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1# This file is part of daf_butler. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (http://www.lsst.org). 

6# See the COPYRIGHT file at the top-level directory of this distribution 

7# for details of code ownership. 

8# 

9# This program is free software: you can redistribute it and/or modify 

10# it under the terms of the GNU General Public License as published by 

11# the Free Software Foundation, either version 3 of the License, or 

12# (at your option) any later version. 

13# 

14# This program is distributed in the hope that it will be useful, 

15# but WITHOUT ANY WARRANTY; without even the implied warranty of 

16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

17# GNU General Public License for more details. 

18# 

19# You should have received a copy of the GNU General Public License 

20# along with this program. If not, see <http://www.gnu.org/licenses/>. 

21from __future__ import annotations 

22 

23__all__ = ["SqliteDatabase"] 

24 

25from contextlib import closing 

26import copy 

27from typing import Any, ContextManager, Dict, List, Optional 

28from dataclasses import dataclass 

29import os 

30import urllib.parse 

31 

32import sqlite3 

33import sqlalchemy 

34import sqlalchemy.ext.compiler 

35 

36from ..interfaces import Database, ReadOnlyDatabaseError, StaticTablesContext 

37from ...core import ddl 

38 

39 

40def _onSqlite3Connect(dbapiConnection: sqlite3.Connection, 

41 connectionRecord: sqlalchemy.pool._ConnectionRecord) -> None: 

42 assert isinstance(dbapiConnection, sqlite3.Connection) 

43 # Prevent pysqlite from emitting BEGIN and COMMIT statements. 

44 dbapiConnection.isolation_level = None 

45 # Enable foreign keys 

46 with closing(dbapiConnection.cursor()) as cursor: 

47 cursor.execute("PRAGMA foreign_keys=ON;") 

48 cursor.execute("PRAGMA busy_timeout = 300000;") # in ms, so 5min (way longer than should be needed) 

49 

50 

51def _onSqlite3Begin(connection: sqlalchemy.engine.Connection) -> sqlalchemy.engine.Connection: 

52 assert connection.dialect.name == "sqlite" 

53 # Replace pysqlite's buggy transaction handling that never BEGINs with our 

54 # own that does, and tell SQLite to try to acquire a lock as soon as we 

55 # start a transaction (this should lead to more blocking and fewer 

56 # deadlocks). 

57 connection.execute("BEGIN IMMEDIATE") 

58 return connection 

59 

60 

61class _Replace(sqlalchemy.sql.Insert): 

62 """A SQLAlchemy query that compiles to INSERT ... ON CONFLICT REPLACE 

63 on the primary key constraint for the table. 

64 """ 

65 pass 

66 

67 

68# Hard to infer what types these should be from SQLAlchemy docs; just disable 

69# static typing by calling everything "Any". 

70@sqlalchemy.ext.compiler.compiles(_Replace, "sqlite") 

71def _replace(insert: Any, compiler: Any, **kwargs: Any) -> Any: 

72 """Generate an INSERT ... ON CONFLICT REPLACE query. 

73 """ 

74 # SQLite and PostgreSQL use similar syntax for their ON CONFLICT extension, 

75 # but SQLAlchemy only knows about PostgreSQL's, so we have to compile some 

76 # custom text SQL ourselves. 

77 result = compiler.visit_insert(insert, **kwargs) 

78 preparer = compiler.preparer 

79 pk_columns = ", ".join([preparer.format_column(col) for col in insert.table.primary_key]) 

80 result += f" ON CONFLICT ({pk_columns})" 

81 columns = [preparer.format_column(col) for col in insert.table.columns 

82 if col.name not in insert.table.primary_key] 

83 updates = ", ".join([f"{col} = excluded.{col}" for col in columns]) 

84 result += f" DO UPDATE SET {updates}" 

85 return result 

86 

87 

88_AUTOINCR_TABLE_SPEC = ddl.TableSpec( 

89 fields=[ddl.FieldSpec(name="id", dtype=sqlalchemy.Integer, primaryKey=True)] 

90) 

91 

92 

93@dataclass 

94class _AutoincrementCompoundKeyWorkaround: 

95 """A workaround for SQLite's lack of support for compound primary keys that 

96 include an autoincrement field. 

97 """ 

98 

99 table: sqlalchemy.schema.Table 

100 """A single-column internal table that can be inserted into to yield 

101 autoincrement values (`sqlalchemy.schema.Table`). 

102 """ 

103 

104 column: str 

105 """The name of the column in the original table that needs to be populated 

106 with values from the internal table (`str`). 

107 """ 

108 

109 

110class SqliteDatabase(Database): 

111 """An implementation of the `Database` interface for SQLite3. 

