alter delete skeleton

dbms/src/Interpreters/InterpreterAlterQuery.cpp

@@ -50,7 +50,14 @@ BlockIO InterpreterAlterQuery::execute()
 
     AlterCommands alter_commands;
     PartitionCommands partition_commands;
-    parseAlter(alter.parameters, alter_commands, partition_commands);
+    MutationCommands mutation_commands;
+    parseAlter(alter.parameters, alter_commands, partition_commands, mutation_commands);
+
+    if (!mutation_commands.commands.empty())
+    {
+        /// TODO: validate
+        table->mutate(mutation_commands, context);
+    }
 
     partition_commands.validate(table.get());
     for (const PartitionCommand & command : partition_commands)
@@ -79,18 +86,20 @@ BlockIO InterpreterAlterQuery::execute()
         }
     }
 
-    if (alter_commands.empty())
-        return {};
-
+    if (!alter_commands.empty())
+    {
         alter_commands.validate(table.get(), context);
         table->alter(alter_commands, database_name, table_name, context);
+    }
 
     return {};
 }
 
 void InterpreterAlterQuery::parseAlter(
     const ASTAlterQuery::ParameterContainer & params_container,
-    AlterCommands & out_alter_commands, PartitionCommands & out_partition_commands)
+    AlterCommands & out_alter_commands,
+    PartitionCommands & out_partition_commands,
+    MutationCommands & out_mutation_commands)
 {
     const DataTypeFactory & data_type_factory = DataTypeFactory::instance();
 
@@ -186,6 +195,10 @@ void InterpreterAlterQuery::parseAlter(
         {
             out_partition_commands.emplace_back(PartitionCommand::freezePartition(params.partition, params.with_name));
         }
+        else if (params.type == ASTAlterQuery::DELETE)
+        {
+            out_mutation_commands.commands.emplace_back(MutationCommand::delete_(params.predicate));
+        }
         else
             throw Exception("Wrong parameter type in ALTER query", ErrorCodes::LOGICAL_ERROR);
     }

dbms/src/Interpreters/InterpreterAlterQuery.h

@@ -2,6 +2,7 @@
 
 #include <Storages/IStorage.h>
 #include <Storages/AlterCommands.h>
+#include <Storages/MutationCommands.h>
 #include <Interpreters/Context.h>
 #include <Interpreters/IInterpreter.h>
 #include <Parsers/ASTAlterQuery.h>
@@ -102,7 +103,9 @@ private:
     const Context & context;
 
     static void parseAlter(const ASTAlterQuery::ParameterContainer & params,
-        AlterCommands & out_alter_commands, PartitionCommands & out_partition_commands);
+        AlterCommands & out_alter_commands,
+        PartitionCommands & out_partition_commands,
+        MutationCommands & out_mutation_commands);
 };
 
 }

dbms/src/Parsers/ASTAlterQuery.cpp

@@ -17,7 +17,9 @@ void ASTAlterQuery::Parameters::clone(Parameters & p) const
     p = *this;
     if (col_decl)           p.col_decl = col_decl->clone();
     if (column)             p.column = column->clone();
+    if (primary_key)        p.primary_key = primary_key->clone();
     if (partition)          p.partition = partition->clone();
+    if (predicate)          p.predicate = predicate->clone();
 }
 
 void ASTAlterQuery::addParameters(const Parameters & params)
@@ -31,6 +33,8 @@ void ASTAlterQuery::addParameters(const Parameters & params)
         children.push_back(params.partition);
     if (params.primary_key)
         children.push_back(params.primary_key);
+    if (params.predicate)
+        children.push_back(params.predicate);
 }
 
 /** Get the text that identifies this element. */
@@ -150,6 +154,11 @@ void ASTAlterQuery::formatQueryImpl(const FormatSettings & settings, FormatState
                     << " " << std::quoted(p.with_name, '\'');
             }
         }
+        else if (p.type == ASTAlterQuery::DELETE)
+        {
+            settings.ostr << (settings.hilite ? hilite_keyword : "") << indent_str << "DELETE WHERE " << (settings.hilite ? hilite_none : "");
+            p.predicate->formatImpl(settings, state, frame);
+        }
         else
             throw Exception("Unexpected type of ALTER", ErrorCodes::UNEXPECTED_AST_STRUCTURE);
 

dbms/src/Parsers/ASTAlterQuery.h

@@ -31,6 +31,8 @@ public:
         FETCH_PARTITION,
         FREEZE_PARTITION,
 
+        DELETE,
+
         NO_TYPE,
     };
 
