Alter remove column properties and TTLs (#14742)

src/Databases/DatabaseOrdinary.cpp

@@ -291,6 +291,8 @@ void DatabaseOrdinary::alterTable(const Context & context, const StorageID & tab
 
             if (metadata.table_ttl.definition_ast)
                 storage_ast.set(storage_ast.ttl_table, metadata.table_ttl.definition_ast);
+            else if (storage_ast.ttl_table != nullptr) /// TTL was removed
+                storage_ast.ttl_table = nullptr;
 
             if (metadata.settings_changes)
                 storage_ast.set(storage_ast.settings, metadata.settings_changes);

src/Interpreters/InterpreterAlterQuery.cpp

@@ -222,6 +222,11 @@ AccessRightsElements InterpreterAlterQuery::getRequiredAccessForCommand(const AS
             required_access.emplace_back(AccessType::ALTER_TTL, database, table);
             break;
         }
+        case ASTAlterCommand::REMOVE_TTL:
+        {
+            required_access.emplace_back(AccessType::ALTER_TTL, database, table);
+            break;
+        }
         case ASTAlterCommand::MATERIALIZE_TTL:
         {
             required_access.emplace_back(AccessType::ALTER_MATERIALIZE_TTL, database, table);

src/Parsers/ASTAlterQuery.cpp

@@ -99,12 +99,19 @@ void ASTAlterCommand::formatImpl(
         settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << "MODIFY COLUMN " << (if_exists ? "IF EXISTS " : "") << (settings.hilite ? hilite_none : "");
         col_decl->formatImpl(settings, state, frame);
 
-        if (first)
+        if (!remove_property.empty())
-            settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << " FIRST " << (settings.hilite ? hilite_none : "");
-        else if (column)    /// AFTER
         {
-            settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << " AFTER " << (settings.hilite ? hilite_none : "");
+            settings.ostr << (settings.hilite ? hilite_keyword : "") << " REMOVE " << remove_property;
-            column->formatImpl(settings, state, frame);
+        }
+        else
+        {
+            if (first)
+                settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << " FIRST " << (settings.hilite ? hilite_none : "");
+            else if (column)    /// AFTER
+            {
+                settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << " AFTER " << (settings.hilite ? hilite_none : "");
+                column->formatImpl(settings, state, frame);
+            }
         }
     }
     else if (type == ASTAlterCommand::COMMENT_COLUMN)
@@ -280,6 +287,10 @@ void ASTAlterCommand::formatImpl(
         settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << "MODIFY TTL " << (settings.hilite ? hilite_none : "");
         ttl->formatImpl(settings, state, frame);
     }
+    else if (type == ASTAlterCommand::REMOVE_TTL)
+    {
+        settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << "REMOVE TTL" << (settings.hilite ? hilite_none : "");
+    }
     else if (type == ASTAlterCommand::MATERIALIZE_TTL)
     {
         settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << "MATERIALIZE TTL"

src/Parsers/ASTAlterQuery.h

@@ -36,6 +36,7 @@ public:
         MATERIALIZE_TTL,
         MODIFY_SETTING,
         MODIFY_QUERY,
+        REMOVE_TTL,
 
         ADD_INDEX,
         DROP_INDEX,
@@ -167,6 +168,9 @@ public:
     /// Target column name
     ASTPtr rename_to;
 
+    /// Which property user want to remove
+    String remove_property;
+
     String getID(char delim) const override { return "AlterCommand" + (delim + std::to_string(static_cast<int>(type))); }
 
     ASTPtr clone() const override;

src/Parsers/ParserAlterQuery.cpp

@@ -82,12 +82,23 @@ bool ParserAlterCommand::parseImpl(Pos & pos, ASTPtr & node, Expected & expected
     ParserKeyword s_where("WHERE");
     ParserKeyword s_to("TO");
 
+    ParserKeyword s_remove("REMOVE");
+    ParserKeyword s_default("DEFAULT");
+    ParserKeyword s_materialized("MATERIALIZED");
+    ParserKeyword s_alias("ALIAS");
+    ParserKeyword s_comment("COMMENT");
+    ParserKeyword s_codec("CODEC");
+    ParserKeyword s_ttl("TTL");
+
+    ParserKeyword s_remove_ttl("REMOVE TTL");
+
     ParserCompoundIdentifier parser_name;
     ParserStringLiteral parser_string_literal;
+    ParserIdentifier parser_remove_property;
     ParserCompoundColumnDeclaration parser_col_decl;
     ParserIndexDeclaration parser_idx_decl;
     ParserConstraintDeclaration parser_constraint_decl;
-    ParserCompoundColumnDeclaration parser_modify_col_decl(false);
+    ParserCompoundColumnDeclaration parser_modify_col_decl(false, false, true);
     ParserPartition parser_partition;
     ParserExpression parser_exp_elem;
     ParserList parser_assignment_list(
@@ -433,14 +444,33 @@ bool ParserAlterCommand::parseImpl(Pos & pos, ASTPtr & node, Expected & expected
             if (!parser_modify_col_decl.parse(pos, command->col_decl, expected))
                 return false;
 
