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.
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.
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
20 namespace Wikimedia\Rdbms
;
22 use InvalidArgumentException
;
23 use Wikimedia\ScopedCallback
;
28 * @defgroup Database Database
29 * This group deals with database interface functions
30 * and query specifics/optimisations.
33 * Basic database interface for live and lazy-loaded relation database handles
35 * @note: IDatabase and DBConnRef should be updated to reflect any changes
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;
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';
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';
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';
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';
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';
77 /** @var int Combine list with comma delimeters */
79 /** @var int Combine list with AND clauses */
81 /** @var int Convert map into a SET clause */
83 /** @var int Treat as field name and do not apply value escaping */
85 /** @var int Combine list with OR clauses */
88 /** @var int Enable debug logging */
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!) */
94 /** @var int Automatically start a transaction before running a query if none is active */
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 */
106 /** @var int Enable compression in connection protocol */
107 const DBO_COMPRESS
= 512;
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.
114 * @return string Version information from the database server
116 public function getServerInfo();
119 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
121 * Unbuffered queries are very troublesome in MySQL:
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.
128 * - Unbuffered queries cause the MySQL server to use large amounts of
129 * memory and to hold broad locks which block other queries.
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
135 * @param null|bool $buffer
136 * @return null|bool The previous value of the flag
138 public function bufferResults( $buffer = null );
141 * Gets the current transaction level.
143 * Historically, transactions were allowed to be "nested". This is no
144 * longer supported, so this function really only returns a boolean.
146 * @return int The previous value
148 public function trxLevel();
151 * Get the UNIX timestamp of the time that the transaction was established
153 * This can be used to reason about the staleness of SELECT data
154 * in REPEATABLE-READ transaction isolation level.
156 * @return float|null Returns null if there is not active transaction
159 public function trxTimestamp();
162 * @return bool Whether an explicit transaction or atomic sections are still open
165 public function explicitTrxActive();
168 * Get/set the table prefix.
169 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
170 * @return string The previous table prefix.
172 public function tablePrefix( $prefix = null );
175 * Get/set the db schema.
176 * @param string $schema The database schema to set, or omitted to leave it unchanged.
177 * @return string The previous db schema.
179 public function dbSchema( $schema = null );
182 * Get properties passed down from the server info array of the load
185 * @param string $name The entry of the info array to get, or null to get the
188 * @return array|mixed|null
190 public function getLBInfo( $name = null );
193 * Set the LB info array, or a member of it. If called with one parameter,
194 * the LB info array is set to that parameter. If it is called with two
195 * parameters, the member with the given name is set to the given value.
197 * @param string $name
198 * @param array $value
200 public function setLBInfo( $name, $value = null );
203 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
205 * @param IDatabase $conn
208 public function setLazyMasterHandle( IDatabase
$conn );
211 * Returns true if this database does an implicit sort when doing GROUP BY
214 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
216 public function implicitGroupby();
219 * Returns true if this database does an implicit order by when the column has an index
220 * For example: SELECT page_title FROM page LIMIT 1
224 public function implicitOrderby();
227 * Return the last query that went through IDatabase::query()
230 public function lastQuery();
233 * Returns true if the connection may have been used for write queries.
234 * Should return true if unsure.
237 * @deprecated Since 1.31; use lastDoneWrites()
239 public function doneWrites();
242 * Returns the last time the connection may have been used for write queries.
243 * Should return a timestamp if unsure.
245 * @return int|float UNIX timestamp or false
248 public function lastDoneWrites();
251 * @return bool Whether there is a transaction open with possible write queries
254 public function writesPending();
257 * Returns true if there is a transaction/round open with possible write
258 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
259 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
263 public function writesOrCallbacksPending();
266 * Get the time spend running write queries for this transaction
268 * High times could be due to scanning, updates, locking, and such
270 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
271 * @return float|bool Returns false if not transaction is active
274 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
277 * Get the list of method names that did write queries for this transaction
282 public function pendingWriteCallers();
285 * Get the number of affected rows from pending write queries
290 public function pendingWriteRowsAffected();
293 * Is a connection to the database open?
296 public function isOpen();
299 * Set a flag for this connection
301 * @param int $flag DBO_* constants from Defines.php:
302 * - DBO_DEBUG: output some debug info (same as debug())
303 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
304 * - DBO_TRX: automatically start transactions
305 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
306 * and removes it in command line mode
307 * - DBO_PERSISTENT: use persistant database connection
308 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
310 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
313 * Clear a flag for this connection
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]
324 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
327 * Restore the flags to their prior state before the last setFlag/clearFlag call
329 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
332 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
335 * Returns a boolean whether the flag $flag is set for this connection
337 * @param int $flag DBO_* constants from Defines.php:
338 * - DBO_DEBUG: output some debug info (same as debug())
339 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
340 * - DBO_TRX: automatically start transactions
341 * - DBO_PERSISTENT: use persistant database connection
344 public function getFlag( $flag );
349 public function getDomainID();
352 * Alias for getDomainID()
357 public function getWikiID();
360 * Get the type of the DBMS, as it appears in $wgDBtype.
364 public function getType();
367 * Open a new connection to the database (closing any existing one)
369 * @param string $server Database server host
370 * @param string $user Database user name
371 * @param string $password Database user password
372 * @param string $dbName Database name
374 * @throws DBConnectionError
376 public function open( $server, $user, $password, $dbName );
379 * Fetch the next row from the given result object, in object form.
380 * Fields can be retrieved with $row->fieldname, with fields acting like
382 * If no more rows are available, false is returned.
384 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
385 * @return stdClass|bool
386 * @throws DBUnexpectedError Thrown if the database returns an error
388 public function fetchObject( $res );
391 * Fetch the next row from the given result object, in associative array
392 * form. Fields are retrieved with $row['fieldname'].
393 * If no more rows are available, false is returned.
395 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
397 * @throws DBUnexpectedError Thrown if the database returns an error
399 public function fetchRow( $res );
402 * Get the number of rows in a result object
404 * @param mixed $res A SQL result
407 public function numRows( $res );
410 * Get the number of fields in a result object
411 * @see https://secure.php.net/mysql_num_fields
413 * @param mixed $res A SQL result
416 public function numFields( $res );
419 * Get a field name in a result object
420 * @see https://secure.php.net/mysql_field_name
422 * @param mixed $res A SQL result
426 public function fieldName( $res, $n );
429 * Get the inserted value of an auto-increment row
431 * This should only be called after an insert that used an auto-incremented
432 * value. If no such insert was previously done in the current database
433 * session, the return value is undefined.
