Drop wfRunHooks, deprecated since 1.25
[lhc/web/wiklou.git] / includes / libs / rdbms / database / IDatabase.php
1 <?php
2 /**
3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
16 * http://www.gnu.org/copyleft/gpl.html
17 *
18 * @file
19 */
20 namespace Wikimedia\Rdbms;
21
22 use InvalidArgumentException;
23 use Wikimedia\ScopedCallback;
24 use RuntimeException;
25 use stdClass;
26
27 /**
28 * @defgroup Database Database
29 * This group deals with database interface functions
30 * and query specifics/optimisations.
31 */
32 /**
33 * Basic database interface for live and lazy-loaded relation database handles
34 *
35 * @note IDatabase and DBConnRef should be updated to reflect any changes
36 * @ingroup Database
37 */
38 interface IDatabase {
39 /** @var int Callback triggered immediately due to no active transaction */
40 const TRIGGER_IDLE = 1;
41 /** @var int Callback triggered by COMMIT */
42 const TRIGGER_COMMIT = 2;
43 /** @var int Callback triggered by ROLLBACK */
44 const TRIGGER_ROLLBACK = 3;
45
46 /** @var string Transaction is requested by regular caller outside of the DB layer */
47 const TRANSACTION_EXPLICIT = '';
48 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
49 const TRANSACTION_INTERNAL = 'implicit';
50
51 /** @var string Atomic section is not cancelable */
52 const ATOMIC_NOT_CANCELABLE = '';
53 /** @var string Atomic section is cancelable */
54 const ATOMIC_CANCELABLE = 'cancelable';
55
56 /** @var string Commit/rollback is from outside the IDatabase handle and connection manager */
57 const FLUSHING_ONE = '';
58 /** @var string Commit/rollback is from the connection manager for the IDatabase handle */
59 const FLUSHING_ALL_PEERS = 'flush';
60 /** @var string Commit/rollback is from the IDatabase handle internally */
61 const FLUSHING_INTERNAL = 'flush-internal';
62
63 /** @var string Do not remember the prior flags */
64 const REMEMBER_NOTHING = '';
65 /** @var string Remember the prior flags */
66 const REMEMBER_PRIOR = 'remember';
67 /** @var string Restore to the prior flag state */
68 const RESTORE_PRIOR = 'prior';
69 /** @var string Restore to the initial flag state */
70 const RESTORE_INITIAL = 'initial';
71
72 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
73 const ESTIMATE_TOTAL = 'total';
74 /** @var string Estimate time to apply (scanning, applying) */
75 const ESTIMATE_DB_APPLY = 'apply';
76
77 /** @var int Combine list with comma delimeters */
78 const LIST_COMMA = 0;
79 /** @var int Combine list with AND clauses */
80 const LIST_AND = 1;
81 /** @var int Convert map into a SET clause */
82 const LIST_SET = 2;
83 /** @var int Treat as field name and do not apply value escaping */
84 const LIST_NAMES = 3;
85 /** @var int Combine list with OR clauses */
86 const LIST_OR = 4;
87
88 /** @var int Enable debug logging */
89 const DBO_DEBUG = 1;
90 /** @var int Disable query buffering (only one result set can be iterated at a time) */
91 const DBO_NOBUFFER = 2;
92 /** @var int Ignore query errors (internal use only!) */
93 const DBO_IGNORE = 4;
94 /** @var int Automatically start a transaction before running a query if none is active */
95 const DBO_TRX = 8;
96 /** @var int Use DBO_TRX in non-CLI mode */
97 const DBO_DEFAULT = 16;
98 /** @var int Use DB persistent connections if possible */
99 const DBO_PERSISTENT = 32;
100 /** @var int DBA session mode; mostly for Oracle */
101 const DBO_SYSDBA = 64;
102 /** @var int Schema file mode; mostly for Oracle */
103 const DBO_DDLMODE = 128;
104 /** @var int Enable SSL/TLS in connection protocol */
105 const DBO_SSL = 256;
106 /** @var int Enable compression in connection protocol */
107 const DBO_COMPRESS = 512;
108
109 /**
110 * A string describing the current software version, and possibly
111 * other details in a user-friendly way. Will be listed on Special:Version, etc.
112 * Use getServerVersion() to get machine-friendly information.
113 *
114 * @return string Version information from the database server
115 */
116 public function getServerInfo();
117
118 /**
119 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
120 *
121 * Unbuffered queries are very troublesome in MySQL:
122 *
123 * - If another query is executed while the first query is being read
124 * out, the first query is killed. This means you can't call normal
125 * Database functions while you are reading an unbuffered query result
126 * from a normal Database connection.
127 *
128 * - Unbuffered queries cause the MySQL server to use large amounts of
129 * memory and to hold broad locks which block other queries.
130 *
131 * If you want to limit client-side memory, it's almost always better to
132 * split up queries into batches using a LIMIT clause than to switch off
133 * buffering.
134 *
135 * @param null|bool $buffer
136 * @return null|bool The previous value of the flag
137 */
138 public function bufferResults( $buffer = null );
139
140 /**
141 * Gets the current transaction level.
142 *
143 * Historically, transactions were allowed to be "nested". This is no
144 * longer supported, so this function really only returns a boolean.
145 *
146 * @return int The previous value
147 */
148 public function trxLevel();
149
150 /**
151 * Get the UNIX timestamp of the time that the transaction was established
152 *
153 * This can be used to reason about the staleness of SELECT data
154 * in REPEATABLE-READ transaction isolation level.
155 *
156 * @return float|null Returns null if there is not active transaction
157 * @since 1.25
158 */
159 public function trxTimestamp();
160
161 /**
162 * @return bool Whether an explicit transaction or atomic sections are still open
163 * @since 1.28
164 */
165 public function explicitTrxActive();
166
167 /**
168 * Assert that all explicit transactions or atomic sections have been closed.
169 * @throws DBTransactionError
170 * @since 1.32
171 */
172 public function assertNoOpenTransactions();
173
174 /**
175 * Get/set the table prefix.
176 * @param string|null $prefix The table prefix to set, or omitted to leave it unchanged.
177 * @return string The previous table prefix.
178 */
179 public function tablePrefix( $prefix = null );
180
181 /**
182 * Get/set the db schema.
183 * @param string|null $schema The database schema to set, or omitted to leave it unchanged.
184 * @return string The previous db schema.
185 */
186 public function dbSchema( $schema = null );
187
188 /**
189 * Get properties passed down from the server info array of the load
190 * balancer.
191 *
192 * @param string|null $name The entry of the info array to get, or null to get the
193 * whole array
194 *
195 * @return array|mixed|null
196 */
197 public function getLBInfo( $name = null );
198
199 /**
200 * Set the LB info array, or a member of it. If called with one parameter,
201 * the LB info array is set to that parameter. If it is called with two
202 * parameters, the member with the given name is set to the given value.
203 *
204 * @param string $name
205 * @param array|null $value
206 */
207 public function setLBInfo( $name, $value = null );
208
209 /**
210 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
211 *
212 * @param IDatabase $conn
213 * @since 1.27
214 */
215 public function setLazyMasterHandle( IDatabase $conn );
216
217 /**
218 * Returns true if this database does an implicit sort when doing GROUP BY
219 *
220 * @return bool
221 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
222 */
223 public function implicitGroupby();
224
225 /**
226 * Returns true if this database does an implicit order by when the column has an index
227 * For example: SELECT page_title FROM page LIMIT 1
228 *
229 * @return bool
230 */
231 public function implicitOrderby();
232
233 /**
234 * Return the last query that went through IDatabase::query()
235 * @return string
236 */
237 public function lastQuery();
238
239 /**
240 * Returns true if the connection may have been used for write queries.
241 * Should return true if unsure.
242 *
243 * @return bool
244 * @deprecated Since 1.31; use lastDoneWrites()
245 */
246 public function doneWrites();
247
248 /**
249 * Returns the last time the connection may have been used for write queries.
250 * Should return a timestamp if unsure.