-            if (s_first.ignore(pos, expected))
+            if (s_remove.ignore(pos, expected))
-                command->first = true;
-            else if (s_after.ignore(pos, expected))
             {
-                if (!parser_name.parse(pos, command->column, expected))
+                if (s_default.ignore(pos, expected))
+                    command->remove_property = "DEFAULT";
+                else if (s_materialized.ignore(pos, expected))
+                    command->remove_property = "MATERIALIZED";
+                else if (s_alias.ignore(pos, expected))
+                    command->remove_property = "ALIAS";
+                else if (s_comment.ignore(pos, expected))
+                    command->remove_property = "COMMENT";
+                else if (s_codec.ignore(pos, expected))
+                    command->remove_property = "CODEC";
+                else if (s_ttl.ignore(pos, expected))
+                    command->remove_property = "TTL";
+                else
                     return false;
             }
-
+            else
+            {
+                if (s_first.ignore(pos, expected))
+                    command->first = true;
+                else if (s_after.ignore(pos, expected))
+                {
+                    if (!parser_name.parse(pos, command->column, expected))
+                        return false;
+                }
+            }
             command->type = ASTAlterCommand::MODIFY_COLUMN;
         }
         else if (s_modify_order_by.ignore(pos, expected))
@@ -496,6 +526,10 @@ bool ParserAlterCommand::parseImpl(Pos & pos, ASTPtr & node, Expected & expected
                 return false;
             command->type = ASTAlterCommand::MODIFY_TTL;
         }
+        else if (s_remove_ttl.ignore(pos, expected))
+        {
+            command->type = ASTAlterCommand::REMOVE_TTL;
+        }
         else if (s_materialize_ttl.ignore(pos, expected))
         {
             command->type = ASTAlterCommand::MATERIALIZE_TTL;

src/Parsers/ParserCreateQuery.h

@@ -90,8 +90,10 @@ template <typename NameParser>
 class IParserColumnDeclaration : public IParserBase
 {
 public:
-    explicit IParserColumnDeclaration(bool require_type_ = true, bool allow_null_modifiers_ = false)
+    explicit IParserColumnDeclaration(bool require_type_ = true, bool allow_null_modifiers_ = false, bool check_keywords_after_name_ = false)
-    : require_type(require_type_), allow_null_modifiers(allow_null_modifiers_)
+    : require_type(require_type_)
+    , allow_null_modifiers(allow_null_modifiers_)
+    , check_keywords_after_name(check_keywords_after_name_)
     {
     }
 
@@ -104,6 +106,7 @@ protected:
 
     bool require_type = true;
     bool allow_null_modifiers = false;
+    bool check_keywords_after_name = false;
 };
 
 using ParserColumnDeclaration = IParserColumnDeclaration<ParserIdentifier>;
@@ -122,6 +125,7 @@ bool IParserColumnDeclaration<NameParser>::parseImpl(Pos & pos, ASTPtr & node, E
     ParserKeyword s_comment{"COMMENT"};
     ParserKeyword s_codec{"CODEC"};
     ParserKeyword s_ttl{"TTL"};
+    ParserKeyword s_remove{"REMOVE"};
     ParserTernaryOperatorExpression expr_parser;
     ParserStringLiteral string_literal_parser;
     ParserCodec codec_parser;
@@ -132,6 +136,24 @@ bool IParserColumnDeclaration<NameParser>::parseImpl(Pos & pos, ASTPtr & node, E
     if (!name_parser.parse(pos, name, expected))
         return false;
 
+    const auto column_declaration = std::make_shared<ASTColumnDeclaration>();
+    tryGetIdentifierNameInto(name, column_declaration->name);
+
+    /// This keyword may occur only in MODIFY COLUMN query. We check it here
+    /// because ParserDataType parses types as an arbitrary identifiers and
+    /// doesn't check that parsed string is existing data type. In this way
+    /// REMOVE keyword can be parsed as data type and further parsing will fail.
+    /// So we just check this keyword and in case of success return column
+    /// column declaration with name only.
+    if (s_remove.checkWithoutMoving(pos, expected))
+    {
+        if (!check_keywords_after_name)
+            return false;
+
+        node = column_declaration;
+        return true;
+    }
+
     /** column name should be followed by type name if it
       *    is not immediately followed by {DEFAULT, MATERIALIZED, ALIAS, COMMENT}
       */
@@ -197,9 +219,7 @@ bool IParserColumnDeclaration<NameParser>::parseImpl(Pos & pos, ASTPtr & node, E
             return false;
     }
 
-    const auto column_declaration = std::make_shared<ASTColumnDeclaration>();
     node = column_declaration;
-    tryGetIdentifierNameInto(name, column_declaration->name);
 
     if (type)
     {

src/Storages/AlterCommands.cpp

@@ -43,6 +43,30 @@ namespace ErrorCodes
     extern const int NOT_IMPLEMENTED;
 }
 