437 public function insertId();
440 * Change the position of the cursor in a result object
441 * @see https://secure.php.net/mysql_data_seek
443 * @param mixed $res A SQL result
446 public function dataSeek( $res, $row );
449 * Get the last error number
450 * @see https://secure.php.net/mysql_errno
454 public function lastErrno();
457 * Get a description of the last error
458 * @see https://secure.php.net/mysql_error
462 public function lastError();
465 * Get the number of rows affected by the last write query
466 * @see https://secure.php.net/mysql_affected_rows
470 public function affectedRows();
473 * Returns a wikitext link to the DB's website, e.g.,
474 * return "[https://www.mysql.com/ MySQL]";
475 * Should at least contain plain text, if for some reason
476 * your database has no website.
478 * @return string Wikitext of a link to the server software's web site
480 public function getSoftwareLink();
483 * A string describing the current software version, like from
484 * mysql_get_server_info().
486 * @return string Version information from the database server.
488 public function getServerVersion();
491 * Close the database connection
493 * This should only be called after any transactions have been resolved,
494 * aside from read-only transactions (assuming no callbacks are registered).
495 * If a transaction is still open anyway, it will be committed if possible.
498 * @return bool Operation success. true if already closed.
500 public function close();
503 * Run an SQL query and return the result. Normally throws a DBQueryError
504 * on failure. If errors are ignored, returns false instead.
506 * If a connection loss is detected, then an attempt to reconnect will be made.
507 * For queries that involve no larger transactions or locks, they will be re-issued
508 * for convenience, provided the connection was re-established.
510 * In new code, the query wrappers select(), insert(), update(), delete(),
511 * etc. should be used where possible, since they give much better DBMS
512 * independence and automatically quote or validate user input in a variety
513 * of contexts. This function is generally only useful for queries which are
514 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
517 * However, the query wrappers themselves should call this function.
519 * @param string $sql SQL query
520 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
521 * comment (you can use __METHOD__ or add some extra info)
522 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
523 * maybe best to catch the exception instead?
524 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
525 * for a successful read query, or false on failure if $tempIgnore set
528 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
531 * Free a result object returned by query() or select(). It's usually not
532 * necessary to call this, just use unset() or let the variable holding
533 * the result object go out of scope.
535 * @param mixed $res A SQL result
537 public function freeResult( $res );
540 * A SELECT wrapper which returns a single field from a single result row.
542 * Usually throws a DBQueryError on failure. If errors are explicitly
543 * ignored, returns false on failure.
545 * If no result rows are returned from the query, false is returned.
547 * @param string|array $table Table name. See IDatabase::select() for details.
548 * @param string $var The field name to select. This must be a valid SQL
549 * fragment: do not use unvalidated user input.
550 * @param string|array $cond The condition array. See IDatabase::select() for details.
551 * @param string $fname The function name of the caller.
552 * @param string|array $options The query options. See IDatabase::select() for details.
553 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
555 * @return mixed The value from the field
558 public function selectField(
559 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
563 * A SELECT wrapper which returns a list of single field values from result rows.
565 * Usually throws a DBQueryError on failure. If errors are explicitly
566 * ignored, returns false on failure.
568 * If no result rows are returned from the query, false is returned.
570 * @param string|array $table Table name. See IDatabase::select() for details.
571 * @param string $var The field name to select. This must be a valid SQL
572 * fragment: do not use unvalidated user input.
573 * @param string|array $cond The condition array. See IDatabase::select() for details.
574 * @param string $fname The function name of the caller.
575 * @param string|array $options The query options. See IDatabase::select() for details.
576 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
578 * @return array The values from the field
582 public function selectFieldValues(
583 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
587 * Execute a SELECT query constructed using the various parameters provided.
588 * See below for full details of the parameters.
590 * @param string|array $table Table name
591 * @param string|array $vars Field names
592 * @param string|array $conds Conditions
593 * @param string $fname Caller function name
594 * @param array $options Query options
595 * @param array $join_conds Join conditions
598 * @param string|array $table
600 * May be either an array of table names, or a single string holding a table
601 * name. If an array is given, table aliases can be specified, for example:
605 * This includes the user table in the query, with the alias "a" available
606 * for use in field names (e.g. a.user_name).
608 * A derived table, defined by the result of selectSQLText(), requires an alias
609 * key and a Subquery instance value which wraps the SQL query, for example:
611 * [ 'c' => new Subquery( 'SELECT ...' ) ]
613 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
614 * constructed using nested arrays. For example,
616 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
618 * along with `$join_conds` like
620 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
622 * will produce SQL something like
624 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
626 * All of the table names given here are automatically run through
627 * Database::tableName(), which causes the table prefix (if any) to be
628 * added, and various other table name mappings to be performed.
630 * Do not use untrusted user input as a table name. Alias names should
631 * not have characters outside of the Basic multilingual plane.
633 * @param string|array $vars
635 * May be either a field name or an array of field names. The field names
636 * can be complete fragments of SQL, for direct inclusion into the SELECT
637 * query. If an array is given, field aliases can be specified, for example:
639 * [ 'maxrev' => 'MAX(rev_id)' ]
641 * This includes an expression with the alias "maxrev" in the query.
643 * If an expression is given, care must be taken to ensure that it is
646 * Untrusted user input must not be passed to this parameter.
648 * @param string|array $conds
650 * May be either a string containing a single condition, or an array of
651 * conditions. If an array is given, the conditions constructed from each
652 * element are combined with AND.
654 * Array elements may take one of two forms:
656 * - Elements with a numeric key are interpreted as raw SQL fragments.
657 * - Elements with a string key are interpreted as equality conditions,
658 * where the key is the field name.
659 * - If the value of such an array element is a scalar (such as a
660 * string), it will be treated as data and thus quoted appropriately.
661 * If it is null, an IS NULL clause will be added.
662 * - If the value is an array, an IN (...) clause will be constructed
663 * from its non-null elements, and an IS NULL clause will be added
664 * if null is present, such that the field may match any of the
665 * elements in the array. The non-null elements will be quoted.
