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# pragma once
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# include <Core/Types.h>
# 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>
# include <functional>
# include <memory>
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namespace DB
{
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class Context ;
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struct Settings ;
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struct ConstraintsDescription ;
class ColumnsDescription ;
struct IndicesDescription ;
struct TableStructureWriteLockHolder ;
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class ASTCreateQuery ;
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using Dictionaries = std : : set < String > ;
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class ASTCreateQuery ;
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namespace ErrorCodes
{
extern const int NOT_IMPLEMENTED ;
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extern const int CANNOT_GET_CREATE_TABLE_QUERY ;
extern const int CANNOT_GET_CREATE_DICTIONARY_QUERY ;
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}
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class IDatabaseTablesIterator
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{
public :
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virtual void next ( ) = 0 ;
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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virtual UUID uuid ( ) const { return UUIDHelpers : : Nil ; }
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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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{
private :
Tables tables ;
Tables : : iterator it ;
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protected :
DatabaseTablesSnapshotIterator ( DatabaseTablesSnapshotIterator & & other )
{
size_t idx = std : : distance ( other . tables . begin ( ) , other . it ) ;
std : : swap ( tables , other . tables ) ;
other . it = other . tables . end ( ) ;
it = tables . begin ( ) ;
std : : advance ( it , idx ) ;
}
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public :
DatabaseTablesSnapshotIterator ( Tables & tables_ ) : tables ( tables_ ) , it ( tables . begin ( ) ) { }
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.
class DatabaseDictionariesSnapshotIterator
{
private :
Dictionaries dictionaries ;
Dictionaries : : iterator it ;
public :
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DatabaseDictionariesSnapshotIterator ( ) = default ;
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DatabaseDictionariesSnapshotIterator ( Dictionaries & dictionaries_ ) : dictionaries ( dictionaries_ ) , it ( dictionaries . begin ( ) ) { }
DatabaseDictionariesSnapshotIterator ( Dictionaries & & dictionaries_ ) : dictionaries ( dictionaries_ ) , it ( dictionaries . begin ( ) ) { }
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 > ;
using DatabaseDictionariesIteratorPtr = std : : unique_ptr < DatabaseDictionariesSnapshotIterator > ;
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/** Database engine.
* 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 ;
* - retrieving a list of all tables ;
* - creating and dropping tables ;
* - renaming tables and moving between databases with same engine .
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*/
class IDatabase : public std : : enable_shared_from_this < IDatabase >
{
public :
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IDatabase ( ) = delete ;
IDatabase ( String database_name_ ) : database_name ( std : : move ( database_name_ ) ) { }
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/// Get name of database engine.
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 (
const Context & context ,
const String & name ) const = 0 ;
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/// Check the existence of the dictionary
virtual bool isDictionaryExist (
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const Context & /*context*/ ,
const String & /*name*/ ) const
{
return false ;
}
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/// Get the table for work. Return nullptr if there is no table.
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virtual StoragePtr tryGetTable (
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.
/// 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 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 ( [[maybe_unused]] const FilterByNameFunction & filter_by_dictionary_name = { } )
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{
return std : : make_unique < DatabaseDictionariesSnapshotIterator > ( ) ;
}
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/// Get an iterator to pass through all the tables and dictionary tables.
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virtual DatabaseTablesIteratorPtr getTablesWithDictionaryTablesIterator ( const FilterByNameFunction & filter_by_name = { } )
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{
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return getTablesIterator ( 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*/ ,
const String & /*name*/ ,
const StoragePtr & /*table*/ ,
const ASTPtr & /*query*/ )
{
throw Exception ( " There is no CREATE TABLE query for Database " + getEngineName ( ) , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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/// Add the dictionary to the database. Record its presence in the metadata.
virtual void createDictionary (
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const Context & /*context*/ ,
const String & /*dictionary_name*/ ,
const ASTPtr & /*query*/ )
{
throw Exception ( " There is no CREATE DICTIONARY query for Database " + getEngineName ( ) , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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/// Delete the table from the database, drop table and delete the metadata.
virtual void dropTable (
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const Context & /*context*/ ,
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const String & /*name*/ ,
[[maybe_unused]] bool no_delay = false )
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{
throw Exception ( " There is no DROP TABLE query for Database " + getEngineName ( ) , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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/// Delete the dictionary from the database. Delete the metadata.
virtual void removeDictionary (
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const Context & /*context*/ ,
const String & /*dictionary_name*/ )
{
throw Exception ( " There is no DROP DICTIONARY query for Database " + getEngineName ( ) , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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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*/ , [[maybe_unused]] const String & relative_table_path = { } )
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{
throw Exception ( " There is no ATTACH TABLE query for Database " + getEngineName ( ) , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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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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{
throw Exception ( " There is no ATTACH DICTIONARY query for Database " + getEngineName ( ) , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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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*/ )
{
throw Exception ( " There is no DETACH TABLE query for Database " + getEngineName ( ) , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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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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{
throw Exception ( " There is no DETACH DICTIONARY query for Database " + getEngineName ( ) , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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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*/ ,
const String & /*name*/ ,
IDatabase & /*to_database*/ ,
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const String & /*to_name*/ ,
bool /*exchange*/ )
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{
throw Exception ( getEngineName ( ) + " : renameTable() is not supported " , ErrorCodes : : NOT_IMPLEMENTED ) ;
}
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using ASTModifier = std : : function < void ( IAST & ) > ;
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/// Change the table structure in metadata.
/// 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 StorageID & /*table_id*/ ,
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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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{
return static_cast < time_t > ( 0 ) ;
}
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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
{
return getCreateTableQueryImpl ( context , name , false ) ;
}
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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
{
return getCreateDictionaryQueryImpl ( context , name , false ) ;
}
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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
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
virtual String getMetadataPath ( ) const { return { } ; }
/// 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 :
virtual ASTPtr getCreateTableQueryImpl ( const Context & /*context*/ , const String & /*name*/ , bool throw_on_error ) const
{
if ( throw_on_error )
throw Exception ( " There is no SHOW CREATE TABLE query for Database " + getEngineName ( ) , ErrorCodes : : CANNOT_GET_CREATE_TABLE_QUERY ) ;
return nullptr ;
}
virtual ASTPtr getCreateDictionaryQueryImpl ( const Context & /*context*/ , const String & /*name*/ , bool throw_on_error ) const
{
if ( throw_on_error )
throw Exception ( " There is no SHOW CREATE DICTIONARY query for Database " + getEngineName ( ) , ErrorCodes : : CANNOT_GET_CREATE_DICTIONARY_QUERY ) ;
return nullptr ;
}
String database_name ;
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} ;
using DatabasePtr = std : : shared_ptr < IDatabase > ;
using Databases = std : : map < String , DatabasePtr > ;
}