112 

113 Parameters 

114 ---------- 

115 connection : `sqlalchemy.engine.Connection` 

116 An existing connection created by a previous call to `connect`. 

117 origin : `int` 

118 An integer ID that should be used as the default for any datasets, 

119 quanta, or other entities that use a (autoincrement, origin) compound 

120 primary key. 

121 namespace : `str`, optional 

122 The namespace (schema) this database is associated with. If `None`, 

123 the default schema for the connection is used (which may be `None`). 

124 writeable : `bool`, optional 

125 If `True`, allow write operations on the database, including 

126 ``CREATE TABLE``. 

127 

128 Notes 

129 ----- 

130 The case where ``namespace is not None`` is not yet tested, and may be 

131 broken; we need an API for attaching to different databases in order to 

132 write those tests, but haven't yet worked out what is common/different 

133 across databases well enough to define it. 

134 """ 

135 

136 def __init__(self, *, connection: sqlalchemy.engine.Connection, origin: int, 

137 namespace: Optional[str] = None, writeable: bool = True): 

138 super().__init__(origin=origin, connection=connection, namespace=namespace) 

139 # Get the filename from a call to 'PRAGMA database_list'. 

140 with closing(connection.connection.cursor()) as cursor: 

141 dbList = list(cursor.execute("PRAGMA database_list").fetchall()) 

142 if len(dbList) == 0: 

143 raise RuntimeError("No database in connection.") 

144 if namespace is None: 

145 namespace = "main" 

146 for _, dbname, filename in dbList: 

147 if dbname == namespace: 

148 break 

149 else: 

150 raise RuntimeError(f"No '{namespace}' database in connection.") 

151 if not filename: 

152 self.filename = None 

153 else: 

154 self.filename = filename 

155 self._writeable = writeable 

156 self._autoincr: Dict[str, _AutoincrementCompoundKeyWorkaround] = {} 

157 

158 @classmethod 

159 def makeDefaultUri(cls, root: str) -> Optional[str]: 

160 return "sqlite:///" + os.path.join(root, "gen3.sqlite3") 

161 

162 @classmethod 

163 def connect(cls, uri: Optional[str] = None, *, filename: Optional[str] = None, 

164 writeable: bool = True) -> sqlalchemy.engine.Connection: 

165 """Create a `sqlalchemy.engine.Connection` from a SQLAlchemy URI or 

166 filename. 

167 

168 Parameters 

169 ---------- 

170 uri : `str` 

171 A SQLAlchemy URI connection string. 

172 filename : `str` 

173 Name of the SQLite database file, or `None` to use an in-memory 

174 database. Ignored if ``uri is not None``. 

175 origin : `int` 

176 An integer ID that should be used as the default for any datasets, 

177 quanta, or other entities that use a (autoincrement, origin) 

178 compound primary key. 

179 writeable : `bool`, optional 

180 If `True`, allow write operations on the database, including 

181 ``CREATE TABLE``. 

182 

183 Returns 

184 ------- 

185 cs : `sqlalchemy.engine.Connection` 

186 A database connection and transaction state. 

187 """ 

188 # In order to be able to tell SQLite that we want a read-only or 

189 # read-write connection, we need to make the SQLite DBAPI connection 

190 # with a "URI"-based connection string. SQLAlchemy claims it can do 

191 # this 

192 # (https://docs.sqlalchemy.org/en/13/dialects/sqlite.html#uri-connections), 

193 # but it doesn't seem to work as advertised. To work around this, we 

194 # use the 'creator' argument to sqlalchemy.engine.create_engine, which 

195 # lets us pass a callable that creates the DBAPI connection. 

196 if uri is None: 

197 if filename is None: 

198 target = ":memory:" 

199 uri = "sqlite://" 

200 else: 

201 target = f"file:{filename}" 

202 uri = f"sqlite:///{filename}" 

203 else: 

204 parsed = urllib.parse.urlparse(uri) 

205 queries = parsed.query.split("&") 

206 if "uri=true" in queries: 

207 # This is a SQLAlchemy URI that is already trying to make a 

208 # SQLite connection via a SQLite URI, and hence there may 

209 # be URI components for both SQLite and SQLAlchemy. We 

210 # don't need to support that, and it'd be a 

211 # reimplementation of all of the (broken) logic in 

212 # SQLAlchemy for doing this, so we just don't. 

213 raise NotImplementedError("SQLite connection strings with 'uri=true' are not supported.") 

214 # This is just a SQLAlchemy URI with a non-URI SQLite 

215 # connection string inside it. Pull that out so we can use it 

216 # in the creator call. 