+namespace
+{
+
+AlterCommand::RemoveProperty removePropertyFromString(const String & property)
+{
+    if (property.empty())
+        return AlterCommand::RemoveProperty::NO_PROPERTY;
+    else if (property == "DEFAULT")
+        return AlterCommand::RemoveProperty::DEFAULT;
+    else if (property == "MATERIALIZED")
+        return AlterCommand::RemoveProperty::MATERIALIZED;
+    else if (property == "ALIAS")
+        return AlterCommand::RemoveProperty::ALIAS;
+    else if (property == "COMMENT")
+        return AlterCommand::RemoveProperty::COMMENT;
+    else if (property == "CODEC")
+        return AlterCommand::RemoveProperty::CODEC;
+    else if (property == "TTL")
+        return AlterCommand::RemoveProperty::TTL;
+
+    throw Exception(ErrorCodes::BAD_ARGUMENTS, "Cannot remove unknown property '{}'", property);
+}
+
+}
 
 std::optional<AlterCommand> AlterCommand::parse(const ASTAlterCommand * command_ast)
 {
@@ -111,8 +135,9 @@ std::optional<AlterCommand> AlterCommand::parse(const ASTAlterCommand * command_
         command.type = AlterCommand::MODIFY_COLUMN;
 
         const auto & ast_col_decl = command_ast->col_decl->as<ASTColumnDeclaration &>();
-
         command.column_name = ast_col_decl.name;
+        command.to_remove = removePropertyFromString(command_ast->remove_property);
+
         if (ast_col_decl.type)
         {
             command.data_type = data_type_factory.get(ast_col_decl.type);
@@ -237,6 +262,13 @@ std::optional<AlterCommand> AlterCommand::parse(const ASTAlterCommand * command_
         command.ttl = command_ast->ttl;
         return command;
     }
+    else if (command_ast->type == ASTAlterCommand::REMOVE_TTL)
+    {
+        AlterCommand command;
+        command.ast = command_ast->clone();
+        command.type = AlterCommand::REMOVE_TTL;
+        return command;
+    }
     else if (command_ast->type == ASTAlterCommand::MODIFY_SETTING)
     {
         AlterCommand command;
@@ -301,24 +333,45 @@ void AlterCommand::apply(StorageInMemoryMetadata & metadata, const Context & con
     {
         metadata.columns.modify(column_name, after_column, first, [&](ColumnDescription & column)
         {
-            if (codec)
+            if (to_remove == RemoveProperty::DEFAULT
-                column.codec = CompressionCodecFactory::instance().validateCodecAndGetPreprocessedAST(codec, data_type ? data_type : column.type, false);
+                || to_remove == RemoveProperty::MATERIALIZED
-
+                || to_remove == RemoveProperty::ALIAS)
-            if (comment)
-                column.comment = *comment;
-
-            if (ttl)
-                column.ttl = ttl;
-
-            if (data_type)
-                column.type = data_type;
-
-            /// User specified default expression or changed
-            /// datatype. We have to replace default.
-            if (default_expression || data_type)
             {
-                column.default_desc.kind = default_kind;
+                column.default_desc = ColumnDefault{};
-                column.default_desc.expression = default_expression;
+            }
+            else if (to_remove == RemoveProperty::CODEC)
+            {
+                column.codec.reset();
+            }
+            else if (to_remove == RemoveProperty::COMMENT)
+            {
+                column.comment = String{};
+            }
+            else if (to_remove == RemoveProperty::TTL)
+            {
+                column.ttl.reset();
+            }
+            else
+            {
+                if (codec)
+                    column.codec = CompressionCodecFactory::instance().validateCodecAndGetPreprocessedAST(codec, data_type ? data_type : column.type, false);
+
+                if (comment)
+                    column.comment = *comment;
+
+                if (ttl)
+                    column.ttl = ttl;
+
+                if (data_type)
+                    column.type = data_type;
+
+                /// User specified default expression or changed
+                /// datatype. We have to replace default.
+                if (default_expression || data_type)
+                {
+                    column.default_desc.kind = default_kind;
+                    column.default_desc.expression = default_expression;
+                }
             }
         });
 
@@ -450,6 +503,10 @@ void AlterCommand::apply(StorageInMemoryMetadata & metadata, const Context & con
     {
         metadata.table_ttl = TTLTableDescription::getTTLForTableFromAST(ttl, metadata.columns, context, metadata.primary_key);
     }
+    else if (type == REMOVE_TTL)
+    {
+        metadata.table_ttl = TTLTableDescription{};
+    }
     else if (type == MODIFY_QUERY)
     {
         metadata.select = SelectQueryDescription::getSelectQueryFromASTForMatView(select, context);
@@ -584,6 +641,10 @@ bool AlterCommand::isRequireMutationStage(const StorageInMemoryMetadata & metada
     if (ignore)
         return false;
 
+    /// We remove properties on metadata level
+    if (isRemovingProperty() || type == REMOVE_TTL)
+        return false;
+
     if (type == DROP_COLUMN || type == DROP_INDEX || type == RENAME_COLUMN)
         return true;
 
@@ -636,6 +697,11 @@ bool AlterCommand::isTTLAlter(const StorageInMemoryMetadata & metadata) const
     return ttl_changed;
 }
 
+bool AlterCommand::isRemovingProperty() const
+{
+    return to_remove != RemoveProperty::NO_PROPERTY;
+}
+
 std::optional<MutationCommand> AlterCommand::tryConvertToMutationCommand(StorageInMemoryMetadata & metadata, const Context & context) const
 {
     if (!isRequireMutationStage(metadata))
@@ -716,6 +782,8 @@ String alterTypeToString(const AlterCommand::Type type)
         return "MODIFY QUERY";
     case AlterCommand::Type::RENAME_COLUMN:
         return "RENAME COLUMN";
+    case AlterCommand::Type::REMOVE_TTL:
+        return "REMOVE TTL";
     }
     __builtin_unreachable();
 }
@@ -783,14 +851,15 @@ void AlterCommands::prepare(const StorageInMemoryMetadata & metadata)
             if (!has_column && command.if_exists)
                 command.ignore = true;
 