251 *
252 * @return int|float UNIX timestamp or false
253 * @since 1.24
254 */
255 public function lastDoneWrites();
256
257 /**
258 * @return bool Whether there is a transaction open with possible write queries
259 * @since 1.27
260 */
261 public function writesPending();
262
263 /**
264 * @return bool Whether there is a transaction open with pre-commit callbacks pending
265 * @since 1.32
266 */
267 public function preCommitCallbacksPending();
268
269 /**
270 * Whether there is a transaction open with either possible write queries
271 * or unresolved pre-commit/commit/resolution callbacks pending
272 *
273 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
274 *
275 * @return bool
276 */
277 public function writesOrCallbacksPending();
278
279 /**
280 * Get the time spend running write queries for this transaction
281 *
282 * High times could be due to scanning, updates, locking, and such
283 *
284 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
285 * @return float|bool Returns false if not transaction is active
286 * @since 1.26
287 */
288 public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL );
289
290 /**
291 * Get the list of method names that did write queries for this transaction
292 *
293 * @return array
294 * @since 1.27
295 */
296 public function pendingWriteCallers();
297
298 /**
299 * Get the number of affected rows from pending write queries
300 *
301 * @return int
302 * @since 1.30
303 */
304 public function pendingWriteRowsAffected();
305
306 /**
307 * Is a connection to the database open?
308 * @return bool
309 */
310 public function isOpen();
311
312 /**
313 * Set a flag for this connection
314 *
315 * @param int $flag DBO_* constants from Defines.php:
316 * - DBO_DEBUG: output some debug info (same as debug())
317 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
318 * - DBO_TRX: automatically start transactions
319 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
320 * and removes it in command line mode
321 * - DBO_PERSISTENT: use persistant database connection
322 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
323 */
324 public function setFlag( $flag, $remember = self::REMEMBER_NOTHING );
325
326 /**
327 * Clear a flag for this connection
328 *
329 * @param int $flag DBO_* constants from Defines.php:
330 * - DBO_DEBUG: output some debug info (same as debug())
331 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
332 * - DBO_TRX: automatically start transactions
333 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
334 * and removes it in command line mode
335 * - DBO_PERSISTENT: use persistant database connection
336 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
337 */
338 public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING );
339
340 /**
341 * Restore the flags to their prior state before the last setFlag/clearFlag call
342 *
343 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
344 * @since 1.28
345 */
346 public function restoreFlags( $state = self::RESTORE_PRIOR );
347
348 /**
349 * Returns a boolean whether the flag $flag is set for this connection
350 *
351 * @param int $flag DBO_* constants from Defines.php:
352 * - DBO_DEBUG: output some debug info (same as debug())
353 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
354 * - DBO_TRX: automatically start transactions
355 * - DBO_PERSISTENT: use persistant database connection
356 * @return bool
357 */
358 public function getFlag( $flag );
359
360 /**
361 * @return string
362 */
363 public function getDomainID();
364
365 /**
366 * Alias for getDomainID()
367 *
368 * @return string
369 * @deprecated 1.30
370 */
371 public function getWikiID();
372
373 /**
374 * Get the type of the DBMS, as it appears in $wgDBtype.
375 *
376 * @return string
377 */
378 public function getType();
379
380 /**
381 * Fetch the next row from the given result object, in object form.
382 * Fields can be retrieved with $row->fieldname, with fields acting like
383 * member variables.
384 * If no more rows are available, false is returned.
385 *
386 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
387 * @return stdClass|bool
388 * @throws DBUnexpectedError Thrown if the database returns an error
389 */
390 public function fetchObject( $res );
391
392 /**
393 * Fetch the next row from the given result object, in associative array
394 * form. Fields are retrieved with $row['fieldname'].
395 * If no more rows are available, false is returned.
396 *
397 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
398 * @return array|bool
399 * @throws DBUnexpectedError Thrown if the database returns an error
400 */
401 public function fetchRow( $res );
402
403 /**
404 * Get the number of rows in a query result. If the query did not return
405 * any rows (for example, if it was a write query), this returns zero.
406 *
407 * @param mixed $res A SQL result
408 * @return int
409 */
410 public function numRows( $res );
411
412 /**
413 * Get the number of fields in a result object
414 * @see https://secure.php.net/mysql_num_fields
415 *
416 * @param mixed $res A SQL result
417 * @return int
418 */
419 public function numFields( $res );
420
421 /**
422 * Get a field name in a result object
423 * @see https://secure.php.net/mysql_field_name
424 *
425 * @param mixed $res A SQL result
426 * @param int $n
427 * @return string
428 */
429 public function fieldName( $res, $n );
430
431 /**
432 * Get the inserted value of an auto-increment row
433 *
434 * This should only be called after an insert that used an auto-incremented
435 * value. If no such insert was previously done in the current database
436 * session, the return value is undefined.
437 *
438 * @return int
439 */
440 public function insertId();
441
442 /**
443 * Change the position of the cursor in a result object
444 * @see https://secure.php.net/mysql_data_seek
445 *
446 * @param mixed $res A SQL result
447 * @param int $row
448 */
449 public function dataSeek( $res, $row );
450
451 /**
452 * Get the last error number
453 * @see https://secure.php.net/mysql_errno
454 *
455 * @return int
456 */
457 public function lastErrno();
458
459 /**
460 * Get a description of the last error
461 * @see https://secure.php.net/mysql_error
462 *
463 * @return string
464 */
465 public function lastError();
466
467 /**
468 * Get the number of rows affected by the last write query
469 * @see https://secure.php.net/mysql_affected_rows
470 *
471 * @return int
472 */
473 public function affectedRows();
474
475 /**
476 * Returns a wikitext link to the DB's website, e.g.,
477 * return "[https://www.mysql.com/ MySQL]";
478 * Should at least contain plain text, if for some reason
479 * your database has no website.
480 *
481 * @return string Wikitext of a link to the server software's web site
482 */
483 public function getSoftwareLink();
484
485 /**
486 * A string describing the current software version, like from
487 * mysql_get_server_info().
488 *
489 * @return string Version information from the database server.
490 */
491 public function getServerVersion();
492
493 /**
494 * Close the database connection
495 *
496 * This should only be called after any transactions have been resolved,
497 * aside from read-only automatic transactions (assuming no callbacks are registered).
498 * If a transaction is still open anyway, it will be rolled back.
499 *
500 * @throws DBError
501 * @return bool Operation success. true if already closed.
502 */
503 public function close();
504
505 /**
506 * Run an SQL query and return the result. Normally throws a DBQueryError
507 * on failure. If errors are ignored, returns false instead.
508 *
509 * If a connection loss is detected, then an attempt to reconnect will be made.
510 * For queries that involve no larger transactions or locks, they will be re-issued
511 * for convenience, provided the connection was re-established.
512 *
513 * In new code, the query wrappers select(), insert(), update(), delete(),
514 * etc. should be used where possible, since they give much better DBMS
515 * independence and automatically quote or validate user input in a variety
516 * of contexts. This function is generally only useful for queries which are
517 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
518 * as CREATE TABLE.
519 *
520 * However, the query wrappers themselves should call this function.
521 *
522 * @param string $sql SQL query
523 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
524 * comment (you can use __METHOD__ or add some extra info)
525 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
526 * maybe best to catch the exception instead?
527 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
528 * for a successful read query, or false on failure if $tempIgnore set
529 * @throws DBError
530 */
531 public function query( $sql, $fname = __METHOD__, $tempIgnore = false );
532
533 /**
534 * Free a result object returned by query() or select(). It's usually not
535 * necessary to call this, just use unset() or let the variable holding
536 * the result object go out of scope.
537 *
538 * @param mixed $res A SQL result
539 */
540 public function freeResult( $res );
541
542 /**
543 * A SELECT wrapper which returns a single field from a single result row.
544 *
545 * Usually throws a DBQueryError on failure. If errors are explicitly
546 * ignored, returns false on failure.
547 *
548 * If no result rows are returned from the query, false is returned.
549 *
550 * @param string|array $table Table name. See IDatabase::select() for details.
551 * @param string $var The field name to select. This must be a valid SQL
552 * fragment: do not use unvalidated user input.
553 * @param string|array $cond The condition array. See IDatabase::select() for details.
554 * @param string $fname The function name of the caller.
555 * @param string|array $options The query options. See IDatabase::select() for details.
556 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
557 *
558 * @return mixed The value from the field
559 * @throws DBError
560 */
561 public function selectField(
562 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
563 );
564
565 /**
566 * A SELECT wrapper which returns a list of single field values from result rows.
567 *
568 * Usually throws a DBQueryError on failure. If errors are explicitly
569 * ignored, returns false on failure.
570 *
571 * If no result rows are returned from the query, false is returned.
572 *
573 * @param string|array $table Table name. See IDatabase::select() for details.
574 * @param string $var The field name to select. This must be a valid SQL
575 * fragment: do not use unvalidated user input.
576 * @param string|array $cond The condition array. See IDatabase::select() for details.
