ClickHouse/src/Storages/MutationCommands.h

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#pragma once
#include <optional>
#include <vector>
#include <memory>
#include <unordered_map>
#include <Parsers/ASTAlterQuery.h>
#include <Storages/IStorage_fwd.h>
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#include <DataTypes/IDataType.h>
#include <Core/Names.h>
namespace DB
{
class Context;
class WriteBuffer;
class ReadBuffer;
/// Represents set of actions which should be applied
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/// to values from set of columns which satisfy predicate.
struct MutationCommand
{
ASTPtr ast; /// The AST of the whole command
enum Type
{
EMPTY, /// Not used.
DELETE,
UPDATE,
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MATERIALIZE_INDEX,
MATERIALIZE_PROJECTION,
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READ_COLUMN, /// Read column and apply conversions (MODIFY COLUMN alter query).
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DROP_COLUMN,
DROP_INDEX,
DROP_PROJECTION,
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MATERIALIZE_TTL,
RENAME_COLUMN,
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MATERIALIZE_COLUMN,
};
Type type = EMPTY;
/// WHERE part of mutation
ASTPtr predicate;
/// Columns with corresponding actions
std::unordered_map<String, ASTPtr> column_to_update_expression;
/// For MATERIALIZE INDEX and PROJECTION
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String index_name;
String projection_name;
/// For MATERIALIZE INDEX, UPDATE and DELETE.
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ASTPtr partition;
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/// For reads, drops and etc.
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String column_name;
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DataTypePtr data_type; /// Maybe empty if we just want to drop column
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/// We need just clear column, not drop from metadata.
bool clear = false;
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/// Column rename_to
String rename_to;
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/// If parse_alter_commands, than consider more Alter commands as mutation commands
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static std::optional<MutationCommand> parse(ASTAlterCommand * command, bool parse_alter_commands = false);
};
/// Multiple mutation commands, possible from different ALTER queries
class MutationCommands : public std::vector<MutationCommand>
{
public:
std::shared_ptr<ASTExpressionList> ast() const;
void writeText(WriteBuffer & out) const;
void readText(ReadBuffer & in);
};
using MutationCommandsConstPtr = std::shared_ptr<MutationCommands>;
}