667 * Note that expressions are often DBMS-dependent in their syntax.
668 * DBMS-independent wrappers are provided for constructing several types of
669 * expression commonly used in condition queries. See:
670 * - IDatabase::buildLike()
671 * - IDatabase::conditional()
673 * Untrusted user input is safe in the values of string keys, however untrusted
674 * input must not be used in the array key names or in the values of numeric keys.
675 * Escaping of untrusted input used in values of numeric keys should be done via
676 * IDatabase::addQuotes()
678 * @param string|array $options
680 * Optional: Array of query options. Boolean options are specified by
681 * including them in the array as a string value with a numeric key, for
686 * The supported options are:
688 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
689 * with LIMIT can theoretically be used for paging through a result set,
690 * but this is discouraged for performance reasons.
692 * - LIMIT: Integer: return at most this many rows. The rows are sorted
693 * and then the first rows are taken until the limit is reached. LIMIT
694 * is applied to a result set after OFFSET.
696 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
697 * changed until the next COMMIT.
699 * - DISTINCT: Boolean: return only unique result rows.
701 * - GROUP BY: May be either an SQL fragment string naming a field or
702 * expression to group by, or an array of such SQL fragments.
704 * - HAVING: May be either an string containing a HAVING clause or an array of
705 * conditions building the HAVING clause. If an array is given, the conditions
706 * constructed from each element are combined with AND.
708 * - ORDER BY: May be either an SQL fragment giving a field name or
709 * expression to order by, or an array of such SQL fragments.
711 * - USE INDEX: This may be either a string giving the index name to use
712 * for the query, or an array. If it is an associative array, each key
713 * gives the table name (or alias), each value gives the index name to
714 * use for that table. All strings are SQL fragments and so should be
715 * validated by the caller.
717 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
720 * And also the following boolean MySQL extensions, see the MySQL manual
723 * - LOCK IN SHARE MODE
727 * - SQL_BUFFER_RESULT
729 * - SQL_CALC_FOUND_ROWS
734 * @param string|array $join_conds
736 * Optional associative array of table-specific join conditions. In the
737 * most common case, this is unnecessary, since the join condition can be
738 * in $conds. However, it is useful for doing a LEFT JOIN.
740 * The key of the array contains the table name or alias. The value is an
741 * array with two elements, numbered 0 and 1. The first gives the type of
742 * join, the second is the same as the $conds parameter. Thus it can be
743 * an SQL fragment, or an array where the string keys are equality and the
744 * numeric keys are SQL fragments all AND'd together. For example:
746 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
748 * @return IResultWrapper Resulting rows
751 public function select(
752 $table, $vars, $conds = '', $fname = __METHOD__
,
753 $options = [], $join_conds = []
757 * The equivalent of IDatabase::select() except that the constructed SQL
758 * is returned, instead of being immediately executed. This can be useful for
759 * doing UNION queries, where the SQL text of each query is needed. In general,
760 * however, callers outside of Database classes should just use select().
762 * @see IDatabase::select()
764 * @param string|array $table Table name
765 * @param string|array $vars Field names
766 * @param string|array $conds Conditions
767 * @param string $fname Caller function name
768 * @param string|array $options Query options
769 * @param string|array $join_conds Join conditions
770 * @return string SQL query string
772 public function selectSQLText(
773 $table, $vars, $conds = '', $fname = __METHOD__
,
774 $options = [], $join_conds = []
778 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
779 * that a single row object is returned. If the query returns no rows,
782 * @param string|array $table Table name
783 * @param string|array $vars Field names
784 * @param array $conds Conditions
785 * @param string $fname Caller function name
786 * @param string|array $options Query options
787 * @param array|string $join_conds Join conditions
789 * @return stdClass|bool
792 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
793 $options = [], $join_conds = []
797 * Estimate the number of rows in dataset
799 * MySQL allows you to estimate the number of rows that would be returned
800 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
801 * index cardinality statistics, and is notoriously inaccurate, especially
802 * when large numbers of rows have recently been added or deleted.
804 * For DBMSs that don't support fast result size estimation, this function
805 * will actually perform the SELECT COUNT(*).
807 * Takes the same arguments as IDatabase::select().
809 * @param string $table Table name
810 * @param string $var Column for which NULL values are not counted [default "*"]
811 * @param array|string $conds Filters on the table
812 * @param string $fname Function name for profiling
813 * @param array $options Options for select
814 * @param array|string $join_conds Join conditions
815 * @return int Row count
818 public function estimateRowCount(
819 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
823 * Get the number of rows in dataset
825 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
827 * Takes the same arguments as IDatabase::select().
829 * @since 1.27 Added $join_conds parameter
831 * @param array|string $tables Table names
832 * @param string $var Column for which NULL values are not counted [default "*"]
833 * @param array|string $conds Filters on the table
834 * @param string $fname Function name for profiling
835 * @param array $options Options for select
836 * @param array $join_conds Join conditions (since 1.27)
837 * @return int Row count
840 public function selectRowCount(
841 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
845 * Determines whether a field exists in a table
847 * @param string $table Table name
848 * @param string $field Filed to check on that table
849 * @param string $fname Calling function name (optional)
850 * @return bool Whether $table has filed $field
853 public function fieldExists( $table, $field, $fname = __METHOD__
);
856 * Determines whether an index exists
857 * Usually throws a DBQueryError on failure
858 * If errors are explicitly ignored, returns NULL on failure
860 * @param string $table
861 * @param string $index
862 * @param string $fname
866 public function indexExists( $table, $index, $fname = __METHOD__
);
869 * Query whether a given table exists
871 * @param string $table
872 * @param string $fname
876 public function tableExists( $table, $fname = __METHOD__
);
879 * INSERT wrapper, inserts an array into a table.
883 * - A single associative array. The array keys are the field names, and
884 * the values are the values to insert. The values are treated as data
885 * and will be quoted appropriately. If NULL is inserted, this will be
886 * converted to a database NULL.
887 * - An array with numeric keys, holding a list of associative arrays.
888 * This causes a multi-row INSERT on DBMSs that support it. The keys in
889 * each subarray must be identical to each other, and in the same order.
