mirror of
https://github.com/ClickHouse/ClickHouse.git
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152 lines
4.2 KiB
C++
152 lines
4.2 KiB
C++
#pragma once
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#include <Poco/DirectoryIterator.h>
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#include <Interpreters/Context.h>
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#include <Databases/DatabasesCommon.h>
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#include <Common/ThreadPool.h>
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namespace DB
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{
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struct CachedTable
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{
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StoragePtr table;
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time_t last_touched;
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time_t metadata_modification_time;
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CachedTable() {}
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CachedTable(const StoragePtr & table_, time_t last_touched_, time_t metadata_modification_time_)
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: table(table_), last_touched(last_touched_), metadata_modification_time(metadata_modification_time_) {}
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};
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using TablesCache = std::unordered_map<String, CachedTable>;
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class DatabaseLazyIterator;
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/** Lazy engine of databases.
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* Works like DatabaseOrdinary, but stores in memory only cache.
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* Can be used only with *Log engines.
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*/
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class DatabaseLazy : public IDatabase
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{
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public:
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DatabaseLazy(const String & name_, const String & metadata_path_, time_t expiration_time_, const Context & context);
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String getEngineName() const override { return "Lazy"; }
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void loadTables(
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Context & context,
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bool has_force_restore_data_flag) override;
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void createTable(
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const Context & context,
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const String & table_name,
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const StoragePtr & table,
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const ASTPtr & query) override;
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void removeTable(
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const Context & context,
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const String & table_name) override;
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void renameTable(
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const Context & context,
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const String & table_name,
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IDatabase & to_database,
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const String & to_table_name,
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TableStructureWriteLockHolder &) override;
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void alterTable(
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const Context & context,
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const String & name,
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const ColumnsDescription & columns,
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const IndicesDescription & indices,
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const ConstraintsDescription & constraints,
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const ASTModifier & engine_modifier) override;
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time_t getTableMetadataModificationTime(
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const Context & context,
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const String & table_name) override;
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ASTPtr getCreateTableQuery(
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const Context & context,
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const String & table_name) const override;
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ASTPtr tryGetCreateTableQuery(
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const Context & context,
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const String & table_name) const override;
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ASTPtr getCreateDatabaseQuery(const Context & context) const override;
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String getDataPath() const override;
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String getDatabaseName() const override;
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String getMetadataPath() const override;
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String getTableMetadataPath(const String & table_name) const override;
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void drop() override;
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bool isTableExist(
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const Context & context,
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const String & table_name) const override;
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StoragePtr tryGetTable(
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const Context & context,
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const String & table_name) const override;
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bool empty(const Context & context) const override;
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DatabaseIteratorPtr getIterator(const Context & context, const FilterByNameFunction & filter_by_table_name = {}) override;
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void attachTable(const String & table_name, const StoragePtr & table) override;
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StoragePtr detachTable(const String & table_name) override;
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void shutdown() override;
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~DatabaseLazy() override;
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private:
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String name;
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const String metadata_path;
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const String data_path;
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const time_t expiration_time;
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mutable std::mutex tables_mutex;
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mutable TablesCache tables_cache;
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Poco::Logger * log;
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ASTPtr getCreateTableQueryImpl(const Context & context, const String & table_name, bool throw_on_error) const;
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using IteratingFunction = std::function<bool(const Poco::DirectoryIterator &)>;
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void iterateTableFiles(const IteratingFunction & iterating_function) const;
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StoragePtr loadTable(const Context & context, const String & table_name) const;
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void clearExpiredTables() const;
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friend class DatabaseLazyIterator;
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};
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class DatabaseLazyIterator final : public IDatabaseIterator
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{
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public:
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DatabaseLazyIterator(DatabaseLazy & database_, const Context & context_, Strings && table_names_);
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void next() override;
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bool isValid() const override;
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const String & name() const override;
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const StoragePtr & table() const override;
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private:
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const DatabaseLazy & database;
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const Strings table_names;
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const Context context;
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Strings::const_iterator iterator;
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mutable StoragePtr current_storage;
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};
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}
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