577 * @param string $fname The function name of the caller.
578 * @param string|array $options The query options. See IDatabase::select() for details.
579 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
580 *
581 * @return array The values from the field
582 * @throws DBError
583 * @since 1.25
584 */
585 public function selectFieldValues(
586 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
587 );
588
589 /**
590 * Execute a SELECT query constructed using the various parameters provided.
591 * See below for full details of the parameters.
592 *
593 * @param string|array $table Table name
594 * @param string|array $vars Field names
595 * @param string|array $conds Conditions
596 * @param string $fname Caller function name
597 * @param array $options Query options
598 * @param array $join_conds Join conditions
599 *
600 *
601 * @param string|array $table
602 *
603 * May be either an array of table names, or a single string holding a table
604 * name. If an array is given, table aliases can be specified, for example:
605 *
606 * [ 'a' => 'user' ]
607 *
608 * This includes the user table in the query, with the alias "a" available
609 * for use in field names (e.g. a.user_name).
610 *
611 * A derived table, defined by the result of selectSQLText(), requires an alias
612 * key and a Subquery instance value which wraps the SQL query, for example:
613 *
614 * [ 'c' => new Subquery( 'SELECT ...' ) ]
615 *
616 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
617 * constructed using nested arrays. For example,
618 *
619 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
620 *
621 * along with `$join_conds` like
622 *
623 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
624 *
625 * will produce SQL something like
626 *
627 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
628 *
629 * All of the table names given here are automatically run through
630 * Database::tableName(), which causes the table prefix (if any) to be
631 * added, and various other table name mappings to be performed.
632 *
633 * Do not use untrusted user input as a table name. Alias names should
634 * not have characters outside of the Basic multilingual plane.
635 *
636 * @param string|array $vars
637 *
638 * May be either a field name or an array of field names. The field names
639 * can be complete fragments of SQL, for direct inclusion into the SELECT
640 * query. If an array is given, field aliases can be specified, for example:
641 *
642 * [ 'maxrev' => 'MAX(rev_id)' ]
643 *
644 * This includes an expression with the alias "maxrev" in the query.
645 *
646 * If an expression is given, care must be taken to ensure that it is
647 * DBMS-independent.
648 *
649 * Untrusted user input must not be passed to this parameter.
650 *
651 * @param string|array $conds
652 *
653 * May be either a string containing a single condition, or an array of
654 * conditions. If an array is given, the conditions constructed from each
655 * element are combined with AND.
656 *
657 * Array elements may take one of two forms:
658 *
659 * - Elements with a numeric key are interpreted as raw SQL fragments.
660 * - Elements with a string key are interpreted as equality conditions,
661 * where the key is the field name.
662 * - If the value of such an array element is a scalar (such as a
663 * string), it will be treated as data and thus quoted appropriately.
664 * If it is null, an IS NULL clause will be added.
665 * - If the value is an array, an IN (...) clause will be constructed
666 * from its non-null elements, and an IS NULL clause will be added
667 * if null is present, such that the field may match any of the
668 * elements in the array. The non-null elements will be quoted.
669 *
670 * Note that expressions are often DBMS-dependent in their syntax.
671 * DBMS-independent wrappers are provided for constructing several types of
672 * expression commonly used in condition queries. See:
673 * - IDatabase::buildLike()
674 * - IDatabase::conditional()
675 *
676 * Untrusted user input is safe in the values of string keys, however untrusted
677 * input must not be used in the array key names or in the values of numeric keys.
678 * Escaping of untrusted input used in values of numeric keys should be done via
679 * IDatabase::addQuotes()
680 *
681 * Use an empty array, string, or '*' to update all rows.
682 *
683 * @param string|array $options
684 *
685 * Optional: Array of query options. Boolean options are specified by
686 * including them in the array as a string value with a numeric key, for
687 * example:
688 *
689 * [ 'FOR UPDATE' ]
690 *
691 * The supported options are:
692 *
693 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
694 * with LIMIT can theoretically be used for paging through a result set,
695 * but this is discouraged for performance reasons.
696 *
697 * - LIMIT: Integer: return at most this many rows. The rows are sorted
698 * and then the first rows are taken until the limit is reached. LIMIT
699 * is applied to a result set after OFFSET.
700 *
701 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
702 * changed until the next COMMIT.
703 *
704 * - DISTINCT: Boolean: return only unique result rows.
705 *
706 * - GROUP BY: May be either an SQL fragment string naming a field or
707 * expression to group by, or an array of such SQL fragments.
708 *
709 * - HAVING: May be either an string containing a HAVING clause or an array of
710 * conditions building the HAVING clause. If an array is given, the conditions
711 * constructed from each element are combined with AND.
712 *
713 * - ORDER BY: May be either an SQL fragment giving a field name or
714 * expression to order by, or an array of such SQL fragments.
715 *
716 * - USE INDEX: This may be either a string giving the index name to use
717 * for the query, or an array. If it is an associative array, each key
718 * gives the table name (or alias), each value gives the index name to
719 * use for that table. All strings are SQL fragments and so should be
720 * validated by the caller.
721 *
722 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
723 * instead of SELECT.
724 *
725 * And also the following boolean MySQL extensions, see the MySQL manual
726 * for documentation:
727 *
728 * - LOCK IN SHARE MODE
729 * - STRAIGHT_JOIN
730 * - HIGH_PRIORITY
731 * - SQL_BIG_RESULT
732 * - SQL_BUFFER_RESULT
733 * - SQL_SMALL_RESULT
734 * - SQL_CALC_FOUND_ROWS
735 * - SQL_CACHE
736 * - SQL_NO_CACHE
737 *
738 *
739 * @param string|array $join_conds
740 *
741 * Optional associative array of table-specific join conditions. In the
742 * most common case, this is unnecessary, since the join condition can be
743 * in $conds. However, it is useful for doing a LEFT JOIN.
744 *
745 * The key of the array contains the table name or alias. The value is an
746 * array with two elements, numbered 0 and 1. The first gives the type of
747 * join, the second is the same as the $conds parameter. Thus it can be
748 * an SQL fragment, or an array where the string keys are equality and the
749 * numeric keys are SQL fragments all AND'd together. For example:
750 *
751 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
752 *
753 * @return IResultWrapper Resulting rows
754 * @throws DBError
755 */
756 public function select(
757 $table, $vars, $conds = '', $fname = __METHOD__,
758 $options = [], $join_conds = []
759 );
760
761 /**
762 * The equivalent of IDatabase::select() except that the constructed SQL
763 * is returned, instead of being immediately executed. This can be useful for
764 * doing UNION queries, where the SQL text of each query is needed. In general,
765 * however, callers outside of Database classes should just use select().
766 *
767 * @see IDatabase::select()
768 *
769 * @param string|array $table Table name
770 * @param string|array $vars Field names
771 * @param string|array $conds Conditions
772 * @param string $fname Caller function name
773 * @param string|array $options Query options
774 * @param string|array $join_conds Join conditions
775 * @return string SQL query string
776 */
777 public function selectSQLText(
778 $table, $vars, $conds = '', $fname = __METHOD__,
779 $options = [], $join_conds = []
780 );
781
782 /**
783 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
784 * that a single row object is returned. If the query returns no rows,
785 * false is returned.
786 *
787 * @param string|array $table Table name
788 * @param string|array $vars Field names
789 * @param array $conds Conditions
790 * @param string $fname Caller function name
791 * @param string|array $options Query options
792 * @param array|string $join_conds Join conditions
793 *
794 * @return stdClass|bool
795 * @throws DBError
796 */
797 public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
798 $options = [], $join_conds = []
799 );
800
801 /**
802 * Estimate the number of rows in dataset
803 *
804 * MySQL allows you to estimate the number of rows that would be returned
805 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
806 * index cardinality statistics, and is notoriously inaccurate, especially
807 * when large numbers of rows have recently been added or deleted.
808 *
809 * For DBMSs that don't support fast result size estimation, this function
810 * will actually perform the SELECT COUNT(*).
811 *
812 * Takes the same arguments as IDatabase::select().
813 *
814 * @param string $table Table name
815 * @param string $var Column for which NULL values are not counted [default "*"]
816 * @param array|string $conds Filters on the table
817 * @param string $fname Function name for profiling
818 * @param array $options Options for select
819 * @param array|string $join_conds Join conditions
820 * @return int Row count
821 * @throws DBError
822 */
823 public function estimateRowCount(
824 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
825 );
826
827 /**
828 * Get the number of rows in dataset
829 *
830 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
831 *
832 * Takes the same arguments as IDatabase::select().