891 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
894 * $options is an array of options, with boolean options encoded as values
895 * with numeric keys, in the same style as $options in
896 * IDatabase::select(). Supported options are:
898 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
899 * any rows which cause duplicate key errors are not inserted. It's
900 * possible to determine how many rows were successfully inserted using
901 * IDatabase::affectedRows().
903 * @param string $table Table name. This will be passed through
904 * Database::tableName().
905 * @param array $a Array of rows to insert
906 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
907 * @param array $options Array of options
912 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
915 * UPDATE wrapper. Takes a condition array and a SET array.
917 * @param string $table Name of the table to UPDATE. This will be passed through
918 * Database::tableName().
919 * @param array $values An array of values to SET. For each array element,
920 * the key gives the field name, and the value gives the data to set
921 * that field to. The data will be quoted by IDatabase::addQuotes().
922 * Values with integer keys form unquoted SET statements, which can be used for
923 * things like "field = field + 1" or similar computed values.
924 * @param array $conds An array of conditions (WHERE). See
925 * IDatabase::select() for the details of the format of condition
926 * arrays. Use '*' to update all rows.
927 * @param string $fname The function name of the caller (from __METHOD__),
928 * for logging and profiling.
929 * @param array $options An array of UPDATE options, can be:
930 * - IGNORE: Ignore unique key conflicts
931 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
935 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
938 * Makes an encoded list of strings from an array
940 * These can be used to make conjunctions or disjunctions on SQL condition strings
941 * derived from an array (see IDatabase::select() $conds documentation).
945 * $sql = $db->makeList( [
947 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
948 * ], $db::LIST_AND );
950 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
952 * @param array $a Containing the data
953 * @param int $mode IDatabase class constant:
954 * - IDatabase::LIST_COMMA: Comma separated, no field names
955 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
956 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
957 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
958 * - IDatabase::LIST_NAMES: Comma separated field names
962 public function makeList( $a, $mode = self
::LIST_COMMA
);
965 * Build a partial where clause from a 2-d array such as used for LinkBatch.
966 * The keys on each level may be either integers or strings.
968 * @param array $data Organized as 2-d
969 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
970 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
971 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
972 * @return string|bool SQL fragment, or false if no items in array
974 public function makeWhereFrom2d( $data, $baseKey, $subKey );
977 * Return aggregated value alias
979 * @param array $valuedata
980 * @param string $valuename
984 public function aggregateValue( $valuedata, $valuename = 'value' );
987 * @param string $field
990 public function bitNot( $field );
993 * @param string $fieldLeft
994 * @param string $fieldRight
997 public function bitAnd( $fieldLeft, $fieldRight );
1000 * @param string $fieldLeft
1001 * @param string $fieldRight
1004 public function bitOr( $fieldLeft, $fieldRight );
1007 * Build a concatenation list to feed into a SQL query
1008 * @param array $stringList List of raw SQL expressions; caller is
1009 * responsible for any quoting
1012 public function buildConcat( $stringList );
1015 * Build a GROUP_CONCAT or equivalent statement for a query.
1017 * This is useful for combining a field for several rows into a single string.
1018 * NULL values will not appear in the output, duplicated values will appear,
1019 * and the resulting delimiter-separated values have no defined sort order.
1020 * Code using the results may need to use the PHP unique() or sort() methods.
1022 * @param string $delim Glue to bind the results together
1023 * @param string|array $table Table name
1024 * @param string $field Field name
1025 * @param string|array $conds Conditions
1026 * @param string|array $join_conds Join conditions
1027 * @return string SQL text
1030 public function buildGroupConcatField(
1031 $delim, $table, $field, $conds = '', $join_conds = []
1035 * Build a SUBSTRING function.
1037 * Behavior for non-ASCII values is undefined.
1039 * @param string $input Field name
1040 * @param int $startPosition Positive integer
1041 * @param int|null $length Non-negative integer length or null for no limit
1042 * @throws InvalidArgumentException
1043 * @return string SQL text
1046 public function buildSubString( $input, $startPosition, $length = null );
1049 * @param string $field Field or column to cast
1053 public function buildStringCast( $field );
1056 * @param string $field Field or column to cast
1060 public function buildIntegerCast( $field );
1063 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1065 * @see IDatabase::selectSQLText()
1067 * @param string|array $table Table name
1068 * @param string|array $vars Field names
1069 * @param string|array $conds Conditions
1070 * @param string $fname Caller function name
1071 * @param string|array $options Query options
1072 * @param string|array $join_conds Join conditions
1076 public function buildSelectSubquery(
1077 $table, $vars, $conds = '', $fname = __METHOD__
,
1078 $options = [], $join_conds = []
1082 * Returns true if DBs are assumed to be on potentially different servers
1084 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1085 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1086 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1087 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1092 public function databasesAreIndependent();
1095 * Change the current database
1098 * @return bool Success or failure
1099 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1101 public function selectDB( $db );
1104 * Get the current DB name
1107 public function getDBname();
1110 * Get the server hostname or IP address
1113 public function getServer();
1116 * Adds quotes and backslashes.
1118 * @param string|int|null|bool|Blob $s
1119 * @return string|int
1121 public function addQuotes( $s );
1124 * LIKE statement wrapper, receives a variable-length argument list with
1125 * parts of pattern to match containing either string literals that will be
1126 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1127 * the function could be provided with an array of aforementioned
1130 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1131 * a LIKE clause that searches for subpages of 'My page title'.
1133 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1134 * $query .= $dbr->buildLike( $pattern );
1137 * @return string Fully built LIKE statement
1139 public function buildLike();
1142 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1146 public function anyChar();
1149 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1153 public function anyString();
1156 * Deprecated method, calls should be removed.
1158 * This was formerly used for PostgreSQL and Oracle to handle
1159 * self::insertId() auto-incrementing fields. It is no longer necessary
1160 * since DatabasePostgres::insertId() has been reimplemented using
1161 * `lastval()` and Oracle has been reimplemented using triggers.
1163 * Implementations should return null if inserting `NULL` into an
1164 * auto-incrementing field works, otherwise it should return an instance of
1165 * NextSequenceValue and filter it on calls to relevant methods.
1167 * @deprecated since 1.30, no longer needed
1168 * @param string $seqName
1169 * @return null|NextSequenceValue
1171 public function nextSequenceValue( $seqName );
1174 * REPLACE query wrapper.
