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
;
25 use UnexpectedValueException
;
29 * @defgroup Database Database
30 * This group deals with database interface functions
31 * and query specifics/optimisations.
34 * Basic database interface for live and lazy-loaded relation database handles
36 * @note: IDatabase and DBConnRef should be updated to reflect any changes
40 /** @var int Callback triggered immediately due to no active transaction */
41 const TRIGGER_IDLE
= 1;
42 /** @var int Callback triggered by COMMIT */
43 const TRIGGER_COMMIT
= 2;
44 /** @var int Callback triggered by ROLLBACK */
45 const TRIGGER_ROLLBACK
= 3;
47 /** @var string Transaction is requested by regular caller outside of the DB layer */
48 const TRANSACTION_EXPLICIT
= '';
49 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
50 const TRANSACTION_INTERNAL
= 'implicit';
52 /** @var string Atomic section is not cancelable */
53 const ATOMIC_NOT_CANCELABLE
= '';
54 /** @var string Atomic section is cancelable */
55 const ATOMIC_CANCELABLE
= 'cancelable';
57 /** @var string Commit/rollback is from outside the IDatabase handle and connection manager */
58 const FLUSHING_ONE
= '';
59 /** @var string Commit/rollback is from the connection manager for the IDatabase handle */
60 const FLUSHING_ALL_PEERS
= 'flush';
61 /** @var string Commit/rollback is from the IDatabase handle internally */
62 const FLUSHING_INTERNAL
= 'flush';
64 /** @var string Do not remember the prior flags */
65 const REMEMBER_NOTHING
= '';
66 /** @var string Remember the prior flags */
67 const REMEMBER_PRIOR
= 'remember';
68 /** @var string Restore to the prior flag state */
69 const RESTORE_PRIOR
= 'prior';
70 /** @var string Restore to the initial flag state */
71 const RESTORE_INITIAL
= 'initial';
73 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
74 const ESTIMATE_TOTAL
= 'total';
75 /** @var string Estimate time to apply (scanning, applying) */
76 const ESTIMATE_DB_APPLY
= 'apply';
78 /** @var int Combine list with comma delimeters */
80 /** @var int Combine list with AND clauses */
82 /** @var int Convert map into a SET clause */
84 /** @var int Treat as field name and do not apply value escaping */
86 /** @var int Combine list with OR clauses */
89 /** @var int Enable debug logging */
91 /** @var int Disable query buffering (only one result set can be iterated at a time) */
92 const DBO_NOBUFFER
= 2;
93 /** @var int Ignore query errors (internal use only!) */
95 /** @var int Automatically start a transaction before running a query if none is active */
97 /** @var int Use DBO_TRX in non-CLI mode */
98 const DBO_DEFAULT
= 16;
99 /** @var int Use DB persistent connections if possible */
100 const DBO_PERSISTENT
= 32;
101 /** @var int DBA session mode; mostly for Oracle */
102 const DBO_SYSDBA
= 64;
103 /** @var int Schema file mode; mostly for Oracle */
104 const DBO_DDLMODE
= 128;
105 /** @var int Enable SSL/TLS in connection protocol */
107 /** @var int Enable compression in connection protocol */
108 const DBO_COMPRESS
= 512;
111 * A string describing the current software version, and possibly
112 * other details in a user-friendly way. Will be listed on Special:Version, etc.
113 * Use getServerVersion() to get machine-friendly information.
115 * @return string Version information from the database server
117 public function getServerInfo();
120 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
122 * Unbuffered queries are very troublesome in MySQL:
124 * - If another query is executed while the first query is being read
125 * out, the first query is killed. This means you can't call normal
126 * Database functions while you are reading an unbuffered query result
127 * from a normal Database connection.
129 * - Unbuffered queries cause the MySQL server to use large amounts of
130 * memory and to hold broad locks which block other queries.
132 * If you want to limit client-side memory, it's almost always better to
133 * split up queries into batches using a LIMIT clause than to switch off
136 * @param null|bool $buffer
137 * @return null|bool The previous value of the flag
139 public function bufferResults( $buffer = null );
142 * Gets the current transaction level.