-            if (has_column && command.data_type)
+            if (has_column)
             {
                 auto column_from_table = columns.get(command.column_name);
-                if (!command.default_expression && column_from_table.default_desc.expression)
+                if (command.data_type && !command.default_expression && column_from_table.default_desc.expression)
                 {
                     command.default_kind = column_from_table.default_desc.kind;
                     command.default_expression = column_from_table.default_desc.expression;
                 }
+
             }
         }
         else if (command.type == AlterCommand::ADD_COLUMN)
@@ -857,6 +926,70 @@ void AlterCommands::validate(const StorageInMemoryMetadata & metadata, const Con
 
             if (command.codec)
                 CompressionCodecFactory::instance().validateCodecAndGetPreprocessedAST(command.codec, command.data_type, !context.getSettingsRef().allow_suspicious_codecs);
+            auto column_default = all_columns.getDefault(column_name);
+            if (column_default)
+            {
+                if (command.to_remove == AlterCommand::RemoveProperty::DEFAULT && column_default->kind != ColumnDefaultKind::Default)
+                {
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Cannot remove DEFAULT from column {}, because column default type is {}. Use REMOVE {} to delete it",
+                            backQuote(column_name), toString(column_default->kind), toString(column_default->kind));
+                }
+                if (command.to_remove == AlterCommand::RemoveProperty::MATERIALIZED && column_default->kind != ColumnDefaultKind::Materialized)
+                {
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Cannot remove MATERIALIZED from column {}, because column default type is {}. Use REMOVE {} to delete it",
+                        backQuote(column_name), toString(column_default->kind), toString(column_default->kind));
+                }
+                if (command.to_remove == AlterCommand::RemoveProperty::ALIAS && column_default->kind != ColumnDefaultKind::Alias)
+                {
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Cannot remove ALIAS from column {}, because column default type is {}. Use REMOVE {} to delete it",
+                        backQuote(column_name), toString(column_default->kind), toString(column_default->kind));
+                }
+            }
+
+            if (command.isRemovingProperty())
+            {
+                if (!column_default && command.to_remove == AlterCommand::RemoveProperty::DEFAULT)
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Column {} doesn't have DEFAULT, cannot remove it",
+                        backQuote(column_name));
+
+                if (!column_default && command.to_remove == AlterCommand::RemoveProperty::ALIAS)
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Column {} doesn't have ALIAS, cannot remove it",
+                        backQuote(column_name));
+
+                if (!column_default && command.to_remove == AlterCommand::RemoveProperty::MATERIALIZED)
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Column {} doesn't have MATERIALIZED, cannot remove it",
+                        backQuote(column_name));
+
+                auto column_from_table = all_columns.get(column_name);
+                if (command.to_remove == AlterCommand::RemoveProperty::TTL && column_from_table.ttl == nullptr)
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Column {} doesn't have TTL, cannot remove it",
+                        backQuote(column_name));
+                if (command.to_remove == AlterCommand::RemoveProperty::CODEC && column_from_table.codec == nullptr)
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Column {} doesn't have TTL, cannot remove it",
+                        backQuote(column_name));
+                if (command.to_remove == AlterCommand::RemoveProperty::COMMENT && column_from_table.comment.empty())
+                    throw Exception(
+                        ErrorCodes::BAD_ARGUMENTS,
+                        "Column {} doesn't have COMMENT, cannot remove it",
+                        backQuote(column_name));
+
+            }
 
             modified_columns.emplace(column_name);
         }
@@ -966,6 +1099,10 @@ void AlterCommands::validate(const StorageInMemoryMetadata & metadata, const Con
                 throw Exception{"Cannot rename column from nested struct to normal column and vice versa", ErrorCodes::BAD_ARGUMENTS};
             }
         }
+        else if (command.type == AlterCommand::REMOVE_TTL && !metadata.hasAnyTableTTL())
+        {
+            throw Exception{"Table doesn't have any table TTL expression, cannot remove", ErrorCodes::BAD_ARGUMENTS};
+        }
 
         /// Collect default expressions for MODIFY and ADD comands
         if (command.type == AlterCommand::MODIFY_COLUMN || command.type == AlterCommand::ADD_COLUMN)

src/Storages/AlterCommands.h

@@ -37,6 +37,22 @@ struct AlterCommand
         MODIFY_SETTING,
         MODIFY_QUERY,
         RENAME_COLUMN,
+        REMOVE_TTL,
+    };
+
+    /// Which property user wants to remove from column
+    enum class RemoveProperty
+    {
+        NO_PROPERTY,
+        /// Default specifiers
+        DEFAULT,
+        MATERIALIZED,
+        ALIAS,
+
+        /// Other properties
+        COMMENT,
+        CODEC,
+        TTL
     };
 
     Type type;
@@ -107,16 +123,13 @@ struct AlterCommand
     /// Target column name
     String rename_to;
 
