diff --git a/dbms/src/Storages/MergeTree/MergeTreeData.cpp b/dbms/src/Storages/MergeTree/MergeTreeData.cpp
index 899b3552c8d..8e7146e4bfa 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeData.cpp
+++ b/dbms/src/Storages/MergeTree/MergeTreeData.cpp
@@ -117,7 +117,8 @@ MergeTreeData::MergeTreeData(
 
     initPrimaryKey();
 
-    if (sampling_expression && (!primary_expr_ast || !primary_key_sample.has(sampling_expression->getColumnName())))
+    if (sampling_expression && (!primary_expr_ast || !primary_key_sample.has(sampling_expression->getColumnName()))
+        && !attach && !settings.compatibility_allow_sampling_expression_not_in_primary_key) /// This is for backward compatibility.
         throw Exception("Sampling expression must be present in the primary key", ErrorCodes::BAD_ARGUMENTS);
 
     MergeTreeDataFormatVersion min_format_version(0);
@@ -125,7 +126,7 @@ MergeTreeData::MergeTreeData(
     {
         try
         {
-            String partition_expr_str = "toYYYYMM(" + date_column_name + ")";
+            String partition_expr_str = "toYYYYMM(" + backQuoteIfNeed(date_column_name) + ")";
             ParserNotEmptyExpressionList parser(/* allow_alias_without_as_keyword = */ false);
             partition_expr_ast = parseQuery(
                 parser, partition_expr_str.data(), partition_expr_str.data() + partition_expr_str.length(), "partition expression");
diff --git a/dbms/src/Storages/MergeTree/MergeTreeSettings.h b/dbms/src/Storages/MergeTree/MergeTreeSettings.h
index bfd2b91dd8d..f91ca880a66 100644
--- a/dbms/src/Storages/MergeTree/MergeTreeSettings.h
+++ b/dbms/src/Storages/MergeTree/MergeTreeSettings.h
@@ -122,7 +122,15 @@ struct MergeTreeSettings
     M(SettingUInt64, vertical_merge_algorithm_min_rows_to_activate, 16 * DEFAULT_MERGE_BLOCK_SIZE)            \
                                                                                                               \
     /** Minimal amount of non-PK columns to activate Vertical merge algorithm */                              \
-    M(SettingUInt64, vertical_merge_algorithm_min_columns_to_activate, 11)
+    M(SettingUInt64, vertical_merge_algorithm_min_columns_to_activate, 11)                                    \
+                                                                                                              \
+    /** Compatibility settings */                                                                             \
+                                                                                                              \
+    /** Allow to create a table with sampling expression not in primary key.                                  \
+      * This is needed only to temporarily allow to run the server with wrong tables                          \
+      *  for backward compatibility.                                                                          \
+      */                                                                                                      \
+    M(SettingBool, compatibility_allow_sampling_expression_not_in_primary_key, false)                         \
 
     /// Settings that should not change after the creation of a table.
 #define APPLY_FOR_IMMUTABLE_MERGE_TREE_SETTINGS(M)  \