144 * Historically, transactions were allowed to be "nested". This is no
145 * longer supported, so this function really only returns a boolean.
147 * @return int The previous value
149 public function trxLevel();
152 * Get the UNIX timestamp of the time that the transaction was established
154 * This can be used to reason about the staleness of SELECT data
155 * in REPEATABLE-READ transaction isolation level.
157 * @return float|null Returns null if there is not active transaction
160 public function trxTimestamp();
163 * @return bool Whether an explicit transaction or atomic sections are still open
166 public function explicitTrxActive();
169 * Get/set the table prefix.
170 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
171 * @return string The previous table prefix.
173 public function tablePrefix( $prefix = null );
176 * Get/set the db schema.
177 * @param string $schema The database schema to set, or omitted to leave it unchanged.
178 * @return string The previous db schema.
180 public function dbSchema( $schema = null );
183 * Get properties passed down from the server info array of the load
186 * @param string $name The entry of the info array to get, or null to get the
189 * @return array|mixed|null
191 public function getLBInfo( $name = null );
194 * Set the LB info array, or a member of it. If called with one parameter,
195 * the LB info array is set to that parameter. If it is called with two
196 * parameters, the member with the given name is set to the given value.
198 * @param string $name
199 * @param array $value
201 public function setLBInfo( $name, $value = null );
204 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
206 * @param IDatabase $conn
209 public function setLazyMasterHandle( IDatabase
$conn );
212 * Returns true if this database does an implicit sort when doing GROUP BY
215 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
217 public function implicitGroupby();
220 * Returns true if this database does an implicit order by when the column has an index
221 * For example: SELECT page_title FROM page LIMIT 1
225 public function implicitOrderby();
228 * Return the last query that went through IDatabase::query()
231 public function lastQuery();
234 * Returns true if the connection may have been used for write queries.
235 * Should return true if unsure.
238 * @deprecated Since 1.31; use lastDoneWrites()
240 public function doneWrites();
243 * Returns the last time the connection may have been used for write queries.
244 * Should return a timestamp if unsure.
246 * @return int|float UNIX timestamp or false
249 public function lastDoneWrites();
252 * @return bool Whether there is a transaction open with possible write queries
255 public function writesPending();
258 * Returns true if there is a transaction/round open with possible write
259 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
260 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
264 public function writesOrCallbacksPending();
267 * Get the time spend running write queries for this transaction
269 * High times could be due to scanning, updates, locking, and such
271 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
272 * @return float|bool Returns false if not transaction is active
275 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
278 * Get the list of method names that did write queries for this transaction
283 public function pendingWriteCallers();
286 * Get the number of affected rows from pending write queries
291 public function pendingWriteRowsAffected();
294 * Is a connection to the database open?
297 public function isOpen();
300 * Set a flag for this connection
302 * @param int $flag DBO_* constants from Defines.php:
303 * - DBO_DEBUG: output some debug info (same as debug())
304 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
305 * - DBO_TRX: automatically start transactions
306 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
307 * and removes it in command line mode
308 * - DBO_PERSISTENT: use persistant database connection
309 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
311 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
314 * Clear a flag for this connection
316 * @param int $flag DBO_* constants from Defines.php:
317 * - DBO_DEBUG: output some debug info (same as debug())
318 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
319 * - DBO_TRX: automatically start transactions
320 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
321 * and removes it in command line mode
322 * - DBO_PERSISTENT: use persistant database connection
323 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
325 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
328 * Restore the flags to their prior state before the last setFlag/clearFlag call
330 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
333 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
336 * Returns a boolean whether the flag $flag is set for this connection
338 * @param int $flag DBO_* constants from Defines.php:
339 * - DBO_DEBUG: output some debug info (same as debug())
340 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
341 * - DBO_TRX: automatically start transactions
342 * - DBO_PERSISTENT: use persistant database connection
345 public function getFlag( $flag );
350 public function getDomainID();
353 * Alias for getDomainID()
358 public function getWikiID();
361 * Get the type of the DBMS, as it appears in $wgDBtype.