+    /// What to remove from column (or TTL)
+    RemoveProperty to_remove = RemoveProperty::NO_PROPERTY;
+
     static std::optional<AlterCommand> parse(const ASTAlterCommand * command);
 
     void apply(StorageInMemoryMetadata & metadata, const Context & context) const;
 
-    /// Checks that alter query changes data. For MergeTree:
-    ///    * column files (data and marks)
-    ///    * each part meta (columns.txt)
-    /// in each part on disk (it's not lightweight alter).
-    bool isModifyingData(const StorageInMemoryMetadata & metadata) const;
-
     /// Check that alter command require data modification (mutation) to be
     /// executed. For example, cast from Date to UInt16 type can be executed
     /// without any data modifications. But column drop or modify from UInt16 to
@@ -132,6 +145,9 @@ struct AlterCommand
     /// Checks that any TTL changed by alter
     bool isTTLAlter(const StorageInMemoryMetadata & metadata) const;
 
+    /// Command removing some property from column or table
+    bool isRemovingProperty() const;
+
     /// If possible, convert alter command to mutation command. In other case
     /// return empty optional. Some storages may execute mutations after
     /// metadata changes.
@@ -164,9 +180,6 @@ public:
     /// Commands have to be prepared before apply.
     void apply(StorageInMemoryMetadata & metadata, const Context & context) const;
 
-    /// At least one command modify data on disk.
-    bool isModifyingData(const StorageInMemoryMetadata & metadata) const;
-
     /// At least one command modify settings.
     bool isSettingsAlter() const;
 

src/Storages/StorageReplicatedMergeTree.cpp

@@ -900,10 +900,17 @@ ColumnsDescription new_columns, const ReplicatedMergeTreeTableMetadata::Diff & m
 
         if (metadata_diff.ttl_table_changed)
         {
-            ParserTTLExpressionList parser;
+            if (!metadata_diff.new_ttl_table.empty())
-            auto ttl_for_table_ast = parseQuery(parser, metadata_diff.new_ttl_table, 0, DBMS_DEFAULT_MAX_PARSER_DEPTH);
+            {
-            new_metadata.table_ttl = TTLTableDescription::getTTLForTableFromAST(
+                ParserTTLExpressionList parser;
-                ttl_for_table_ast, new_metadata.columns, global_context, new_metadata.primary_key);
+                auto ttl_for_table_ast = parseQuery(parser, metadata_diff.new_ttl_table, 0, DBMS_DEFAULT_MAX_PARSER_DEPTH);
+                new_metadata.table_ttl = TTLTableDescription::getTTLForTableFromAST(
+                    ttl_for_table_ast, new_metadata.columns, global_context, new_metadata.primary_key);
+            }
+            else /// TTL was removed
+            {
+                new_metadata.table_ttl = TTLTableDescription{};
+            }
         }
     }
 
@@ -3818,7 +3825,12 @@ void StorageReplicatedMergeTree::alter(
             future_metadata_in_zk.partition_key = serializeAST(*future_metadata.partition_key.expression_list_ast);
 
         if (ast_to_str(future_metadata.table_ttl.definition_ast) != ast_to_str(current_metadata->table_ttl.definition_ast))
-            future_metadata_in_zk.ttl_table = serializeAST(*future_metadata.table_ttl.definition_ast);
+        {
+            if (future_metadata.table_ttl.definition_ast)
+                future_metadata_in_zk.ttl_table = serializeAST(*future_metadata.table_ttl.definition_ast);
+            else /// TTL was removed
+                future_metadata_in_zk.ttl_table = "";
+        }
 
         String new_indices_str = future_metadata.secondary_indices.toString();
         if (new_indices_str != current_metadata->secondary_indices.toString())

tests/queries/0_stateless/01493_alter_remove_no_property_zookeeper.reference

@@ -0,0 +1,4 @@
+CREATE TABLE default.no_prop_table\n(\n    `some_column` UInt64\n)\nENGINE = MergeTree()\nORDER BY tuple()\nSETTINGS index_granularity = 8192
+CREATE TABLE default.no_prop_table\n(\n    `some_column` UInt64\n)\nENGINE = MergeTree()\nORDER BY tuple()\nSETTINGS index_granularity = 8192
+CREATE TABLE default.r_no_prop_table\n(\n    `some_column` UInt64\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test/01493_r_no_prop_table\', \'1\')\nORDER BY tuple()\nSETTINGS index_granularity = 8192
+CREATE TABLE default.r_no_prop_table\n(\n    `some_column` UInt64\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test/01493_r_no_prop_table\', \'1\')\nORDER BY tuple()\nSETTINGS index_granularity = 8192

