Remove only one target row match restriction from MERGE USING

h2/src/docsrc/html/changelog.html

@@ -21,6 +21,8 @@ Change Log
 
 <h2>Next Version (unreleased)</h2>
 <ul>
+<li>Issue #1493: MERGE statement fails when it updates more than one row
+</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

@@ -219,45 +219,29 @@ public class MergeUsing extends Prepared {
     }
 
     private boolean isTargetRowFound() {
+        boolean matched = false;
         try (ResultInterface rows = targetMatchQuery.query(0)) {
-            if (!rows.next()) {
-                return false;
-            }
-            Value targetRowId = rows.currentRow()[0];
-            Integer number = targetRowidsRemembered.get(targetRowId);
-            // throw and exception if we have processed this _ROWID_ before...
-            if (number != null) {
-                throw DbException.get(ErrorCode.DUPLICATE_KEY_1,
-                        "Merge using ON column expression, " +
-                        "duplicate _ROWID_ target record already updated, deleted or inserted:_ROWID_="
-                                + targetRowId + ":in:"
-                                + targetTableFilter.getTable()
-                                + ":conflicting source row number:"
-                                + number);
-            }
-            // remember the source column values we have used before (they
-            // are the effective ON clause keys
-            // and should not be repeated
-            targetRowidsRemembered.put(targetRowId, sourceQueryRowNumber);
-            if (rows.next()) {
-                int rowCount;
-                if (rows.isLazy()) {
-                    for (rowCount = 2; rows.next(); rowCount++) {
-                    }
-                } else {
-                    rowCount = rows.getRowCount();
+            while (rows.next()) {
+                Value targetRowId = rows.currentRow()[0];
+                Integer number = targetRowidsRemembered.get(targetRowId);
+                // throw and exception if we have processed this _ROWID_ before...
+                if (number != null) {
+                    throw DbException.get(ErrorCode.DUPLICATE_KEY_1,
+                            "Merge using ON column expression, " +
+                            "duplicate _ROWID_ target record already updated, deleted or inserted:_ROWID_="
+                                    + targetRowId + ":in:"
+                                    + targetTableFilter.getTable()
+                                    + ":conflicting source row number:"
+                                    + number);
                 }
-                throw DbException.get(ErrorCode.DUPLICATE_KEY_1,
-                        "Duplicate key updated "
-                                + rowCount
-                                + " rows at once, only 1 expected:_ROWID_="
-                                + targetRowId + ":in:"
-                                + targetTableFilter.getTable()
-                                + ":conflicting source row number:"
-                                + targetRowidsRemembered.get(targetRowId));
+                // remember the source column values we have used before (they
+                // are the effective ON clause keys
+                // and should not be repeated
+                targetRowidsRemembered.put(targetRowId, sourceQueryRowNumber);
+                matched = true;
             }
-            return true;
         }
+        return matched;
     }
 
     // Use the regular merge syntax as our plan SQL

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);
 
-        // Duplicate key updated 3 rows at once, only 1 expected
-        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 (PARENT.ID = 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, "Duplicate key updated 3 rows at once, only 1 expected");
         // Missing target columns in ON expression
         testMergeUsingException(
                 "CREATE TABLE PARENT AS (SELECT 1 AS ID, 'Marcy'||X AS NAME FROM SYSTEM_RANGE(1,3) );"
@@ -220,18 +208,6 @@ public class TestMergeUsing extends TestDb implements Trigger {
                 "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");
-        // Missing source 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 (PARENT.ID = 1) 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, "Duplicate key updated 3 rows at once, only 1 expected");
         // 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

@@ -233,5 +233,18 @@ SELECT * FROM TEST;
 > 3  30
 > rows: 3
 
+MERGE INTO TEST USING (SELECT 1) ON (ID = ID)
+    WHEN MATCHED THEN UPDATE SET VALUE = 40
+    WHEN NOT MATCHED THEN INSERT VALUES (4, 40);
+> update count: 3
+
+SELECT * FROM TEST;
+> ID VALUE
+> -- -----
+> 1  40
+> 2  40
+> 3  40
+> rows: 3
+
 DROP TABLE TEST;
 > ok