diff --git a/src/Storages/IStorage.h b/src/Storages/IStorage.h
index 1309b727a74..eb69264c6c8 100644
--- a/src/Storages/IStorage.h
+++ b/src/Storages/IStorage.h
@@ -138,7 +138,9 @@ public:
 public:
 
     StorageInMemoryMetadata getInMemoryMetadata() const { return *metadata.get(); }
+
     StorageMetadataPtr getInMemoryMetadataPtr() const { return metadata.get(); }
+
     void setInMemoryMetadata(const StorageInMemoryMetadata & metadata_)
     {
         metadata.set(std::make_unique<StorageInMemoryMetadata>(metadata_));
diff --git a/src/Storages/MergeTree/MergeTreeData.cpp b/src/Storages/MergeTree/MergeTreeData.cpp
index 72937bd7102..dfc7636b3e4 100644
--- a/src/Storages/MergeTree/MergeTreeData.cpp
+++ b/src/Storages/MergeTree/MergeTreeData.cpp
@@ -118,7 +118,7 @@ const char * DELETE_ON_DESTROY_MARKER_PATH = "delete-on-destroy.txt";
 MergeTreeData::MergeTreeData(
     const StorageID & table_id_,
     const String & relative_data_path_,
-    StorageInMemoryMetadata metadata_,
+    const StorageInMemoryMetadata & metadata_,
     Context & context_,
     const String & date_column_name,
     const MergingParams & merging_params_,
@@ -143,15 +143,11 @@ MergeTreeData::MergeTreeData(
         throw Exception("MergeTree storages require data path", ErrorCodes::INCORRECT_FILE_NAME);
 
     MergeTreeDataFormatVersion min_format_version(0);
-    /// TODO(alesap) Move to register methods
     if (!date_column_name.empty())
     {
         try
         {
-            auto partition_by_ast = makeASTFunction("toYYYYMM", std::make_shared<ASTIdentifier>(date_column_name));
-            metadata_.partition_key = KeyDescription::getKeyFromAST(partition_by_ast, metadata_.columns, global_context);
             initPartitionKey(metadata_.partition_key);
-
             if (minmax_idx_date_column_pos == -1)
                 throw Exception("Could not find Date column", ErrorCodes::BAD_TYPE_OF_FIELD);
         }
diff --git a/src/Storages/MergeTree/MergeTreeData.h b/src/Storages/MergeTree/MergeTreeData.h
index 2e6c0bfc903..c6721658d78 100644
--- a/src/Storages/MergeTree/MergeTreeData.h
+++ b/src/Storages/MergeTree/MergeTreeData.h
@@ -324,7 +324,7 @@ public:
     /// attach - whether the existing table is attached or the new table is created.
     MergeTreeData(const StorageID & table_id_,
                   const String & relative_data_path_,
-                  StorageInMemoryMetadata metadata_,
+                  const StorageInMemoryMetadata & metadata_,
                   Context & context_,
                   const String & date_column_name,
                   const MergingParams & merging_params_,
diff --git a/src/Storages/MergeTree/registerStorageMergeTree.cpp b/src/Storages/MergeTree/registerStorageMergeTree.cpp
index 98884de985e..1ecac8f413d 100644
--- a/src/Storages/MergeTree/registerStorageMergeTree.cpp
+++ b/src/Storages/MergeTree/registerStorageMergeTree.cpp
@@ -570,6 +570,12 @@ static StoragePtr create(const StorageFactory::Arguments & args)
             throw Exception(
                 "Date column name must be an unquoted string" + getMergeTreeVerboseHelp(is_extended_storage_def),
                 ErrorCodes::BAD_ARGUMENTS);
+
+        auto partition_by_ast = makeASTFunction("toYYYYMM", std::make_shared<ASTIdentifier>(date_column_name));
+
+        metadata.partition_key = KeyDescription::getKeyFromAST(partition_by_ast, metadata.columns, args.context);
+
+
         ++arg_num;
 
         /// If there is an expression for sampling
diff --git a/src/Storages/StorageInMemoryMetadata.h b/src/Storages/StorageInMemoryMetadata.h
index bda48bc19cb..756b11150fb 100644
--- a/src/Storages/StorageInMemoryMetadata.h
+++ b/src/Storages/StorageInMemoryMetadata.h
@@ -14,9 +14,6 @@
 namespace DB
 {
 
-/// Structure represent table metadata stored in memory.
-/// Only one storage engine support all fields -- MergeTree.
-/// Complete table AST can be recreated from this struct.
 struct StorageInMemoryMetadata
 {
     /// Columns of table with their names, types,