tests/queries/0_stateless/01493_alter_remove_no_property_zookeeper.sql

@@ -0,0 +1,51 @@
+DROP TABLE IF EXISTS no_prop_table;
+
+CREATE TABLE no_prop_table
+(
+    some_column UInt64
+)
+ENGINE MergeTree()
+ORDER BY tuple();
+
+SHOW CREATE TABLE no_prop_table;
+
+-- just nothing happened
+ALTER TABLE no_prop_table MODIFY COLUMN some_column REMOVE DEFAULT; --{serverError 36}
+ALTER TABLE no_prop_table MODIFY COLUMN some_column REMOVE MATERIALIZED; --{serverError 36}
+ALTER TABLE no_prop_table MODIFY COLUMN some_column REMOVE ALIAS; --{serverError 36}
+ALTER TABLE no_prop_table MODIFY COLUMN some_column REMOVE CODEC; --{serverError 36}
+ALTER TABLE no_prop_table MODIFY COLUMN some_column REMOVE COMMENT; --{serverError 36}
+ALTER TABLE no_prop_table MODIFY COLUMN some_column REMOVE TTL; --{serverError 36}
+
+ALTER TABLE no_prop_table REMOVE TTL; --{serverError 36}
+
+SHOW CREATE TABLE no_prop_table;
+
+DROP TABLE IF EXISTS no_prop_table;
+
+DROP TABLE IF EXISTS r_no_prop_table;
+
+CREATE TABLE r_no_prop_table
+(
+  some_column UInt64
+)
+ENGINE ReplicatedMergeTree('/clickhouse/test/01493_r_no_prop_table', '1')
+ORDER BY tuple();
+
+SHOW CREATE TABLE r_no_prop_table;
+
+ALTER TABLE r_no_prop_table MODIFY COLUMN some_column REMOVE DEFAULT; --{serverError 36}
+ALTER TABLE r_no_prop_table MODIFY COLUMN some_column REMOVE MATERIALIZED; --{serverError 36}
+ALTER TABLE r_no_prop_table MODIFY COLUMN some_column REMOVE ALIAS; --{serverError 36}
+ALTER TABLE r_no_prop_table MODIFY COLUMN some_column REMOVE CODEC; --{serverError 36}
+ALTER TABLE r_no_prop_table MODIFY COLUMN some_column REMOVE COMMENT; --{serverError 36}
+ALTER TABLE r_no_prop_table MODIFY COLUMN some_column REMOVE TTL; --{serverError 36}
+
+ALTER TABLE r_no_prop_table REMOVE TTL;  --{serverError 36}
+
+SHOW CREATE TABLE r_no_prop_table;
+
+ALTER TABLE r_no_prop_table MODIFY COLUMN some_column REMOVE ttl;  --{serverError 36}
+ALTER TABLE r_no_prop_table remove TTL;  --{serverError 36}
+
+DROP TABLE IF EXISTS r_no_prop_table;

tests/queries/0_stateless/01493_alter_remove_properties.reference

@@ -0,0 +1,20 @@
+CREATE TABLE default.prop_table\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_materialized` UInt64 MATERIALIZED column_default * 42,\n    `column_alias` UInt64 ALIAS column_default + 1,\n    `column_codec` String CODEC(ZSTD(10)),\n    `column_comment` Date COMMENT \'Some comment\',\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = MergeTree()\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+42	1764	43	str	2019-10-01	1
+CREATE TABLE default.prop_table\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_materialized` UInt64 MATERIALIZED column_default * 42,\n    `column_alias` UInt64 ALIAS column_default + 1,\n    `column_codec` String CODEC(ZSTD(10)),\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = MergeTree()\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+CREATE TABLE default.prop_table\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_materialized` UInt64 MATERIALIZED column_default * 42,\n    `column_alias` UInt64 ALIAS column_default + 1,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = MergeTree()\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+42	1764	0	str	2019-10-01	1
+CREATE TABLE default.prop_table\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_materialized` UInt64 MATERIALIZED column_default * 42,\n    `column_alias` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = MergeTree()\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+42	1764	0	str	2019-10-01	1
+42	1764	33	trs	2020-01-01	2
+CREATE TABLE default.prop_table\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_materialized` UInt64,\n    `column_alias` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = MergeTree()\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+42	1764	0	str	2019-10-01	1
+42	1764	33	trs	2020-01-01	2
+42	11	44	rts	2020-02-01	3
+CREATE TABLE default.prop_table\n(\n    `column_default` UInt64,\n    `column_materialized` UInt64,\n    `column_alias` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = MergeTree()\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+42	1764	0	str	2019-10-01	1
+42	1764	33	trs	2020-01-01	2
+42	11	44	rts	2020-02-01	3
+0	22	55	tsr	2020-03-01	4
+CREATE TABLE default.prop_table\n(\n    `column_default` UInt64,\n    `column_materialized` UInt64,\n    `column_alias` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = MergeTree()\nORDER BY tuple()\nSETTINGS index_granularity = 8192
+CREATE TABLE default.prop_table\n(\n    `column_default` UInt64,\n    `column_materialized` UInt64,\n    `column_alias` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64\n)\nENGINE = MergeTree()\nORDER BY tuple()\nSETTINGS index_granularity = 8192
+4