833 *
834 * @since 1.27 Added $join_conds parameter
835 *
836 * @param array|string $tables Table names
837 * @param string $var Column for which NULL values are not counted [default "*"]
838 * @param array|string $conds Filters on the table
839 * @param string $fname Function name for profiling
840 * @param array $options Options for select
841 * @param array $join_conds Join conditions (since 1.27)
842 * @return int Row count
843 * @throws DBError
844 */
845 public function selectRowCount(
846 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
847 );
848
849 /**
850 * Lock all rows meeting the given conditions/options FOR UPDATE
851 *
852 * @param array|string $table Table names
853 * @param array|string $conds Filters on the table
854 * @param string $fname Function name for profiling
855 * @param array $options Options for select ("FOR UPDATE" is added automatically)
856 * @param array $join_conds Join conditions
857 * @return int Number of matching rows found (and locked)
858 * @since 1.32
859 */
860 public function lockForUpdate(
861 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
862 );
863
864 /**
865 * Determines whether a field exists in a table
866 *
867 * @param string $table Table name
868 * @param string $field Filed to check on that table
869 * @param string $fname Calling function name (optional)
870 * @return bool Whether $table has filed $field
871 * @throws DBError
872 */
873 public function fieldExists( $table, $field, $fname = __METHOD__ );
874
875 /**
876 * Determines whether an index exists
877 * Usually throws a DBQueryError on failure
878 * If errors are explicitly ignored, returns NULL on failure
879 *
880 * @param string $table
881 * @param string $index
882 * @param string $fname
883 * @return bool|null
884 * @throws DBError
885 */
886 public function indexExists( $table, $index, $fname = __METHOD__ );
887
888 /**
889 * Query whether a given table exists
890 *
891 * @param string $table
892 * @param string $fname
893 * @return bool
894 * @throws DBError
895 */
896 public function tableExists( $table, $fname = __METHOD__ );
897
898 /**
899 * INSERT wrapper, inserts an array into a table.
900 *
901 * $a may be either:
902 *
903 * - A single associative array. The array keys are the field names, and
904 * the values are the values to insert. The values are treated as data
905 * and will be quoted appropriately. If NULL is inserted, this will be
906 * converted to a database NULL.
907 * - An array with numeric keys, holding a list of associative arrays.
908 * This causes a multi-row INSERT on DBMSs that support it. The keys in
909 * each subarray must be identical to each other, and in the same order.
910 *
911 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
912 * returns success.
913 *
914 * $options is an array of options, with boolean options encoded as values
915 * with numeric keys, in the same style as $options in
916 * IDatabase::select(). Supported options are:
917 *
918 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
919 * any rows which cause duplicate key errors are not inserted. It's
920 * possible to determine how many rows were successfully inserted using
921 * IDatabase::affectedRows().
922 *
923 * @param string $table Table name. This will be passed through
924 * Database::tableName().
925 * @param array $a Array of rows to insert
926 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
927 * @param array $options Array of options
928 *
929 * @return bool
930 * @throws DBError
931 */
932 public function insert( $table, $a, $fname = __METHOD__, $options = [] );
933
934 /**
935 * UPDATE wrapper. Takes a condition array and a SET array.
936 *
937 * @param string $table Name of the table to UPDATE. This will be passed through
938 * Database::tableName().
939 * @param array $values An array of values to SET. For each array element,
940 * the key gives the field name, and the value gives the data to set
941 * that field to. The data will be quoted by IDatabase::addQuotes().
942 * Values with integer keys form unquoted SET statements, which can be used for
943 * things like "field = field + 1" or similar computed values.
944 * @param array $conds An array of conditions (WHERE). See
945 * IDatabase::select() for the details of the format of condition
946 * arrays. Use '*' to update all rows.
947 * @param string $fname The function name of the caller (from __METHOD__),
948 * for logging and profiling.
949 * @param array $options An array of UPDATE options, can be:
950 * - IGNORE: Ignore unique key conflicts
951 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
952 * @return bool
953 * @throws DBError
954 */
955 public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] );
956
957 /**
958 * Makes an encoded list of strings from an array
959 *
960 * These can be used to make conjunctions or disjunctions on SQL condition strings
961 * derived from an array (see IDatabase::select() $conds documentation).
962 *
963 * Example usage:
964 * @code
965 * $sql = $db->makeList( [
966 * 'rev_page' => $id,
967 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
968 * ], $db::LIST_AND );
969 * @endcode
970 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
971 *
972 * @param array $a Containing the data
973 * @param int $mode IDatabase class constant:
974 * - IDatabase::LIST_COMMA: Comma separated, no field names
975 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
976 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
977 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
978 * - IDatabase::LIST_NAMES: Comma separated field names
979 * @throws DBError
980 * @return string
981 */
982 public function makeList( $a, $mode = self::LIST_COMMA );
983
984 /**
985 * Build a partial where clause from a 2-d array such as used for LinkBatch.
986 * The keys on each level may be either integers or strings.
987 *
988 * @param array $data Organized as 2-d
989 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
990 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
991 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
992 * @return string|bool SQL fragment, or false if no items in array
993 */
994 public function makeWhereFrom2d( $data, $baseKey, $subKey );
995
996 /**
997 * Return aggregated value alias
998 *
999 * @param array $valuedata
1000 * @param string $valuename
1001 *
1002 * @return string
1003 */
1004 public function aggregateValue( $valuedata, $valuename = 'value' );
1005
1006 /**
1007 * @param string $field
1008 * @return string
1009 */
1010 public function bitNot( $field );
1011
1012 /**
1013 * @param string $fieldLeft
1014 * @param string $fieldRight
1015 * @return string
1016 */
1017 public function bitAnd( $fieldLeft, $fieldRight );
1018
1019 /**
1020 * @param string $fieldLeft
1021 * @param string $fieldRight
1022 * @return string
1023 */
1024 public function bitOr( $fieldLeft, $fieldRight );
1025
1026 /**
1027 * Build a concatenation list to feed into a SQL query
1028 * @param array $stringList List of raw SQL expressions; caller is
1029 * responsible for any quoting
1030 * @return string
1031 */
1032 public function buildConcat( $stringList );
1033
1034 /**
1035 * Build a GROUP_CONCAT or equivalent statement for a query.
1036 *
1037 * This is useful for combining a field for several rows into a single string.
1038 * NULL values will not appear in the output, duplicated values will appear,
1039 * and the resulting delimiter-separated values have no defined sort order.
1040 * Code using the results may need to use the PHP unique() or sort() methods.
1041 *
1042 * @param string $delim Glue to bind the results together
1043 * @param string|array $table Table name
1044 * @param string $field Field name
1045 * @param string|array $conds Conditions
1046 * @param string|array $join_conds Join conditions
1047 * @return string SQL text
1048 * @since 1.23
1049 */
1050 public function buildGroupConcatField(
1051 $delim, $table, $field, $conds = '', $join_conds = []
1052 );
1053
1054 /**
1055 * Build a SUBSTRING function.
1056 *
1057 * Behavior for non-ASCII values is undefined.
1058 *
1059 * @param string $input Field name
1060 * @param int $startPosition Positive integer
1061 * @param int|null $length Non-negative integer length or null for no limit
1062 * @throws InvalidArgumentException
1063 * @return string SQL text
1064 * @since 1.31
1065 */
1066 public function buildSubString( $input, $startPosition, $length = null );
1067
1068 /**
1069 * @param string $field Field or column to cast
1070 * @return string
1071 * @since 1.28
1072 */
1073 public function buildStringCast( $field );
1074
1075 /**
1076 * @param string $field Field or column to cast
1077 * @return string
1078 * @since 1.31
1079 */
1080 public function buildIntegerCast( $field );
1081
1082 /**
1083 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1084 *
1085 * @see IDatabase::selectSQLText()
1086 *
1087 * @param string|array $table Table name
1088 * @param string|array $vars Field names
1089 * @param string|array $conds Conditions
1090 * @param string $fname Caller function name
1091 * @param string|array $options Query options
1092 * @param string|array $join_conds Join conditions
1093 * @return Subquery
1094 * @since 1.31
1095 */
1096 public function buildSelectSubquery(
1097 $table, $vars, $conds = '', $fname = __METHOD__,
1098 $options = [], $join_conds = []
1099 );
1100
1101 /**
1102 * Returns true if DBs are assumed to be on potentially different servers
1103 *
1104 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1105 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1106 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1107 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1108 *
1109 * @return bool
1110 * @since 1.29
1111 */
1112 public function databasesAreIndependent();
1113
1114 /**
1115 * Change the current database
1116 *
1117 * @param string $db
1118 * @return bool Success or failure
1119 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1120 */
1121 public function selectDB( $db );
1122
1123 /**
1124 * Get the current DB name
1125 * @return string
1126 */
1127 public function getDBname();
1128
1129 /**
1130 * Get the server hostname or IP address
1131 * @return string
1132 */
1133 public function getServer();
1134
1135 /**
1136 * Adds quotes and backslashes.
