Start factoring out PatchSet accesses into a PatchSetUtil class

Replaces the simplest get calls in most callers that didn't require
substantial refactoring. Doesn't actually read notedb yet because
there is no notedb support for patch sets yet.

Change-Id: I7ef198dd1257b833a3a4b21180f5012f6fdc56d4

gerrit-acceptance-framework/src/test/java/com/google/gerrit/acceptance/AbstractDaemonTest.java

@@ -40,6 +40,7 @@ import com.google.gerrit.extensions.common.ChangeInfo;
 import com.google.gerrit.extensions.common.EditInfo;
 import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.reviewdb.client.AccountGroup;
+import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.AnonymousUser;
@@ -58,10 +59,12 @@ import com.google.gerrit.server.index.ChangeIndexer;
 import com.google.gerrit.server.notedb.NotesMigration;
 import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.project.Util;
+import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gerrit.server.query.change.InternalChangeQuery;
 import com.google.gerrit.testutil.ConfigSuite;
 import com.google.gerrit.testutil.TempFileUtil;
 import com.google.gson.Gson;
+import com.google.gwtorm.server.OrmException;
 import com.google.gwtorm.server.SchemaFactory;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
@@ -164,6 +167,9 @@ public abstract class AbstractDaemonTest {
   @GerritPersonIdent
   protected Provider<PersonIdent> serverIdent;
 
+  @Inject
+  protected ChangeData.Factory changeDataFactory;
+
   protected TestRepository<InMemoryRepository> testRepo;
   protected GerritServer server;
   protected TestAccount admin;
@@ -624,4 +630,8 @@ public abstract class AbstractDaemonTest {
       }
     })).containsExactly((Object[])expected).inOrder();
   }
+
+  protected PatchSet getPatchSet(PatchSet.Id psId) throws OrmException {
+    return changeDataFactory.create(db, psId.getParentKey()).patchSet(psId);
+  }
 }

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git/SubmitOnPushIT.java

@@ -27,6 +27,7 @@ import com.google.gerrit.reviewdb.client.PatchSetApproval;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.ApprovalsUtil;
 import com.google.gerrit.server.notedb.ChangeNotes;
+import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 
@@ -145,9 +146,9 @@ public class SubmitOnPushIT extends AbstractDaemonTest {
         "other content", r.getChangeId());
     r.assertOkStatus();
     r.assertChange(Change.Status.MERGED, null, admin);
-    Change c = Iterables.getOnlyElement(
+    ChangeData cd = Iterables.getOnlyElement(
-        queryProvider.get().byKeyPrefix(r.getChangeId())).change();
+        queryProvider.get().byKeyPrefix(r.getChangeId()));
-    assertThat(db.patchSets().byChange(c.getId()).toList()).hasSize(2);
+    assertThat(cd.patchSets()).hasSize(2);
     assertSubmitApproval(r.getPatchSetId());
     assertCommit(project, "refs/heads/master");
   }

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git/VisibleRefFilterIT.java

@@ -187,7 +187,7 @@ public class VisibleRefFilterIT extends AbstractDaemonTest {
     deny(Permission.READ, REGISTERED_USERS, "refs/heads/branch");
 
     Change change1 = db.changes().get(c1);
-    PatchSet ps1 = db.patchSets().get(new PatchSet.Id(c1, 1));
+    PatchSet ps1 = getPatchSet(new PatchSet.Id(c1, 1));
 
     // Admin's edit is not visible.
     setApiUser(admin);
@@ -214,7 +214,7 @@ public class VisibleRefFilterIT extends AbstractDaemonTest {
       allow(Permission.READ, REGISTERED_USERS, "refs/heads/branch");
 
       Change change1 = db.changes().get(c1);
-      PatchSet ps1 = db.patchSets().get(new PatchSet.Id(c1, 1));
+      PatchSet ps1 = getPatchSet(new PatchSet.Id(c1, 1));
       setApiUser(admin);
       editModifier.createEdit(change1, ps1);
       setApiUser(user);

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/change/ConsistencyCheckerIT.java

@@ -208,8 +208,8 @@ public class ConsistencyCheckerIT extends AbstractDaemonTest {
 
     c = db.changes().get(c.getId());
     assertThat(c.currentPatchSetId().get()).isEqualTo(1);
-    assertThat(db.patchSets().get(ps1.getId())).isNotNull();
+    assertThat(getPatchSet(ps1.getId())).isNotNull();
-    assertThat(db.patchSets().get(ps2.getId())).isNull();
+    assertThat(getPatchSet(ps2.getId())).isNull();
   }
 
   @Test
@@ -256,10 +256,10 @@ public class ConsistencyCheckerIT extends AbstractDaemonTest {
 
     c = db.changes().get(c.getId());
     assertThat(c.currentPatchSetId().get()).isEqualTo(3);
-    assertThat(db.patchSets().get(ps1.getId())).isNotNull();
+    assertThat(getPatchSet(ps1.getId())).isNotNull();
-    assertThat(db.patchSets().get(ps2.getId())).isNull();
+    assertThat(getPatchSet(ps2.getId())).isNull();
-    assertThat(db.patchSets().get(ps3.getId())).isNotNull();
+    assertThat(getPatchSet(ps3.getId())).isNotNull();
-    assertThat(db.patchSets().get(ps4.getId())).isNull();
+    assertThat(getPatchSet(ps4.getId())).isNull();
   }
 
   @Test
@@ -284,7 +284,7 @@ public class ConsistencyCheckerIT extends AbstractDaemonTest {
 
     c = db.changes().get(c.getId());
     assertThat(c.currentPatchSetId().get()).isEqualTo(1);
-    assertThat(db.patchSets().get(ps1.getId())).isNotNull();
+    assertThat(getPatchSet(ps1.getId())).isNotNull();
   }
 
   @Test
@@ -442,7 +442,7 @@ public class ConsistencyCheckerIT extends AbstractDaemonTest {
     c = db.changes().get(c.getId());
     PatchSet.Id psId2 = new PatchSet.Id(c.getId(), 2);
     assertThat(c.currentPatchSetId()).isEqualTo(psId2);
-    assertThat(db.patchSets().get(psId2).getRevision().get())
+    assertThat(getPatchSet(psId2).getRevision().get())
         .isEqualTo(mergedAs.name());
 
     assertProblems(c);
@@ -484,7 +484,7 @@ public class ConsistencyCheckerIT extends AbstractDaemonTest {
     c = db.changes().get(c.getId());
     PatchSet.Id psId2 = new PatchSet.Id(c.getId(), 2);
     assertThat(c.currentPatchSetId()).isEqualTo(psId2);
-    assertThat(db.patchSets().get(psId2).getRevision().get())
+    assertThat(getPatchSet(psId2).getRevision().get())
         .isEqualTo(mergedAs.name());
 
     assertProblems(c);

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/change/GetRelatedIT.java

@@ -47,9 +47,6 @@ public class GetRelatedIT extends AbstractDaemonTest {
   @Inject
   private ChangeEditModifier editModifier;
 
-  @Inject
-  private ChangeData.Factory changeDataFactory;
-
   @Test
   public void getRelatedNoResult() throws Exception {
     PushOneCommit push = pushFactory.create(db, admin.getIdent(), testRepo);
@@ -521,7 +518,7 @@ public class GetRelatedIT extends AbstractDaemonTest {
     pushHead(testRepo, "refs/for/master", false);
 
     Change ch2 = getChange(c2_1).change();
-    editModifier.createEdit(ch2, getPatchSet(ch2));
+    editModifier.createEdit(ch2, getPatchSet(ch2.currentPatchSetId()));
     editModifier.modifyFile(editUtil.byChange(ch2).get(), "a.txt",
         RestSession.newRawInput(new byte[] {'a'}));
     ObjectId editRev =
@@ -569,7 +566,7 @@ public class GetRelatedIT extends AbstractDaemonTest {
     }
 
     // Pretend PS1,1 was pushed before the groups field was added.
-    PatchSet ps1_1 = db.patchSets().get(psId1_1);
+    PatchSet ps1_1 = getPatchSet(psId1_1);
     ps1_1.setGroups(null);
     db.patchSets().update(ImmutableList.of(ps1_1));
     indexer.index(changeDataFactory.create(db, psId1_1.getParentKey()));
@@ -614,10 +611,6 @@ public class GetRelatedIT extends AbstractDaemonTest {
     return getChange(c).change().currentPatchSetId();
   }
 
-  private PatchSet getPatchSet(Change c) throws OrmException {
-    return db.patchSets().get(c.currentPatchSetId());
-  }
-
   private ChangeData getChange(ObjectId c) throws OrmException {
     return Iterables.getOnlyElement(queryProvider.get().byCommit(c));
   }

gerrit-httpd/src/main/java/com/google/gerrit/httpd/raw/CatServlet.java

@@ -22,6 +22,7 @@ import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CurrentUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.edit.ChangeEdit;
 import com.google.gerrit.server.edit.ChangeEditUtil;
 import com.google.gerrit.server.project.ChangeControl;
@@ -53,16 +54,19 @@ public class CatServlet extends HttpServlet {
   private final Provider<CurrentUser> userProvider;
   private final ChangeControl.GenericFactory changeControl;
   private final ChangeEditUtil changeEditUtil;
+  private final PatchSetUtil psUtil;
 
   @Inject
   CatServlet(Provider<ReviewDb> sf,
       ChangeControl.GenericFactory ccf,
       Provider<CurrentUser> usrprv,
-      ChangeEditUtil ceu) {
+      ChangeEditUtil ceu,
+      PatchSetUtil psu) {
     requestDb = sf;
     changeControl = ccf;
     userProvider = usrprv;
     changeEditUtil = ceu;
+    psUtil = psu;
   }
 
   @Override
@@ -135,7 +139,8 @@ public class CatServlet extends HttpServlet {
           return;
         }
       } else {
-        PatchSet patchSet = db.patchSets().get(patchKey.getParentKey());
+        PatchSet patchSet =
+            psUtil.get(db, control.getNotes(), patchKey.getParentKey());
         if (patchSet == null) {
           rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
           return;

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/changedetail/PatchSetDetailFactory.java

@@ -14,6 +14,8 @@
 
 package com.google.gerrit.httpd.rpc.changedetail;
 
