mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-19 06:01:57 +00:00
84 lines
2.9 KiB
C++
84 lines
2.9 KiB
C++
#pragma once
|
|
|
|
#include <Interpreters/ExpressionAnalyzer.h>
|
|
#include <Interpreters/ExpressionActions.h>
|
|
#include <Interpreters/InterpreterSelectQuery.h>
|
|
#include <DataStreams/IBlockInputStream.h>
|
|
#include <Storages/IStorage.h>
|
|
#include <Storages/MutationCommands.h>
|
|
|
|
|
|
namespace DB
|
|
{
|
|
|
|
class Context;
|
|
|
|
/// Create an input stream that will read data from storage and apply mutation commands (UPDATEs, DELETEs)
|
|
/// to this data.
|
|
class MutationsInterpreter
|
|
{
|
|
public:
|
|
MutationsInterpreter(StoragePtr storage_, std::vector<MutationCommand> commands_, const Context & context_)
|
|
: storage(std::move(storage_))
|
|
, commands(std::move(commands_))
|
|
, context(context_)
|
|
{
|
|
}
|
|
|
|
void validate();
|
|
|
|
/// Return false if the data isn't going to be changed by mutations.
|
|
bool isStorageTouchedByMutations() const;
|
|
|
|
/// The resulting stream will return blocks containing changed columns only.
|
|
BlockInputStreamPtr execute();
|
|
|
|
private:
|
|
void prepare(bool dry_run);
|
|
|
|
BlockInputStreamPtr addStreamsForLaterStages(BlockInputStreamPtr in) const;
|
|
|
|
private:
|
|
StoragePtr storage;
|
|
std::vector<MutationCommand> commands;
|
|
const Context & context;
|
|
|
|
/// A sequence of mutation commands is executed as a sequence of stages. Each stage consists of several
|
|
/// filters, followed by updating values of some columns. Commands can reuse expressions calculated by the
|
|
/// previous commands in the same stage, but at the end of each stage intermediate columns are thrown away
|
|
/// (they may contain wrong values because the column values have been updated).
|
|
///
|
|
/// If an UPDATE command changes some columns that some MATERIALIZED columns depend on, a stage to
|
|
/// recalculate these columns is added.
|
|
///
|
|
/// Each stage has output_columns that contain columns that are changed at the end of that stage
|
|
/// plus columns needed for the next mutations.
|
|
///
|
|
/// First stage is special: it can contain only DELETEs and is executed using InterpreterSelectQuery
|
|
/// to take advantage of table indexes (if there are any).
|
|
|
|
struct Stage
|
|
{
|
|
ASTs filters;
|
|
std::unordered_map<String, ASTPtr> column_to_updated;
|
|
|
|
/// Contains columns that are changed by this stage,
|
|
/// columns changed by the previous stages and also columns needed by the next stages.
|
|
NameSet output_columns;
|
|
|
|
std::unique_ptr<ExpressionAnalyzer> analyzer;
|
|
|
|
/// A chain of actions needed to execute this stage.
|
|
/// First steps calculate filter columns for DELETEs (in the same order as in `filter_column_names`),
|
|
/// then there is (possibly) an UPDATE stage, and finally a projection stage.
|
|
ExpressionActionsChain expressions_chain;
|
|
Names filter_column_names;
|
|
};
|
|
|
|
std::unique_ptr<InterpreterSelectQuery> interpreter_select;
|
|
std::vector<Stage> stages;
|
|
bool is_prepared = false; /// Has the sequence of stages been prepared.
|
|
};
|
|
|
|
}
|