1137 *
1138 * @param string|int|null|bool|Blob $s
1139 * @return string|int
1140 */
1141 public function addQuotes( $s );
1142
1143 /**
1144 * LIKE statement wrapper, receives a variable-length argument list with
1145 * parts of pattern to match containing either string literals that will be
1146 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1147 * the function could be provided with an array of aforementioned
1148 * parameters.
1149 *
1150 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1151 * a LIKE clause that searches for subpages of 'My page title'.
1152 * Alternatively:
1153 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1154 * $query .= $dbr->buildLike( $pattern );
1155 *
1156 * @since 1.16
1157 * @return string Fully built LIKE statement
1158 */
1159 public function buildLike();
1160
1161 /**
1162 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1163 *
1164 * @return LikeMatch
1165 */
1166 public function anyChar();
1167
1168 /**
1169 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1170 *
1171 * @return LikeMatch
1172 */
1173 public function anyString();
1174
1175 /**
1176 * Deprecated method, calls should be removed.
1177 *
1178 * This was formerly used for PostgreSQL and Oracle to handle
1179 * self::insertId() auto-incrementing fields. It is no longer necessary
1180 * since DatabasePostgres::insertId() has been reimplemented using
1181 * `lastval()` and Oracle has been reimplemented using triggers.
1182 *
1183 * Implementations should return null if inserting `NULL` into an
1184 * auto-incrementing field works, otherwise it should return an instance of
1185 * NextSequenceValue and filter it on calls to relevant methods.
1186 *
1187 * @deprecated since 1.30, no longer needed
1188 * @param string $seqName
1189 * @return null|NextSequenceValue
1190 */
1191 public function nextSequenceValue( $seqName );
1192
1193 /**
1194 * REPLACE query wrapper.
1195 *
1196 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1197 * except that when there is a duplicate key error, the old row is deleted
1198 * and the new row is inserted in its place.
1199 *
1200 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1201 * perform the delete, we need to know what the unique indexes are so that
1202 * we know how to find the conflicting rows.
1203 *
1204 * It may be more efficient to leave off unique indexes which are unlikely
1205 * to collide. However if you do this, you run the risk of encountering
1206 * errors which wouldn't have occurred in MySQL.
1207 *
1208 * @param string $table The table to replace the row(s) in.
1209 * @param array $uniqueIndexes Either a list of fields that define a unique index or
1210 * an array of such lists if there are multiple unique indexes defined in the schema
1211 * @param array $rows Can be either a single row to insert, or multiple rows,
1212 * in the same format as for IDatabase::insert()
1213 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1214 * @throws DBError
1215 */
1216 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ );
1217
1218 /**
1219 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1220 *
1221 * This updates any conflicting rows (according to the unique indexes) using
1222 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1223 *
1224 * $rows may be either:
1225 * - A single associative array. The array keys are the field names, and
1226 * the values are the values to insert. The values are treated as data
1227 * and will be quoted appropriately. If NULL is inserted, this will be
1228 * converted to a database NULL.
1229 * - An array with numeric keys, holding a list of associative arrays.
1230 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1231 * each subarray must be identical to each other, and in the same order.
1232 *
1233 * It may be more efficient to leave off unique indexes which are unlikely
1234 * to collide. However if you do this, you run the risk of encountering
1235 * errors which wouldn't have occurred in MySQL.
1236 *
1237 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1238 * returns success.
1239 *
1240 * @since 1.22
1241 *
1242 * @param string $table Table name. This will be passed through Database::tableName().
1243 * @param array $rows A single row or list of rows to insert
1244 * @param array $uniqueIndexes Either a list of fields that define a unique index or
1245 * an array of such lists if there are multiple unique indexes defined in the schema
1246 * @param array $set An array of values to SET. For each array element, the
1247 * key gives the field name, and the value gives the data to set that
1248 * field to. The data will be quoted by IDatabase::addQuotes().
1249 * Values with integer keys form unquoted SET statements, which can be used for
1250 * things like "field = field + 1" or similar computed values.
1251 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1252 * @throws DBError
1253 * @return bool
1254 */
1255 public function upsert(
1256 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1257 );
1258
1259 /**
1260 * DELETE where the condition is a join.
1261 *
1262 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1263 * we use sub-selects
1264 *
1265 * For safety, an empty $conds will not delete everything. If you want to
1266 * delete all rows where the join condition matches, set $conds='*'.
1267 *
1268 * DO NOT put the join condition in $conds.
1269 *
1270 * @param string $delTable The table to delete from.
1271 * @param string $joinTable The other table.
1272 * @param string $delVar The variable to join on, in the first table.
1273 * @param string $joinVar The variable to join on, in the second table.
1274 * @param array $conds Condition array of field names mapped to variables,
1275 * ANDed together in the WHERE clause
1276 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1277 * @throws DBError
1278 */
1279 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1280 $fname = __METHOD__
1281 );
1282
1283 /**
1284 * DELETE query wrapper.
1285 *
1286 * @param string $table Table name
1287 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1288 * for the format. Use $conds == "*" to delete all rows
1289 * @param string $fname Name of the calling function
1290 * @throws DBUnexpectedError
1291 * @return bool|IResultWrapper
1292 * @throws DBError
1293 */
1294 public function delete( $table, $conds, $fname = __METHOD__ );
1295
1296 /**
1297 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1298 * into another table.
1299 *
1300 * @warning If the insert will use an auto-increment or sequence to
1301 * determine the value of a column, this may break replication on
1302 * databases using statement-based replication if the SELECT is not
1303 * deterministically ordered.
1304 *
1305 * @param string $destTable The table name to insert into
1306 * @param string|array $srcTable May be either a table name, or an array of table names
1307 * to include in a join.
1308 *
1309 * @param array $varMap Must be an associative array of the form
1310 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1311 * rather than field names, but strings should be quoted with
1312 * IDatabase::addQuotes()
1313 *
1314 * @param array $conds Condition array. See $conds in IDatabase::select() for
1315 * the details of the format of condition arrays. May be "*" to copy the
1316 * whole table.
1317 *
1318 * @param string $fname The function name of the caller, from __METHOD__
1319 *
1320 * @param array $insertOptions Options for the INSERT part of the query, see
1321 * IDatabase::insert() for details. Also, one additional option is
1322 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1323 * an auto-increment or sequence to determine any column values.
1324 * @param array $selectOptions Options for the SELECT part of the query, see
1325 * IDatabase::select() for details.
1326 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1327 * IDatabase::select() for details.
1328 *
1329 * @return bool
1330 * @throws DBError
1331 */
1332 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1333 $fname = __METHOD__,
1334 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1335 );
1336
1337 /**
1338 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1339 * within the UNION construct.
1340 * @return bool
1341 */
1342 public function unionSupportsOrderAndLimit();
1343
1344 /**
1345 * Construct a UNION query
1346 * This is used for providing overload point for other DB abstractions
1347 * not compatible with the MySQL syntax.
1348 * @param array $sqls SQL statements to combine
1349 * @param bool $all Use UNION ALL
1350 * @return string SQL fragment
1351 */
1352 public function unionQueries( $sqls, $all );
1353
1354 /**
1355 * Construct a UNION query for permutations of conditions
1356 *
1357 * Databases sometimes have trouble with queries that have multiple values
1358 * for multiple condition parameters combined with limits and ordering.
1359 * This method constructs queries for the Cartesian product of the
1360 * conditions and unions them all together.
1361 *
1362 * @see IDatabase::select()
1363 * @since 1.30
1364 * @param string|array $table Table name
1365 * @param string|array $vars Field names
1366 * @param array $permute_conds Conditions for the Cartesian product. Keys
1367 * are field names, values are arrays of the possible values for that
1368 * field.
1369 * @param string|array $extra_conds Additional conditions to include in the
1370 * query.
1371 * @param string $fname Caller function name
1372 * @param string|array $options Query options. In addition to the options
1373 * recognized by IDatabase::select(), the following may be used:
1374 * - NOTALL: Set to use UNION instead of UNION ALL.