217 if parsed.path.startswith("/"): 

218 filename = parsed.path[1:] 

219 target = f"file:{filename}" 

220 else: 

221 filename = None 

222 target = ":memory:" 

223 if filename is None: 

224 if not writeable: 

225 raise NotImplementedError("Read-only :memory: databases are not supported.") 

226 else: 

227 if writeable: 

228 target += '?mode=rwc&uri=true' 

229 else: 

230 target += '?mode=ro&uri=true' 

231 

232 def creator() -> sqlite3.Connection: 

233 return sqlite3.connect(target, check_same_thread=False, uri=True) 

234 

235 engine = sqlalchemy.engine.create_engine(uri, poolclass=sqlalchemy.pool.NullPool, 

236 creator=creator) 

237 

238 sqlalchemy.event.listen(engine, "connect", _onSqlite3Connect) 

239 sqlalchemy.event.listen(engine, "begin", _onSqlite3Begin) 

240 try: 

241 return engine.connect() 

242 except sqlalchemy.exc.OperationalError as err: 

243 raise RuntimeError(f"Error creating connection with uri='{uri}', filename='{filename}', " 

244 f"target={target}.") from err 

245 

246 @classmethod 

247 def fromConnection(cls, connection: sqlalchemy.engine.Connection, *, origin: int, 

248 namespace: Optional[str] = None, writeable: bool = True) -> Database: 

249 return cls(connection=connection, origin=origin, writeable=writeable, namespace=namespace) 

250 

251 def isWriteable(self) -> bool: 

252 return self._writeable 

253 

254 def __str__(self) -> str: 

255 if self.filename: 

256 return f"SQLite3@{self.filename}" 

257 else: 

258 return "SQLite3@:memory:" 

259 

260 # MyPy claims that the return type here isn't covariant with the return 

261 # type of the base class method, which is formally correct but irrelevant 

262 # - the base class return type is _GeneratorContextManager, but only 

263 # because it's generated by the contextmanager decorator. 

264 def declareStaticTables(self, *, create: bool) -> ContextManager[StaticTablesContext]: # type: ignore 

265 # If the user asked for an in-memory, writeable database, then we may 

266 # need to re-create schema even if create=False because schema can be 

267 # lost on re-connect. This is only really relevant for tests, and it's 

268 # convenient there. 

269 if self.filename is None and self.isWriteable(): 

270 inspector = sqlalchemy.engine.reflection.Inspector(self._connection) 

271 tables = inspector.get_table_names(schema=self.namespace) 

272 if not tables: 

273 create = True 

274 return super().declareStaticTables(create=create) 

275 

276 def _convertFieldSpec(self, table: str, spec: ddl.FieldSpec, metadata: sqlalchemy.MetaData, 

277 **kwargs: Any) -> sqlalchemy.schema.Column: 

278 if spec.autoincrement: 

279 if not spec.primaryKey: 

280 raise RuntimeError(f"Autoincrement field {table}.{spec.name} that is not a " 

281 f"primary key is not supported.") 

282 if spec.dtype != sqlalchemy.Integer: 

283 # SQLite's autoincrement is really limited; it only works if 

284 # the column type is exactly "INTEGER". But it also doesn't 

285 # care about the distinctions between different integer types, 

286 # so it's safe to change it. 

287 spec = copy.copy(spec) 

288 spec.dtype = sqlalchemy.Integer 

289 return super()._convertFieldSpec(table, spec, metadata, **kwargs) 

290 

291 def _makeColumnConstraints(self, table: str, spec: ddl.FieldSpec) -> List[sqlalchemy.CheckConstraint]: 

292 # For sqlite we force constraints on all string columns since sqlite 

293 # ignores everything otherwise and this leads to problems with 

294 # other databases. 

295 

296 constraints = [] 

297 if spec.dtype == sqlalchemy.String: 

298 name = self.shrinkDatabaseEntityName("_".join([table, "len", spec.name])) 

299 constraints.append(sqlalchemy.CheckConstraint(f"length({spec.name})<={spec.length}" 

300 # Oracle converts 

301 # empty strings to 

302 # NULL so check 

303 f" AND length({spec.name})>=1", 

304 name=name)) 

305 

306 constraints.extend(super()._makeColumnConstraints(table, spec)) 

307 return constraints 

308 

309 def _convertTableSpec(self, name: str, spec: ddl.TableSpec, metadata: sqlalchemy.MetaData, 

310 **kwargs: Any) -> sqlalchemy.schema.Table: 

311 primaryKeyFieldNames = set(field.name for field in spec.fields if field.primaryKey) 

312 autoincrFieldNames = set(field.name for field in spec.fields if field.autoincrement) 

313 if len(autoincrFieldNames) > 1: 

314 raise RuntimeError("At most one autoincrement field per table is allowed.") 

