diff --git a/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java b/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
index 482868c..47de0b6 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
@@ -36,7 +36,6 @@
 import com.google.gerrit.elasticsearch.bulk.DeleteRequest;
 import com.google.gerrit.entities.converter.ProtoConverter;
 import com.google.gerrit.exceptions.StorageException;
-import com.google.gerrit.index.FieldDef;
 import com.google.gerrit.index.FieldType;
 import com.google.gerrit.index.Index;
 import com.google.gerrit.index.QueryOptions;
@@ -246,13 +245,12 @@
   protected abstract V fromDocument(JsonObject doc, Set<String> fields);
 
   protected FieldBundle toFieldBundle(JsonObject doc) {
-    Map<String, FieldDef<V, ?>> allFields = getSchema().getFields();
     ListMultimap<String, Object> rawFields = ArrayListMultimap.create();
     for (Map.Entry<String, JsonElement> element :
         doc.get(client.adapter().rawFieldsKey()).getAsJsonObject().entrySet()) {
       checkArgument(
-          allFields.containsKey(element.getKey()), "Unrecognized field " + element.getKey());
-      FieldType<?> type = allFields.get(element.getKey()).getType();
+          getSchema().hasField(element.getKey()), "Unrecognized field " + element.getKey());
+      FieldType<?> type = getSchema().getSchemaField(element.getKey()).getType();
       Iterable<JsonElement> innerItems =
           element.getValue().isJsonArray()
               ? element.getValue().getAsJsonArray()
diff --git a/src/main/java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java b/src/main/java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java
index 1e94148..012e97c 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java
@@ -93,15 +93,14 @@
   @Override
   public DataSource<AccountState> getSource(Predicate<AccountState> p, QueryOptions opts)
       throws QueryParseException {
+    boolean useLegacyNumericFields = schema.hasField(AccountField.ID_FIELD_SPEC);
     JsonArray sortArray =
         getSortArray(
-            schema.useLegacyNumericFields()
-                ? AccountField.ID.getName()
-                : AccountField.ID_STR.getName());
+            useLegacyNumericFields
+                ? AccountField.ID_FIELD_SPEC.getName()
+                : AccountField.ID_STR_FIELD_SPEC.getName());
     return new ElasticQuerySource(
-        p,
-        opts.filterFields(o -> IndexUtils.accountFields(o, schema.useLegacyNumericFields())),
-        sortArray);
+        p, opts.filterFields(o -> IndexUtils.accountFields(o, useLegacyNumericFields)), sortArray);
   }
 
   @Override
@@ -131,9 +130,9 @@
             source
                 .getAsJsonObject()
                 .get(
-                    schema.useLegacyNumericFields()
-                        ? AccountField.ID.getName()
-                        : AccountField.ID_STR.getName())
+                    schema.hasField(AccountField.ID_FIELD_SPEC)
+                        ? AccountField.ID_FIELD_SPEC.getName()
+                        : AccountField.ID_STR_FIELD_SPEC.getName())
                 .getAsInt());
     // Use the AccountCache rather than depending on any stored fields in the document (of which
     // there shouldn't be any). The most expensive part to compute anyway is the effective group
diff --git a/src/main/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java b/src/main/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
index 8504e16..7b97d8a 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
@@ -25,9 +25,9 @@
 import com.google.gerrit.entities.Project;
 import com.google.gerrit.entities.converter.ChangeProtoConverter;
 import com.google.gerrit.exceptions.StorageException;
-import com.google.gerrit.index.FieldDef;
 import com.google.gerrit.index.QueryOptions;
 import com.google.gerrit.index.Schema;
+import com.google.gerrit.index.SchemaFieldDefs.SchemaField;
 import com.google.gerrit.index.query.DataSource;
 import com.google.gerrit.index.query.Predicate;
 import com.google.gerrit.index.query.QueryParseException;
@@ -70,7 +70,6 @@
   private final ChangeMapping mapping;
   private final ChangeData.Factory changeDataFactory;
   private final Schema<ChangeData> schema;
-  private final FieldDef<ChangeData, ?> idField;
   private final ImmutableSet<String> skipFields;
 