1176 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1177 * except that when there is a duplicate key error, the old row is deleted
1178 * and the new row is inserted in its place.
1180 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1181 * perform the delete, we need to know what the unique indexes are so that
1182 * we know how to find the conflicting rows.
1184 * It may be more efficient to leave off unique indexes which are unlikely
1185 * to collide. However if you do this, you run the risk of encountering
1186 * errors which wouldn't have occurred in MySQL.
1188 * @param string $table The table to replace the row(s) in.
1189 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1190 * a field name or an array of field names
1191 * @param array $rows Can be either a single row to insert, or multiple rows,
1192 * in the same format as for IDatabase::insert()
1193 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1196 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1199 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1201 * This updates any conflicting rows (according to the unique indexes) using
1202 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1204 * $rows may be either:
1205 * - A single associative array. The array keys are the field names, and
1206 * the values are the values to insert. The values are treated as data
1207 * and will be quoted appropriately. If NULL is inserted, this will be
1208 * converted to a database NULL.
1209 * - An array with numeric keys, holding a list of associative arrays.
1210 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1211 * each subarray must be identical to each other, and in the same order.
1213 * It may be more efficient to leave off unique indexes which are unlikely
1214 * to collide. However if you do this, you run the risk of encountering
1215 * errors which wouldn't have occurred in MySQL.
1217 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1222 * @param string $table Table name. This will be passed through Database::tableName().
1223 * @param array $rows A single row or list of rows to insert
1224 * @param array $uniqueIndexes List of single field names or field name tuples
1225 * @param array $set An array of values to SET. For each array element, the
1226 * key gives the field name, and the value gives the data to set that
1227 * field to. The data will be quoted by IDatabase::addQuotes().
1228 * Values with integer keys form unquoted SET statements, which can be used for
1229 * things like "field = field + 1" or similar computed values.
1230 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1234 public function upsert(
1235 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1239 * DELETE where the condition is a join.
1241 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1242 * we use sub-selects
1244 * For safety, an empty $conds will not delete everything. If you want to
1245 * delete all rows where the join condition matches, set $conds='*'.
1247 * DO NOT put the join condition in $conds.
1249 * @param string $delTable The table to delete from.
1250 * @param string $joinTable The other table.
1251 * @param string $delVar The variable to join on, in the first table.
1252 * @param string $joinVar The variable to join on, in the second table.
1253 * @param array $conds Condition array of field names mapped to variables,
1254 * ANDed together in the WHERE clause
1255 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1258 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1263 * DELETE query wrapper.
1265 * @param string $table Table name
1266 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1267 * for the format. Use $conds == "*" to delete all rows
1268 * @param string $fname Name of the calling function
1269 * @throws DBUnexpectedError
1270 * @return bool|IResultWrapper
1273 public function delete( $table, $conds, $fname = __METHOD__
);
1276 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1277 * into another table.
1279 * @warning If the insert will use an auto-increment or sequence to
1280 * determine the value of a column, this may break replication on
1281 * databases using statement-based replication if the SELECT is not
1282 * deterministically ordered.
1284 * @param string $destTable The table name to insert into
1285 * @param string|array $srcTable May be either a table name, or an array of table names
1286 * to include in a join.
1288 * @param array $varMap Must be an associative array of the form
1289 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1290 * rather than field names, but strings should be quoted with
1291 * IDatabase::addQuotes()
1293 * @param array $conds Condition array. See $conds in IDatabase::select() for
1294 * the details of the format of condition arrays. May be "*" to copy the
1297 * @param string $fname The function name of the caller, from __METHOD__
1299 * @param array $insertOptions Options for the INSERT part of the query, see
1300 * IDatabase::insert() for details. Also, one additional option is
1301 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1302 * an auto-increment or sequence to determine any column values.
1303 * @param array $selectOptions Options for the SELECT part of the query, see
1304 * IDatabase::select() for details.
1305 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1306 * IDatabase::select() for details.
1311 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1312 $fname = __METHOD__
,
1313 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1317 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1318 * within the UNION construct.
1321 public function unionSupportsOrderAndLimit();
1324 * Construct a UNION query
1325 * This is used for providing overload point for other DB abstractions
1326 * not compatible with the MySQL syntax.
1327 * @param array $sqls SQL statements to combine
1328 * @param bool $all Use UNION ALL
1329 * @return string SQL fragment
1331 public function unionQueries( $sqls, $all );
1334 * Construct a UNION query for permutations of conditions
1336 * Databases sometimes have trouble with queries that have multiple values
1337 * for multiple condition parameters combined with limits and ordering.
1338 * This method constructs queries for the Cartesian product of the
1339 * conditions and unions them all together.
1341 * @see IDatabase::select()
1343 * @param string|array $table Table name
1344 * @param string|array $vars Field names
1345 * @param array $permute_conds Conditions for the Cartesian product. Keys
1346 * are field names, values are arrays of the possible values for that
1348 * @param string|array $extra_conds Additional conditions to include in the
1350 * @param string $fname Caller function name
1351 * @param string|array $options Query options. In addition to the options
1352 * recognized by IDatabase::select(), the following may be used:
1353 * - NOTALL: Set to use UNION instead of UNION ALL.
1354 * - INNER ORDER BY: If specified and supported, subqueries will use this
1355 * instead of ORDER BY.
1356 * @param string|array $join_conds Join conditions
1357 * @return string SQL query string.
1359 public function unionConditionPermutations(
1360 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1361 $options = [], $join_conds = []
1365 * Returns an SQL expression for a simple conditional. This doesn't need
1366 * to be overridden unless CASE isn't supported in your DBMS.
1368 * @param string|array $cond SQL expression which will result in a boolean value
1369 * @param string $trueVal SQL expression to return if true
1370 * @param string $falseVal SQL expression to return if false
1371 * @return string SQL fragment
1373 public function conditional( $cond, $trueVal, $falseVal );
1376 * Returns a command for str_replace function in SQL query.
