Sanity checks for MergeTreeSettings

programs/server/Server.cpp

@@ -641,6 +641,9 @@ int Server::main(const std::vector<std::string> & /*args*/)
     global_context->setFormatSchemaPath(format_schema_path.path());
     format_schema_path.createDirectories();
 
+    /// Check sanity of MergeTreeSettings on server startup
+    global_context->getMergeTreeSettings().sanityCheck(settings);
+
     /// Limit on total memory usage
     size_t max_server_memory_usage = config().getUInt64("max_server_memory_usage", 0);
 

src/Storages/MergeTree/MergeTreeData.cpp

@@ -147,6 +147,10 @@ MergeTreeData::MergeTreeData(
     if (relative_data_path.empty())
         throw Exception("MergeTree storages require data path", ErrorCodes::INCORRECT_FILE_NAME);
 
+    /// Check sanity of MergeTreeSettings. Only when table is created.
+    if (!attach)
+        settings->sanityCheck(global_context.getSettingsRef());
+
     MergeTreeDataFormatVersion min_format_version(0);
     if (!date_column_name.empty())
     {

src/Storages/MergeTree/MergeTreeSettings.cpp

@@ -76,4 +76,31 @@ void MergeTreeSettings::loadFromQuery(ASTStorage & storage_def)
 #undef ADD_IF_ABSENT
 }
 
+void MergeTreeSettings::sanityCheck(const Settings & query_settings) const
+{
+    if (number_of_free_entries_in_pool_to_execute_mutation >= query_settings.background_pool_size)
+    {
+        throw Exception(ErrorCodes::BAD_ARGUMENTS, "The value of 'number_of_free_entries_in_pool_to_execute_mutation' setting"
+            " ({}) (default values are defined in <merge_tree> section of config.xml"
+            " or the value can be specified per table in SETTINGS section of CREATE TABLE query)"
+            " is greater or equals to the value of 'background_pool_size'"
+            " ({}) (the value is defined in users.xml for default profile)."
+            " This indicates incorrect configuration because mutations cannot work with these settings.",
+            number_of_free_entries_in_pool_to_execute_mutation,
+            query_settings.background_pool_size);
+    }
+
+    if (number_of_free_entries_in_pool_to_lower_max_size_of_merge >= query_settings.background_pool_size)
+    {
+        throw Exception(ErrorCodes::BAD_ARGUMENTS, "The value of 'number_of_free_entries_in_pool_to_lower_max_size_of_merge' setting"
+            " ({}) (default values are defined in <merge_tree> section of config.xml"
+            " or the value can be specified per table in SETTINGS section of CREATE TABLE query)"
+            " is greater or equals to the value of 'background_pool_size'"
+            " ({}) (the value is defined in users.xml for default profile)."
+            " This indicates incorrect configuration because the maximum size of merge will be always lowered.",
+            number_of_free_entries_in_pool_to_execute_mutation,
+            query_settings.background_pool_size);
+    }
+}
+
 }

src/Storages/MergeTree/MergeTreeSettings.h

@@ -18,6 +18,7 @@ namespace DB
 {
 
 class ASTStorage;
+struct Settings;
 
 /** Settings for the MergeTree family of engines.
   * Could be loaded from config or from a CREATE TABLE query (SETTINGS clause).
@@ -127,6 +128,9 @@ struct MergeTreeSettings : public SettingsCollection<MergeTreeSettings>
         return name == "min_bytes_for_wide_part" || name == "min_rows_for_wide_part"
             || name == "min_bytes_for_compact_part" || name == "min_rows_for_compact_part";
     }
+
+    /// Check that the values are sane taking also query-level settings into account.
+    void sanityCheck(const Settings & query_settings) const;
 };
 
 using MergeTreeSettingsPtr = std::shared_ptr<const MergeTreeSettings>;

tests/queries/0_stateless/01419_merge_tree_settings_sanity_check.sql

@@ -0,0 +1,21 @@
+CREATE TABLE mytable_local
+(
+    created          DateTime,
+    eventday         Date,
+    user_id          UInt32
+)
+ENGINE = MergeTree()
+PARTITION BY toYYYYMM(eventday)
+ORDER BY (eventday, user_id)
+SETTINGS number_of_free_entries_in_pool_to_execute_mutation = 100; -- { serverError 36 }
+
+CREATE TABLE mytable_local
+(
+    created          DateTime,
+    eventday         Date,
+    user_id          UInt32
+)
+ENGINE = MergeTree()
+PARTITION BY toYYYYMM(eventday)
+ORDER BY (eventday, user_id)
+SETTINGS number_of_free_entries_in_pool_to_lower_max_size_of_merge = 100; -- { serverError 36 }