tests/queries/0_stateless/01493_alter_remove_properties.sql

@@ -0,0 +1,72 @@
+DROP TABLE IF EXISTS prop_table;
+
+CREATE TABLE prop_table
+(
+    column_default UInt64 DEFAULT 42,
+    column_materialized UInt64 MATERIALIZED column_default * 42,
+    column_alias UInt64 ALIAS column_default + 1,
+    column_codec String CODEC(ZSTD(10)),
+    column_comment Date COMMENT 'Some comment',
+    column_ttl UInt64 TTL column_comment + INTERVAL 1 MONTH
+)
+ENGINE MergeTree()
+ORDER BY tuple()
+TTL column_comment + INTERVAL 2 MONTH;
+
+SHOW CREATE TABLE prop_table;
+
+SYSTEM STOP TTL MERGES prop_table;
+
+INSERT INTO prop_table (column_codec, column_comment, column_ttl) VALUES ('str', toDate('2019-10-01'), 1);
+
+SELECT column_default, column_materialized, column_alias, column_codec, column_comment, column_ttl FROM prop_table;
+
+ALTER TABLE prop_table MODIFY COLUMN column_comment REMOVE COMMENT;
+
+SHOW CREATE TABLE prop_table;
+
+ALTER TABLE prop_table MODIFY COLUMN column_codec REMOVE CODEC;
+
+SHOW CREATE TABLE prop_table;
+
+ALTER TABLE prop_table MODIFY COLUMN column_alias REMOVE ALIAS;
+
+SELECT column_default, column_materialized, column_alias, column_codec, column_comment, column_ttl FROM prop_table;
+
+SHOW CREATE TABLE prop_table;
+
+INSERT INTO prop_table (column_alias, column_codec, column_comment, column_ttl) VALUES (33, 'trs', toDate('2020-01-01'), 2);
+
+SELECT column_default, column_materialized, column_alias, column_codec, column_comment, column_ttl FROM prop_table ORDER BY column_ttl;
+
+ALTER TABLE prop_table MODIFY COLUMN column_materialized REMOVE MATERIALIZED;
+
+SHOW CREATE TABLE prop_table;
+
+INSERT INTO prop_table (column_materialized, column_alias, column_codec, column_comment, column_ttl) VALUES (11, 44, 'rts', toDate('2020-02-01'), 3);
+
+SELECT column_default, column_materialized, column_alias, column_codec, column_comment, column_ttl FROM prop_table ORDER BY column_ttl;
+
+ALTER TABLE prop_table MODIFY COLUMN column_default REMOVE DEFAULT;
+
+SHOW CREATE TABLE prop_table;
+
+INSERT INTO prop_table (column_materialized, column_alias, column_codec, column_comment, column_ttl) VALUES (22, 55, 'tsr', toDate('2020-03-01'), 4);
+
+SELECT column_default, column_materialized, column_alias, column_codec, column_comment, column_ttl FROM prop_table ORDER BY column_ttl;
+
+ALTER TABLE prop_table REMOVE TTL;
+
+SHOW CREATE TABLE prop_table;
+
+ALTER TABLE prop_table MODIFY COLUMN column_ttl REMOVE TTL;
+
+SHOW CREATE TABLE prop_table;
+
+SYSTEM START TTL MERGES prop_table;
+
+OPTIMIZE TABLE prop_table FINAL;
+
+SELECT COUNT() FROM prop_table;
+
+DROP TABLE IF EXISTS prop_table;

tests/queries/0_stateless/01493_alter_remove_properties_zookeeper.reference

@@ -0,0 +1,21 @@
+CREATE TABLE default.r_prop_table1\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_codec` String CODEC(ZSTD(10)),\n    `column_comment` Date COMMENT \'Some comment\',\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'1\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+CREATE TABLE default.r_prop_table2\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_codec` String CODEC(ZSTD(10)),\n    `column_comment` Date COMMENT \'Some comment\',\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'2\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+====== remove column comment ======
+CREATE TABLE default.r_prop_table1\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_codec` String CODEC(ZSTD(10)),\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'1\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+CREATE TABLE default.r_prop_table2\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_codec` String CODEC(ZSTD(10)),\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'2\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+====== remove column codec ======
+CREATE TABLE default.r_prop_table1\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'1\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+CREATE TABLE default.r_prop_table2\n(\n    `column_default` UInt64 DEFAULT 42,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'2\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+====== remove column default ======
+42	str	1
+0	tsr	2
+CREATE TABLE default.r_prop_table1\n(\n    `column_default` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'1\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+CREATE TABLE default.r_prop_table2\n(\n    `column_default` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64 TTL column_comment + toIntervalMonth(1)\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'2\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+====== remove column TTL ======
+CREATE TABLE default.r_prop_table1\n(\n    `column_default` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'1\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+CREATE TABLE default.r_prop_table2\n(\n    `column_default` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'2\')\nORDER BY tuple()\nTTL column_comment + toIntervalMonth(2)\nSETTINGS index_granularity = 8192
+====== remove table TTL ======
+CREATE TABLE default.r_prop_table1\n(\n    `column_default` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'1\')\nORDER BY tuple()\nSETTINGS index_granularity = 8192
+CREATE TABLE default.r_prop_table2\n(\n    `column_default` UInt64,\n    `column_codec` String,\n    `column_comment` Date,\n    `column_ttl` UInt64\n)\nENGINE = ReplicatedMergeTree(\'/clickhouse/test_01493/r_prop_table\', \'2\')\nORDER BY tuple()\nSETTINGS index_granularity = 8192
+3
+3