   @Inject
@@ -86,8 +85,6 @@
     this.changeDataFactory = changeDataFactory;
     this.schema = schema;
     this.mapping = new ChangeMapping(schema, client.adapter());
-    this.idField =
-        this.schema.useLegacyNumericFields() ? ChangeField.LEGACY_ID : ChangeField.LEGACY_ID_STR;
     this.skipFields =
         MergeabilityComputationBehavior.fromConfig(gerritConfig).includeInIndex()
             ? ImmutableSet.of()
@@ -112,8 +109,7 @@
   @Override
   public DataSource<ChangeData> getSource(Predicate<ChangeData> p, QueryOptions opts)
       throws QueryParseException {
-    QueryOptions filteredOpts =
-        opts.filterFields(o -> IndexUtils.changeFields(o, schema.useLegacyNumericFields()));
+    QueryOptions filteredOpts = opts.filterFields(o -> IndexUtils.changeFields(o));
     return new ElasticQuerySource(p, filteredOpts, getSortArray());
   }
 
@@ -124,7 +120,7 @@
     JsonArray sortArray = new JsonArray();
     addNamedElement(ChangeField.UPDATED.getName(), properties, sortArray);
     addNamedElement(ChangeField.MERGED_ON.getName(), getMergedOnSortOptions(), sortArray);
-    addNamedElement(idField.getName(), properties, sortArray);
+    addNamedElement(ChangeField.LEGACY_ID_STR.getName(), properties, sortArray);
     return sortArray;
   }
 
@@ -162,7 +158,7 @@
     JsonElement c = source.get(ChangeField.CHANGE.getName());
 
     if (c == null) {
-      int id = source.get(idField.getName()).getAsInt();
+      int id = source.get(ChangeField.LEGACY_ID_STR.getName()).getAsInt();
       // IndexUtils#changeFields ensures either CHANGE or PROJECT is always present.
       String projectName = requireNonNull(source.get(ChangeField.PROJECT.getName()).getAsString());
       return changeDataFactory.create(Project.nameKey(projectName), Change.id(id));
@@ -172,7 +168,7 @@
         changeDataFactory.create(
             parseProtoFrom(decodeBase64(c.getAsString()), ChangeProtoConverter.INSTANCE));
 
-    for (FieldDef<ChangeData, ?> field : getSchema().getFields().values()) {
+    for (SchemaField<ChangeData, ?> field : getSchema().getSchemaFields().values()) {
       if (fields.contains(field.getName()) && source.get(field.getName()) != null) {
         field.setIfPossible(cd, new ElasticStoredValue(source.get(field.getName())));
       }
diff --git a/src/main/java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java b/src/main/java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java
index e0b337e..863e893 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java
@@ -93,7 +93,7 @@
   @Override
   public DataSource<InternalGroup> getSource(Predicate<InternalGroup> p, QueryOptions opts)
       throws QueryParseException {
-    JsonArray sortArray = getSortArray(GroupField.UUID.getName());
+    JsonArray sortArray = getSortArray(GroupField.UUID_FIELD_SPEC.getName());
     return new ElasticQuerySource(p, opts.filterFields(IndexUtils::groupFields), sortArray);
   }
 
