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85 lines
2.4 KiB
C++
85 lines
2.4 KiB
C++
#pragma once
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#include <Databases/DatabaseAtomic.h>
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#include <Common/ZooKeeper/ZooKeeper.h>
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#include <Core/BackgroundSchedulePool.h>
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#include <DataStreams/BlockIO.h>
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#include <DataStreams/OneBlockInputStream.h>
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namespace DB
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{
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/** DatabaseReplicated engine
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* supports replication of metadata
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* via DDL log being written to ZooKeeper
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* and executed on all of the replicas
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* for a given database.
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*
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* One Clickhouse server can have multiple
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* replicated databases running and updating
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* at the same time.
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*
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* The engine has two parameters ZooKeeper path and
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* replica name.
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* The same ZooKeeper path corresponds to the same
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* database. Replica names MUST be different for all replicas
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* of the same database.
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*
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* Using this engine, creation of Replicated tables
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* requires no ZooKeeper path and replica name parameters.
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* Table's replica name is the same as database replica name.
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* Table's ZooKeeper path is a concatenation of database
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* ZooKeeper path, /tables/, and UUID of the table.
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*/
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class DatabaseReplicated : public DatabaseAtomic
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{
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public:
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DatabaseReplicated(const String & name_, const String & metadata_path_, const String & zookeeper_path_, const String & replica_name_, Context & context);
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~DatabaseReplicated();
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void drop(const Context & /*context*/) override;
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String getEngineName() const override { return "Replicated"; }
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void propose(const ASTPtr & query) override;
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BlockIO getFeedback();
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String zookeeper_path;
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String replica_name;
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private:
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void createDatabaseZKNodes();
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void runBackgroundLogExecutor();
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void executeLogName(const String &);
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void writeLastExecutedToDiskAndZK();
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void loadMetadataFromSnapshot();
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void createSnapshot();
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void RemoveOutdatedSnapshotsAndLog();
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std::unique_ptr<Context> current_context; // to run executeQuery
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std::mutex log_name_mutex;
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String log_name_to_exec_with_result;
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int snapshot_period;
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int feedback_timeout;
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String last_executed_log_entry = "";
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BackgroundSchedulePool::TaskHolder background_log_executor;
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zkutil::ZooKeeperPtr current_zookeeper; /// Use only the methods below.
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mutable std::mutex current_zookeeper_mutex; /// To recreate the session in the background thread.
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zkutil::ZooKeeperPtr tryGetZooKeeper() const;
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zkutil::ZooKeeperPtr getZooKeeper() const;
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void setZooKeeper(zkutil::ZooKeeperPtr zookeeper);
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};
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}
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