ClickHouse/src/Processors/QueryPlan/QueryPlan.h

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#pragma once
#include <memory>
#include <list>
#include <vector>
#include <set>
#include <Core/Names.h>
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namespace DB
{
class DataStream;
class IQueryPlanStep;
using QueryPlanStepPtr = std::unique_ptr<IQueryPlanStep>;
class QueryPipeline;
using QueryPipelinePtr = std::unique_ptr<QueryPipeline>;
class Context;
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class WriteBuffer;
class QueryPlan;
using QueryPlanPtr = std::unique_ptr<QueryPlan>;
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class Pipe;
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/// A tree of query steps.
/// The goal of QueryPlan is to build QueryPipeline.
/// QueryPlan let delay pipeline creation which is helpful for pipeline-level optimisations.
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class QueryPlan
{
public:
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QueryPlan();
~QueryPlan();
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QueryPlan(QueryPlan &&);
QueryPlan & operator=(QueryPlan &&);
void unitePlans(QueryPlanStepPtr step, std::vector<QueryPlanPtr> plans);
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void addStep(QueryPlanStepPtr step);
bool isInitialized() const { return root != nullptr; } /// Tree is not empty
bool isCompleted() const; /// Tree is not empty and root hasOutputStream()
const DataStream & getCurrentDataStream() const; /// Checks that (isInitialized() && !isCompleted())
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void optimize();
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QueryPipelinePtr buildQueryPipeline();
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/// If initialized, build pipeline and convert to pipe. Otherwise, return empty pipe.
Pipe convertToPipe();
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struct ExplainPlanOptions
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{
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/// Add output header to step.
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bool header = false;
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/// Add description of step.
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bool description = true;
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/// Add detailed information about step actions.
bool actions = false;
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};
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struct ExplainPipelineOptions
{
/// Show header of output ports.
bool header = false;
};
void explainPlan(WriteBuffer & buffer, const ExplainPlanOptions & options);
void explainPipeline(WriteBuffer & buffer, const ExplainPipelineOptions & options);
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/// Set upper limit for the recommend number of threads. Will be applied to the newly-created pipelines.
/// TODO: make it in a better way.
void setMaxThreads(size_t max_threads_) { max_threads = max_threads_; }
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size_t getMaxThreads() const { return max_threads; }
void addInterpreterContext(std::shared_ptr<Context> context);
/// Tree node. Step and it's children.
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struct Node
{
QueryPlanStepPtr step;
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std::vector<Node *> children = {};
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};
using Nodes = std::list<Node>;
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private:
Nodes nodes;
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Node * root = nullptr;
void checkInitialized() const;
void checkNotCompleted() const;
/// Those fields are passed to QueryPipeline.
size_t max_threads = 0;
std::vector<std::shared_ptr<Context>> interpreter_context;
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};
}