+import static com.google.common.base.Preconditions.checkArgument;
+
 import com.google.common.base.Optional;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.PatchSetDetail;
@@ -24,7 +26,6 @@ import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.httpd.rpc.Handler;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.AccountPatchReview;
-import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchLineComment;
 import com.google.gerrit.reviewdb.client.PatchSet;
@@ -32,6 +33,7 @@ import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.PatchLineCommentsUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.edit.ChangeEdit;
 import com.google.gerrit.server.edit.ChangeEditUtil;
 import com.google.gerrit.server.notedb.ChangeNotes;
@@ -76,6 +78,7 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
   private final Provider<CurrentUser> userProvider;
   private final ChangeControl.GenericFactory changeControlFactory;
   private final PatchLineCommentsUtil plcUtil;
+  private final PatchSetUtil psUtil;
   private final ChangeEditUtil editUtil;
 
   private Project.NameKey project;
@@ -95,6 +98,7 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
       final Provider<CurrentUser> userProvider,
       final ChangeControl.GenericFactory changeControlFactory,
       final PatchLineCommentsUtil plcUtil,
+      final PatchSetUtil psUtil,
       ChangeEditUtil editUtil,
       @Assisted("psIdBase") @Nullable final PatchSet.Id psIdBase,
       @Assisted("psIdNew") final PatchSet.Id psIdNew,
@@ -105,10 +109,16 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
     this.userProvider = userProvider;
     this.changeControlFactory = changeControlFactory;
     this.plcUtil = plcUtil;
+    this.psUtil = psUtil;
     this.editUtil = editUtil;
 
     this.psIdBase = psIdBase;
     this.psIdNew = psIdNew;
+    if (psIdBase != null && psIdNew != null) {
+      checkArgument(psIdBase.getParentKey().equals(psIdNew.getParentKey()),
+          "cannot compare PatchSets from different changes: %s and %s",
+          psIdBase, psIdNew);
+    }
     this.diffPrefs = diffPrefs;
   }
 
@@ -117,32 +127,35 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
       PatchSetInfoNotAvailableException, NoSuchChangeException, AuthException,
       IOException {
     Optional<ChangeEdit> edit = null;
+    ChangeNotes notes;
     if (control == null || patchSet == null) {
       control = changeControlFactory.validateFor(psIdNew.getParentKey(),
           userProvider.get());
+      notes = control.getNotes();
       if (psIdNew.get() == 0) {
-        Change change = db.changes().get(psIdNew.getParentKey());
+        edit = editUtil.byChange(control.getChange());
-        edit = editUtil.byChange(change);
         if (edit.isPresent()) {
           patchSet = edit.get().getBasePatchSet();
         }
       } else {
-        patchSet = db.patchSets().get(psIdNew);
+        patchSet = psUtil.get(db, notes, psIdNew);
       }
       if (patchSet == null) {
         throw new NoSuchEntityException();
       }
+    } else {
+      notes = control.getNotes();
     }
     project = control.getProject().getNameKey();
     final PatchList list;
 
     try {
       if (psIdBase != null) {
-        oldId = toObjectId(psIdBase);
+        oldId = toObjectId(psUtil.get(db, notes, psIdBase));
         if (edit != null && edit.isPresent()) {
           newId = edit.get().getEditCommit().toObjectId();
         } else {
-          newId = toObjectId(psIdNew);
+          newId = toObjectId(patchSet);
         }
 
         list = listFor(keyFor(diffPrefs.ignoreWhitespace));
@@ -159,7 +172,6 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
       byKey.put(p.getKey(), p);
     }
 
-    ChangeNotes notes = control.getNotes();
     if (edit == null) {
       for (PatchLineComment c : plcUtil.publishedByPatchSet(db, notes, psIdNew)) {
         final Patch p = byKey.get(c.getKey().getParentKey());
@@ -202,17 +214,11 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
     return detail;
   }
 
-  private ObjectId toObjectId(final PatchSet.Id psId) throws OrmException,
+  private ObjectId toObjectId(PatchSet ps) throws NoSuchEntityException {
-      NoSuchEntityException {
-    final PatchSet ps = db.patchSets().get(psId);
-    if (ps == null) {
-      throw new NoSuchEntityException();
-    }
-
     try {
       return ObjectId.fromString(ps.getRevision().get());
     } catch (IllegalArgumentException e) {
-      log.error("Patch set " + psId + " has invalid revision");
+      log.error("Patch set " + ps.getId() + " has invalid revision");
       throw new NoSuchEntityException();
     }
   }

gerrit-server/src/main/java/com/google/gerrit/server/ApprovalCopier.java

@@ -67,18 +67,21 @@ public class ApprovalCopier {
   private final ChangeKindCache changeKindCache;
   private final LabelNormalizer labelNormalizer;
   private final ChangeData.Factory changeDataFactory;
+  private final PatchSetUtil psUtil;
 
   @Inject
   ApprovalCopier(GitRepositoryManager repoManager,
       ProjectCache projectCache,
       ChangeKindCache changeKindCache,
       LabelNormalizer labelNormalizer,
-      ChangeData.Factory changeDataFactory) {
+      ChangeData.Factory changeDataFactory,
+      PatchSetUtil psUtil) {
     this.repoManager = repoManager;
     this.projectCache = projectCache;
     this.changeKindCache = changeKindCache;
     this.labelNormalizer = labelNormalizer;
     this.changeDataFactory = changeDataFactory;
+    this.psUtil = psUtil;
   }
 
   public void copy(ReviewDb db, ChangeControl ctl, PatchSet ps)
@@ -88,7 +91,7 @@ public class ApprovalCopier {
 
   Iterable<PatchSetApproval> getForPatchSet(ReviewDb db,
       ChangeControl ctl, PatchSet.Id psId) throws OrmException {
-    PatchSet ps = db.patchSets().get(psId);
+    PatchSet ps = psUtil.get(db, ctl.getNotes(), psId);
     if (ps == null) {
       return Collections.emptyList();
     }

gerrit-server/src/main/java/com/google/gerrit/server/ChangeUtil.java

@@ -36,6 +36,7 @@ import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.git.UpdateException;
 import com.google.gerrit.server.git.validators.CommitValidators;
 import com.google.gerrit.server.mail.RevertedSender;
+import com.google.gerrit.server.notedb.ChangeNotes;
 import com.google.gerrit.server.notedb.ChangeUpdate;
 import com.google.gerrit.server.project.ChangeControl;
 import com.google.gerrit.server.project.NoSuchChangeException;
@@ -164,6 +165,7 @@ public class ChangeUtil {
   private final Provider<ReviewDb> db;
   private final Sequences seq;
   private final Provider<InternalChangeQuery> queryProvider;
+  private final PatchSetUtil psUtil;
   private final ChangeControl.GenericFactory changeControlFactory;
   private final RevertedSender.Factory revertedSenderFactory;
   private final ChangeInserter.Factory changeInserterFactory;
@@ -177,6 +179,7 @@ public class ChangeUtil {
       Provider<ReviewDb> db,
       Sequences seq,
       Provider<InternalChangeQuery> queryProvider,
+      PatchSetUtil psUtil,
       ChangeControl.GenericFactory changeControlFactory,
       RevertedSender.Factory revertedSenderFactory,
       ChangeInserter.Factory changeInserterFactory,
@@ -188,6 +191,7 @@ public class ChangeUtil {
     this.db = db;
     this.seq = seq;
     this.queryProvider = queryProvider;
+    this.psUtil = psUtil;
     this.changeControlFactory = changeControlFactory;
     this.revertedSenderFactory = revertedSenderFactory;
     this.changeInserterFactory = changeInserterFactory;
@@ -203,7 +207,7 @@ public class ChangeUtil {
       MissingObjectException, IncorrectObjectTypeException, IOException,
       RestApiException, UpdateException {
     Change.Id changeIdToRevert = patchSetId.getParentKey();
-    PatchSet patch = db.get().patchSets().get(patchSetId);
+    PatchSet patch = psUtil.get(db.get(), ctl.getNotes(), patchSetId);
     if (patch == null) {
       throw new NoSuchChangeException(changeIdToRevert);
     }
@@ -295,16 +299,17 @@ public class ChangeUtil {
     }
   }
 
-  public String getMessage(Change change)
+  public String getMessage(ChangeNotes notes)
       throws NoSuchChangeException, OrmException,
       MissingObjectException, IncorrectObjectTypeException, IOException {
-    Change.Id changeId = change.getId();
+    Change.Id changeId = notes.getChangeId();
-    PatchSet ps = db.get().patchSets().get(change.currentPatchSetId());
+    PatchSet ps = psUtil.current(db.get(), notes);
     if (ps == null) {
       throw new NoSuchChangeException(changeId);
     }
 
-    try (Repository git = gitManager.openRepository(change.getProject());
+    try (Repository git =
+          gitManager.openRepository(notes.getChange().getProject());
         RevWalk revWalk = new RevWalk(git)) {
       RevCommit commit = revWalk.parseCommit(
           ObjectId.fromString(ps.getRevision().get()));

gerrit-server/src/main/java/com/google/gerrit/server/PatchSetUtil.java

@@ -0,0 +1,48 @@
+// Copyright (C) 2016 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;
+
+import com.google.common.collect.ImmutableList;
+import com.google.gerrit.reviewdb.client.PatchSet;
+import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.notedb.ChangeNotes;
+import com.google.gwtorm.server.OrmException;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+
+/** Utilities for manipulating patch sets. */
+@Singleton
+public class PatchSetUtil {
+  @Inject
+  PatchSetUtil() {
+  }
+
+  public PatchSet current(ReviewDb db, ChangeNotes notes)
+      throws OrmException {
+    return get(db, notes, notes.getChange().currentPatchSetId());
+  }
+
+  @SuppressWarnings("unused") // TODO(dborowitz): Read from notedb.
+  public PatchSet get(ReviewDb db, ChangeNotes notes, PatchSet.Id psId)
+      throws OrmException {
+    return db.patchSets().get(psId);
+  }
+
+  public ImmutableList<PatchSet> byChange(ReviewDb db, ChangeNotes notes)
+      throws OrmException {
+    return ChangeUtil.PS_ID_ORDER.immutableSortedCopy(
+        db.patchSets().byChange(notes.getChangeId()));
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/change/Abandon.java

@@ -32,6 +32,7 @@ import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.ChangeMessagesUtil;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.BatchUpdate.ChangeContext;
 import com.google.gerrit.server.git.BatchUpdate.Context;
@@ -58,6 +59,7 @@ public class Abandon implements RestModifyView<ChangeResource, AbandonInput>,
   private final Provider<ReviewDb> dbProvider;
   private final ChangeJson.Factory json;
   private final ChangeMessagesUtil cmUtil;
+  private final PatchSetUtil psUtil;
   private final BatchUpdate.Factory batchUpdateFactory;
 
   @Inject
@@ -66,12 +68,14 @@ public class Abandon implements RestModifyView<ChangeResource, AbandonInput>,
       Provider<ReviewDb> dbProvider,
       ChangeJson.Factory json,
       ChangeMessagesUtil cmUtil,
+      PatchSetUtil psUtil,
       BatchUpdate.Factory batchUpdateFactory) {
     this.hooks = hooks;
     this.abandonedSenderFactory = abandonedSenderFactory;
     this.dbProvider = dbProvider;
     this.json = json;
     this.cmUtil = cmUtil;
+    this.psUtil = psUtil;
     this.batchUpdateFactory = batchUpdateFactory;
   }
 
@@ -125,7 +129,7 @@ public class Abandon implements RestModifyView<ChangeResource, AbandonInput>,
         throw new ResourceConflictException(
             "draft changes cannot be abandoned");
       }
-      patchSet = ctx.getDb().patchSets().get(psId);
+      patchSet = psUtil.get(ctx.getDb(), ctx.getNotes(), psId);
       change.setStatus(Change.Status.ABANDONED);
       change.setLastUpdatedOn(ctx.getWhen());
       ctx.saveChange();

