Terminate sortkey with prejudice

It has not been used by the search system since 2.8 and all code using
it in a meaningful way in Gerrit has been removed. Now we can remove
it from the database and API classes.

This requires a schema upgrade to delete the column and rebuild some
indexes to use last_updated_on instead of sort_key.

Change-Id: I87660f8e0e44bf11bafd9fa24f990351759df3fb

gerrit-server/src/main/java/com/google/gerrit/server/schema/SchemaVersion.java

@@ -32,7 +32,7 @@ import java.util.List;
 /** A version of the database schema. */
 public abstract class SchemaVersion {
   /** The current schema version. */
-  public static final Class<Schema_101> C = Schema_101.class;
+  public static final Class<Schema_102> C = Schema_102.class;
 
   public static class Module extends AbstractModule {
     @Override

gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_102.java

@@ -0,0 +1,51 @@
+// Copyright (C) 2014 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.schema;
+
+import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gwtorm.jdbc.JdbcSchema;
+import com.google.gwtorm.schema.sql.DialectPostgreSQL;
+import com.google.gwtorm.schema.sql.SqlDialect;
+import com.google.gwtorm.server.OrmException;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+
+import java.sql.SQLException;
+import java.sql.Statement;
+
+public class Schema_102 extends SchemaVersion {
+  @Inject
+  Schema_102(Provider<Schema_100> prior) {
+    super(prior);
+  }
+
+  @Override
+  protected void migrateData(ReviewDb db, UpdateUI ui)
+      throws OrmException, SQLException {
+    JdbcSchema schema = (JdbcSchema) db;
+    SqlDialect dialect = schema.getDialect();
+    try (Statement stmt = schema.getConnection().createStatement()) {
+      stmt.executeUpdate("DROP INDEX changes_byProjectOpen");
+      if (dialect instanceof DialectPostgreSQL) {
+        stmt.executeUpdate("CREATE INDEX changes_byProjectOpen"
+            + " ON changes (dest_project_name, last_updated_on)"
+            + " WHERE open = 'Y'");
+      } else {
+        stmt.executeUpdate("CREATE INDEX changes_byProjectOpen"
+            + " ON changes (open, dest_project_name, last_updated_on)");
+      }
+    }
+  }
+}