Removed huge chunk of bad code

dbms/src/Storages/MergeTree/MergeTreeData.h

@@ -538,8 +538,6 @@ public:
       */
     static ASTPtr extractKeyExpressionList(const ASTPtr & node);
 
-    Names getColumnsRequiredForPartitionKey() const override { return (partition_key_expr ? partition_key_expr->getRequiredColumns() : Names{}); }
-
     bool hasSortingKey() const { return !sorting_key_columns.empty(); }
     bool hasPrimaryKey() const { return !primary_key_columns.empty(); }
     bool hasSkipIndices() const { return !skip_indices.empty(); }
@@ -548,13 +546,14 @@ public:
     ASTPtr getPartitionKeyAST() const override { return partition_by_ast; }
     ASTPtr getSortingKeyAST() const override { return sorting_key_expr_ast; }
     ASTPtr getPrimaryKeyAST() const override { return primary_key_expr_ast; }
+    ASTPtr getSamplingKeyAST() const override { return sample_by_ast; }
 
+    Names getColumnsRequiredForPartitionKey() const override { return (partition_key_expr ? partition_key_expr->getRequiredColumns() : Names{}); }
     Names getColumnsRequiredForSortingKey() const override { return sorting_key_expr->getRequiredColumns(); }
     Names getColumnsRequiredForPrimaryKey() const override { return primary_key_expr->getRequiredColumns(); }
+    Names getColumnsRequiredForSampling() const override { return columns_required_for_sampling; }
 
     bool supportsSampling() const override { return sample_by_ast != nullptr; }
-    ASTPtr getSamplingExpression() const { return sample_by_ast; }
-    Names getColumnsRequiredForSampling() const override { return columns_required_for_sampling; }
 
     /// Check that the part is not broken and calculate the checksums for it if they are not present.
     MutableDataPartPtr loadPartAndFixMetadata(const String & relative_path);

dbms/src/Storages/MergeTree/MergeTreeDataSelectExecutor.cpp

@@ -449,7 +449,7 @@ BlockInputStreams MergeTreeDataSelectExecutor::readFromParts(
                     throw Exception("Sampling column not in primary key", ErrorCodes::ILLEGAL_COLUMN);
 
                 ASTPtr args = std::make_shared<ASTExpressionList>();
-                args->children.push_back(data.getSamplingExpression());
+                args->children.push_back(data.getSamplingKeyAST());
                 args->children.push_back(std::make_shared<ASTLiteral>(lower));
 
                 lower_function = std::make_shared<ASTFunction>();
@@ -466,7 +466,7 @@ BlockInputStreams MergeTreeDataSelectExecutor::readFromParts(
                     throw Exception("Sampling column not in primary key", ErrorCodes::ILLEGAL_COLUMN);
 
                 ASTPtr args = std::make_shared<ASTExpressionList>();
-                args->children.push_back(data.getSamplingExpression());
+                args->children.push_back(data.getSamplingKeyAST());
                 args->children.push_back(std::make_shared<ASTLiteral>(upper));
 
                 upper_function = std::make_shared<ASTFunction>();

dbms/src/Storages/System/StorageSystemColumns.cpp

@@ -36,10 +36,10 @@ StorageSystemColumns::StorageSystemColumns(const std::string & name_)
         { "marks_bytes",                std::make_shared<DataTypeUInt64>() },
         { "comment",                    std::make_shared<DataTypeString>() },
         { "is_in_partition_key", std::make_shared<DataTypeUInt8>() },
-        { "is_in_sorting_key", std::make_shared<DataTypeUInt8>() },
-        { "is_in_primary_key", std::make_shared<DataTypeUInt8>() },
-        { "is_in_sampling_key", std::make_shared<DataTypeUInt8>() },
-        { "compression_codec", std::make_shared<DataTypeString>() },
+        { "is_in_sorting_key",   std::make_shared<DataTypeUInt8>() },
+        { "is_in_primary_key",   std::make_shared<DataTypeUInt8>() },
+        { "is_in_sampling_key",  std::make_shared<DataTypeUInt8>() },
+        { "compression_codec",   std::make_shared<DataTypeString>() },
     }));
 }