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeEdits.java

@@ -41,6 +41,7 @@ import com.google.gerrit.extensions.restapi.RestView;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.WebLinks;
 import com.google.gerrit.server.edit.ChangeEdit;
 import com.google.gerrit.server.edit.ChangeEditJson;
@@ -150,6 +151,7 @@ public class ChangeEdits implements
     private final Provider<ReviewDb> db;
     private final ChangeEditUtil editUtil;
     private final ChangeEditModifier editModifier;
+    private final PatchSetUtil psUtil;
     private final Put putEdit;
     private final Change change;
     private final String path;
@@ -158,12 +160,14 @@ public class ChangeEdits implements
     Create(Provider<ReviewDb> db,
         ChangeEditUtil editUtil,
         ChangeEditModifier editModifier,
+        PatchSetUtil psUtil,
         Put putEdit,
         @Assisted Change change,
         @Assisted @Nullable String path) {
       this.db = db;
       this.editUtil = editUtil;
       this.editModifier = editModifier;
+      this.psUtil = psUtil;
       this.putEdit = putEdit;
       this.change = change;
       this.path = path;
@@ -179,7 +183,7 @@ public class ChangeEdits implements
             "edit already exists for the change %s",
             resource.getId()));
       }
-      edit = createEdit();
+      edit = createEdit(resource);
       if (!Strings.isNullOrEmpty(path)) {
         putEdit.apply(new ChangeEditResource(resource, edit.get(), path),
             input);
@@ -187,10 +191,11 @@ public class ChangeEdits implements
       return Response.none();
     }
 
-    private Optional<ChangeEdit> createEdit() throws AuthException,
+    private Optional<ChangeEdit> createEdit(ChangeResource resource)
-        IOException, ResourceConflictException, OrmException {
+        throws AuthException, IOException, ResourceConflictException,
+        OrmException {
       editModifier.createEdit(change,
-          db.get().patchSets().get(change.currentPatchSetId()));
+          psUtil.current(db.get(), resource.getNotes()));
       return editUtil.byChange(change);
     }
   }
@@ -206,16 +211,19 @@ public class ChangeEdits implements
 
     private final ChangeEditUtil editUtil;
     private final ChangeEditModifier editModifier;
+    private final PatchSetUtil psUtil;
     private final Provider<ReviewDb> db;
     private final String path;
 
     @Inject
     DeleteFile(ChangeEditUtil editUtil,
         ChangeEditModifier editModifier,
+        PatchSetUtil psUtil,
         Provider<ReviewDb> db,
         @Assisted String path) {
       this.editUtil = editUtil;
       this.editModifier = editModifier;
+      this.psUtil = psUtil;
       this.db = db;
       this.path = path;
     }
@@ -233,8 +241,8 @@ public class ChangeEdits implements
         // Even if the latest patch set changed since the user triggered
         // the operation, deleting the whole file is probably still what
         // they intended.
-        editModifier.createEdit(rsrc.getChange(), db.get().patchSets().get(
+        editModifier.createEdit(rsrc.getChange(),
-            rsrc.getChange().currentPatchSetId()));
+            psUtil.current(db.get(), rsrc.getNotes()));
         edit = editUtil.byChange(rsrc.getChange());
         editModifier.deleteFile(edit.get(), path);
       }
@@ -321,14 +329,17 @@ public class ChangeEdits implements
     private final Provider<ReviewDb> db;
     private final ChangeEditUtil editUtil;
     private final ChangeEditModifier editModifier;
+    private final PatchSetUtil psUtil;
 
     @Inject
     Post(Provider<ReviewDb> db,
         ChangeEditUtil editUtil,
-        ChangeEditModifier editModifier) {
+        ChangeEditModifier editModifier,
+        PatchSetUtil psUtil) {
       this.db = db;
       this.editUtil = editUtil;
       this.editModifier = editModifier;
+      this.psUtil = psUtil;
     }
 
     @Override
@@ -337,7 +348,7 @@ public class ChangeEdits implements
         ResourceConflictException, OrmException {
       Optional<ChangeEdit> edit = editUtil.byChange(resource.getChange());
       if (!edit.isPresent()) {
-        edit = createEdit(resource.getChange());
+        edit = createEdit(resource);
       }
 
       if (input != null) {
@@ -351,12 +362,12 @@ public class ChangeEdits implements
       return Response.none();
     }
 
-    private Optional<ChangeEdit> createEdit(Change change)
+    private Optional<ChangeEdit> createEdit(ChangeResource resource)
         throws AuthException, IOException, ResourceConflictException,
         OrmException {
-      editModifier.createEdit(change,
+      editModifier.createEdit(resource.getChange(),
-          db.get().patchSets().get(change.currentPatchSetId()));
+          psUtil.current(db.get(), resource.getNotes()));
-      return editUtil.byChange(change);
+      return editUtil.byChange(resource.getChange());
     }
   }
 
@@ -496,14 +507,17 @@ public class ChangeEdits implements
     private final Provider<ReviewDb> db;
     private final ChangeEditModifier editModifier;
     private final ChangeEditUtil editUtil;
+    private final PatchSetUtil psUtil;
 
     @Inject
     EditMessage(Provider<ReviewDb> db,
         ChangeEditModifier editModifier,
-        ChangeEditUtil editUtil) {
+        ChangeEditUtil editUtil,
+        PatchSetUtil psUtil) {
       this.db = db;
       this.editModifier = editModifier;
       this.editUtil = editUtil;
+      this.psUtil = psUtil;
     }
 
     @Override
@@ -513,7 +527,7 @@ public class ChangeEdits implements
       Optional<ChangeEdit> edit = editUtil.byChange(rsrc.getChange());
       if (!edit.isPresent()) {
         editModifier.createEdit(rsrc.getChange(),
-            db.get().patchSets().get(rsrc.getChange().currentPatchSetId()));
+            psUtil.current(db.get(), rsrc.getNotes()));
         edit = editUtil.byChange(rsrc.getChange());
       }
 

gerrit-server/src/main/java/com/google/gerrit/server/change/CherryPickChange.java

@@ -30,6 +30,7 @@ import com.google.gerrit.server.ChangeMessagesUtil;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.GerritPersonIdent;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.Sequences;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.CodeReviewCommit;
@@ -81,6 +82,7 @@ public class CherryPickChange {
   private final PatchSetInserter.Factory patchSetInserterFactory;
   private final MergeUtil.Factory mergeUtilFactory;
   private final ChangeMessagesUtil changeMessagesUtil;
+  private final PatchSetUtil psUtil;
   private final ChangeUpdate.Factory updateFactory;
   private final BatchUpdate.Factory batchUpdateFactory;
 
@@ -95,6 +97,7 @@ public class CherryPickChange {
       PatchSetInserter.Factory patchSetInserterFactory,
       MergeUtil.Factory mergeUtilFactory,
       ChangeMessagesUtil changeMessagesUtil,
+      PatchSetUtil psUtil,
       ChangeUpdate.Factory updateFactory,
       BatchUpdate.Factory batchUpdateFactory) {
     this.db = db;
@@ -107,6 +110,7 @@ public class CherryPickChange {
     this.patchSetInserterFactory = patchSetInserterFactory;
     this.mergeUtilFactory = mergeUtilFactory;
     this.changeMessagesUtil = changeMessagesUtil;
+    this.psUtil = psUtil;
     this.updateFactory = updateFactory;
     this.batchUpdateFactory = batchUpdateFactory;
   }
@@ -177,10 +181,13 @@ public class CherryPickChange {
           throw new InvalidChangeOperationException("Several changes with key "
               + changeKey + " reside on the same branch. "
               + "Cannot create a new patch set.");
-        } else if (destChanges.size() == 1) {
+        }
+        if (destChanges.size() == 1) {
           // The change key exists on the destination branch. The cherry pick
           // will be added as a new patch set.
-          return insertPatchSet(git, revWalk, oi, destChanges.get(0).change(),
+          ChangeControl destCtl = refControl.getProjectControl()
+              .controlFor(destChanges.get(0).change());
+          return insertPatchSet(git, revWalk, oi, destCtl,
               cherryPickCommit, refControl, identifiedUser);
         } else {
           // Change key not found on destination branch. We can create a new
@@ -208,15 +215,16 @@ public class CherryPickChange {
   }
 
   private Change.Id insertPatchSet(Repository git, RevWalk revWalk,
-      ObjectInserter oi, Change change, CodeReviewCommit cherryPickCommit,
+      ObjectInserter oi, ChangeControl ctl, CodeReviewCommit cherryPickCommit,
       RefControl refControl, IdentifiedUser identifiedUser)
       throws IOException, OrmException, UpdateException, RestApiException {
+    Change change = ctl.getChange();
     PatchSet.Id psId =
         ChangeUtil.nextPatchSetId(git, change.currentPatchSetId());
     PatchSetInserter inserter = patchSetInserterFactory
         .create(refControl, psId, cherryPickCommit);
     PatchSet.Id newPatchSetId = inserter.getPatchSetId();
-    PatchSet current = db.get().patchSets().get(change.currentPatchSetId());
+    PatchSet current = psUtil.current(db.get(), ctl.getNotes());
 
     try (BatchUpdate bu = batchUpdateFactory.create(
         db.get(), change.getDest().getParentKey(), identifiedUser,

gerrit-server/src/main/java/com/google/gerrit/server/change/CreateChange.java

@@ -37,6 +37,7 @@ import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.GerritPersonIdent;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.Sequences;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.git.BatchUpdate;
@@ -84,6 +85,7 @@ public class CreateChange implements
   private final ChangeJson.Factory jsonFactory;
   private final ChangeUtil changeUtil;
   private final BatchUpdate.Factory updateFactory;
+  private final PatchSetUtil psUtil;
   private final boolean allowDrafts;
 
   @Inject
@@ -97,6 +99,7 @@ public class CreateChange implements
       ChangeJson.Factory json,
       ChangeUtil changeUtil,
       BatchUpdate.Factory updateFactory,
+      PatchSetUtil psUtil,
       @GerritServerConfig Config config) {
     this.db = db;
     this.gitManager = gitManager;
@@ -108,6 +111,7 @@ public class CreateChange implements
     this.jsonFactory = json;
     this.changeUtil = changeUtil;
     this.updateFactory = updateFactory;
+    this.psUtil = psUtil;
     this.allowDrafts = config.getBoolean("change", "allowDrafts", true);
   }
 
@@ -168,8 +172,7 @@ public class CreateChange implements
           throw new InvalidChangeOperationException(
               "Base change not found: " + input.baseChange);
         }
-        PatchSet ps =
+        PatchSet ps = psUtil.current(db.get(), ctl.getNotes());
-            db.get().patchSets().get(ctl.getChange().currentPatchSetId());
         parentCommit = ObjectId.fromString(ps.getRevision().get());
         groups = ps.getGroups();
       } else {

gerrit-server/src/main/java/com/google/gerrit/server/change/CreateDraftComment.java

@@ -33,6 +33,7 @@ import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.PatchLineCommentsUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.BatchUpdate.ChangeContext;
 import com.google.gerrit.server.git.UpdateException;
@@ -50,6 +51,7 @@ public class CreateDraftComment implements RestModifyView<RevisionResource, Draf
   private final BatchUpdate.Factory updateFactory;
   private final Provider<CommentJson> commentJson;
   private final PatchLineCommentsUtil plcUtil;
+  private final PatchSetUtil psUtil;
   private final PatchListCache patchListCache;
 
