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https://github.com/ClickHouse/ClickHouse.git
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309 lines
12 KiB
C++
309 lines
12 KiB
C++
#pragma once
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#include <Core/Types.h>
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#include <Parsers/IAST_fwd.h>
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#include <Storages/IStorage_fwd.h>
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#include <Storages/StorageInMemoryMetadata.h>
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#include <Dictionaries/IDictionary.h>
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#include <Common/Exception.h>
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#include <ctime>
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#include <functional>
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#include <memory>
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namespace DB
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{
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class Context;
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struct Settings;
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struct ConstraintsDescription;
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class ColumnsDescription;
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struct IndicesDescription;
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struct TableStructureWriteLockHolder;
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class ASTCreateQuery;
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using Dictionaries = std::set<String>;
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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 CANNOT_GET_CREATE_DICTIONARY_QUERY;
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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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virtual const StoragePtr & table() const = 0;
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virtual ~IDatabaseTablesIterator() = default;
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};
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/// Copies list of tables and iterates through such snapshot.
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class DatabaseTablesSnapshotIterator final : 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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public:
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DatabaseTablesSnapshotIterator(Tables & tables_) : tables(tables_), it(tables.begin()) {}
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DatabaseTablesSnapshotIterator(Tables && tables_) : tables(tables_), it(tables.begin()) {}
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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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/// Copies list of dictionaries and iterates through such snapshot.
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class DatabaseDictionariesSnapshotIterator
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{
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private:
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Dictionaries dictionaries;
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Dictionaries::iterator it;
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public:
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DatabaseDictionariesSnapshotIterator() = default;
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DatabaseDictionariesSnapshotIterator(Dictionaries & dictionaries_) : dictionaries(dictionaries_), it(dictionaries.begin()) {}
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DatabaseDictionariesSnapshotIterator(Dictionaries && dictionaries_) : dictionaries(dictionaries_), it(dictionaries.begin()) {}
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void next() { ++it; }
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bool isValid() const { return !dictionaries.empty() && it != dictionaries.end(); }
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const String & name() const { return *it; }
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};
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using DatabaseTablesIteratorPtr = std::unique_ptr<IDatabaseTablesIterator>;
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using DatabaseDictionariesIteratorPtr = std::unique_ptr<DatabaseDictionariesSnapshotIterator>;
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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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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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/// 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(Context & /*context*/, bool /*has_force_restore_data_flag*/) {}
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/// Check the existence of the table.
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virtual bool isTableExist(
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const Context & context,
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const String & name) const = 0;
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/// Check the existence of the dictionary
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virtual bool isDictionaryExist(
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const Context & /*context*/,
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const String & /*name*/) const
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{
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return false;
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}
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/// Get the table for work. Return nullptr if there is no table.
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virtual StoragePtr tryGetTable(
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const Context & context,
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const String & name) const = 0;
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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(const Context & context, const FilterByNameFunction & filter_by_table_name = {}) = 0;
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/// Get an iterator to pass through all the dictionaries.
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virtual DatabaseDictionariesIteratorPtr getDictionariesIterator(const Context & /*context*/, [[maybe_unused]] const FilterByNameFunction & filter_by_dictionary_name = {})
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{
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return std::make_unique<DatabaseDictionariesSnapshotIterator>();
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}
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/// Get an iterator to pass through all the tables and dictionary tables.
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virtual DatabaseTablesIteratorPtr getTablesWithDictionaryTablesIterator(const Context & context, const FilterByNameFunction & filter_by_name = {})
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{
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return getTablesIterator(context, filter_by_name);
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}
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/// Is the database empty.
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virtual bool empty(const Context & context) 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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const Context & /*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("There is no CREATE TABLE query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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/// Add the dictionary to the database. Record its presence in the metadata.
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virtual void createDictionary(
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const Context & /*context*/,
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const String & /*dictionary_name*/,
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const ASTPtr & /*query*/)
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{
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throw Exception("There is no CREATE DICTIONARY query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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/// Delete the table from the database. Delete the metadata.
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virtual void removeTable(
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const Context & /*context*/,
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const String & /*name*/)
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{
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throw Exception("There is no DROP TABLE query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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/// Delete the dictionary from the database. Delete the metadata.
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virtual void removeDictionary(
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const Context & /*context*/,
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const String & /*dictionary_name*/)
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{
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throw Exception("There is no DROP DICTIONARY query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED);
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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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virtual void attachTable(const String & /*name*/, const StoragePtr & /*table*/)
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{
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throw Exception("There is no ATTACH TABLE query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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/// Add dictionary to the database, but do not add it to the metadata. The database may not support this method.
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/// If dictionaries_lazy_load is false it also starts loading the dictionary asynchronously.
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virtual void attachDictionary(const String & /*name*/, const Context & /*context*/)
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{
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throw Exception("There is no ATTACH DICTIONARY query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED);
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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(const String & /*name*/)
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{
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throw Exception("There is no DETACH TABLE query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED);
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}
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/// Forget about the dictionary without deleting it. The database may not support this method.
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virtual void detachDictionary(const String & /*name*/, const Context & /*context*/)
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{
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throw Exception("There is no DETACH DICTIONARY query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED);
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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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const Context & /*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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TableStructureWriteLockHolder &)
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{
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throw Exception(getEngineName() + ": renameTable() is not supported", ErrorCodes::NOT_IMPLEMENTED);
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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 TableStructureLock 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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const Context & /*context*/,
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const String & /*name*/,
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const StorageInMemoryMetadata & /*metadata*/)
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{
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throw Exception(getEngineName() + ": alterTable() is not supported", ErrorCodes::NOT_IMPLEMENTED);
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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 Context & context, const String & name) const noexcept
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{
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return getCreateTableQueryImpl(context, name, false);
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}
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ASTPtr getCreateTableQuery(const Context & context, const String & name) const
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{
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return getCreateTableQueryImpl(context, name, true);
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}
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/// Get the CREATE DICTIONARY query for the dictionary. Returns nullptr if dictionary doesn't exists.
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ASTPtr tryGetCreateDictionaryQuery(const Context & context, const String & name) const noexcept
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{
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return getCreateDictionaryQueryImpl(context, name, false);
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}
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ASTPtr getCreateDictionaryQuery(const Context & context, const String & name) const
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{
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return getCreateDictionaryQueryImpl(context, name, 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 Context & /*context*/) const = 0;
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/// Get name of database.
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String getDatabaseName() const { return database_name; }
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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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/// 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(const Context & /*context*/) {}
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virtual ~IDatabase() {}
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protected:
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virtual ASTPtr getCreateTableQueryImpl(const Context & /*context*/, const String & /*name*/, bool throw_on_error) const
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{
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if (throw_on_error)
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throw Exception("There is no SHOW CREATE TABLE query for Database" + getEngineName(), ErrorCodes::CANNOT_GET_CREATE_TABLE_QUERY);
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return nullptr;
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}
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virtual ASTPtr getCreateDictionaryQueryImpl(const Context & /*context*/, const String & /*name*/, bool throw_on_error) const
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{
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if (throw_on_error)
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throw Exception("There is no SHOW CREATE DICTIONARY query for Database" + getEngineName(), ErrorCodes::CANNOT_GET_CREATE_DICTIONARY_QUERY);
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return nullptr;
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}
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String database_name;
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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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