@@ -120,7 +120,8 @@
     }
 
     AccountGroup.UUID uuid =
-        AccountGroup.uuid(source.getAsJsonObject().get(GroupField.UUID.getName()).getAsString());
+        AccountGroup.uuid(
+            source.getAsJsonObject().get(GroupField.UUID_FIELD_SPEC.getName()).getAsString());
     // Use the GroupCache rather than depending on any stored fields in the
     // document (of which there shouldn't be any).
     return groupCache.get().get(uuid).orElse(null);
diff --git a/src/main/java/com/google/gerrit/elasticsearch/ElasticMapping.java b/src/main/java/com/google/gerrit/elasticsearch/ElasticMapping.java
index 9ea9fcb..48cb10a 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/ElasticMapping.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/ElasticMapping.java
@@ -15,9 +15,9 @@
 package com.google.gerrit.elasticsearch;
 
 import com.google.common.collect.ImmutableMap;
-import com.google.gerrit.index.FieldDef;
 import com.google.gerrit.index.FieldType;
 import com.google.gerrit.index.Schema;
+import com.google.gerrit.index.SchemaFieldDefs.SchemaField;
 import com.google.gson.annotations.SerializedName;
 import java.util.Map;
 
@@ -28,7 +28,7 @@
 
   static Mapping createMapping(Schema<?> schema, ElasticQueryAdapter adapter) {
     ElasticMapping.Builder mapping = new ElasticMapping.Builder(adapter);
-    for (FieldDef<?, ?> field : schema.getFields().values()) {
+    for (SchemaField<?, ?> field : schema.getSchemaFields().values()) {
       String name = field.getName();
       FieldType<?> fieldType = field.getType();
       if (fieldType == FieldType.EXACT) {
@@ -50,7 +50,7 @@
       }
     }
     mapping.addSourceIncludes(
-        schema.getFields().values().stream()
+        schema.getSchemaFields().values().stream()
             .filter(f -> f.isStored())
             .map(f -> f.getName())
             .toArray(String[]::new));
diff --git a/src/main/java/com/google/gerrit/elasticsearch/ElasticQueryBuilder.java b/src/main/java/com/google/gerrit/elasticsearch/ElasticQueryBuilder.java
index 3580089..df28dcc 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/ElasticQueryBuilder.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/ElasticQueryBuilder.java
@@ -17,8 +17,8 @@
 import com.google.gerrit.elasticsearch.builders.BoolQueryBuilder;
 import com.google.gerrit.elasticsearch.builders.QueryBuilder;
 import com.google.gerrit.elasticsearch.builders.QueryBuilders;
-import com.google.gerrit.index.FieldDef;
 import com.google.gerrit.index.FieldType;
+import com.google.gerrit.index.SchemaFieldDefs.SchemaField;
 import com.google.gerrit.index.query.AndPredicate;
 import com.google.gerrit.index.query.IndexPredicate;
 import com.google.gerrit.index.query.IntegerRangePredicate;
@@ -79,7 +79,7 @@
 
   private <T> QueryBuilder fieldQuery(IndexPredicate<T> p) throws QueryParseException {
     FieldType<?> type = p.getType();
-    FieldDef<?, ?> field = p.getField();
+    SchemaField<?, ?> field = p.getField();
     String name = field.getName();
     String value = p.getValue();
 
diff --git a/src/main/java/com/google/gerrit/elasticsearch/ElasticStoredValue.java b/src/main/java/com/google/gerrit/elasticsearch/ElasticStoredValue.java
index a02a715..bd7c1c3 100644
--- a/src/main/java/com/google/gerrit/elasticsearch/ElasticStoredValue.java
+++ b/src/main/java/com/google/gerrit/elasticsearch/ElasticStoredValue.java
@@ -18,6 +18,7 @@
 
 import com.google.gerrit.index.StoredValue;
 import com.google.gson.JsonElement;
+import com.google.protobuf.MessageLite;
 import java.sql.Timestamp;
 import java.time.Instant;
 import java.time.format.DateTimeFormatter;
@@ -83,4 +84,16 @@
         .map(f -> AbstractElasticIndex.decodeBase64(f.getAsString()))
         .collect(toImmutableList());
   }
+
+  @Override
+  public MessageLite asProto() {
+    // Elasticsearch does not store protos
+    return null;
+  }
+
+  @Override
+  public Iterable<MessageLite> asProtos() {
+    // Elasticsearch does not store protos
+    return null;
+  }
 }