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374 lines
14 KiB
C++
374 lines
14 KiB
C++
#pragma once
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#include <Core/UUID.h>
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#include <Databases/LoadingStrictnessLevel.h>
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#include <Interpreters/Context_fwd.h>
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#include <Parsers/IAST_fwd.h>
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#include <Storages/IStorage_fwd.h>
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#include <base/types.h>
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#include <Common/Exception.h>
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#include <Common/ThreadPool_fwd.h>
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#include <QueryPipeline/BlockIO.h>
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#include <ctime>
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#include <functional>
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#include <memory>
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#include <mutex>
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#include <vector>
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#include <map>
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namespace DB
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{
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struct Settings;
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struct ConstraintsDescription;
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struct IndicesDescription;
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struct StorageInMemoryMetadata;
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struct StorageID;
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class ASTCreateQuery;
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class AlterCommands;
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class SettingsChanges;
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using DictionariesWithID = std::vector<std::pair<String, UUID>>;
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struct ParsedTablesMetadata;
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struct QualifiedTableName;
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class IRestoreCoordination;
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namespace ErrorCodes
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{
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extern const int NOT_IMPLEMENTED;
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extern const int CANNOT_GET_CREATE_TABLE_QUERY;
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extern const int LOGICAL_ERROR;
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}
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class IDatabaseTablesIterator
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{
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public:
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virtual void next() = 0;
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virtual bool isValid() const = 0;
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virtual const String & name() const = 0;
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/// This method can return nullptr if it's Lazy database
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/// (a database with support for lazy tables loading
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/// - it maintains a list of tables but tables are loaded lazily).
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virtual const StoragePtr & table() const = 0;
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explicit IDatabaseTablesIterator(const String & database_name_) : database_name(database_name_) { }
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explicit IDatabaseTablesIterator(String && database_name_) : database_name(std::move(database_name_)) { }
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virtual ~IDatabaseTablesIterator() = default;
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virtual UUID uuid() const { return UUIDHelpers::Nil; }
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const String & databaseName() const { assert(!database_name.empty()); return database_name; }
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protected:
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String database_name;
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};
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/// Copies list of tables and iterates through such snapshot.
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class DatabaseTablesSnapshotIterator : public IDatabaseTablesIterator
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{
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private:
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Tables tables;
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Tables::iterator it;
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protected:
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DatabaseTablesSnapshotIterator(DatabaseTablesSnapshotIterator && other) noexcept
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: IDatabaseTablesIterator(std::move(other.database_name))
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{
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size_t idx = std::distance(other.tables.begin(), other.it);
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std::swap(tables, other.tables);
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other.it = other.tables.end();
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it = tables.begin();
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std::advance(it, idx);
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}
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public:
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DatabaseTablesSnapshotIterator(const Tables & tables_, const String & database_name_)
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: IDatabaseTablesIterator(database_name_), tables(tables_), it(tables.begin())
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{
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}
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DatabaseTablesSnapshotIterator(Tables && tables_, String && database_name_)
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: IDatabaseTablesIterator(std::move(database_name_)), tables(std::move(tables_)), it(tables.begin())
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{
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}
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void next() override { ++it; }
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bool isValid() const override { return it != tables.end(); }
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const String & name() const override { return it->first; }
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const StoragePtr & table() const override { return it->second; }
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};
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using DatabaseTablesIteratorPtr = std::unique_ptr<IDatabaseTablesIterator>;
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/** Database engine.
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* It is responsible for:
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* - initialization of set of known tables and dictionaries;
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* - checking existence of a table and getting a table object;
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* - retrieving a list of all tables;
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* - creating and dropping tables;
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* - renaming tables and moving between databases with same engine.
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*/
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class IDatabase : public std::enable_shared_from_this<IDatabase>
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{
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public:
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IDatabase() = delete;
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explicit IDatabase(String database_name_) : database_name(std::move(database_name_)) {}
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/// Get name of database engine.
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virtual String getEngineName() const = 0;
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virtual bool canContainMergeTreeTables() const { return true; }
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virtual bool canContainDistributedTables() const { return true; }
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/// Load a set of existing tables.
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/// You can call only once, right after the object is created.
