1 | #pragma once |
2 | |
3 | #include <Core/Types.h> |
4 | #include <Parsers/IAST_fwd.h> |
5 | #include <Storages/IStorage_fwd.h> |
6 | #include <Storages/StorageInMemoryMetadata.h> |
7 | #include <Dictionaries/IDictionary.h> |
8 | #include <Common/Exception.h> |
9 | |
10 | #include <ctime> |
11 | #include <functional> |
12 | #include <memory> |
13 | |
14 | |
15 | namespace DB |
16 | { |
17 | |
18 | class Context; |
19 | struct Settings; |
20 | struct ConstraintsDescription; |
21 | class ColumnsDescription; |
22 | struct IndicesDescription; |
23 | struct TableStructureWriteLockHolder; |
24 | class ASTCreateQuery; |
25 | using Dictionaries = std::set<String>; |
26 | |
27 | namespace ErrorCodes |
28 | { |
29 | extern const int NOT_IMPLEMENTED; |
30 | extern const int CANNOT_GET_CREATE_TABLE_QUERY; |
31 | extern const int CANNOT_GET_CREATE_TABLE_QUERY; |
32 | extern const int CANNOT_GET_CREATE_DICTIONARY_QUERY; |
33 | } |
34 | |
35 | class IDatabaseTablesIterator |
36 | { |
37 | public: |
38 | virtual void next() = 0; |
39 | virtual bool isValid() const = 0; |
40 | |
41 | virtual const String & name() const = 0; |
42 | virtual const StoragePtr & table() const = 0; |
43 | |
44 | virtual ~IDatabaseTablesIterator() = default; |
45 | }; |
46 | |
47 | /// Copies list of tables and iterates through such snapshot. |
48 | class DatabaseTablesSnapshotIterator : public IDatabaseTablesIterator |
49 | { |
50 | private: |
51 | Tables tables; |
52 | Tables::iterator it; |
53 | |
54 | public: |
55 | DatabaseTablesSnapshotIterator(Tables & tables_) : tables(tables_), it(tables.begin()) {} |
56 | |
57 | DatabaseTablesSnapshotIterator(Tables && tables_) : tables(tables_), it(tables.begin()) {} |
58 | |
59 | void next() { ++it; } |
60 | |
61 | bool isValid() const { return it != tables.end(); } |
62 | |
63 | const String & name() const { return it->first; } |
64 | |
65 | const StoragePtr & table() const { return it->second; } |
66 | }; |
67 | |
68 | /// Copies list of dictionaries and iterates through such snapshot. |
69 | class DatabaseDictionariesSnapshotIterator |
70 | { |
71 | private: |
72 | Dictionaries dictionaries; |
73 | Dictionaries::iterator it; |
74 | |
75 | public: |
76 | DatabaseDictionariesSnapshotIterator() = default; |
77 | DatabaseDictionariesSnapshotIterator(Dictionaries & dictionaries_) : dictionaries(dictionaries_), it(dictionaries.begin()) {} |
78 | |
79 | DatabaseDictionariesSnapshotIterator(Dictionaries && dictionaries_) : dictionaries(dictionaries_), it(dictionaries.begin()) {} |
80 | |
81 | void next() { ++it; } |
82 | |
83 | bool isValid() const { return !dictionaries.empty() && it != dictionaries.end(); } |
84 | |
85 | const String & name() const { return *it; } |
86 | }; |
87 | |
88 | using DatabaseTablesIteratorPtr = std::unique_ptr<IDatabaseTablesIterator>; |
89 | using DatabaseDictionariesIteratorPtr = std::unique_ptr<DatabaseDictionariesSnapshotIterator>; |
90 | |
91 | |
92 | /** Database engine. |
93 | * It is responsible for: |
94 | * - initialization of set of known tables and dictionaries; |
95 | * - checking existence of a table and getting a table object; |
96 | * - retrieving a list of all tables; |
97 | * - creating and dropping tables; |
98 | * - renaming tables and moving between databases with same engine. |
99 | */ |
100 | |
101 | class IDatabase : public std::enable_shared_from_this<IDatabase> |
102 | { |
103 | public: |
104 | IDatabase() = delete; |
105 | IDatabase(String database_name_) : database_name(std::move(database_name_)) {} |
106 | |
107 | /// Get name of database engine. |
108 | virtual String getEngineName() const = 0; |
109 | |
110 | /// Load a set of existing tables. |
111 | /// You can call only once, right after the object is created. |
112 | virtual void loadStoredObjects(Context & /*context*/, bool /*has_force_restore_data_flag*/) {} |
113 | |
114 | /// Check the existence of the table. |
115 | virtual bool isTableExist( |
116 | const Context & context, |
117 | const String & name) const = 0; |
118 | |
119 | /// Check the existence of the dictionary |
120 | virtual bool isDictionaryExist( |
121 | const Context & /*context*/, |
122 | const String & /*name*/) const |
123 | { |
124 | return false; |
125 | } |
126 | |
127 | /// Get the table for work. Return nullptr if there is no table. |
128 | virtual StoragePtr tryGetTable( |
129 | const Context & context, |
