From 9b120a0b484a2df3091dc5dc150cb9edb2fd4f71 Mon Sep 17 00:00:00 2001
From: Yanjun Huang <yanjun@yahoo.com>
Date: Fri, 18 Mar 2016 17:36:40 -0700
Subject: [PATCH] Add total number of fields limit to index mapping

This is to prevent mapping explosion when dynamic keys such as UUID are used as field names. index.mapping.total_fields.limit specifies the total number of fields an index can have. An exception will be thrown when the limit is reached. The default limit is 500. Setting the limit to 0 will disable the checking. This setting is runtime adjustable.
---
 .../common/settings/IndexScopedSettings.java             | 1 +
 .../org/elasticsearch/index/mapper/MapperService.java    | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/core/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java b/core/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java
index b8b751477408a..b5bdccd3b14de 100644
--- a/core/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java
+++ b/core/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java
@@ -127,6 +127,7 @@ public final class IndexScopedSettings extends AbstractScopedSettings {
         PercolatorQueriesRegistry.INDEX_MAP_UNMAPPED_FIELDS_AS_STRING_SETTING,
         MapperService.INDEX_MAPPER_DYNAMIC_SETTING,
         MapperService.INDEX_MAPPING_NESTED_FIELDS_LIMIT_SETTING,
+        MapperService.INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING,
         BitsetFilterCache.INDEX_LOAD_RANDOM_ACCESS_FILTERS_EAGERLY_SETTING,
         IndexModule.INDEX_STORE_TYPE_SETTING,
         IndexModule.INDEX_QUERY_CACHE_TYPE_SETTING,
diff --git a/core/src/main/java/org/elasticsearch/index/mapper/MapperService.java b/core/src/main/java/org/elasticsearch/index/mapper/MapperService.java
index b25f5f6a02dfd..bc5b68ef499d2 100755
--- a/core/src/main/java/org/elasticsearch/index/mapper/MapperService.java
+++ b/core/src/main/java/org/elasticsearch/index/mapper/MapperService.java
@@ -82,6 +82,7 @@ public enum MergeReason {
 
     public static final String DEFAULT_MAPPING = "_default_";
     public static final Setting<Long> INDEX_MAPPING_NESTED_FIELDS_LIMIT_SETTING = Setting.longSetting("index.mapping.nested_fields.limit", 50L, 0, true, Setting.Scope.INDEX);
+    public static final Setting<Long> INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING = Setting.longSetting("index.mapping.total_fields.limit", 500L, 0, true, Setting.Scope.INDEX);
     public static final boolean INDEX_MAPPER_DYNAMIC_DEFAULT = true;
     public static final Setting<Boolean> INDEX_MAPPER_DYNAMIC_SETTING = Setting.boolSetting("index.mapper.dynamic", INDEX_MAPPER_DYNAMIC_DEFAULT, false, Setting.Scope.INDEX);
     private static ObjectHashSet<String> META_FIELDS = ObjectHashSet.from(
@@ -281,6 +282,7 @@ private synchronized DocumentMapper merge(DocumentMapper mapper, MergeReason rea
 
         if (reason == MergeReason.MAPPING_UPDATE) {
             checkNestedFieldsLimit(fullPathObjectMappers);
+            checkTotalFieldsLimit(objectMappers.size() + fieldMappers.size());
         }
 
         Set<String> parentTypes = this.parentTypes;
@@ -400,6 +402,13 @@ private void checkNestedFieldsLimit(Map<String, ObjectMapper> fullPathObjectMapp
         }
     }
 
+    private void checkTotalFieldsLimit(long totalMappers) {
+        long allowedTotalFields = indexSettings.getValue(INDEX_MAPPING_TOTAL_FIELDS_LIMIT_SETTING);
+        if (allowedTotalFields > 0 && allowedTotalFields < totalMappers) {
+            throw new IllegalArgumentException("Limit of total fields [" + allowedTotalFields + "] in index [" + index().getName() + "] has been exceeded");
+        }
+    }
+
     public DocumentMapper parse(String mappingType, CompressedXContent mappingSource, boolean applyDefault) throws MapperParsingException {
         String defaultMappingSource;
         if (PercolatorService.TYPE_NAME.equals(mappingType)) {