1375 * - INNER ORDER BY: If specified and supported, subqueries will use this
1376 * instead of ORDER BY.
1377 * @param string|array $join_conds Join conditions
1378 * @return string SQL query string.
1379 */
1380 public function unionConditionPermutations(
1381 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
1382 $options = [], $join_conds = []
1383 );
1384
1385 /**
1386 * Returns an SQL expression for a simple conditional. This doesn't need
1387 * to be overridden unless CASE isn't supported in your DBMS.
1388 *
1389 * @param string|array $cond SQL expression which will result in a boolean value
1390 * @param string $trueVal SQL expression to return if true
1391 * @param string $falseVal SQL expression to return if false
1392 * @return string SQL fragment
1393 */
1394 public function conditional( $cond, $trueVal, $falseVal );
1395
1396 /**
1397 * Returns a command for str_replace function in SQL query.
1398 * Uses REPLACE() in MySQL
1399 *
1400 * @param string $orig Column to modify
1401 * @param string $old Column to seek
1402 * @param string $new Column to replace with
1403 *
1404 * @return string
1405 */
1406 public function strreplace( $orig, $old, $new );
1407
1408 /**
1409 * Determines how long the server has been up
1410 *
1411 * @return int
1412 * @throws DBError
1413 */
1414 public function getServerUptime();
1415
1416 /**
1417 * Determines if the last failure was due to a deadlock
1418 *
1419 * Note that during a deadlock, the prior transaction will have been lost
1420 *
1421 * @return bool
1422 */
1423 public function wasDeadlock();
1424
1425 /**
1426 * Determines if the last failure was due to a lock timeout
1427 *
1428 * Note that during a lock wait timeout, the prior transaction will have been lost
1429 *
1430 * @return bool
1431 */
1432 public function wasLockTimeout();
1433
1434 /**
1435 * Determines if the last query error was due to a dropped connection
1436 *
1437 * Note that during a connection loss, the prior transaction will have been lost
1438 *
1439 * @return bool
1440 * @since 1.31
1441 */
1442 public function wasConnectionLoss();
1443
1444 /**
1445 * Determines if the last failure was due to the database being read-only.
1446 *
1447 * @return bool
1448 */
1449 public function wasReadOnlyError();
1450
1451 /**
1452 * Determines if the last query error was due to something outside of the query itself
1453 *
1454 * Note that the transaction may have been lost, discarding prior writes and results
1455 *
1456 * @return bool
1457 */
1458 public function wasErrorReissuable();
1459
1460 /**
1461 * Wait for the replica DB to catch up to a given master position
1462 *
1463 * @param DBMasterPos $pos
1464 * @param int $timeout The maximum number of seconds to wait for synchronisation
1465 * @return int|null Zero if the replica DB was past that position already,
1466 * greater than zero if we waited for some period of time, less than
1467 * zero if it timed out, and null on error
1468 * @throws DBError
1469 */
1470 public function masterPosWait( DBMasterPos $pos, $timeout );
1471
1472 /**
1473 * Get the replication position of this replica DB
1474 *
1475 * @return DBMasterPos|bool False if this is not a replica DB
1476 * @throws DBError
1477 */
1478 public function getReplicaPos();
1479
1480 /**
1481 * Get the position of this master
1482 *
1483 * @return DBMasterPos|bool False if this is not a master
1484 * @throws DBError
1485 */
1486 public function getMasterPos();
1487
1488 /**
1489 * @return bool Whether the DB is marked as read-only server-side
1490 * @since 1.28
1491 */
1492 public function serverIsReadOnly();
1493
1494 /**
1495 * Run a callback as soon as the current transaction commits or rolls back.
1496 * An error is thrown if no transaction is pending. Queries in the function will run in
1497 * AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1498 * that they begin.
1499 *
1500 * This is useful for combining cooperative locks and DB transactions.
1501 *
1502 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1503 *
1504 * The callback takes the following arguments:
1505 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1506 * - This IDatabase instance (since 1.32)
1507 *
1508 * @param callable $callback
1509 * @param string $fname Caller name
1510 * @return mixed
1511 * @since 1.28
1512 */
1513 public function onTransactionResolution( callable $callback, $fname = __METHOD__ );
1514
1515 /**
1516 * Run a callback as soon as there is no transaction pending.
1517 * If there is a transaction and it is rolled back, then the callback is cancelled.
1518 *
1519 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1520 * of the round, just after all peer transactions COMMIT. If the transaction round
1521 * is rolled back, then the callback is cancelled.
1522 *
1523 * Queries in the function will run in AUTOCOMMIT mode unless there are begin() calls.
1524 * Callbacks must commit any transactions that they begin.
1525 *
1526 * This is useful for updates to different systems or when separate transactions are needed.
1527 * For example, one might want to enqueue jobs into a system outside the database, but only
1528 * after the database is updated so that the jobs will see the data when they actually run.
1529 * It can also be used for updates that easily suffer from lock timeouts and deadlocks,
1530 * but where atomicity is not essential.
1531 *
1532 * Avoid using IDatabase instances aside from this one in the callback, unless such instances
1533 * never have IDatabase::DBO_TRX set. This keeps callbacks from interfering with one another.
1534 *
1535 * Updates will execute in the order they were enqueued.
1536 *
1537 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1538 *
1539 * The callback takes the following arguments:
1540 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1541 * - This IDatabase instance (since 1.32)
1542 *
1543 * @param callable $callback
1544 * @param string $fname Caller name
1545 * @since 1.32
1546 */
1547 public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ );
1548
1549 /**
1550 * Alias for onTransactionCommitOrIdle() for backwards-compatibility
1551 *
1552 * @param callable $callback
1553 * @param string $fname
1554 * @return mixed
1555 * @since 1.20
1556 * @deprecated Since 1.32
1557 */
1558 public function onTransactionIdle( callable $callback, $fname = __METHOD__ );
1559
1560 /**
1561 * Run a callback before the current transaction commits or now if there is none.
1562 * If there is a transaction and it is rolled back, then the callback is cancelled.
1563 *
1564 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1565 * of the round, just before all peer transactions COMMIT. If the transaction round
1566 * is rolled back, then the callback is cancelled.
1567 *
1568 * Callbacks must not start nor commit any transactions. If no transaction is active,
1569 * then a transaction will wrap the callback.
1570 *
1571 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1572 * but where atomicity is strongly desired for these updates and some related updates.
1573 *
1574 * Updates will execute in the order they were enqueued.
1575 *
1576 * The callback takes the one argument:
1577 * - This IDatabase instance (since 1.32)
1578 *
1579 * @param callable $callback
1580 * @param string $fname Caller name
1581 * @since 1.22
1582 */
1583 public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ );
1584
1585 /**
1586 * Run a callback after each time any transaction commits or rolls back
1587 *
1588 * The callback takes two arguments:
1589 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1590 * - This IDatabase object
1591 * Callbacks must commit any transactions that they begin.
1592 *
1593 * Registering a callback here will not affect writesOrCallbacks() pending.
1594 *
1595 * Since callbacks from this or onTransactionCommitOrIdle() can start and end transactions,
1596 * a single call to IDatabase::commit might trigger multiple runs of the listener callbacks.
1597 *
1598 * @param string $name Callback name
1599 * @param callable|null $callback Use null to unset a listener
1600 * @return mixed
1601 * @since 1.28
1602 */
1603 public function setTransactionListener( $name, callable $callback = null );
1604
1605 /**
1606 * Begin an atomic section of SQL statements
1607 *
1608 * Start an implicit transaction if no transaction is already active, set a savepoint
1609 * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
1610 * that the transaction is not committed prematurely. The end of the section must be
1611 * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
1612 * have layers of inner sections (sub-sections), but all sections must be ended in order
1613 * of innermost to outermost. Transactions cannot be started or committed until all
1614 * atomic sections are closed.
1615 *
1616 * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
1617 * by discarding the section's writes. This should not be used for failures when:
1618 * - upsert() could easily be used instead
1619 * - insert() with IGNORE could easily be used instead
1620 * - select() with FOR UPDATE could be checked before issuing writes instead
1621 * - The failure is from code that runs after the first write but doesn't need to
1622 * - The failures are from contention solvable via onTransactionPreCommitOrIdle()
1623 * - The failures are deadlocks; the RDBMs usually discard the whole transaction
1624 *
1625 * @note callers must use additional measures for situations involving two or more
1626 * (peer) transactions (e.g. updating two database servers at once). The transaction
1627 * and savepoint logic of this method only applies to this specific IDatabase instance.