tests/queries/0_stateless/01493_alter_remove_properties_zookeeper.sql

@@ -0,0 +1,92 @@
+DROP TABLE IF EXISTS r_prop_table1;
+DROP TABLE IF EXISTS r_prop_table2;
+
+SET replication_alter_partitions_sync = 2;
+
+CREATE TABLE r_prop_table1
+(
+  column_default UInt64 DEFAULT 42,
+  column_codec String CODEC(ZSTD(10)),
+  column_comment Date COMMENT 'Some comment',
+  column_ttl UInt64 TTL column_comment + INTERVAL 1 MONTH
+)
+ENGINE ReplicatedMergeTree('/clickhouse/test_01493/r_prop_table', '1')
+ORDER BY tuple()
+TTL column_comment + INTERVAL 2 MONTH;
+
+CREATE TABLE r_prop_table2
+(
+  column_default UInt64 DEFAULT 42,
+  column_codec String CODEC(ZSTD(10)),
+  column_comment Date COMMENT 'Some comment',
+  column_ttl UInt64 TTL column_comment + INTERVAL 1 MONTH
+)
+ENGINE ReplicatedMergeTree('/clickhouse/test_01493/r_prop_table', '2')
+ORDER BY tuple()
+TTL column_comment + INTERVAL 2 MONTH;
+
+SHOW CREATE TABLE r_prop_table1;
+SHOW CREATE TABLE r_prop_table2;
+
+INSERT INTO r_prop_table1 (column_codec, column_comment, column_ttl) VALUES ('str', toDate('2020-10-01'), 1);
+
+SYSTEM SYNC REPLICA r_prop_table2;
+
+SELECT '====== remove column comment ======';
+ALTER TABLE r_prop_table1 MODIFY COLUMN column_comment REMOVE COMMENT;
+
+SHOW CREATE TABLE r_prop_table1;
+SHOW CREATE TABLE r_prop_table2;
+
+DETACH TABLE r_prop_table1;
+ATTACH TABLE r_prop_table1;
+
+SELECT '====== remove column codec ======';
+ALTER TABLE r_prop_table2 MODIFY COLUMN column_codec REMOVE CODEC;
+
+SHOW CREATE TABLE r_prop_table1;
+SHOW CREATE TABLE r_prop_table2;
+
+SELECT '====== remove column default ======';
+ALTER TABLE r_prop_table2 MODIFY COLUMN column_default REMOVE DEFAULT;
+
+INSERT INTO r_prop_table1 (column_codec, column_comment, column_ttl) VALUES ('tsr', now(), 2);
+
+SYSTEM SYNC REPLICA r_prop_table2;
+
+SELECT column_default, column_codec, column_ttl FROM r_prop_table1 ORDER BY column_ttl;
+
+DETACH TABLE r_prop_table2;
+ATTACH TABLE r_prop_table2;
+
+SHOW CREATE TABLE r_prop_table1;
+SHOW CREATE TABLE r_prop_table2;
+
+SELECT '====== remove column TTL ======';
+ALTER TABLE r_prop_table2 MODIFY COLUMN column_ttl REMOVE TTL;
+
+SHOW CREATE TABLE r_prop_table1;
+SHOW CREATE TABLE r_prop_table2;
+
+SELECT '====== remove table TTL ======';
+ALTER TABLE r_prop_table1 REMOVE TTL;
+
+INSERT INTO r_prop_table1 (column_codec, column_comment, column_ttl) VALUES ('rts', now() - INTERVAL 1 YEAR, 3);
+
+SYSTEM SYNC REPLICA r_prop_table2;
+
+DETACH TABLE r_prop_table2;
+ATTACH TABLE r_prop_table2;
+
+SHOW CREATE TABLE r_prop_table1;
+SHOW CREATE TABLE r_prop_table2;
+
+OPTIMIZE TABLE r_prop_table2 FINAL;
+
+SYSTEM SYNC REPLICA r_prop_table1;
+
+SELECT COUNT() FROM r_prop_table1;
+SELECT COUNT() FROM r_prop_table2;
+
+DROP TABLE IF EXISTS r_prop_table1;
+DROP TABLE IF EXISTS r_prop_table2;

tests/queries/0_stateless/01493_alter_remove_wrong_default.reference

@@ -0,0 +1 @@
+CREATE TABLE default.default_table\n(\n    `key` UInt64 DEFAULT 42,\n    `value1` UInt64 MATERIALIZED key * key,\n    `value2` UInt64 ALIAS value1 * key\n)\nENGINE = MergeTree()\nORDER BY tuple()\nSETTINGS index_granularity = 8192

tests/queries/0_stateless/01493_alter_remove_wrong_default.sql

@@ -0,0 +1,22 @@
+DROP TABLE IF EXISTS default_table;
+
+CREATE TABLE default_table (
+  key UInt64 DEFAULT 42,
+  value1 UInt64 MATERIALIZED key * key,
+  value2 ALIAS value1 * key
+)
+ENGINE = MergeTree()
+ORDER BY tuple();
+
+ALTER TABLE default_table MODIFY COLUMN key REMOVE MATERIALIZED; --{serverError 36}
+ALTER TABLE default_table MODIFY COLUMN key REMOVE ALIAS; --{serverError 36}
+
+ALTER TABLE default_table MODIFY COLUMN value1 REMOVE DEFAULT; --{serverError 36}
+ALTER TABLE default_table MODIFY COLUMN value1 REMOVE ALIAS; --{serverError 36}
+
+ALTER TABLE default_table MODIFY COLUMN value2 REMOVE DEFAULT; --{serverError 36}
+ALTER TABLE default_table MODIFY COLUMN value2 REMOVE MATERIALIZED; --{serverError 36}
+
+SHOW CREATE TABLE default_table;
+
+DROP TABLE IF EXISTS default_table;