1377 * Uses REPLACE() in MySQL
1379 * @param string $orig Column to modify
1380 * @param string $old Column to seek
1381 * @param string $new Column to replace with
1385 public function strreplace( $orig, $old, $new );
1388 * Determines how long the server has been up
1393 public function getServerUptime();
1396 * Determines if the last failure was due to a deadlock
1398 * Note that during a deadlock, the prior transaction will have been lost
1402 public function wasDeadlock();
1405 * Determines if the last failure was due to a lock timeout
1407 * Note that during a lock wait timeout, the prior transaction will have been lost
1411 public function wasLockTimeout();
1414 * Determines if the last query error was due to a dropped connection
1416 * Note that during a connection loss, the prior transaction will have been lost
1421 public function wasConnectionLoss();
1424 * Determines if the last failure was due to the database being read-only.
1428 public function wasReadOnlyError();
1431 * Determines if the last query error was due to something outside of the query itself
1433 * Note that the transaction may have been lost, discarding prior writes and results
1437 public function wasErrorReissuable();
1440 * Wait for the replica DB to catch up to a given master position
1442 * @param DBMasterPos $pos
1443 * @param int $timeout The maximum number of seconds to wait for synchronisation
1444 * @return int|null Zero if the replica DB was past that position already,
1445 * greater than zero if we waited for some period of time, less than
1446 * zero if it timed out, and null on error
1449 public function masterPosWait( DBMasterPos
$pos, $timeout );
1452 * Get the replication position of this replica DB
1454 * @return DBMasterPos|bool False if this is not a replica DB
1457 public function getReplicaPos();
1460 * Get the position of this master
1462 * @return DBMasterPos|bool False if this is not a master
1465 public function getMasterPos();
1468 * @return bool Whether the DB is marked as read-only server-side
1471 public function serverIsReadOnly();
1474 * Run a callback as soon as the current transaction commits or rolls back.
1475 * An error is thrown if no transaction is pending. Queries in the function will run in
1476 * AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1479 * This is useful for combining cooperative locks and DB transactions.
1481 * @note: do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1483 * The callback takes the following arguments:
1484 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1485 * - This IDatabase instance (since 1.32)
1487 * @param callable $callback
1488 * @param string $fname Caller name
1492 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1495 * Run a callback as soon as there is no transaction pending.
1496 * If there is a transaction and it is rolled back, then the callback is cancelled.
1498 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1499 * of the round, just after all peer transactions COMMIT. If the transaction round
1500 * is rolled back, then the callback is cancelled.
1502 * Queries in the function will run in AUTOCOMMIT mode unless there are begin() calls.
1503 * Callbacks must commit any transactions that they begin.
1505 * This is useful for updates to different systems or when separate transactions are needed.
1506 * For example, one might want to enqueue jobs into a system outside the database, but only
1507 * after the database is updated so that the jobs will see the data when they actually run.
1508 * It can also be used for updates that easily suffer from lock timeouts and deadlocks,
1509 * but where atomicity is not essential.
1511 * Updates will execute in the order they were enqueued.
1513 * @note: do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1515 * The callback takes the following arguments:
1516 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1517 * - This IDatabase instance (since 1.32)
1519 * @param callable $callback
1520 * @param string $fname Caller name
1523 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1526 * Run a callback before the current transaction commits or now if there is none.
1527 * If there is a transaction and it is rolled back, then the callback is cancelled.
1529 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1530 * of the round, just before all peer transactions COMMIT. If the transaction round
1531 * is rolled back, then the callback is cancelled.
1533 * Callbacks must not start nor commit any transactions. If no transaction is active,
1534 * then a transaction will wrap the callback.
1536 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1537 * but where atomicity is strongly desired for these updates and some related updates.
1539 * Updates will execute in the order they were enqueued.
1541 * The callback takes the one argument:
1542 * - This IDatabase instance (since 1.32)
1544 * @param callable $callback
1545 * @param string $fname Caller name
1548 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1551 * Run a callback each time any transaction commits or rolls back
1553 * The callback takes two arguments:
1554 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1555 * - This IDatabase object
1556 * Callbacks must commit any transactions that they begin.
1558 * Registering a callback here will not affect writesOrCallbacks() pending
1560 * @param string $name Callback name
1561 * @param callable|null $callback Use null to unset a listener
1565 public function setTransactionListener( $name, callable
$callback = null );
1568 * Begin an atomic section of SQL statements
1570 * Start an implicit transaction if no transaction is already active, set a savepoint
1571 * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
1572 * that the transaction is not committed prematurely. The end of the section must be
1573 * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
1574 * have layers of inner sections (sub-sections), but all sections must be ended in order
1575 * of innermost to outermost. Transactions cannot be started or committed until all
1576 * atomic sections are closed.
1578 * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
1579 * by discarding the section's writes. This should not be used for failures when:
1580 * - upsert() could easily be used instead
1581 * - insert() with IGNORE could easily be used instead
1582 * - select() with FOR UPDATE could be checked before issuing writes instead
1583 * - The failure is from code that runs after the first write but doesn't need to
1584 * - The failures are from contention solvable via onTransactionPreCommitOrIdle()
1585 * - The failures are deadlocks; the RDBMs usually discard the whole transaction
1587 * @note: callers must use additional measures for situations involving two or more
1588 * (peer) transactions (e.g. updating two database servers at once). The transaction
1589 * and savepoint logic of this method only applies to this specific IDatabase instance.
1593 * // Start a transaction if there isn't one already
1594 * $dbw->startAtomic( __METHOD__ );
1595 * // Serialize these thread table updates
1596 * $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
1597 * // Add a new comment for the thread
1598 * $dbw->insert( 'comment', $row, __METHOD__ );
1599 * $cid = $db->insertId();
1600 * // Update thread reference to last comment
1601 * $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
1602 * // Demark the end of this conceptual unit of updates
1603 * $dbw->endAtomic( __METHOD__ );
1606 * Example usage (atomic changes that might have to be discarded):
1608 * // Start a transaction if there isn't one already
1609 * $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
1610 * // Create new record metadata row
1611 * $dbw->insert( 'records', $row, __METHOD__ );
1612 * // Figure out where to store the data based on the new row's ID
1613 * $path = $recordDirectory . '/' . $dbw->insertId();
1614 * // Write the record data to the storage system
1615 * $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
1616 * if ( $status->isOK() ) {
1617 * // Try to cleanup files orphaned by transaction rollback
1618 * $dbw->onTransactionResolution(
1619 * function ( $type ) use ( $fileBackend, $path ) {
1620 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1621 * $fileBackend->delete( [ 'src' => $path ] );
1626 * // Demark the end of this conceptual unit of updates
1627 * $dbw->endAtomic( __METHOD__ );
1629 * // Discard these writes from the transaction (preserving prior writes)
1630 * $dbw->cancelAtomic( __METHOD__, $sectionId );
1635 * @param string $fname
1636 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1637 * savepoint and enable self::cancelAtomic() for this section.