1628 *
1629 * Example usage:
1630 * @code
1631 * // Start a transaction if there isn't one already
1632 * $dbw->startAtomic( __METHOD__ );
1633 * // Serialize these thread table updates
1634 * $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
1635 * // Add a new comment for the thread
1636 * $dbw->insert( 'comment', $row, __METHOD__ );
1637 * $cid = $db->insertId();
1638 * // Update thread reference to last comment
1639 * $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
1640 * // Demark the end of this conceptual unit of updates
1641 * $dbw->endAtomic( __METHOD__ );
1642 * @endcode
1643 *
1644 * Example usage (atomic changes that might have to be discarded):
1645 * @code
1646 * // Start a transaction if there isn't one already
1647 * $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
1648 * // Create new record metadata row
1649 * $dbw->insert( 'records', $row, __METHOD__ );
1650 * // Figure out where to store the data based on the new row's ID
1651 * $path = $recordDirectory . '/' . $dbw->insertId();
1652 * // Write the record data to the storage system
1653 * $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
1654 * if ( $status->isOK() ) {
1655 * // Try to cleanup files orphaned by transaction rollback
1656 * $dbw->onTransactionResolution(
1657 * function ( $type ) use ( $fileBackend, $path ) {
1658 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1659 * $fileBackend->delete( [ 'src' => $path ] );
1660 * }
1661 * },
1662 * __METHOD__
1663 * );
1664 * // Demark the end of this conceptual unit of updates
1665 * $dbw->endAtomic( __METHOD__ );
1666 * } else {
1667 * // Discard these writes from the transaction (preserving prior writes)
1668 * $dbw->cancelAtomic( __METHOD__, $sectionId );
1669 * }
1670 * @endcode
1671 *
1672 * @since 1.23
1673 * @param string $fname
1674 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1675 * savepoint and enable self::cancelAtomic() for this section.
1676 * @return AtomicSectionIdentifier section ID token
1677 * @throws DBError
1678 */
1679 public function startAtomic( $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE );
1680
1681 /**
1682 * Ends an atomic section of SQL statements
1683 *
1684 * Ends the next section of atomic SQL statements and commits the transaction
1685 * if necessary.
1686 *
1687 * @since 1.23
1688 * @see IDatabase::startAtomic
1689 * @param string $fname
1690 * @throws DBError
1691 */
1692 public function endAtomic( $fname = __METHOD__ );
1693
1694 /**
1695 * Cancel an atomic section of SQL statements
1696 *
1697 * This will roll back only the statements executed since the start of the
1698 * most recent atomic section, and close that section. If a transaction was
1699 * open before the corresponding startAtomic() call, any statements before
1700 * that call are *not* rolled back and the transaction remains open. If the
1701 * corresponding startAtomic() implicitly started a transaction, that
1702 * transaction is rolled back.
1703 *
1704 * @note callers must use additional measures for situations involving two or more
1705 * (peer) transactions (e.g. updating two database servers at once). The transaction
1706 * and savepoint logic of startAtomic() are bound to specific IDatabase instances.
1707 *
1708 * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
1709 *
1710 * @note As a micro-optimization to save a few DB calls, this method may only
1711 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1712 * @since 1.31
1713 * @see IDatabase::startAtomic
1714 * @param string $fname
1715 * @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
1716 * passing this enables cancellation of unclosed nested sections [optional]
1717 * @throws DBError
1718 */
1719 public function cancelAtomic( $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null );
1720
1721 /**
1722 * Perform an atomic section of reversable SQL statements from a callback
1723 *
1724 * The $callback takes the following arguments:
1725 * - This database object
1726 * - The value of $fname
1727 *
1728 * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
1729 * If any exception occurs during execution of the callback, it will be handled as follows:
1730 * - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
1731 * (and only) statements executed during the atomic section. If that succeeds, then the
1732 * exception will be re-thrown; if it fails, then a different exception will be thrown
1733 * and any further query attempts will fail until rollback() is called.
1734 * - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
1735 * end of the section and the error will be re-thrown. Any further query attempts will
1736 * fail until rollback() is called.
1737 *
1738 * This method is convenient for letting calls to the caller of this method be wrapped
1739 * in a try/catch blocks for exception types that imply that the caller failed but was
1740 * able to properly discard the changes it made in the transaction. This method can be
1741 * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
1742 *
1743 * Example usage, "RecordStore::save" method:
1744 * @code
1745 * $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
1746 * // Create new record metadata row
1747 * $dbw->insert( 'records', $record->toArray(), __METHOD__ );
1748 * // Figure out where to store the data based on the new row's ID
1749 * $path = $this->recordDirectory . '/' . $dbw->insertId();
1750 * // Write the record data to the storage system;
1751 * // blob store throughs StoreFailureException on failure
1752 * $this->blobStore->create( $path, $record->getJSON() );
1753 * // Try to cleanup files orphaned by transaction rollback
1754 * $dbw->onTransactionResolution(
1755 * function ( $type ) use ( $path ) {
1756 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1757 * $this->blobStore->delete( $path );
1758 * }
1759 * },
1760 * __METHOD__
1761 * );
1762 * }, $dbw::ATOMIC_CANCELABLE );
1763 * @endcode
1764 *
1765 * Example usage, caller of the "RecordStore::save" method:
1766 * @code
1767 * $dbw->startAtomic( __METHOD__ );
1768 * // ...various SQL writes happen...
1769 * try {
1770 * $recordStore->save( $record );
1771 * } catch ( StoreFailureException $e ) {
1772 * // ...various SQL writes happen...
1773 * }
1774 * // ...various SQL writes happen...
1775 * $dbw->endAtomic( __METHOD__ );
1776 * @endcode
1777 *
1778 * @see Database::startAtomic
1779 * @see Database::endAtomic
1780 * @see Database::cancelAtomic
1781 *
1782 * @param string $fname Caller name (usually __METHOD__)
1783 * @param callable $callback Callback that issues DB updates
1784 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1785 * savepoint and enable self::cancelAtomic() for this section.
1786 * @return mixed $res Result of the callback (since 1.28)
1787 * @throws DBError
1788 * @throws RuntimeException
1789 * @since 1.27; prior to 1.31 this did a rollback() instead of
1790 * cancelAtomic(), and assumed no callers up the stack would ever try to
1791 * catch the exception.
1792 */
1793 public function doAtomicSection(
1794 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
1795 );
1796
1797 /**
1798 * Begin a transaction. If a transaction is already in progress,
1799 * that transaction will be committed before the new transaction is started.
1800 *
1801 * Only call this from code with outer transcation scope.
1802 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1803 * Nesting of transactions is not supported.
1804 *
1805 * Note that when the DBO_TRX flag is set (which is usually the case for web
1806 * requests, but not for maintenance scripts), any previous database query
1807 * will have started a transaction automatically.
1808 *
1809 * Nesting of transactions is not supported. Attempts to nest transactions
1810 * will cause a warning, unless the current transaction was started
1811 * automatically because of the DBO_TRX flag.
1812 *
1813 * @param string $fname Calling function name
1814 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1815 * @throws DBError
1816 */
1817 public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT );
1818
1819 /**
1820 * Commits a transaction previously started using begin().
1821 * If no transaction is in progress, a warning is issued.
1822 *
1823 * Only call this from code with outer transcation scope.
1824 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1825 * Nesting of transactions is not supported.
1826 *
1827 * @param string $fname
1828 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1829 * constant to disable warnings about explicitly committing implicit transactions,
1830 * or calling commit when no transaction is in progress.
1831 *
1832 * This will trigger an exception if there is an ongoing explicit transaction.
1833 *
1834 * Only set the flush flag if you are sure that these warnings are not applicable,
1835 * and no explicit transactions are open.
1836 *
1837 * @throws DBError
1838 */
1839 public function commit( $fname = __METHOD__, $flush = '' );
1840
1841 /**
1842 * Rollback a transaction previously started using begin().
1843 * If no transaction is in progress, a warning is issued.
1844 *
1845 * Only call this from code with outer transcation scope.
