Fix for a bug where we would sometimes use the wrong unique constraint to…

Fix for a bug where we would sometimes use the wrong unique constraint to validate foreign key constraints.

h2/src/docsrc/html/changelog.html

@@ -20,6 +20,7 @@ Change Log
 <h2>Next Version (unreleased)</h2>
 <ul><li>PostgreSQL compatibility: support for EXTRACT(WEEK FROM dateColumn).
     Thanks to Prashant Bhat for the patch!
+<ul><li>Fix for a bug where we would sometimes use the wrong unique constraint to validate foreign key constraints.
 </li></ul>
 
 <h2>Version 1.3.169 (2012-09-09)</h2>

h2/src/main/org/h2/command/ddl/AlterTableAddConstraint.java

@@ -207,7 +207,7 @@ public class AlterTableAddConstraint extends SchemaCommand {
                 refIndex = null;
             }
             if (refIndex == null) {
-                refIndex = getUniqueIndex(refTable, refIndexColumns);
+                refIndex = getIndex(refTable, refIndexColumns);
                 if (refIndex == null) {
                     refIndex = createIndex(refTable, refIndexColumns, true);
                     isRefOwner = true;

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

@@ -47,6 +47,7 @@ public class TestTriggersConstraints extends TestBase implements Trigger {
         testTriggerAlterTable();
         testTriggers();
         testConstraints();
+        testMultiPartForeignKeys();
         deleteDb("trigger");
     }
 
@@ -366,6 +367,37 @@ public class TestTriggersConstraints extends TestBase implements Trigger {
         conn.close();
     }
 
+    /**
+     * Regression test: we had a bug where the AlterTableAddConstraint class used to sometimes pick the wrong
+     * unique index for a foreign key.
+     */
+    private void testMultiPartForeignKeys() throws SQLException {
+        Connection conn = getConnection("trigger");
+        Statement stat = conn.createStatement();
+        stat.execute("DROP TABLE IF EXISTS TEST1");
+        stat.execute("DROP TABLE IF EXISTS TEST2");
+        
+        stat.execute("create table test1(id int primary key, col1 int)");
+        stat.execute("alter table test1 add constraint unq_test1 " +
+                "unique (id,col1)");
+        
+        stat.execute("create table test2(id int primary key, col1 int)");
+        stat.execute("alter table test2 add constraint fk_test2 " +
+                "foreign key(id,col1) references test1 (id,col1)");
+        
+        stat.execute("insert into test1 values (1,1)");
+        stat.execute("insert into test1 values (2,2)");
+        stat.execute("insert into test1 values (3,3)");
+        stat.execute("insert into test2 values (1,1)");
+        assertThrows(23506, stat).execute("insert into test2 values (2,1)");
+        assertSingleValue(stat, "select count(*) from test1", 3);
+        assertSingleValue(stat, "select count(*) from test2", 1);
+        
+        stat.execute("drop table test1");
+        stat.execute("drop table test2");
+        conn.close();
+    }
+    
     private void testTriggers() throws SQLException {
         mustNotCallTrigger = false;
         Connection conn = getConnection("trigger");