1638 * @return AtomicSectionIdentifier section ID token
1641 public function startAtomic( $fname = __METHOD__
, $cancelable = self
::ATOMIC_NOT_CANCELABLE
);
1644 * Ends an atomic section of SQL statements
1646 * Ends the next section of atomic SQL statements and commits the transaction
1650 * @see IDatabase::startAtomic
1651 * @param string $fname
1654 public function endAtomic( $fname = __METHOD__
);
1657 * Cancel an atomic section of SQL statements
1659 * This will roll back only the statements executed since the start of the
1660 * most recent atomic section, and close that section. If a transaction was
1661 * open before the corresponding startAtomic() call, any statements before
1662 * that call are *not* rolled back and the transaction remains open. If the
1663 * corresponding startAtomic() implicitly started a transaction, that
1664 * transaction is rolled back.
1666 * @note: callers must use additional measures for situations involving two or more
1667 * (peer) transactions (e.g. updating two database servers at once). The transaction
1668 * and savepoint logic of startAtomic() are bound to specific IDatabase instances.
1670 * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
1672 * @note As a micro-optimization to save a few DB calls, this method may only
1673 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1675 * @see IDatabase::startAtomic
1676 * @param string $fname
1677 * @param AtomicSectionIdentifier $sectionId Section ID from startAtomic();
1678 * passing this enables cancellation of unclosed nested sections [optional]
1681 public function cancelAtomic( $fname = __METHOD__
, AtomicSectionIdentifier
$sectionId = null );
1684 * Perform an atomic section of reversable SQL statements from a callback
1686 * The $callback takes the following arguments:
1687 * - This database object
1688 * - The value of $fname
1690 * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
1691 * If any exception occurs during execution of the callback, it will be handled as follows:
1692 * - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
1693 * (and only) statements executed during the atomic section. If that succeeds, then the
1694 * exception will be re-thrown; if it fails, then a different exception will be thrown
1695 * and any further query attempts will fail until rollback() is called.
1696 * - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
1697 * end of the section and the error will be re-thrown. Any further query attempts will
1698 * fail until rollback() is called.
1700 * This method is convenient for letting calls to the caller of this method be wrapped
1701 * in a try/catch blocks for exception types that imply that the caller failed but was
1702 * able to properly discard the changes it made in the transaction. This method can be
1703 * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
1705 * Example usage, "RecordStore::save" method:
1707 * $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
1708 * // Create new record metadata row
1709 * $dbw->insert( 'records', $record->toArray(), __METHOD__ );
1710 * // Figure out where to store the data based on the new row's ID
1711 * $path = $this->recordDirectory . '/' . $dbw->insertId();
1712 * // Write the record data to the storage system;
1713 * // blob store throughs StoreFailureException on failure
1714 * $this->blobStore->create( $path, $record->getJSON() );
1715 * // Try to cleanup files orphaned by transaction rollback
1716 * $dbw->onTransactionResolution(
1717 * function ( $type ) use ( $path ) {
1718 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1719 * $this->blobStore->delete( $path );
1724 * }, $dbw::ATOMIC_CANCELABLE );
1727 * Example usage, caller of the "RecordStore::save" method:
1729 * $dbw->startAtomic( __METHOD__ );
1730 * // ...various SQL writes happen...
1732 * $recordStore->save( $record );
1733 * } catch ( StoreFailureException $e ) {
1734 * // ...various SQL writes happen...
1736 * // ...various SQL writes happen...
1737 * $dbw->endAtomic( __METHOD__ );
1740 * @see Database::startAtomic
1741 * @see Database::endAtomic
1742 * @see Database::cancelAtomic
1744 * @param string $fname Caller name (usually __METHOD__)
1745 * @param callable $callback Callback that issues DB updates
1746 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1747 * savepoint and enable self::cancelAtomic() for this section.
1748 * @return mixed $res Result of the callback (since 1.28)
1750 * @throws RuntimeException
1751 * @since 1.27; prior to 1.31 this did a rollback() instead of
1752 * cancelAtomic(), and assumed no callers up the stack would ever try to
1753 * catch the exception.
1755 public function doAtomicSection(
1756 $fname, callable
$callback, $cancelable = self
::ATOMIC_NOT_CANCELABLE
1760 * Begin a transaction. If a transaction is already in progress,
1761 * that transaction will be committed before the new transaction is started.
1763 * Only call this from code with outer transcation scope.
1764 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1765 * Nesting of transactions is not supported.
1767 * Note that when the DBO_TRX flag is set (which is usually the case for web
1768 * requests, but not for maintenance scripts), any previous database query
1769 * will have started a transaction automatically.
1771 * Nesting of transactions is not supported. Attempts to nest transactions
1772 * will cause a warning, unless the current transaction was started
1773 * automatically because of the DBO_TRX flag.
1775 * @param string $fname Calling function name
1776 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1779 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1782 * Commits a transaction previously started using begin().
1783 * If no transaction is in progress, a warning is issued.
1785 * Only call this from code with outer transcation scope.
1786 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1787 * Nesting of transactions is not supported.
1789 * @param string $fname
1790 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1791 * constant to disable warnings about explicitly committing implicit transactions,
1792 * or calling commit when no transaction is in progress.
1794 * This will trigger an exception if there is an ongoing explicit transaction.
1796 * Only set the flush flag if you are sure that these warnings are not applicable,
1797 * and no explicit transactions are open.
1801 public function commit( $fname = __METHOD__
, $flush = '' );
1804 * Rollback a transaction previously started using begin().
1805 * If no transaction is in progress, a warning is issued.
1807 * Only call this from code with outer transcation scope.