   @Inject
@@ -57,11 +59,13 @@ public class CreateDraftComment implements RestModifyView<RevisionResource, Draf
       BatchUpdate.Factory updateFactory,
       Provider<CommentJson> commentJson,
       PatchLineCommentsUtil plcUtil,
+      PatchSetUtil psUtil,
       PatchListCache patchListCache) {
     this.db = db;
     this.updateFactory = updateFactory;
     this.commentJson = commentJson;
     this.plcUtil = plcUtil;
+    this.psUtil = psUtil;
     this.patchListCache = patchListCache;
   }
 
@@ -102,7 +106,7 @@ public class CreateDraftComment implements RestModifyView<RevisionResource, Draf
     @Override
     public void updateChange(ChangeContext ctx)
         throws ResourceNotFoundException, OrmException {
-      PatchSet ps = ctx.getDb().patchSets().get(psId);
+      PatchSet ps = psUtil.get(ctx.getDb(), ctx.getNotes(), psId);
       if (ps == null) {
         throw new ResourceNotFoundException("patch set not found: " + psId);
       }

gerrit-server/src/main/java/com/google/gerrit/server/change/DeleteDraftChangeOp.java

@@ -16,6 +16,7 @@ package com.google.gerrit.server.change;
 
 import static com.google.common.base.Preconditions.checkState;
 
+import com.google.common.collect.ImmutableList;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.MethodNotAllowedException;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
@@ -23,6 +24,7 @@ import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.StarredChangesUtil;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.git.BatchUpdate;
@@ -44,14 +46,17 @@ class DeleteDraftChangeOp extends BatchUpdate.Op {
     return cfg.getBoolean("change", "allowDrafts", true);
   }
 
+  private final PatchSetUtil psUtil;
   private final StarredChangesUtil starredChangesUtil;
   private final boolean allowDrafts;
 
   private Change.Id id;
 
   @Inject
-  DeleteDraftChangeOp(StarredChangesUtil starredChangesUtil,
+  DeleteDraftChangeOp(PatchSetUtil psUtil,
+      StarredChangesUtil starredChangesUtil,
       @GerritServerConfig Config cfg) {
+    this.psUtil = psUtil;
     this.starredChangesUtil = starredChangesUtil;
     this.allowDrafts = allowDrafts(cfg);
   }
@@ -76,7 +81,8 @@ class DeleteDraftChangeOp extends BatchUpdate.Op {
     if (!ctx.getControl().canDeleteDraft(ctx.getDb())) {
       throw new AuthException("Not permitted to delete this draft change");
     }
-    List<PatchSet> patchSets = ctx.getDb().patchSets().byChange(id).toList();
+    List<PatchSet> patchSets = ImmutableList.copyOf(
+        psUtil.byChange(ctx.getDb(), ctx.getNotes()));
     for (PatchSet ps : patchSets) {
       if (!ps.isDraft()) {
         throw new ResourceConflictException("Cannot delete draft change " + id

gerrit-server/src/main/java/com/google/gerrit/server/change/DeleteDraftComment.java

@@ -27,6 +27,7 @@ import com.google.gerrit.reviewdb.client.PatchLineComment;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.PatchLineCommentsUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.change.DeleteDraftComment.Input;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.BatchUpdate.ChangeContext;
@@ -47,16 +48,19 @@ public class DeleteDraftComment
 
   private final Provider<ReviewDb> db;
   private final PatchLineCommentsUtil plcUtil;
+  private final PatchSetUtil psUtil;
   private final BatchUpdate.Factory updateFactory;
   private final PatchListCache patchListCache;
 
   @Inject
   DeleteDraftComment(Provider<ReviewDb> db,
       PatchLineCommentsUtil plcUtil,
+      PatchSetUtil psUtil,
       BatchUpdate.Factory updateFactory,
       PatchListCache patchListCache) {
     this.db = db;
     this.plcUtil = plcUtil;
+    this.psUtil = psUtil;
     this.updateFactory = updateFactory;
     this.patchListCache = patchListCache;
   }
@@ -90,7 +94,7 @@ public class DeleteDraftComment
         return; // Nothing to do.
       }
       PatchSet.Id psId = key.getParentKey().getParentKey();
-      PatchSet ps = ctx.getDb().patchSets().get(psId);
+      PatchSet ps = psUtil.get(ctx.getDb(), ctx.getNotes(), psId);
       if (ps == null) {
         throw new ResourceNotFoundException("patch set not found: " + psId);
       }

gerrit-server/src/main/java/com/google/gerrit/server/change/DeleteDraftPatchSet.java

@@ -28,6 +28,7 @@ import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.PatchSetInfo;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.ChangeUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.change.DeleteDraftPatchSet.Input;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.git.BatchUpdate;
@@ -57,6 +58,7 @@ public class DeleteDraftPatchSet implements RestModifyView<RevisionResource, Inp
   private final Provider<ReviewDb> db;
   private final BatchUpdate.Factory updateFactory;
   private final PatchSetInfoFactory patchSetInfoFactory;
+  private final PatchSetUtil psUtil;
   private final Provider<DeleteDraftChangeOp> deleteChangeOpProvider;
   private final boolean allowDrafts;
 
@@ -64,11 +66,13 @@ public class DeleteDraftPatchSet implements RestModifyView<RevisionResource, Inp
   public DeleteDraftPatchSet(Provider<ReviewDb> db,
       BatchUpdate.Factory updateFactory,
       PatchSetInfoFactory patchSetInfoFactory,
+      PatchSetUtil psUtil,
       Provider<DeleteDraftChangeOp> deleteChangeOpProvider,
       @GerritServerConfig Config cfg) {
     this.db = db;
     this.updateFactory = updateFactory;
     this.patchSetInfoFactory = patchSetInfoFactory;
+    this.psUtil = psUtil;
     this.deleteChangeOpProvider = deleteChangeOpProvider;
     this.allowDrafts = cfg.getBoolean("change", "allowDrafts", true);
   }
@@ -98,7 +102,7 @@ public class DeleteDraftPatchSet implements RestModifyView<RevisionResource, Inp
     @Override
     public void updateChange(ChangeContext ctx)
         throws RestApiException, OrmException, IOException {
-      patchSet = ctx.getDb().patchSets().get(psId);
+      patchSet = psUtil.get(ctx.getDb(), ctx.getNotes(), psId);
       if (patchSet == null) {
         return; // Nothing to do.
       }
@@ -143,7 +147,7 @@ public class DeleteDraftPatchSet implements RestModifyView<RevisionResource, Inp
     private void deleteOrUpdateDraftChange(ChangeContext ctx)
         throws OrmException, RestApiException {
       Change c = ctx.getChange();
-      if (Iterables.isEmpty(ctx.getDb().patchSets().byChange(c.getId()))) {
+      if (Iterables.isEmpty(psUtil.byChange(ctx.getDb(), ctx.getNotes()))) {
         deleteChangeOp = deleteChangeOpProvider.get();
         deleteChangeOp.updateChange(ctx);
         return;

gerrit-server/src/main/java/com/google/gerrit/server/change/Files.java

@@ -34,6 +34,7 @@ import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CurrentUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.patch.PatchList;
 import com.google.gerrit.server.patch.PatchListCache;
@@ -108,6 +109,7 @@ public class Files implements ChildCollection<RevisionResource, FileResource> {
     private final Revisions revisions;
     private final GitRepositoryManager gitManager;
     private final PatchListCache patchListCache;
+    private final PatchSetUtil psUtil;
 
     @Inject
     ListFiles(Provider<ReviewDb> db,
@@ -115,13 +117,15 @@ public class Files implements ChildCollection<RevisionResource, FileResource> {
         FileInfoJson fileInfoJson,
         Revisions revisions,
         GitRepositoryManager gitManager,
-        PatchListCache patchListCache) {
+        PatchListCache patchListCache,
+        PatchSetUtil psUtil) {
       this.db = db;
       this.self = self;
       this.fileInfoJson = fileInfoJson;
       this.revisions = revisions;
       this.gitManager = gitManager;
       this.patchListCache = patchListCache;
+      this.psUtil = psUtil;
     }
 
     public ListFiles setReviewed(boolean r) {
@@ -262,7 +266,7 @@ public class Files implements ChildCollection<RevisionResource, FileResource> {
           TreeWalk tw = new TreeWalk(reader)) {
         PatchList oldList = patchListCache.get(
             resource.getChange(),
-            db.get().patchSets().get(old));
+            psUtil.get(db.get(), resource.getNotes(), old));
 
         PatchList curList = patchListCache.get(
             resource.getChange(),

gerrit-server/src/main/java/com/google/gerrit/server/change/GetContent.java

@@ -46,7 +46,8 @@ public class GetContent implements RestReadView<FileResource> {
       OrmException {
     String path = rsrc.getPatchKey().get();
     if (Patch.COMMIT_MSG.equals(path)) {
-      String msg = changeUtil.getMessage(rsrc.getRevision().getChange());
+      String msg = changeUtil.getMessage(
+          rsrc.getRevision().getChangeResource().getNotes());
       return BinaryResult.create(msg)
           .setContentType(FileContentUtil.TEXT_X_GERRIT_COMMIT_MESSAGE)
           .base64();

gerrit-server/src/main/java/com/google/gerrit/server/change/GetRelated.java

@@ -23,7 +23,9 @@ import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CommonConverters;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.change.RelatedChangesSorter.PatchSetData;
+import com.google.gerrit.server.notedb.ChangeNotes;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gerrit.server.query.change.InternalChangeQuery;
 import com.google.gwtorm.server.OrmException;
@@ -45,14 +47,17 @@ import java.util.Set;
 public class GetRelated implements RestReadView<RevisionResource> {
   private final Provider<ReviewDb> db;
   private final Provider<InternalChangeQuery> queryProvider;
+  private final PatchSetUtil psUtil;
   private final RelatedChangesSorter sorter;
 
   @Inject
   GetRelated(Provider<ReviewDb> db,
       Provider<InternalChangeQuery> queryProvider,
+      PatchSetUtil psUtil,
       RelatedChangesSorter sorter) {
     this.db = db;
     this.queryProvider = queryProvider;
+    this.psUtil = psUtil;
     this.sorter = sorter;
   }
 
@@ -66,7 +71,7 @@ public class GetRelated implements RestReadView<RevisionResource> {
 
   private List<ChangeAndCommit> getRelated(RevisionResource rsrc)
       throws OrmException, IOException {
-    Set<String> groups = getAllGroups(rsrc.getChange().getId());
+    Set<String> groups = getAllGroups(rsrc.getNotes());
     if (groups.isEmpty()) {
       return Collections.emptyList();
     }
@@ -109,9 +114,9 @@ public class GetRelated implements RestReadView<RevisionResource> {
     return result;
   }
 