365 public function getType();
368 * Open a new connection to the database (closing any existing one)
370 * @param string $server Database server host
371 * @param string $user Database user name
372 * @param string $password Database user password
373 * @param string $dbName Database name
375 * @throws DBConnectionError
377 public function open( $server, $user, $password, $dbName );
380 * Fetch the next row from the given result object, in object form.
381 * Fields can be retrieved with $row->fieldname, with fields acting like
383 * If no more rows are available, false is returned.
385 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
386 * @return stdClass|bool
387 * @throws DBUnexpectedError Thrown if the database returns an error
389 public function fetchObject( $res );
392 * Fetch the next row from the given result object, in associative array
393 * form. Fields are retrieved with $row['fieldname'].
394 * If no more rows are available, false is returned.
396 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
398 * @throws DBUnexpectedError Thrown if the database returns an error
400 public function fetchRow( $res );
403 * Get the number of rows in a result object
405 * @param mixed $res A SQL result
408 public function numRows( $res );
411 * Get the number of fields in a result object
412 * @see https://secure.php.net/mysql_num_fields
414 * @param mixed $res A SQL result
417 public function numFields( $res );
420 * Get a field name in a result object
421 * @see https://secure.php.net/mysql_field_name
423 * @param mixed $res A SQL result
427 public function fieldName( $res, $n );
430 * Get the inserted value of an auto-increment row
432 * This should only be called after an insert that used an auto-incremented
433 * value. If no such insert was previously done in the current database
434 * session, the return value is undefined.
438 public function insertId();
441 * Change the position of the cursor in a result object
442 * @see https://secure.php.net/mysql_data_seek
444 * @param mixed $res A SQL result
447 public function dataSeek( $res, $row );
450 * Get the last error number
451 * @see https://secure.php.net/mysql_errno
455 public function lastErrno();
458 * Get a description of the last error
459 * @see https://secure.php.net/mysql_error
463 public function lastError();
466 * Get the number of rows affected by the last write query
467 * @see https://secure.php.net/mysql_affected_rows
471 public function affectedRows();
474 * Returns a wikitext link to the DB's website, e.g.,
475 * return "[https://www.mysql.com/ MySQL]";
476 * Should at least contain plain text, if for some reason
477 * your database has no website.
479 * @return string Wikitext of a link to the server software's web site
481 public function getSoftwareLink();
484 * A string describing the current software version, like from
485 * mysql_get_server_info().
487 * @return string Version information from the database server.
489 public function getServerVersion();
492 * Close the database connection
494 * This should only be called after any transactions have been resolved,
495 * aside from read-only transactions (assuming no callbacks are registered).
496 * If a transaction is still open anyway, it will be committed if possible.
499 * @return bool Operation success. true if already closed.
501 public function close();
504 * Run an SQL query and return the result. Normally throws a DBQueryError
505 * on failure. If errors are ignored, returns false instead.
507 * If a connection loss is detected, then an attempt to reconnect will be made.
508 * For queries that involve no larger transactions or locks, they will be re-issued
509 * for convenience, provided the connection was re-established.
511 * In new code, the query wrappers select(), insert(), update(), delete(),
512 * etc. should be used where possible, since they give much better DBMS
513 * independence and automatically quote or validate user input in a variety
514 * of contexts. This function is generally only useful for queries which are
515 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
518 * However, the query wrappers themselves should call this function.
520 * @param string $sql SQL query
521 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
522 * comment (you can use __METHOD__ or add some extra info)
523 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
524 * maybe best to catch the exception instead?
525 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
526 * for a successful read query, or false on failure if $tempIgnore set
529 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
532 * Free a result object returned by query() or select(). It's usually not
533 * necessary to call this, just use unset() or let the variable holding
534 * the result object go out of scope.
536 * @param mixed $res A SQL result
538 public function freeResult( $res );
541 * A SELECT wrapper which returns a single field from a single result row.