@@ -59,6 +61,9 @@ public:
           */
         ASTPtr partition;
 
+        /// For DELETE WHERE: the predicate that filters the rows to delete.
+        ASTPtr predicate;
+
         bool detach = false;        /// true for DETACH PARTITION
 
         bool part = false;          /// true for ATTACH PART

dbms/src/Parsers/ParserAlterQuery.cpp

@@ -33,6 +33,8 @@ bool ParserAlterQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
     ParserKeyword s_with("WITH");
     ParserKeyword s_name("NAME");
 
+    ParserKeyword s_delete_where("DELETE WHERE");
+
     ParserToken s_dot(TokenType::Dot);
     ParserToken s_comma(TokenType::Comma);
 
@@ -41,6 +43,7 @@ bool ParserAlterQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
     ParserCompoundColumnDeclaration parser_col_decl;
     ParserPartition parser_partition;
     ParserStringLiteral parser_string_literal;
+    ParserExpressionWithOptionalAlias exp_elem(false);
 
     ASTPtr table;
     ASTPtr database;
@@ -206,6 +209,13 @@ bool ParserAlterQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
 
             params.type = ASTAlterQuery::MODIFY_PRIMARY_KEY;
         }
+        else if (s_delete_where.ignore(pos, expected))
+        {
+            if (!exp_elem.parse(pos, params.predicate, expected))
+                return false;
+
+            params.type = ASTAlterQuery::DELETE;
+        }
         else
             return false;
 

dbms/src/Parsers/ParserAlterQuery.h

@@ -16,6 +16,7 @@ namespace DB
   *     [DROP|DETACH|ATTACH PARTITION|PART partition, ...]
   *     [FETCH PARTITION partition FROM ...]
   *     [FREEZE PARTITION]
+  *     [DELETE WHERE ...]
   */
 class ParserAlterQuery : public IParserBase
 {

dbms/src/Storages/IStorage.h

@@ -40,6 +40,7 @@ using StorageWeakPtr = std::weak_ptr<IStorage>;
 struct Settings;
 
 class AlterCommands;
+struct MutationCommands;
 
 
 /** Does not allow changing the table description (including rename and delete the table).
@@ -260,6 +261,12 @@ public:
         throw Exception("Method optimize is not supported by storage " + getName(), ErrorCodes::NOT_IMPLEMENTED);
     }
 
+    /// Mutate the table contents
+    virtual void mutate(const MutationCommands &, const Context &)
+    {
+        throw Exception("Mutations are not supported by storage " + getName(), ErrorCodes::NOT_IMPLEMENTED);
+    }
+
     /** If the table have to do some complicated work on startup,
       *  that must be postponed after creation of table object
       *  (like launching some background threads),

dbms/src/Storages/MutationCommands.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <Parsers/IAST.h>
+
+
+namespace DB
+{
+
+struct MutationCommand
+{
+    enum Type
+    {
+        DELETE,
+    };
+
+    Type type;
+
+    ASTPtr predicate;
+
+    static MutationCommand delete_(const ASTPtr & predicate)
+    {
+        MutationCommand res;
+        res.type = DELETE;
+        res.predicate = predicate;
+        return res;
+    }
+};
+
+struct MutationCommands
+{
+    std::vector<MutationCommand> commands;
+};
+
+}

dbms/src/Storages/StorageMergeTree.cpp

@@ -221,6 +221,15 @@ void StorageMergeTree::alter(
 }
 
 
+void StorageMergeTree::mutate(const MutationCommands & commands, const Context & /*context*/)
+{
+    for (const auto & cmd : commands.commands)
+    {
+        LOG_TRACE(log, "MUTATION type: " << cmd.type << " predicate: " << cmd.predicate);
+    }
+}
+
+
 /// While exists, marks parts as 'currently_merging' and reserves free space on filesystem.
 /// It's possible to mark parts before.
 struct CurrentlyMergingPartsTagger

dbms/src/Storages/StorageMergeTree.h

@@ -77,6 +77,8 @@ public:
 
     void alter(const AlterCommands & params, const String & database_name, const String & table_name, const Context & context) override;
 
+    void mutate(const MutationCommands & commands, const Context & context) override;
+
     bool checkTableCanBeDropped() const override;
 
     MergeTreeData & getData() { return data; }