-  private Set<String> getAllGroups(Change.Id changeId) throws OrmException {
+  private Set<String> getAllGroups(ChangeNotes notes) throws OrmException {
     Set<String> result = new HashSet<>();
-    for (PatchSet ps : db.get().patchSets().byChange(changeId)) {
+    for (PatchSet ps : psUtil.byChange(db.get(), notes)) {
       List<String> groups = ps.getGroups();
       if (groups != null) {
         result.addAll(groups);

gerrit-server/src/main/java/com/google/gerrit/server/change/IncludedIn.java

@@ -23,6 +23,7 @@ import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.project.ChangeControl;
 import com.google.gwtorm.server.OrmException;
@@ -47,14 +48,17 @@ class IncludedIn implements RestReadView<ChangeResource> {
 
   private final Provider<ReviewDb> db;
   private final GitRepositoryManager repoManager;
+  private final PatchSetUtil psUtil;
   private final DynamicMap<ExternalIncludedIn> includedIn;
 
   @Inject
   IncludedIn(Provider<ReviewDb> db,
       GitRepositoryManager repoManager,
+      PatchSetUtil psUtil,
       DynamicMap<ExternalIncludedIn> includedIn) {
     this.db = db;
     this.repoManager = repoManager;
+    this.psUtil = psUtil;
     this.includedIn = includedIn;
   }
 
@@ -62,8 +66,7 @@ class IncludedIn implements RestReadView<ChangeResource> {
   public IncludedInInfo apply(ChangeResource rsrc) throws BadRequestException,
       ResourceConflictException, OrmException, IOException {
     ChangeControl ctl = rsrc.getControl();
-    PatchSet ps =
+    PatchSet ps = psUtil.current(db.get(), rsrc.getNotes());
-        db.get().patchSets().get(ctl.getChange().currentPatchSetId());
     Project.NameKey project = ctl.getProject().getNameKey();
     try (Repository r = repoManager.openRepository(project);
         RevWalk rw = new RevWalk(r)) {

gerrit-server/src/main/java/com/google/gerrit/server/change/PatchSetInserter.java

@@ -34,13 +34,13 @@ import com.google.gerrit.server.ApprovalCopier;
 import com.google.gerrit.server.ApprovalsUtil;
 import com.google.gerrit.server.ChangeMessagesUtil;
 import com.google.gerrit.server.ChangeUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.events.CommitReceivedEvent;
 import com.google.gerrit.server.git.BanCommit;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.BatchUpdate.ChangeContext;
 import com.google.gerrit.server.git.BatchUpdate.Context;
 import com.google.gerrit.server.git.BatchUpdate.RepoContext;
-import com.google.gerrit.server.git.GroupCollector;
 import com.google.gerrit.server.git.validators.CommitValidationException;
 import com.google.gerrit.server.git.validators.CommitValidators;
 import com.google.gerrit.server.mail.ReplacePatchSetSender;
@@ -84,6 +84,7 @@ public class PatchSetInserter extends BatchUpdate.Op {
   private final ApprovalsUtil approvalsUtil;
   private final ApprovalCopier approvalCopier;
   private final ChangeMessagesUtil cmUtil;
+  private final PatchSetUtil psUtil;
 
   // Assisted-injected fields.
   private final PatchSet.Id psId;
@@ -119,6 +120,7 @@ public class PatchSetInserter extends BatchUpdate.Op {
       PatchSetInfoFactory patchSetInfoFactory,
       CommitValidators.Factory commitValidatorsFactory,
       ReplacePatchSetSender.Factory replacePatchSetFactory,
+      PatchSetUtil psUtil,
       @Assisted RefControl refControl,
       @Assisted PatchSet.Id psId,
       @Assisted RevCommit commit) {
@@ -130,6 +132,7 @@ public class PatchSetInserter extends BatchUpdate.Op {
     this.patchSetInfoFactory = patchSetInfoFactory;
     this.commitValidatorsFactory = commitValidatorsFactory;
     this.replacePatchSetFactory = replacePatchSetFactory;
+    this.psUtil = psUtil;
 
     this.refControl = refControl;
     this.psId = psId;
@@ -232,7 +235,8 @@ public class PatchSetInserter extends BatchUpdate.Op {
     if (groups != null) {
       patchSet.setGroups(groups);
     } else {
-      patchSet.setGroups(GroupCollector.getCurrentGroups(db, change));
+      PatchSet prevPs = psUtil.current(ctx.getDb(), ctx.getNotes());
+      patchSet.setGroups(prevPs != null ? prevPs.getGroups() : null);
     }
     db.patchSets().insert(Collections.singleton(patchSet));
 

gerrit-server/src/main/java/com/google/gerrit/server/change/PostReview.java

@@ -59,6 +59,7 @@ import com.google.gerrit.server.ChangeMessagesUtil;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.PatchLineCommentsUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.account.AccountsCollection;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.BatchUpdate.ChangeContext;
@@ -102,6 +103,7 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
   private final ApprovalsUtil approvalsUtil;
   private final ChangeMessagesUtil cmUtil;
   private final PatchLineCommentsUtil plcUtil;
+  private final PatchSetUtil psUtil;
   private final PatchListCache patchListCache;
   private final AccountsCollection accounts;
   private final EmailReviewComments.Factory email;
@@ -115,6 +117,7 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
       ApprovalsUtil approvalsUtil,
       ChangeMessagesUtil cmUtil,
       PatchLineCommentsUtil plcUtil,
+      PatchSetUtil psUtil,
       PatchListCache patchListCache,
       AccountsCollection accounts,
       EmailReviewComments.Factory email,
@@ -124,6 +127,7 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
     this.changes = changes;
     this.changeDataFactory = changeDataFactory;
     this.plcUtil = plcUtil;
+    this.psUtil = psUtil;
     this.patchListCache = patchListCache;
     this.approvalsUtil = approvalsUtil;
     this.cmUtil = cmUtil;
@@ -354,7 +358,7 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
         throws OrmException, ResourceConflictException {
       user = ctx.getUser().asIdentifiedUser();
       change = ctx.getChange();
-      ps = ctx.getDb().patchSets().get(psId);
+      ps = psUtil.get(ctx.getDb(), ctx.getNotes(), psId);
       boolean dirty = false;
       dirty |= insertComments(ctx);
       dirty |= updateLabels(ctx);

gerrit-server/src/main/java/com/google/gerrit/server/change/PostReviewers.java

@@ -36,6 +36,7 @@ import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.ApprovalsUtil;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.AccountLoader;
 import com.google.gerrit.server.account.AccountsCollection;
@@ -76,6 +77,7 @@ public class PostReviewers implements RestModifyView<ChangeResource, AddReviewer
   private final AccountsCollection accounts;
   private final ReviewerResource.Factory reviewerFactory;
   private final ApprovalsUtil approvalsUtil;
+  private final PatchSetUtil psUtil;
   private final AddReviewerSender.Factory addReviewerSenderFactory;
   private final GroupsCollection groupsCollection;
   private final GroupMembers.Factory groupMembersFactory;
@@ -94,6 +96,7 @@ public class PostReviewers implements RestModifyView<ChangeResource, AddReviewer
   PostReviewers(AccountsCollection accounts,
       ReviewerResource.Factory reviewerFactory,
       ApprovalsUtil approvalsUtil,
+      PatchSetUtil psUtil,
       AddReviewerSender.Factory addReviewerSenderFactory,
       GroupsCollection groupsCollection,
       GroupMembers.Factory groupMembersFactory,
@@ -110,6 +113,7 @@ public class PostReviewers implements RestModifyView<ChangeResource, AddReviewer
     this.accounts = accounts;
     this.reviewerFactory = reviewerFactory;
     this.approvalsUtil = approvalsUtil;
+    this.psUtil = psUtil;
     this.addReviewerSenderFactory = addReviewerSenderFactory;
     this.groupsCollection = groupsCollection;
     this.groupMembersFactory = groupMembersFactory;
@@ -257,7 +261,7 @@ public class PostReviewers implements RestModifyView<ChangeResource, AddReviewer
     indexFuture.checkedGet();
     emailReviewers(rsrc.getChange(), added);
     if (!added.isEmpty()) {
-      PatchSet patchSet = dbProvider.get().patchSets().get(rsrc.getChange().currentPatchSetId());
+      PatchSet patchSet = psUtil.current(dbProvider.get(), rsrc.getNotes());
       for (PatchSetApproval psa : added) {
         Account account = accountCache.get(psa.getAccountId()).getAccount();
         hooks.doReviewerAddedHook(rsrc.getChange(), account, patchSet, dbProvider.get());

gerrit-server/src/main/java/com/google/gerrit/server/change/PublishDraftPatchSet.java

@@ -37,6 +37,7 @@ import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.ApprovalsUtil;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.CurrentUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.account.AccountResolver;
 import com.google.gerrit.server.change.PublishDraftPatchSet.Input;
 import com.google.gerrit.server.git.BatchUpdate;
@@ -73,32 +74,35 @@ public class PublishDraftPatchSet implements RestModifyView<RevisionResource, In
   public static class Input {
   }
 
-  private final Provider<ReviewDb> dbProvider;
+  private final AccountResolver accountResolver;
+  private final ApprovalsUtil approvalsUtil;
   private final BatchUpdate.Factory updateFactory;
   private final ChangeHooks hooks;
-  private final ApprovalsUtil approvalsUtil;
-  private final AccountResolver accountResolver;
-  private final PatchSetInfoFactory patchSetInfoFactory;
   private final CreateChangeSender.Factory createChangeSenderFactory;
+  private final PatchSetInfoFactory patchSetInfoFactory;
+  private final PatchSetUtil psUtil;
+  private final Provider<ReviewDb> dbProvider;
   private final ReplacePatchSetSender.Factory replacePatchSetFactory;
 
   @Inject
   public PublishDraftPatchSet(
-      Provider<ReviewDb> dbProvider,
+      AccountResolver accountResolver,
+      ApprovalsUtil approvalsUtil,
       BatchUpdate.Factory updateFactory,
       ChangeHooks hooks,
-      ApprovalsUtil approvalsUtil,
-      AccountResolver accountResolver,
-      PatchSetInfoFactory patchSetInfoFactory,
       CreateChangeSender.Factory createChangeSenderFactory,
+      PatchSetInfoFactory patchSetInfoFactory,
+      PatchSetUtil psUtil,
+      Provider<ReviewDb> dbProvider,
       ReplacePatchSetSender.Factory replacePatchSetFactory) {
-    this.dbProvider = dbProvider;
+    this.accountResolver = accountResolver;
+    this.approvalsUtil = approvalsUtil;
     this.updateFactory = updateFactory;
     this.hooks = hooks;
-    this.approvalsUtil = approvalsUtil;
-    this.accountResolver = accountResolver;
-    this.patchSetInfoFactory = patchSetInfoFactory;
     this.createChangeSenderFactory = createChangeSenderFactory;
+    this.patchSetInfoFactory = patchSetInfoFactory;
+    this.psUtil = psUtil;
+    this.dbProvider = dbProvider;
     this.replacePatchSetFactory = replacePatchSetFactory;
   }
 