130 | const String & name) const = 0; |
131 | |
132 | using FilterByNameFunction = std::function<bool(const String &)>; |
133 | |
134 | /// Get an iterator that allows you to pass through all the tables. |
135 | /// 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. |
136 | virtual DatabaseTablesIteratorPtr getTablesIterator(const Context & context, const FilterByNameFunction & filter_by_table_name = {}) = 0; |
137 | |
138 | /// Get an iterator to pass through all the dictionaries. |
139 | virtual DatabaseDictionariesIteratorPtr getDictionariesIterator(const Context & /*context*/, [[maybe_unused]] const FilterByNameFunction & filter_by_dictionary_name = {}) |
140 | { |
141 | return std::make_unique<DatabaseDictionariesSnapshotIterator>(); |
142 | } |
143 | |
144 | /// Get an iterator to pass through all the tables and dictionary tables. |
145 | virtual DatabaseTablesIteratorPtr getTablesWithDictionaryTablesIterator(const Context & context, const FilterByNameFunction & filter_by_name = {}) |
146 | { |
147 | return getTablesIterator(context, filter_by_name); |
148 | } |
149 | |
150 | /// Is the database empty. |
151 | virtual bool empty(const Context & context) const = 0; |
152 | |
153 | /// Add the table to the database. Record its presence in the metadata. |
154 | virtual void createTable( |
155 | const Context & /*context*/, |
156 | const String & /*name*/, |
157 | const StoragePtr & /*table*/, |
158 | const ASTPtr & /*query*/) |
159 | { |
160 | throw Exception("There is no CREATE TABLE query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED); |
161 | } |
162 | |
163 | /// Add the dictionary to the database. Record its presence in the metadata. |
164 | virtual void createDictionary( |
165 | const Context & /*context*/, |
166 | const String & /*dictionary_name*/, |
167 | const ASTPtr & /*query*/) |
168 | { |
169 | throw Exception("There is no CREATE DICTIONARY query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED); |
170 | } |
171 | |
172 | /// Delete the table from the database. Delete the metadata. |
173 | virtual void removeTable( |
174 | const Context & /*context*/, |
175 | const String & /*name*/) |
176 | { |
177 | throw Exception("There is no DROP TABLE query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED); |
178 | } |
179 | |
180 | /// Delete the dictionary from the database. Delete the metadata. |
181 | virtual void removeDictionary( |
182 | const Context & /*context*/, |
183 | const String & /*dictionary_name*/) |
184 | { |
185 | throw Exception("There is no DROP DICTIONARY query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED); |
186 | } |
187 | |
188 | /// Add a table to the database, but do not add it to the metadata. The database may not support this method. |
189 | virtual void attachTable(const String & /*name*/, const StoragePtr & /*table*/) |
190 | { |
191 | throw Exception("There is no ATTACH TABLE query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED); |
192 | } |
193 | |
194 | /// Add dictionary to the database, but do not add it to the metadata. The database may not support this method. |
195 | /// If dictionaries_lazy_load is false it also starts loading the dictionary asynchronously. |
196 | virtual void attachDictionary(const String & /*name*/, const Context & /*context*/) |
197 | { |
198 | throw Exception("There is no ATTACH DICTIONARY query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED); |
199 | } |
200 | |
201 | /// Forget about the table without deleting it, and return it. The database may not support this method. |
202 | virtual StoragePtr detachTable(const String & /*name*/) |
203 | { |
204 | throw Exception("There is no DETACH TABLE query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED); |
205 | } |
206 | |
207 | /// Forget about the dictionary without deleting it. The database may not support this method. |
208 | virtual void detachDictionary(const String & /*name*/, const Context & /*context*/) |
209 | { |
210 | throw Exception("There is no DETACH DICTIONARY query for Database" + getEngineName(), ErrorCodes::NOT_IMPLEMENTED); |
211 | } |
212 | |
213 | /// Rename the table and possibly move the table to another database. |
214 | virtual void renameTable( |
215 | const Context & /*context*/, |
216 | const String & /*name*/, |
217 | IDatabase & /*to_database*/, |
218 | const String & /*to_name*/, |
219 | TableStructureWriteLockHolder &) |
