Merge pull request #659 from pkures/master

fixing incorrect index reuse in AlterTableAddConstraint.java

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

@@ -212,7 +212,7 @@ public class AlterTableAddConstraint extends SchemaCommand {
                 isOwner = true;
                 index.getIndexType().setBelongsToConstraint(true);
             } else {
-                index = getIndex(table, indexColumns, true);
+                index = getIndex(table, indexColumns, false);
                 if (index == null) {
                     index = createIndex(table, indexColumns, false);
                     isOwner = true;
@@ -329,29 +329,30 @@ public class AlterTableAddConstraint extends SchemaCommand {
         }
         return null;
     }
+    
 
+    // all cols must be in the index key, the order doesn't matter and there must be no other fields in the index key
     private static boolean canUseUniqueIndex(Index idx, Table table,
-            IndexColumn[] cols) {
+        IndexColumn[] cols) {
         if (idx.getTable() != table || !idx.getIndexType().isUnique()) {
             return false;
         }
         Column[] indexCols = idx.getColumns();
-        if (indexCols.length > cols.length) {
-            return false;
+
+        HashSet<Column> indexColsSet = New.hashSet();
+
+        for (Column c : indexCols) {
+            indexColsSet.add(c);
         }
-        HashSet<Column> set = New.hashSet();
+
+        HashSet<Column> colsSet = New.hashSet();
+
         for (IndexColumn c : cols) {
-            set.add(c.column);
+            colsSet.add(c.column);
         }
-        for (Column c : indexCols) {
-            // all columns of the index must be part of the list,
-            // but not all columns of the list need to be part of the index
-            if (!set.contains(c)) {
-                return false;
-            }
-        }
-        return true;
-    }
+    
+      return colsSet.equals(indexColsSet);
+    }        
 
     private static boolean canUseIndex(Index existingIndex, Table table,
             IndexColumn[] cols, boolean moreColumnsOk) {

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

@@ -150,18 +150,6 @@ public class TestCases extends TestBase {
                 "foreign key(a_id) references a(id)");
         stat.execute("update a set x=200");
         stat.execute("drop table if exists a, b");
-
-        stat.execute("drop all objects");
-        stat.execute("create table parent(id int primary key)");
-        stat.execute("create table child(id int, parent_id int, x int)");
-        stat.execute("create index y on child(parent_id, x)");
-        stat.execute("alter table child add constraint z " +
-                "foreign key(parent_id) references parent(id)");
-        ResultSet rs = stat.executeQuery(
-                "select * from information_schema.indexes where table_name = 'CHILD'");
-        while (rs.next()) {
-            assertEquals("Y", rs.getString("index_name"));
-        }
         conn.close();
     }
 

h2/src/test/org/h2/test/scripts/TestScript.java

@@ -77,7 +77,9 @@ public class TestScript extends TestBase {
             return;
         }
         reconnectOften = !config.memory && config.big;
+        
         testScript("testScript.sql");
+        testScript("altertable-index-reuse.sql");
         testScript("query-optimisations.sql");
         testScript("commands-dml-script.sql");
         testScript("commands-dml-create-view.sql");

h2/src/test/org/h2/test/scripts/altertable-index-reuse.sql

+-- Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
+-- and the EPL 1.0 (http://h2database.com/html/license.html).
+-- Initial Developer: H2 Group
+--
+
+CREATE TABLE "domains" ("id" bigint NOT NULL auto_increment PRIMARY KEY);
+> ok
+
+CREATE TABLE "users" ("id" bigint NOT NULL auto_increment PRIMARY KEY,"username" varchar_ignorecase(255),"domain" bigint,"desc" varchar_ignorecase(255));
+> ok
+
+-- adds constraint on (domain,username) and generates unique index domainusername_key_INDEX_xxx
+ALTER TABLE "users" ADD CONSTRAINT "domainusername_key" UNIQUE ("domain","username");
+> ok
+
+-- adds foreign key on domain - if domainusername_key didn't exist it would create unique index on domain, but it reuses the existing index  
+ALTER TABLE "users"  ADD CONSTRAINT "udomain_fkey" FOREIGN KEY ("domain") REFERENCES "domains"("id") ON DELETE RESTRICT;
+> ok
+
+-- now we drop the domainusername_key, but domainusername_key_INDEX_xxx is used by udomain_fkey and was not being dropped 
+-- this was an issue, because it's a unique index and still enforcing constraint on (domain,username)
+ALTER TABLE "users" DROP CONSTRAINT "domainusername_key";
+> ok
+
+insert into "domains" ("id") VALUES (1);
+> update count: 1
+
+insert into "users" ("username","domain","desc") VALUES ('test',1,'first user');
+> update count: 1
+
+-- should work,because we dropped domainusername_key, but failed: Unique index or primary key violation
+INSERT INTO "users" ("username","domain","desc") VALUES ('test',1,'second user'); 
+> update count: 1