@@ -170,7 +174,7 @@ public class PublishDraftPatchSet implements RestModifyView<RevisionResource, In
         throw new AuthException("Cannot publish this draft patch set");
       }
       if (patchSet == null) {
-        patchSet = ctx.getDb().patchSets().get(psId);
+        patchSet = psUtil.get(ctx.getDb(), ctx.getNotes(), psId);
         if (patchSet == null) {
           throw new ResourceNotFoundException(psId.toString());
         }

gerrit-server/src/main/java/com/google/gerrit/server/change/PutDraftComment.java

@@ -32,6 +32,7 @@ import com.google.gerrit.reviewdb.client.PatchLineComment;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.PatchLineCommentsUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.BatchUpdate.ChangeContext;
 import com.google.gerrit.server.git.UpdateException;
@@ -50,6 +51,7 @@ public class PutDraftComment implements RestModifyView<DraftCommentResource, Dra
   private final Provider<ReviewDb> db;
   private final DeleteDraftComment delete;
   private final PatchLineCommentsUtil plcUtil;
+  private final PatchSetUtil psUtil;
   private final BatchUpdate.Factory updateFactory;
   private final Provider<CommentJson> commentJson;
   private final PatchListCache patchListCache;
@@ -58,12 +60,14 @@ public class PutDraftComment implements RestModifyView<DraftCommentResource, Dra
   PutDraftComment(Provider<ReviewDb> db,
       DeleteDraftComment delete,
       PatchLineCommentsUtil plcUtil,
+      PatchSetUtil psUtil,
       BatchUpdate.Factory updateFactory,
       Provider<CommentJson> commentJson,
       PatchListCache patchListCache) {
     this.db = db;
     this.delete = delete;
     this.plcUtil = plcUtil;
+    this.psUtil = psUtil;
     this.updateFactory = updateFactory;
     this.commentJson = commentJson;
     this.patchListCache = patchListCache;
@@ -118,7 +122,8 @@ public class PutDraftComment implements RestModifyView<DraftCommentResource, Dra
 
       PatchSet.Id psId = comment.getKey().getParentKey().getParentKey();
       ChangeUpdate update = ctx.getUpdate(psId);
-      PatchSet ps = ctx.getDb().patchSets().get(psId);
+
+      PatchSet ps = psUtil.get(ctx.getDb(), ctx.getNotes(), psId);
       if (ps == null) {
         throw new ResourceNotFoundException("patch set not found: " + psId);
       }

gerrit-server/src/main/java/com/google/gerrit/server/change/Rebase.java

@@ -183,6 +183,8 @@ public class Rebase implements RestModifyView<RevisionResource, RebaseInput>,
       return db.patchSets().get(basePatchSetId);
     }
 
+    // TODO(dborowitz): Use PatchSetUtil; requires additional refactoring as we
+    // just turn around and get the change at the caller.
     // Try parsing base as a change number (assume current patch set).
     PatchSet basePatchSet = null;
     Integer baseChangeId = Ints.tryParse(base);

gerrit-server/src/main/java/com/google/gerrit/server/change/RebaseChangeEdit.java

@@ -28,6 +28,7 @@ import com.google.gerrit.extensions.restapi.RestModifyView;
 import com.google.gerrit.extensions.restapi.RestView;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.edit.ChangeEdit;
 import com.google.gerrit.server.edit.ChangeEditModifier;
 import com.google.gerrit.server.edit.ChangeEditUtil;
@@ -79,14 +80,17 @@ public class RebaseChangeEdit implements
 
     private final ChangeEditModifier editModifier;
     private final ChangeEditUtil editUtil;
+    private final PatchSetUtil psUtil;
     private final Provider<ReviewDb> db;
 
     @Inject
     Rebase(ChangeEditModifier editModifier,
         ChangeEditUtil editUtil,
+        PatchSetUtil psUtil,
         Provider<ReviewDb> db) {
       this.editModifier = editModifier;
       this.editUtil = editUtil;
+      this.psUtil = psUtil;
       this.db = db;
     }
 
@@ -101,8 +105,7 @@ public class RebaseChangeEdit implements
             rsrc.getChange().getChangeId()));
       }
 
-      PatchSet current = db.get().patchSets().get(
+      PatchSet current = psUtil.current(db.get(), rsrc.getNotes());
-          rsrc.getChange().currentPatchSetId());
       if (current.getId().equals(edit.get().getBasePatchSet().getId())) {
         throw new ResourceConflictException(String.format(
             "edit for change %s is already on latest patch set: %s",

gerrit-server/src/main/java/com/google/gerrit/server/change/Restore.java

@@ -32,6 +32,7 @@ import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.ChangeMessagesUtil;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.BatchUpdate.ChangeContext;
 import com.google.gerrit.server.git.BatchUpdate.Context;
@@ -58,6 +59,7 @@ public class Restore implements RestModifyView<ChangeResource, RestoreInput>,
   private final Provider<ReviewDb> dbProvider;
   private final ChangeJson.Factory json;
   private final ChangeMessagesUtil cmUtil;
+  private final PatchSetUtil psUtil;
   private final BatchUpdate.Factory batchUpdateFactory;
 
   @Inject
@@ -66,12 +68,14 @@ public class Restore implements RestModifyView<ChangeResource, RestoreInput>,
       Provider<ReviewDb> dbProvider,
       ChangeJson.Factory json,
       ChangeMessagesUtil cmUtil,
+      PatchSetUtil psUtil,
       BatchUpdate.Factory batchUpdateFactory) {
     this.hooks = hooks;
     this.restoredSenderFactory = restoredSenderFactory;
     this.dbProvider = dbProvider;
     this.json = json;
     this.cmUtil = cmUtil;
+    this.psUtil = psUtil;
     this.batchUpdateFactory = batchUpdateFactory;
   }
 
@@ -113,7 +117,7 @@ public class Restore implements RestModifyView<ChangeResource, RestoreInput>,
       if (change == null || change.getStatus() != Status.ABANDONED) {
         throw new ResourceConflictException("change is " + status(change));
       }
-      patchSet = ctx.getDb().patchSets().get(psId);
+      patchSet = psUtil.get(ctx.getDb(), ctx.getNotes(), psId);
       change.setStatus(Status.NEW);
       change.setLastUpdatedOn(ctx.getWhen());
       ctx.saveChange();

gerrit-server/src/main/java/com/google/gerrit/server/change/Revisions.java

@@ -26,6 +26,7 @@ import com.google.gerrit.extensions.restapi.RestView;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.RevId;
 import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.edit.ChangeEdit;
 import com.google.gerrit.server.edit.ChangeEditUtil;
 import com.google.gwtorm.server.OrmException;
@@ -42,14 +43,17 @@ public class Revisions implements ChildCollection<ChangeResource, RevisionResour
   private final DynamicMap<RestView<RevisionResource>> views;
   private final Provider<ReviewDb> dbProvider;
   private final ChangeEditUtil editUtil;
+  private final PatchSetUtil psUtil;
 
   @Inject
   Revisions(DynamicMap<RestView<RevisionResource>> views,
       Provider<ReviewDb> dbProvider,
-      ChangeEditUtil editUtil) {
+      ChangeEditUtil editUtil,
+      PatchSetUtil psUtil) {
     this.views = views;
     this.dbProvider = dbProvider;
     this.editUtil = editUtil;
+    this.psUtil = psUtil;
   }
 
   @Override
@@ -67,8 +71,7 @@ public class Revisions implements ChildCollection<ChangeResource, RevisionResour
       throws ResourceNotFoundException, AuthException, OrmException,
       IOException {
     if (id.equals("current")) {
-      PatchSet.Id p = change.getChange().currentPatchSetId();
+      PatchSet ps = psUtil.current(dbProvider.get(), change.getNotes());
-      PatchSet ps = p != null ? dbProvider.get().patchSets().get(p) : null;
       if (ps != null && visible(change, ps)) {
         return new RevisionResource(change, ps).doNotCache();
       }
@@ -123,9 +126,8 @@ public class Revisions implements ChildCollection<ChangeResource, RevisionResour
 
   private List<RevisionResource> byLegacyPatchSetId(ChangeResource change,
       String id) throws OrmException {
-    PatchSet ps = dbProvider.get().patchSets().get(new PatchSet.Id(
+    PatchSet ps = psUtil.get(dbProvider.get(), change.getNotes(),
-        change.getId(),
+        new PatchSet.Id(change.getId(), Integer.parseInt(id)));
-        Integer.parseInt(id)));
     if (ps != null) {
       return Collections.singletonList(new RevisionResource(change, ps));
     }

gerrit-server/src/main/java/com/google/gerrit/server/edit/ChangeEditUtil.java

@@ -197,6 +197,8 @@ public class ChangeEditUtil {
       int pos = ref.getName().lastIndexOf("/");
       checkArgument(pos > 0, "invalid edit ref: %s", ref.getName());
       String psId = ref.getName().substring(pos + 1);
+      // TODO(dborowitz): Use PatchSetUtil. Requires signature changes to pass
+      // in ChangeNotes.
       return db.get().patchSets().get(new PatchSet.Id(
           change.getId(), Integer.parseInt(psId)));
     } catch (OrmException | NumberFormatException e) {

gerrit-server/src/main/java/com/google/gerrit/server/git/GroupCollector.java

@@ -30,7 +30,6 @@ import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Multimaps;
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
-import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.change.RevisionResource;
@@ -82,12 +81,6 @@ public class GroupCollector {
   private static final Logger log =
       LoggerFactory.getLogger(GroupCollector.class);
 
-  public static List<String> getCurrentGroups(ReviewDb db, Change c)
-      throws OrmException {
-    PatchSet ps = db.patchSets().get(c.currentPatchSetId());
-    return ps != null ? ps.getGroups() : null;
-  }
-
   public static List<String> getDefaultGroups(PatchSet ps) {
     return ImmutableList.of(ps.getRevision().get());
   }
@@ -136,6 +129,7 @@ public class GroupCollector {
         new Lookup() {
           @Override
           public List<String> lookup(PatchSet.Id psId) throws OrmException {
+            // TODO(dborowitz): PatchSetUtil.
             PatchSet ps = db.patchSets().get(psId);
             return ps != null ? ps.getGroups() : null;
           }

gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java

@@ -1032,6 +1032,7 @@ public class MergeOp implements AutoCloseable {
       // modified when using the cherry-pick merge strategy.
       CodeReviewCommit commit = commits.get(c.getId());
       PatchSet.Id mergedId = commit.change().currentPatchSetId();
+      // TODO(dborowitz): Use PatchSetUtil after BatchUpdate migration.
       merged = db.patchSets().get(mergedId);
       c = setMergedPatchSet(c.getId(), mergedId);
       submitter = approvalsUtil.getSubmitter(db, commit.notes(), mergedId);

gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java

@@ -84,6 +84,7 @@ import com.google.gerrit.server.ApprovalsUtil;
 import com.google.gerrit.server.ChangeMessagesUtil;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.Sequences;
 import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.AccountResolver;
@@ -300,6 +301,7 @@ public class ReceiveCommits {
   private final ApprovalsUtil approvalsUtil;
   private final ApprovalCopier approvalCopier;
   private final ChangeMessagesUtil cmUtil;
+  private final PatchSetUtil psUtil;
   private final GitRepositoryManager repoManager;
   private final ProjectCache projectCache;
   private final String canonicalWebUrl;
@@ -372,6 +374,7 @@ public class ReceiveCommits {
       final ApprovalsUtil approvalsUtil,
       final ApprovalCopier approvalCopier,
       final ChangeMessagesUtil cmUtil,
+      final PatchSetUtil psUtil,
       final ProjectCache projectCache,
       final GitRepositoryManager repoManager,
       final TagCache tagCache,
@@ -419,6 +422,7 @@ public class ReceiveCommits {
     this.approvalsUtil = approvalsUtil;
     this.approvalCopier = approvalCopier;
     this.cmUtil = cmUtil;
+    this.psUtil = psUtil;
     this.projectCache = projectCache;
     this.repoManager = repoManager;
     this.canonicalWebUrl = canonicalWebUrl;
@@ -512,7 +516,7 @@ public class ReceiveCommits {
     });
     advHooks.add(rp.getAdvertiseRefsHook());
     advHooks.add(new ReceiveCommitsAdvertiseRefsHook(
-        db, queryProvider, projectControl.getProject().getNameKey()));
+        queryProvider, projectControl.getProject().getNameKey()));
     advHooks.add(new HackPushNegotiateHook());
     rp.setAdvertiseRefsHook(AdvertiseRefsHookChain.newChain(advHooks));
     rp.setPostReceiveHook(lazyPostReceive.get());
@@ -2275,7 +2279,8 @@ public class ReceiveCommits {
         }
 
         if (newPatchSet.getGroups() == null) {
-          newPatchSet.setGroups(GroupCollector.getCurrentGroups(db, change));
+          PatchSet prevPs = psUtil.current(db, update.getChangeNotes());
+          newPatchSet.setGroups(prevPs != null ? prevPs.getGroups() : null);
         }
         db.patchSets().insert(Collections.singleton(newPatchSet));
 