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virtual void loadStoredObjects( /// NOLINT
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ContextMutablePtr /*context*/,
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LoadingStrictnessLevel /*mode*/,
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bool /* skip_startup_tables */)
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{
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}
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virtual bool supportsLoadingInTopologicalOrder() const { return false; }
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virtual void beforeLoadingMetadata(
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ContextMutablePtr /*context*/, LoadingStrictnessLevel /*mode*/)
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{
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}
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virtual void loadTablesMetadata(ContextPtr /*local_context*/, ParsedTablesMetadata & /*metadata*/, bool /*is_startup*/)
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{
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throw Exception(ErrorCodes::LOGICAL_ERROR, "Not implemented");
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}
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virtual void loadTableFromMetadata(ContextMutablePtr /*local_context*/, const String & /*file_path*/, const QualifiedTableName & /*name*/, const ASTPtr & /*ast*/,
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LoadingStrictnessLevel /*mode*/)
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{
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throw Exception(ErrorCodes::LOGICAL_ERROR, "Not implemented");
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}
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virtual void startupTables(ThreadPool & /*thread_pool*/, LoadingStrictnessLevel /*mode*/) {}
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/// Check the existence of the table in memory (attached).
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virtual bool isTableExist(const String & name, ContextPtr context) const = 0;
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/// Check the existence of the table in any state (in active / detached / detached permanently state).
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/// Throws exception when table exists.
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virtual void checkMetadataFilenameAvailability(const String & /*table_name*/) const {}
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/// Get the table for work. Return nullptr if there is no table.
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virtual StoragePtr tryGetTable(const String & name, ContextPtr context) const = 0;
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StoragePtr getTable(const String & name, ContextPtr context) const;
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virtual UUID tryGetTableUUID(const String & /*table_name*/) const { return UUIDHelpers::Nil; }
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using FilterByNameFunction = std::function<bool(const String &)>;
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/// Get an iterator that allows you to pass through all the tables.
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/// It is possible to have "hidden" tables that are not visible when passing through, but are visible if you get them by name using the functions above.
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virtual DatabaseTablesIteratorPtr getTablesIterator(ContextPtr context, const FilterByNameFunction & filter_by_table_name = {}) const = 0; /// NOLINT
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/// Is the database empty.
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virtual bool empty() const = 0;
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/// Add the table to the database. Record its presence in the metadata.
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virtual void createTable(
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ContextPtr /*context*/,
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const String & /*name*/,
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const StoragePtr & /*table*/,
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const ASTPtr & /*query*/)
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "There is no CREATE TABLE query for Database{}", getEngineName());
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}
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/// Delete the table from the database, drop table and delete the metadata.
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virtual void dropTable( /// NOLINT
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ContextPtr /*context*/,
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const String & /*name*/,
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[[maybe_unused]] bool sync = false)
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "There is no DROP TABLE query for Database{}", getEngineName());
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}
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/// Add a table to the database, but do not add it to the metadata. The database may not support this method.
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///
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/// Note: ATTACH TABLE statement actually uses createTable method.
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virtual void attachTable(ContextPtr /* context */, const String & /*name*/, const StoragePtr & /*table*/, [[maybe_unused]] const String & relative_table_path = {}) /// NOLINT
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "There is no ATTACH TABLE query for Database{}", getEngineName());
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}
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/// Forget about the table without deleting it, and return it. The database may not support this method.
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virtual StoragePtr detachTable(ContextPtr /* context */, const String & /*name*/)
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "There is no DETACH TABLE query for Database{}", getEngineName());
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}
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/// Forget about the table without deleting it's data, but rename metadata file to prevent reloading it
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/// with next restart. The database may not support this method.
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virtual void detachTablePermanently(ContextPtr /*context*/, const String & /*name*/)
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "There is no DETACH TABLE PERMANENTLY query for Database{}", getEngineName());
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}
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/// Returns list of table names that were permanently detached.
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/// This list may not be updated in runtime and may be filled only on server startup
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virtual Strings getNamesOfPermanentlyDetachedTables() const
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Cannot get names of permanently detached tables for Database{}", getEngineName());
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}
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/// Rename the table and possibly move the table to another database.
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virtual void renameTable(
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ContextPtr /*context*/,
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const String & /*name*/,
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IDatabase & /*to_database*/,
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const String & /*to_name*/,
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bool /*exchange*/,
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bool /*dictionary*/)
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "{}: renameTable() is not supported", getEngineName());
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}
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using ASTModifier = std::function<void(IAST &)>;
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/// Change the table structure in metadata.
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/// You must call under the alter_lock of the corresponding table . If engine_modifier is empty, then engine does not change.
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virtual void alterTable(
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ContextPtr /*context*/,
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const StorageID & /*table_id*/,
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const StorageInMemoryMetadata & /*metadata*/)
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "{}: alterTable() is not supported", getEngineName());
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}
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/// Returns time of table's metadata change, 0 if there is no corresponding metadata file.
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virtual time_t getObjectMetadataModificationTime(const String & /*name*/) const
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{
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return static_cast<time_t>(0);
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}
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/// Get the CREATE TABLE query for the table. It can also provide information for detached tables for which there is metadata.