1808 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1809 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1810 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1811 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1813 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1815 * @param string $fname Calling function name
1816 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1817 * constant to disable warnings about calling rollback when no transaction is in
1818 * progress. This will silently break any ongoing explicit transaction. Only set the
1819 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1821 * @since 1.23 Added $flush parameter
1823 public function rollback( $fname = __METHOD__
, $flush = '' );
1826 * Commit any transaction but error out if writes or callbacks are pending
1828 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1829 * see a new point-in-time of the database. This is useful when one of many transaction
1830 * rounds finished and significant time will pass in the script's lifetime. It is also
1831 * useful to call on a replica DB after waiting on replication to catch up to the master.
1833 * @param string $fname Calling function name
1837 public function flushSnapshot( $fname = __METHOD__
);
1840 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1841 * to the format used for inserting into timestamp fields in this DBMS.
1843 * The result is unquoted, and needs to be passed through addQuotes()
1844 * before it can be included in raw SQL.
1846 * @param string|int $ts
1850 public function timestamp( $ts = 0 );
1853 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1854 * to the format used for inserting into timestamp fields in this DBMS. If
1855 * NULL is input, it is passed through, allowing NULL values to be inserted
1856 * into timestamp fields.
1858 * The result is unquoted, and needs to be passed through addQuotes()
1859 * before it can be included in raw SQL.
1861 * @param string|int $ts
1865 public function timestampOrNull( $ts = null );
1868 * Ping the server and try to reconnect if it there is no connection
1870 * @param float|null &$rtt Value to store the estimated RTT [optional]
1871 * @return bool Success or failure
1873 public function ping( &$rtt = null );
1876 * Get the amount of replication lag for this database server
1878 * Callers should avoid using this method while a transaction is active
1880 * @return int|bool Database replication lag in seconds or false on error
1883 public function getLag();
1886 * Get the replica DB lag when the current transaction started
1887 * or a general lag estimate if not transaction is active
1889 * This is useful when transactions might use snapshot isolation
1890 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1891 * is this lag plus transaction duration. If they don't, it is still
1892 * safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
1893 * indication of the staleness of subsequent reads.
1895 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1899 public function getSessionLagStatus();
1902 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1906 public function maxListLen();
1909 * Some DBMSs have a special format for inserting into blob fields, they
1910 * don't allow simple quoted strings to be inserted. To insert into such
1911 * a field, pass the data through this function before passing it to
1912 * IDatabase::insert().
1915 * @return string|Blob
1917 public function encodeBlob( $b );
1920 * Some DBMSs return a special placeholder object representing blob fields
1921 * in result objects. Pass the object through this function to return the
1924 * @param string|Blob $b
1927 public function decodeBlob( $b );
1930 * Override database's default behavior. $options include:
1931 * 'connTimeout' : Set the connection timeout value in seconds.
1932 * May be useful for very long batch queries such as
1933 * full-wiki dumps, where a single query reads out over
1936 * @param array $options
1940 public function setSessionOptions( array $options );
1943 * Set variables to be used in sourceFile/sourceStream, in preference to the
1944 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1945 * all. If it's set to false, $GLOBALS will be used.
1947 * @param bool|array $vars Mapping variable name to value.
1949 public function setSchemaVars( $vars );
1952 * Check to see if a named lock is not locked by any thread (non-blocking)
1954 * @param string $lockName Name of lock to poll
1955 * @param string $method Name of method calling us
1960 public function lockIsFree( $lockName, $method );
1963 * Acquire a named lock
1965 * Named locks are not related to transactions
1967 * @param string $lockName Name of lock to aquire
1968 * @param string $method Name of the calling method
1969 * @param int $timeout Acquisition timeout in seconds
1973 public function lock( $lockName, $method, $timeout = 5 );
1978 * Named locks are not related to transactions
1980 * @param string $lockName Name of lock to release
1981 * @param string $method Name of the calling method
1983 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1984 * by this thread (in which case the lock is not released), and NULL if the named lock
1989 public function unlock( $lockName, $method );
1992 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1994 * Only call this from outer transcation scope and when only one DB will be affected.
1995 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1997 * This is suitiable for transactions that need to be serialized using cooperative locks,
1998 * where each transaction can see each others' changes. Any transaction is flushed to clear
1999 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
2000 * the lock will be released unless a transaction is active. If one is active, then the lock
2001 * will be released when it either commits or rolls back.
2003 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
2005 * @param string $lockKey Name of lock to release
2006 * @param string $fname Name of the calling method
2007 * @param int $timeout Acquisition timeout in seconds
2008 * @return ScopedCallback|null
2012 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
2015 * Check to see if a named lock used by lock() use blocking queues
2020 public function namedLocksEnqueue();
2023 * Find out when 'infinity' is. Most DBMSes support this. This is a special
2024 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
2025 * because "i" sorts after all numbers.
2029 public function getInfinity();
2032 * Encode an expiry time into the DBMS dependent format
2034 * @param string $expiry Timestamp for expiry, or the 'infinity' string
2037 public function encodeExpiry( $expiry );
2040 * Decode an expiry time into a DBMS independent format
2042 * @param string $expiry DB timestamp field value for expiry
2043 * @param int $format TS_* constant, defaults to TS_MW
2046 public function decodeExpiry( $expiry, $format = TS_MW
);
2049 * Allow or deny "big selects" for this session only. This is done by setting
2050 * the sql_big_selects session variable.
2052 * This is a MySQL-specific feature.
2054 * @param bool|string $value True for allow, false for deny, or "default" to
2055 * restore the initial value
2057 public function setBigSelects( $value = true );
2060 * @return bool Whether this DB is read-only
2063 public function isReadOnly();
2066 * Make certain table names use their own database, schema, and table prefix
2067 * when passed into SQL queries pre-escaped and without a qualified database name
2069 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
2070 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
2072 * Calling this twice will completely clear any old table aliases. Also, note that
2073 * callers are responsible for making sure the schemas and databases actually exist.
2075 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
2078 public function setTableAliases( array $aliases );
2081 * Convert certain index names to alternative names before querying the DB
2083 * Note that this applies to indexes regardless of the table they belong to.
2085 * This can be employed when an index was renamed X => Y in code, but the new Y-named
2086 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
2087 * the aliases can be removed, and then the old X-named indexes dropped.
2089 * @param string[] $aliases
2093 public function setIndexAliases( array $aliases );
2096 class_alias( IDatabase
::class, 'IDatabase' );