@@ -2705,13 +2710,14 @@ public class ReceiveCommits {
     }
   }
 
-  private Change.Key closeChange(final ReceiveCommand cmd, final PatchSet.Id psi,
+  private Change.Key closeChange(ReceiveCommand cmd, PatchSet.Id psi,
-      final RevCommit commit) throws OrmException, IOException {
+      RevCommit commit) throws OrmException, IOException {
-    final String refName = cmd.getRefName();
+    String refName = cmd.getRefName();
-    final Change.Id cid = psi.getParentKey();
+    Change.Id cid = psi.getParentKey();
 
-    final Change change = db.changes().get(cid);
+    Change change = db.changes().get(cid);
-    final PatchSet ps = db.patchSets().get(psi);
+    ChangeControl ctl = projectControl.controlFor(change);
+    PatchSet ps = psUtil.get(db, ctl.getNotes(), psi);
     if (change == null || ps == null) {
       log.warn(project.getName() + " " + psi + " is missing");
       return null;
@@ -2728,7 +2734,7 @@ public class ReceiveCommits {
 
     ReplaceRequest result = new ReplaceRequest(cid, commit, cmd, false);
     result.change = change;
-    result.changeCtl = projectControl.controlFor(change);
+    result.changeCtl = ctl;
     result.newPatchSet = ps;
     result.info = patchSetInfoFactory.get(rp.getRevWalk(), commit, psi);
     result.mergedIntoRef = refName;

gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommitsAdvertiseRefsHook.java

@@ -21,7 +21,6 @@ import com.google.common.collect.Sets;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.client.RefNames;
-import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gerrit.server.query.change.InternalChangeQuery;
 import com.google.gerrit.server.util.MagicBranch;
@@ -47,14 +46,12 @@ public class ReceiveCommitsAdvertiseRefsHook implements AdvertiseRefsHook {
   private static final Logger log = LoggerFactory
       .getLogger(ReceiveCommitsAdvertiseRefsHook.class);
 
-  private final ReviewDb db;
   private final Provider<InternalChangeQuery> queryProvider;
   private final Project.NameKey projectName;
 
-  public ReceiveCommitsAdvertiseRefsHook(ReviewDb db,
+  public ReceiveCommitsAdvertiseRefsHook(
       Provider<InternalChangeQuery> queryProvider,
       Project.NameKey projectName) {
-    this.db = db;
     this.queryProvider = queryProvider;
     this.projectName = projectName;
   }
@@ -92,22 +89,15 @@ public class ReceiveCommitsAdvertiseRefsHook implements AdvertiseRefsHook {
 
   private Set<ObjectId> advertiseOpenChanges() {
     // Advertise some recent open changes, in case a commit is based on one.
-    final int limit = 32;
+    int limit = 32;
     try {
-      Set<PatchSet.Id> toGet = Sets.newHashSetWithExpectedSize(limit);
+      Set<ObjectId> r = Sets.newHashSetWithExpectedSize(limit);
       for (ChangeData cd : queryProvider.get()
           .enforceVisibility(true)
           .setLimit(limit)
           .byProjectOpen(projectName)) {
-        PatchSet.Id id = cd.change().currentPatchSetId();
+        PatchSet ps = cd.currentPatchSet();
-        if (id != null) {
+        if (ps != null) {
-          toGet.add(id);
-        }
-      }
-
-      Set<ObjectId> r = Sets.newHashSetWithExpectedSize(toGet.size());
-      for (PatchSet ps : db.patchSets().get(toGet)) {
-        if (ps.getRevision() != null && ps.getRevision().get() != null) {
           r.add(ObjectId.fromString(ps.getRevision().get()));
         }
       }

gerrit-server/src/main/java/com/google/gerrit/server/git/strategy/CherryPick.java

@@ -28,7 +28,6 @@ import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.BatchUpdate.ChangeContext;
 import com.google.gerrit.server.git.BatchUpdate.RepoContext;
 import com.google.gerrit.server.git.CodeReviewCommit;
-import com.google.gerrit.server.git.GroupCollector;
 import com.google.gerrit.server.git.IntegrationException;
 import com.google.gerrit.server.git.MergeIdenticalTreeException;
 import com.google.gerrit.server.git.MergeTip;
@@ -167,13 +166,14 @@ public class CherryPick extends SubmitStrategy {
         // Merge conflict; don't update change.
         return;
       }
+      PatchSet prevPs = args.psUtil.current(ctx.getDb(), ctx.getNotes());
       PatchSet ps = new PatchSet(psId);
       ps.setCreatedOn(ctx.getWhen());
       ps.setUploader(args.caller.getAccountId());
       ps.setRevision(new RevId(newCommit.getId().getName()));
 
       Change c = toMerge.change();
-      ps.setGroups(GroupCollector.getCurrentGroups(args.db, c));
+      ps.setGroups(prevPs != null ? prevPs.getGroups() : null);
       args.db.patchSets().insert(Collections.singleton(ps));
       c.setCurrentPatchSet(patchSetInfo);
       ctx.saveChange();

gerrit-server/src/main/java/com/google/gerrit/server/git/strategy/RebaseIfNecessary.java

@@ -144,11 +144,11 @@ public class RebaseIfNecessary extends SubmitStrategy {
         return;
       }
 
+      // Stale read of patch set is ok; see comments in RebaseChangeOp.
+      PatchSet origPs = args.psUtil.get(
+          ctx.getDb(), toMerge.getControl().getNotes(), toMerge.getPatchsetId());
       rebaseOp = args.rebaseFactory.create(
-            toMerge.getControl(),
+            toMerge.getControl(), origPs, mergeTip.getCurrentTip().name())
-            // Racy read of patch set is ok; see comments in RebaseChangeOp.
-            args.db.patchSets().get(toMerge.getPatchsetId()),
-            mergeTip.getCurrentTip().name())
           .setRunHooks(false)
           // Bypass approval copier since we're going to copy all approvals
           // later anyway.

gerrit-server/src/main/java/com/google/gerrit/server/git/strategy/SubmitStrategy.java

@@ -23,6 +23,7 @@ import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.ApprovalsUtil;
 import com.google.gerrit.server.GerritPersonIdent;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.change.RebaseChangeOp;
 import com.google.gerrit.server.git.BatchUpdate;
 import com.google.gerrit.server.git.CodeReviewCommit;
@@ -84,6 +85,7 @@ public abstract class SubmitStrategy {
     final BatchUpdate.Factory batchUpdateFactory;
     final ChangeControl.GenericFactory changeControlFactory;
     final PatchSetInfoFactory patchSetInfoFactory;
+    final PatchSetUtil psUtil;
     final ProjectCache projectCache;
     final PersonIdent serverIdent;
     final RebaseChangeOp.Factory rebaseFactory;
@@ -109,6 +111,7 @@ public abstract class SubmitStrategy {
         ChangeControl.GenericFactory changeControlFactory,
         MergeUtil.Factory mergeUtilFactory,
         PatchSetInfoFactory patchSetInfoFactory,
+        PatchSetUtil psUtil,
         @GerritPersonIdent PersonIdent serverIdent,
         ProjectCache projectCache,
         RebaseChangeOp.Factory rebaseFactory,
@@ -125,6 +128,7 @@ public abstract class SubmitStrategy {
       this.batchUpdateFactory = batchUpdateFactory;
       this.changeControlFactory = changeControlFactory;
       this.patchSetInfoFactory = patchSetInfoFactory;
+      this.psUtil = psUtil;
       this.projectCache = projectCache;
       this.rebaseFactory = rebaseFactory;
 

gerrit-server/src/main/java/com/google/gerrit/server/mail/ChangeEmail.java

@@ -140,7 +140,7 @@ public abstract class ChangeEmail extends NotificationEmail {
 
     if (patchSet == null) {
       try {
-        patchSet = args.db.get().patchSets().get(change.currentPatchSetId());
+        patchSet = changeData.currentPatchSet();
       } catch (OrmException err) {
         patchSet = null;
       }

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchScriptFactory.java

@@ -14,6 +14,8 @@
 
 package com.google.gerrit.server.patch;
 
+import static com.google.common.base.Preconditions.checkArgument;
+
 import com.google.common.base.Optional;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.CommentDetail;
@@ -31,6 +33,7 @@ import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.PatchLineCommentsUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.account.AccountInfoCacheFactory;
 import com.google.gerrit.server.edit.ChangeEdit;
 import com.google.gerrit.server.edit.ChangeEditUtil;
@@ -73,6 +76,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
       LoggerFactory.getLogger(PatchScriptFactory.class);
 
   private final GitRepositoryManager repoManager;
+  private final PatchSetUtil psUtil;
   private final Provider<PatchScriptBuilder> builderFactory;
   private final PatchListCache patchListCache;
   private final ReviewDb db;
@@ -100,10 +104,12 @@ public class PatchScriptFactory implements Callable<PatchScript> {
   private CommentDetail comments;
 
   @Inject
-  PatchScriptFactory(final GitRepositoryManager grm,
+  PatchScriptFactory(GitRepositoryManager grm,
+      PatchSetUtil psUtil,
       Provider<PatchScriptBuilder> builderFactory,
-      final PatchListCache patchListCache, final ReviewDb db,
+      PatchListCache patchListCache,
-      final AccountInfoCacheFactory.Factory aicFactory,
+      ReviewDb db,
+      AccountInfoCacheFactory.Factory aicFactory,
       PatchLineCommentsUtil plcUtil,
       ChangeEditUtil editReader,
       @Assisted ChangeControl control,
@@ -112,6 +118,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
       @Assisted("patchSetB") final PatchSet.Id patchSetB,
       @Assisted DiffPreferencesInfo diffPrefs) {
     this.repoManager = grm;
+    this.psUtil = psUtil;
     this.builderFactory = builderFactory;
     this.patchListCache = patchListCache;
     this.db = db;
@@ -126,6 +133,10 @@ public class PatchScriptFactory implements Callable<PatchScript> {
     this.diffPrefs = diffPrefs;
 
     changeId = patchSetB.getParentKey();
+    checkArgument(
+        patchSetA == null || patchSetA.getParentKey().equals(changeId),
+        "cannot compare PatchSets from different changes: %s and %s",
+        patchSetA, patchSetB);
   }
 
   public void setLoadHistory(boolean load) {
@@ -146,11 +157,15 @@ public class PatchScriptFactory implements Callable<PatchScript> {
     change = control.getChange();
     project = change.getProject();
 