220 | { |
221 | throw Exception(getEngineName() + ": renameTable() is not supported" , ErrorCodes::NOT_IMPLEMENTED); |
222 | } |
223 | |
224 | using ASTModifier = std::function<void(IAST &)>; |
225 | |
226 | /// Change the table structure in metadata. |
227 | /// You must call under the TableStructureLock of the corresponding table . If engine_modifier is empty, then engine does not change. |
228 | virtual void alterTable( |
229 | const Context & /*context*/, |
230 | const String & /*name*/, |
231 | const StorageInMemoryMetadata & /*metadata*/) |
232 | { |
233 | throw Exception(getEngineName() + ": alterTable() is not supported" , ErrorCodes::NOT_IMPLEMENTED); |
234 | } |
235 | |
236 | /// Returns time of table's metadata change, 0 if there is no corresponding metadata file. |
237 | virtual time_t getObjectMetadataModificationTime(const String & /*name*/) const |
238 | { |
239 | return static_cast<time_t>(0); |
240 | } |
241 | |
242 | /// Get the CREATE TABLE query for the table. It can also provide information for detached tables for which there is metadata. |
243 | ASTPtr tryGetCreateTableQuery(const Context & context, const String & name) const noexcept |
244 | { |
245 | return getCreateTableQueryImpl(context, name, false); |
246 | } |
247 | |
248 | ASTPtr getCreateTableQuery(const Context & context, const String & name) const |
249 | { |
250 | return getCreateTableQueryImpl(context, name, true); |
251 | } |
252 | |
253 | /// Get the CREATE DICTIONARY query for the dictionary. Returns nullptr if dictionary doesn't exists. |
254 | ASTPtr tryGetCreateDictionaryQuery(const Context & context, const String & name) const noexcept |
255 | { |
256 | return getCreateDictionaryQueryImpl(context, name, false); |
257 | } |
258 | |
259 | ASTPtr getCreateDictionaryQuery(const Context & context, const String & name) const |
260 | { |
261 | return getCreateDictionaryQueryImpl(context, name, true); |
262 | } |
263 | |
264 | /// Get the CREATE DATABASE query for current database. |
265 | virtual ASTPtr getCreateDatabaseQuery() const = 0; |
266 | |
267 | /// Get name of database. |
268 | String getDatabaseName() const { return database_name; } |
269 | /// Returns path for persistent data storage if the database supports it, empty string otherwise |
270 | virtual String getDataPath() const { return {}; } |
271 | /// Returns path for persistent data storage for table if the database supports it, empty string otherwise. Table must exist |
272 | virtual String getTableDataPath(const String & /*table_name*/) const { return {}; } |
273 | /// Returns path for persistent data storage for CREATE/ATTACH query if the database supports it, empty string otherwise |
274 | virtual String getTableDataPath(const ASTCreateQuery & /*query*/) const { return {}; } |
275 | /// Returns metadata path if the database supports it, empty string otherwise |
276 | virtual String getMetadataPath() const { return {}; } |
277 | /// Returns metadata path of a concrete table if the database supports it, empty string otherwise |
278 | virtual String getObjectMetadataPath(const String & /*table_name*/) const { return {}; } |
279 | |
280 | /// Ask all tables to complete the background threads they are using and delete all table objects. |
281 | virtual void shutdown() = 0; |
282 | |
283 | /// Delete data and metadata stored inside the database, if exists. |
284 | virtual void drop(const Context & /*context*/) {} |
285 | |
286 | virtual ~IDatabase() {} |
287 | |
288 | protected: |
289 | virtual ASTPtr getCreateTableQueryImpl(const Context & /*context*/, const String & /*name*/, bool throw_on_error) const |
290 | { |
291 | if (throw_on_error) |
292 | throw Exception("There is no SHOW CREATE TABLE query for Database" + getEngineName(), ErrorCodes::CANNOT_GET_CREATE_TABLE_QUERY); |
293 | return nullptr; |
294 | } |
295 | |
296 | virtual ASTPtr getCreateDictionaryQueryImpl(const Context & /*context*/, const String & /*name*/, bool throw_on_error) const |
297 | { |
298 | if (throw_on_error) |
299 | throw Exception("There is no SHOW CREATE DICTIONARY query for Database" + getEngineName(), ErrorCodes::CANNOT_GET_CREATE_DICTIONARY_QUERY); |
300 | return nullptr; |
301 | } |
302 | |
303 | String database_name; |
304 | }; |
305 | |
306 | using DatabasePtr = std::shared_ptr<IDatabase>; |
307 | using Databases = std::map<String, DatabasePtr>; |
308 | |
309 | } |
310 | |