1846 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1847 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1848 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1849 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1850 *
1851 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1852 *
1853 * @param string $fname Calling function name
1854 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1855 * constant to disable warnings about calling rollback when no transaction is in
1856 * progress. This will silently break any ongoing explicit transaction. Only set the
1857 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1858 * @throws DBError
1859 * @since 1.23 Added $flush parameter
1860 */
1861 public function rollback( $fname = __METHOD__, $flush = '' );
1862
1863 /**
1864 * Commit any transaction but error out if writes or callbacks are pending
1865 *
1866 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1867 * see a new point-in-time of the database. This is useful when one of many transaction
1868 * rounds finished and significant time will pass in the script's lifetime. It is also
1869 * useful to call on a replica DB after waiting on replication to catch up to the master.
1870 *
1871 * @param string $fname Calling function name
1872 * @throws DBError
1873 * @since 1.28
1874 */
1875 public function flushSnapshot( $fname = __METHOD__ );
1876
1877 /**
1878 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1879 * to the format used for inserting into timestamp fields in this DBMS.
1880 *
1881 * The result is unquoted, and needs to be passed through addQuotes()
1882 * before it can be included in raw SQL.
1883 *
1884 * @param string|int $ts
1885 *
1886 * @return string
1887 */
1888 public function timestamp( $ts = 0 );
1889
1890 /**
1891 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1892 * to the format used for inserting into timestamp fields in this DBMS. If
1893 * NULL is input, it is passed through, allowing NULL values to be inserted
1894 * into timestamp fields.
1895 *
1896 * The result is unquoted, and needs to be passed through addQuotes()
1897 * before it can be included in raw SQL.
1898 *
1899 * @param string|int|null $ts
1900 *
1901 * @return string
1902 */
1903 public function timestampOrNull( $ts = null );
1904
1905 /**
1906 * Ping the server and try to reconnect if it there is no connection
1907 *
1908 * @param float|null &$rtt Value to store the estimated RTT [optional]
1909 * @return bool Success or failure
1910 */
1911 public function ping( &$rtt = null );
1912
1913 /**
1914 * Get the amount of replication lag for this database server
1915 *
1916 * Callers should avoid using this method while a transaction is active
1917 *
1918 * @return int|bool Database replication lag in seconds or false on error
1919 * @throws DBError
1920 */
1921 public function getLag();
1922
1923 /**
1924 * Get the replica DB lag when the current transaction started
1925 * or a general lag estimate if not transaction is active
1926 *
1927 * This is useful when transactions might use snapshot isolation
1928 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1929 * is this lag plus transaction duration. If they don't, it is still
1930 * safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
1931 * indication of the staleness of subsequent reads.
1932 *
1933 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1934 * @throws DBError
1935 * @since 1.27
1936 */
1937 public function getSessionLagStatus();
1938
1939 /**
1940 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1941 *
1942 * @return int
1943 */
1944 public function maxListLen();
1945
1946 /**
1947 * Some DBMSs have a special format for inserting into blob fields, they
1948 * don't allow simple quoted strings to be inserted. To insert into such
1949 * a field, pass the data through this function before passing it to
1950 * IDatabase::insert().
1951 *
1952 * @param string $b
1953 * @return string|Blob
1954 */
1955 public function encodeBlob( $b );
1956
1957 /**
1958 * Some DBMSs return a special placeholder object representing blob fields
1959 * in result objects. Pass the object through this function to return the
1960 * original string.
1961 *
1962 * @param string|Blob $b
1963 * @return string
1964 */
1965 public function decodeBlob( $b );
1966
1967 /**
1968 * Override database's default behavior. $options include:
1969 * 'connTimeout' : Set the connection timeout value in seconds.
1970 * May be useful for very long batch queries such as
1971 * full-wiki dumps, where a single query reads out over
1972 * hours or days.
1973 *
1974 * @param array $options
1975 * @return void
1976 * @throws DBError
1977 */
1978 public function setSessionOptions( array $options );
1979
1980 /**
1981 * Set variables to be used in sourceFile/sourceStream, in preference to the
1982 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1983 * all. If it's set to false, $GLOBALS will be used.
1984 *
1985 * @param bool|array $vars Mapping variable name to value.
1986 */
1987 public function setSchemaVars( $vars );
1988
1989 /**
1990 * Check to see if a named lock is not locked by any thread (non-blocking)
1991 *
1992 * @param string $lockName Name of lock to poll
1993 * @param string $method Name of method calling us
1994 * @return bool
1995 * @throws DBError
1996 * @since 1.20
1997 */
1998 public function lockIsFree( $lockName, $method );
1999
2000 /**
2001 * Acquire a named lock
2002 *
2003 * Named locks are not related to transactions
2004 *
2005 * @param string $lockName Name of lock to aquire
2006 * @param string $method Name of the calling method
2007 * @param int $timeout Acquisition timeout in seconds
2008 * @return bool
2009 * @throws DBError
2010 */
2011 public function lock( $lockName, $method, $timeout = 5 );
2012
2013 /**
2014 * Release a lock
2015 *
2016 * Named locks are not related to transactions
2017 *
2018 * @param string $lockName Name of lock to release
2019 * @param string $method Name of the calling method
2020 *
2021 * @return int Returns 1 if the lock was released, 0 if the lock was not established
2022 * by this thread (in which case the lock is not released), and NULL if the named lock
2023 * did not exist
2024 *
2025 * @throws DBError
2026 */
2027 public function unlock( $lockName, $method );
2028
2029 /**
2030 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
2031 *
2032 * Only call this from outer transcation scope and when only one DB will be affected.
2033 * See https://www.mediawiki.org/wiki/Database_transactions for details.
2034 *
2035 * This is suitiable for transactions that need to be serialized using cooperative locks,
2036 * where each transaction can see each others' changes. Any transaction is flushed to clear
2037 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
2038 * the lock will be released unless a transaction is active. If one is active, then the lock
2039 * will be released when it either commits or rolls back.
2040 *
2041 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
2042 *
2043 * @param string $lockKey Name of lock to release
2044 * @param string $fname Name of the calling method
2045 * @param int $timeout Acquisition timeout in seconds
2046 * @return ScopedCallback|null
2047 * @throws DBError
2048 * @since 1.27
2049 */
2050 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
2051
2052 /**
2053 * Check to see if a named lock used by lock() use blocking queues
2054 *
2055 * @return bool
2056 * @since 1.26
2057 */
2058 public function namedLocksEnqueue();
2059
2060 /**
2061 * Find out when 'infinity' is. Most DBMSes support this. This is a special
2062 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
2063 * because "i" sorts after all numbers.
2064 *
2065 * @return string
2066 */
2067 public function getInfinity();
2068
2069 /**
2070 * Encode an expiry time into the DBMS dependent format
2071 *
2072 * @param string $expiry Timestamp for expiry, or the 'infinity' string
2073 * @return string
2074 */
2075 public function encodeExpiry( $expiry );
2076
2077 /**
2078 * Decode an expiry time into a DBMS independent format
2079 *
2080 * @param string $expiry DB timestamp field value for expiry
2081 * @param int $format TS_* constant, defaults to TS_MW
2082 * @return string
2083 */
2084 public function decodeExpiry( $expiry, $format = TS_MW );
2085
2086 /**
2087 * Allow or deny "big selects" for this session only. This is done by setting
2088 * the sql_big_selects session variable.
2089 *
2090 * This is a MySQL-specific feature.
2091 *
2092 * @param bool|string $value True for allow, false for deny, or "default" to
2093 * restore the initial value
2094 */
2095 public function setBigSelects( $value = true );
2096
2097 /**
2098 * @return bool Whether this DB is read-only
2099 * @since 1.27
2100 */
2101 public function isReadOnly();
2102
2103 /**
2104 * Make certain table names use their own database, schema, and table prefix
2105 * when passed into SQL queries pre-escaped and without a qualified database name
2106 *
2107 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
2108 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
2109 *
2110 * Calling this twice will completely clear any old table aliases. Also, note that
2111 * callers are responsible for making sure the schemas and databases actually exist.
2112 *
2113 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
2114 * @since 1.28
2115 */
2116 public function setTableAliases( array $aliases );
2117
2118 /**
2119 * Convert certain index names to alternative names before querying the DB
2120 *
2121 * Note that this applies to indexes regardless of the table they belong to.
2122 *
2123 * This can be employed when an index was renamed X => Y in code, but the new Y-named
2124 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
2125 * the aliases can be removed, and then the old X-named indexes dropped.
2126 *
2127 * @param string[] $aliases
2128 * @return mixed
2129 * @since 1.31
2130 */
2131 public function setIndexAliases( array $aliases );
2132 }
2133
2134 /**
2135 * @deprecated since 1.29
2136 */
2137 class_alias( IDatabase::class, 'IDatabase' );