-    aId = psa != null ? toObjectId(db, psa) : null;
+    PatchSet psEntityA = psa != null
-    bId = toObjectId(db, psb);
+        ? psUtil.get(db, control.getNotes(), psa) : null;
+    PatchSet psEntityB = psUtil.get(db, control.getNotes(), psb);
 
-    if ((psa != null && !control.isPatchVisible(db.patchSets().get(psa), db)) ||
+    aId = psEntityA != null ? toObjectId(psEntityA) : null;
-        (psb != null && !control.isPatchVisible(db.patchSets().get(psb), db))) {
+    bId = toObjectId(psEntityB);
+
+    if ((psEntityA != null && !control.isPatchVisible(psEntityA, db)) ||
+        (psEntityB != null && !control.isPatchVisible(psEntityB, db))) {
       throw new NoSuchChangeException(changeId);
     }
 
@@ -160,8 +175,9 @@ public class PatchScriptFactory implements Callable<PatchScript> {
         final PatchScriptBuilder b = newBuilder(list, git);
         final PatchListEntry content = list.get(fileName);
 
-        loadCommentsAndHistory(content.getChangeType(), //
+        loadCommentsAndHistory(control.getNotes(),
-            content.getOldName(), //
+            content.getChangeType(),
+            content.getOldName(),
             content.getNewName());
 
         return b.toPatchScript(content, comments, history);
@@ -200,26 +216,20 @@ public class PatchScriptFactory implements Callable<PatchScript> {
     return b;
   }
 
-  private ObjectId toObjectId(final ReviewDb db, final PatchSet.Id psId)
+  private ObjectId toObjectId(PatchSet ps) throws NoSuchChangeException,
-      throws OrmException, NoSuchChangeException, AuthException,
+      AuthException, NoSuchChangeException, IOException {
-      NoSuchChangeException, IOException {
-    if (!changeId.equals(psId.getParentKey())) {
-      throw new NoSuchChangeException(changeId);
-    }
-
-    if (psId.get() == 0) {
-      return getEditRev();
-    }
-    PatchSet ps = db.patchSets().get(psId);
     if (ps == null || ps.getRevision() == null
         || ps.getRevision().get() == null) {
       throw new NoSuchChangeException(changeId);
     }
+    if (ps.getId().get() == 0) {
+      return getEditRev();
+    }
 
     try {
       return ObjectId.fromString(ps.getRevision().get());
     } catch (IllegalArgumentException e) {
-      log.error("Patch set " + psId + " has invalid revision");
+      log.error("Patch set " + ps.getId() + " has invalid revision");
       throw new NoSuchChangeException(changeId, e);
     }
   }
@@ -242,9 +252,9 @@ public class PatchScriptFactory implements Callable<PatchScript> {
     }
   }
 
-  private void loadCommentsAndHistory(final ChangeType changeType,
+  private void loadCommentsAndHistory(ChangeNotes notes, ChangeType changeType,
-      final String oldName, final String newName) throws OrmException {
+      String oldName, String newName) throws OrmException {
-    final Map<Patch.Key, Patch> byKey = new HashMap<>();
+    Map<Patch.Key, Patch> byKey = new HashMap<>();
 
     if (loadHistory) {
       // This seems like a cheap trick. It doesn't properly account for a
@@ -253,7 +263,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
       // proper rename detection between the patch sets.
       //
       history = new ArrayList<>();
-      for (final PatchSet ps : db.patchSets().byChange(changeId)) {
+      for (PatchSet ps : psUtil.byChange(db, notes)) {
         if (!control.isPatchVisible(ps, db)) {
           continue;
         }
@@ -275,12 +285,12 @@ public class PatchScriptFactory implements Callable<PatchScript> {
           }
         }
 
-        final Patch p = new Patch(new Patch.Key(ps.getId(), name));
+        Patch p = new Patch(new Patch.Key(ps.getId(), name));
         history.add(p);
         byKey.put(p.getKey(), p);
       }
       if (edit != null && edit.isPresent()) {
-        final Patch p = new Patch(new Patch.Key(
+        Patch p = new Patch(new Patch.Key(
             new PatchSet.Id(psb.getParentKey(), 0), fileName));
         history.add(p);
         byKey.put(p.getKey(), p);
@@ -288,7 +298,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
     }
 
     if (loadComments && edit == null) {
-      final AccountInfoCacheFactory aic = aicFactory.create();
+      AccountInfoCacheFactory aic = aicFactory.create();
       comments = new CommentDetail(psa, psb);
       switch (changeType) {
         case ADDED:
@@ -312,9 +322,9 @@ public class PatchScriptFactory implements Callable<PatchScript> {
           break;
       }
 
-      final CurrentUser user = control.getUser();
+      CurrentUser user = control.getUser();
       if (user.isIdentifiedUser()) {
-        final Account.Id me = user.getAccountId();
+        Account.Id me = user.getAccountId();
         switch (changeType) {
           case ADDED:
           case MODIFIED:

gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeData.java

@@ -40,6 +40,7 @@ import com.google.gerrit.server.ChangeMessagesUtil;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.PatchLineCommentsUtil;
+import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.change.MergeabilityCache;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.git.MergeUtil;
@@ -137,6 +138,7 @@ public class ChangeData {
       for (ChangeData cd : changes) {
         cd.patchSets();
       }
+      return;
     }
 
     List<ResultSet<PatchSet>> results = new ArrayList<>(BATCH_SIZE);
@@ -167,6 +169,7 @@ public class ChangeData {
       for (ChangeData cd : changes) {
         cd.currentPatchSet();
       }
+      return;
     }
 
     Map<PatchSet.Id, ChangeData> missing = Maps.newHashMap();
@@ -192,6 +195,7 @@ public class ChangeData {
       for (ChangeData cd : changes) {
         cd.currentApprovals();
       }
+      return;
     }
 
     List<ResultSet<PatchSetApproval>> results = new ArrayList<>(BATCH_SIZE);
@@ -281,7 +285,7 @@ public class ChangeData {
    */
   public static ChangeData createForTest(Change.Id id, int currentPatchSetId) {
     ChangeData cd = new ChangeData(null, null, null, null, null, null, null,
-        null, null, null, null, null, null, id);
+        null, null, null, null, null, null, null, id);
     cd.currentPatchSet = new PatchSet(new PatchSet.Id(id, currentPatchSetId));
     return cd;
   }
@@ -296,6 +300,7 @@ public class ChangeData {
   private final ApprovalsUtil approvalsUtil;
   private final ChangeMessagesUtil cmUtil;
   private final PatchLineCommentsUtil plcUtil;
+  private final PatchSetUtil psUtil;
   private final PatchListCache patchListCache;
   private final NotesMigration notesMigration;
   private final MergeabilityCache mergeabilityCache;
@@ -306,7 +311,7 @@ public class ChangeData {
   private String commitMessage;
   private List<FooterLine> commitFooters;
   private PatchSet currentPatchSet;
-  private Collection<PatchSet> patchSets;
+  private List<PatchSet> patchSets;
   private ListMultimap<PatchSet.Id, PatchSetApproval> allApprovals;
   private List<PatchSetApproval> currentApprovals;
   private Map<Integer, List<String>> files = new HashMap<>();
@@ -335,6 +340,7 @@ public class ChangeData {
       ApprovalsUtil approvalsUtil,
       ChangeMessagesUtil cmUtil,
       PatchLineCommentsUtil plcUtil,
+      PatchSetUtil psUtil,
       PatchListCache patchListCache,
       NotesMigration notesMigration,
       MergeabilityCache mergeabilityCache,
@@ -350,6 +356,7 @@ public class ChangeData {
     this.approvalsUtil = approvalsUtil;
     this.cmUtil = cmUtil;
     this.plcUtil = plcUtil;
+    this.psUtil = psUtil;
     this.patchListCache = patchListCache;
     this.notesMigration = notesMigration;
     this.mergeabilityCache = mergeabilityCache;
@@ -367,6 +374,7 @@ public class ChangeData {
       ApprovalsUtil approvalsUtil,
       ChangeMessagesUtil cmUtil,
       PatchLineCommentsUtil plcUtil,
+      PatchSetUtil psUtil,
       PatchListCache patchListCache,
       NotesMigration notesMigration,
       MergeabilityCache mergeabilityCache,
@@ -382,6 +390,7 @@ public class ChangeData {
     this.approvalsUtil = approvalsUtil;
     this.cmUtil = cmUtil;
     this.plcUtil = plcUtil;
+    this.psUtil = psUtil;
     this.patchListCache = patchListCache;
     this.notesMigration = notesMigration;
     this.mergeabilityCache = mergeabilityCache;
@@ -400,6 +409,7 @@ public class ChangeData {
       ApprovalsUtil approvalsUtil,
       ChangeMessagesUtil cmUtil,
       PatchLineCommentsUtil plcUtil,
+      PatchSetUtil psUtil,
       PatchListCache patchListCache,
       NotesMigration notesMigration,
       MergeabilityCache mergeabilityCache,
@@ -415,6 +425,7 @@ public class ChangeData {
     this.approvalsUtil = approvalsUtil;
     this.cmUtil = cmUtil;
     this.plcUtil = plcUtil;
+    this.psUtil = psUtil;
     this.patchListCache = patchListCache;
     this.notesMigration = notesMigration;
     this.mergeabilityCache = mergeabilityCache;
@@ -684,15 +695,14 @@ public class ChangeData {
    * @return patches for the change.
    * @throws OrmException an error occurred reading the database.
    */
-  public Collection<PatchSet> patchSets()
+  public List<PatchSet> patchSets() throws OrmException {
-      throws OrmException {
     if (patchSets == null) {
-      patchSets = db.patchSets().byChange(legacyId).toList();
+      patchSets = psUtil.byChange(db, notes());
     }
     return patchSets;
   }
 
-  public void setPatchSets(Collection<PatchSet> patchSets) {
+  public void setPatchSets(List<PatchSet> patchSets) {
     this.currentPatchSet = null;
     this.patchSets = patchSets;
   }

gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/CommandUtils.java

@@ -78,6 +78,8 @@ public class CommandUtils {
       } catch (IllegalArgumentException e) {
         throw error("\"" + patchIdentity + "\" is not a valid patch set");
       }
+      // TODO(dborowitz): Use PatchSetUtils; probably requires a non-static
+      // implementation.
       PatchSet patchSet = db.patchSets().get(patchSetId);
       if (patchSet == null) {
         throw error("\"" + patchIdentity + "\" no such patch set");