315 if len(primaryKeyFieldNames) > 1 and len(autoincrFieldNames) > 0: 

316 # SQLite's default rowid-based autoincrement doesn't work if the 

317 # field is just one field in a compound primary key. As a 

318 # workaround, we create an extra table with just one column that 

319 # we'll insert into to generate those IDs. That's only safe if 

320 # that single-column table's records are already unique with just 

321 # the autoincrement field, not the rest of the primary key. In 

322 # practice, that means the single-column table's records are those 

323 # for which origin == self.origin. 

324 autoincrFieldName, = autoincrFieldNames 

325 otherPrimaryKeyFieldNames = primaryKeyFieldNames - autoincrFieldNames 

326 if otherPrimaryKeyFieldNames != {"origin"}: 

327 # We need the only other field in the key to be 'origin'. 

328 raise NotImplementedError( 

329 "Compound primary keys with an autoincrement are only supported in SQLite " 

330 "if the only non-autoincrement primary key field is 'origin'." 

331 ) 

332 self._autoincr[name] = _AutoincrementCompoundKeyWorkaround( 

333 table=self._convertTableSpec(f"_autoinc_{name}", _AUTOINCR_TABLE_SPEC, metadata, **kwargs), 

334 column=autoincrFieldName 

335 ) 

336 if not spec.recycleIds: 

337 kwargs = dict(kwargs, sqlite_autoincrement=True) 

338 return super()._convertTableSpec(name, spec, metadata, **kwargs) 

339 

340 def insert(self, table: sqlalchemy.schema.Table, *rows: dict, returnIds: bool = False, 

341 ) -> Optional[List[int]]: 

342 autoincr = self._autoincr.get(table.name) 

343 if autoincr is not None: 

344 # This table has a compound primary key that includes an 

345 # autoincrement. That doesn't work natively in SQLite, so we 

346 # insert into a single-column table and use those IDs. 

347 if not rows: 

348 return [] if returnIds else None 

349 if autoincr.column in rows[0]: 

350 # Caller passed the autoincrement key values explicitly in the 

351 # first row. They had better have done the same for all rows, 

352 # or SQLAlchemy would have a problem, even if we didn't. 

353 assert all(autoincr.column in row for row in rows) 

354 # We need to insert only the values that correspond to 

355 # ``origin == self.origin`` into the single-column table, to 

356 # make sure we don't generate conflicting keys there later. 

357 rowsForAutoincrTable = [dict(id=row[autoincr.column]) 

358 for row in rows if row["origin"] == self.origin] 

359 # Insert into the autoincr table and the target table inside 

360 # a transaction. The main-table insertion can take care of 

361 # returnIds for us. 

362 with self.transaction(): 

363 self._connection.execute(autoincr.table.insert(), *rowsForAutoincrTable) 

364 return super().insert(table, *rows, returnIds=returnIds) 

365 else: 

366 # Caller did not pass autoincrement key values on the first 

367 # row. Make sure they didn't ever do that, and also make 

368 # sure the origin that was passed in is always self.origin, 

369 # because we can't safely generate autoincrement values 

370 # otherwise. 

371 assert all(autoincr.column not in row and row["origin"] == self.origin for row in rows) 

372 # Insert into the autoincr table one by one to get the 

373 # primary key values back, then insert into the target table 

374 # in the same transaction. 

375 with self.transaction(): 

376 newRows = [] 

377 ids = [] 

378 for row in rows: 

379 newRow = row.copy() 

380 id = self._connection.execute(autoincr.table.insert()).inserted_primary_key[0] 

381 newRow[autoincr.column] = id 

382 newRows.append(newRow) 

383 ids.append(id) 

384 # Don't ever ask to returnIds here, because we've already 

385 # got them. 

386 super().insert(table, *newRows) 

387 if returnIds: 

388 return ids 

389 else: 

390 return None 

391 else: 

392 return super().insert(table, *rows, returnIds=returnIds) 

393 

394 def replace(self, table: sqlalchemy.schema.Table, *rows: dict) -> None: 

395 if not self.isWriteable(): 

396 raise ReadOnlyDatabaseError(f"Attempt to replace into read-only database '{self}'.") 

397 if not rows: 

398 return 

399 if table.name in self._autoincr: 

400 raise NotImplementedError( 

401 "replace does not support compound primary keys with autoincrement fields." 

402 ) 

403 self._connection.execute(_Replace(table), *rows) 

404 

405 filename: Optional[str] 

406 """Name of the file this database is connected to (`str` or `None`). 

407 

408 Set to `None` for in-memory databases. 

409 """