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ASTPtr tryGetCreateTableQuery(const String & name, ContextPtr context) const noexcept
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{
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return getCreateTableQueryImpl(name, context, false);
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}
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ASTPtr getCreateTableQuery(const String & name, ContextPtr context) const
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{
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return getCreateTableQueryImpl(name, context, true);
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}
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/// Get the CREATE DATABASE query for current database.
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virtual ASTPtr getCreateDatabaseQuery() const = 0;
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String getDatabaseComment() const
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{
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std::lock_guard lock{mutex};
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return comment;
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}
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void setDatabaseComment(String new_comment)
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{
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std::lock_guard lock{mutex};
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comment = std::move(new_comment);
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}
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/// Get name of database.
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String getDatabaseName() const
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{
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std::lock_guard lock{mutex};
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return database_name;
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}
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/// Get UUID of database.
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virtual UUID getUUID() const { return UUIDHelpers::Nil; }
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virtual void renameDatabase(ContextPtr, const String & /*new_name*/)
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED, "{}: RENAME DATABASE is not supported", getEngineName());
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}
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/// Returns path for persistent data storage if the database supports it, empty string otherwise
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virtual String getDataPath() const { return {}; }
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/// Returns path for persistent data storage for table if the database supports it, empty string otherwise. Table must exist
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virtual String getTableDataPath(const String & /*table_name*/) const { return {}; }
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/// Returns path for persistent data storage for CREATE/ATTACH query if the database supports it, empty string otherwise
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virtual String getTableDataPath(const ASTCreateQuery & /*query*/) const { return {}; }
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/// Returns metadata path if the database supports it, empty string otherwise
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virtual String getMetadataPath() const { return {}; }
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/// Returns metadata path of a concrete table if the database supports it, empty string otherwise
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virtual String getObjectMetadataPath(const String & /*table_name*/) const { return {}; }
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/// All tables and dictionaries should be detached before detaching the database.
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virtual bool shouldBeEmptyOnDetach() const { return true; }
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virtual void assertCanBeDetached(bool /*cleanup*/) {}
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virtual void waitDetachedTableNotInUse(const UUID & /*uuid*/) { }
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virtual void checkDetachedTableNotInUse(const UUID & /*uuid*/) { }
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/// Ask all tables to complete the background threads they are using and delete all table objects.
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virtual void shutdown() = 0;
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/// Delete data and metadata stored inside the database, if exists.
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virtual void drop(ContextPtr /*context*/) {}
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virtual void applySettingsChanges(const SettingsChanges &, ContextPtr)
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{
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throw Exception(ErrorCodes::NOT_IMPLEMENTED,
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"Database engine {} either does not support settings, or does not support altering settings",
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getEngineName());
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}
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virtual bool hasReplicationThread() const { return false; }
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virtual void stopReplication()
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{
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throw Exception(ErrorCodes::LOGICAL_ERROR, "Database engine {} does not run a replication thread!", getEngineName());
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}
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virtual bool shouldReplicateQuery(const ContextPtr & /*query_context*/, const ASTPtr & /*query_ptr*/) const { return false; }
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virtual BlockIO tryEnqueueReplicatedDDL(const ASTPtr & /*query*/, ContextPtr /*query_context*/, [[maybe_unused]] bool internal = false) /// NOLINT
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{
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throw Exception(ErrorCodes::LOGICAL_ERROR, "Database engine {} does not have replicated DDL queue", getEngineName());
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}
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/// Returns CREATE TABLE queries and corresponding tables prepared for writing to a backup.
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virtual std::vector<std::pair<ASTPtr, StoragePtr>> getTablesForBackup(const FilterByNameFunction & filter, const ContextPtr & context) const;
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/// Creates a table restored from backup.
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virtual void createTableRestoredFromBackup(const ASTPtr & create_table_query, ContextMutablePtr context, std::shared_ptr<IRestoreCoordination> restore_coordination, UInt64 timeout_ms);
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virtual ~IDatabase() = default;
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protected:
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virtual ASTPtr getCreateTableQueryImpl(const String & /*name*/, ContextPtr /*context*/, bool throw_on_error) const
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{
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if (throw_on_error)
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throw Exception(ErrorCodes::CANNOT_GET_CREATE_TABLE_QUERY, "There is no SHOW CREATE TABLE query for Database{}", getEngineName());
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return nullptr;
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}
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mutable std::mutex mutex;
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String database_name TSA_GUARDED_BY(mutex);
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String comment TSA_GUARDED_BY(mutex);
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};
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using DatabasePtr = std::shared_ptr<IDatabase>;
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using Databases = std::map<String, DatabasePtr>;
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}
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