFilter, 2, Expression.MAP_INITIAL);
         onCondition.mapColumns(targetTableFilter, 1, Expression.MAP_INITIAL);
 
-        if (keys == null) {
-            keys = buildColumnListFromOnCondition(targetTableFilter.getTable());
-        }
-        if (keys.length == 0) {
-            throw DbException.get(ErrorCode.COLUMN_NOT_FOUND_1,
-                    "No references to target columns found in ON clause:"
-                            + targetTableFilter.toString());
-        }
-
         // only do the optimize now - before we have already gathered the
         // unoptimized column data
         onCondition = onCondition.optimize(session);
@@ -367,13 +345,6 @@ public class MergeUsing extends Prepared {
         targetMatchQuery.prepare();
     }
 
-    private Column[] buildColumnListFromOnCondition(Table table) {
-        HashSet<Column> columns = new HashSet<>();
-        ExpressionVisitor visitor = ExpressionVisitor.getColumnsVisitor(columns, table);
-        onCondition.isEverything(visitor);
-        return columns.toArray(new Column[0]);
-    }
-
     private Expression appendOnCondition(Update updateCommand) {
         if (updateCommand.getCondition() == null) {
             return onCondition;

h2/src/test/org/h2/test/db/TestMergeUsing.java

@@ -196,18 +196,6 @@ public class TestMergeUsing extends TestDb implements Trigger {
                 "SELECT 1 AS ID, 'Marcy'||X||X UNION ALL SELECT 1 AS ID, 'Marcy2'",
                 2);
 
-        // Missing target columns in ON expression
-        testMergeUsingException(
-                "CREATE TABLE PARENT AS (SELECT 1 AS ID, 'Marcy'||X AS NAME FROM SYSTEM_RANGE(1,3) );"
-                        + "CREATE TABLE SOURCE AS (SELECT X AS ID, 'Marcy'||X AS NAME FROM SYSTEM_RANGE(1,3)  );",
-                "MERGE INTO PARENT USING SOURCE ON (1 = SOURCE.ID) WHEN MATCHED THEN " +
-                "UPDATE SET PARENT.NAME = SOURCE.NAME||SOURCE.ID WHERE PARENT.ID = 2 " +
-                "DELETE WHERE PARENT.ID = 1 WHEN NOT MATCHED THEN " +
-                "INSERT (ID, NAME) VALUES (SOURCE.ID, SOURCE.NAME)",
-                GATHER_ORDERED_RESULTS_SQL,
-                "SELECT X AS ID, 'Marcy'||X||X AS NAME FROM SYSTEM_RANGE(2,2) UNION ALL " +
-                "SELECT X AS ID, 'Marcy'||X AS NAME FROM SYSTEM_RANGE(3,3)",
-                3, "No references to target columns found in ON clause");
         // One insert, one update one delete happens, target table missing PK,
         // triggers update all NAME fields
         triggerTestingUpdateCount = 0;

h2/src/test/org/h2/test/scripts/dml/mergeUsing.sql

@@ -29,7 +29,7 @@ EXPLAIN PLAN
             UPDATE SET P.NAME = S.NAME WHERE 2 = 2 WHEN NOT
         MATCHED THEN
             INSERT (ID, NAME) VALUES (S.ID, S.NAME);
->> MERGE INTO PUBLIC.PARENT(ID, NAME) KEY(ID) SELECT X AS ID, ('Coco' || X) AS NAME FROM SYSTEM_RANGE(1, 2) /* PUBLIC.RANGE_INDEX */
+>> MERGE INTO PUBLIC.PARENT(ID, NAME) SELECT X AS ID, ('Coco' || X) AS NAME FROM SYSTEM_RANGE(1, 2) /* PUBLIC.RANGE_INDEX */
 
 DROP TABLE PARENT;
 > ok
@@ -246,5 +246,18 @@ SELECT * FROM TEST;
 > 3  40
 > rows: 3
 
+MERGE INTO TEST USING (SELECT 1) ON (1 = 1)
+    WHEN MATCHED THEN UPDATE SET VALUE = 50
+    WHEN NOT MATCHED THEN INSERT VALUES (5, 50);
+> update count: 3
+
+SELECT * FROM TEST;
+> ID VALUE
+> -- -----
+> 1  50
+> 2  50
+> 3  50
+> rows: 3
+
 DROP TABLE TEST;
 > ok