543 * Usually throws a DBQueryError on failure. If errors are explicitly
544 * ignored, returns false on failure.
546 * If no result rows are returned from the query, false is returned.
548 * @param string|array $table Table name. See IDatabase::select() for details.
549 * @param string $var The field name to select. This must be a valid SQL
550 * fragment: do not use unvalidated user input.
551 * @param string|array $cond The condition array. See IDatabase::select() for details.
552 * @param string $fname The function name of the caller.
553 * @param string|array $options The query options. See IDatabase::select() for details.
554 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
556 * @return mixed The value from the field
559 public function selectField(
560 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
564 * A SELECT wrapper which returns a list of single field values from result rows.
566 * Usually throws a DBQueryError on failure. If errors are explicitly
567 * ignored, returns false on failure.
569 * If no result rows are returned from the query, false is returned.
571 * @param string|array $table Table name. See IDatabase::select() for details.
572 * @param string $var The field name to select. This must be a valid SQL
573 * fragment: do not use unvalidated user input.
574 * @param string|array $cond The condition array. See IDatabase::select() for details.
575 * @param string $fname The function name of the caller.
576 * @param string|array $options The query options. See IDatabase::select() for details.
577 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
579 * @return array The values from the field
583 public function selectFieldValues(
584 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
588 * Execute a SELECT query constructed using the various parameters provided.
589 * See below for full details of the parameters.
591 * @param string|array $table Table name
592 * @param string|array $vars Field names
593 * @param string|array $conds Conditions
594 * @param string $fname Caller function name
595 * @param array $options Query options
596 * @param array $join_conds Join conditions
599 * @param string|array $table
601 * May be either an array of table names, or a single string holding a table
602 * name. If an array is given, table aliases can be specified, for example:
606 * This includes the user table in the query, with the alias "a" available
607 * for use in field names (e.g. a.user_name).
609 * A derived table, defined by the result of selectSQLText(), requires an alias
610 * key and a Subquery instance value which wraps the SQL query, for example:
612 * [ 'c' => new Subquery( 'SELECT ...' ) ]
614 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
615 * constructed using nested arrays. For example,
617 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
619 * along with `$join_conds` like
621 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
623 * will produce SQL something like
625 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
627 * All of the table names given here are automatically run through
628 * Database::tableName(), which causes the table prefix (if any) to be
629 * added, and various other table name mappings to be performed.
631 * Do not use untrusted user input as a table name. Alias names should
632 * not have characters outside of the Basic multilingual plane.
634 * @param string|array $vars
636 * May be either a field name or an array of field names. The field names
637 * can be complete fragments of SQL, for direct inclusion into the SELECT
638 * query. If an array is given, field aliases can be specified, for example:
640 * [ 'maxrev' => 'MAX(rev_id)' ]
642 * This includes an expression with the alias "maxrev" in the query.
644 * If an expression is given, care must be taken to ensure that it is
647 * Untrusted user input must not be passed to this parameter.
649 * @param string|array $conds
651 * May be either a string containing a single condition, or an array of
652 * conditions. If an array is given, the conditions constructed from each
653 * element are combined with AND.
655 * Array elements may take one of two forms:
657 * - Elements with a numeric key are interpreted as raw SQL fragments.
658 * - Elements with a string key are interpreted as equality conditions,
659 * where the key is the field name.
660 * - If the value of such an array element is a scalar (such as a
661 * string), it will be treated as data and thus quoted appropriately.
662 * If it is null, an IS NULL clause will be added.
663 * - If the value is an array, an IN (...) clause will be constructed
664 * from its non-null elements, and an IS NULL clause will be added
665 * if null is present, such that the field may match any of the
666 * elements in the array. The non-null elements will be quoted.
668 * Note that expressions are often DBMS-dependent in their syntax.
669 * DBMS-independent wrappers are provided for constructing several types of
670 * expression commonly used in condition queries. See:
671 * - IDatabase::buildLike()
672 * - IDatabase::conditional()
674 * Untrusted user input is safe in the values of string keys, however untrusted
675 * input must not be used in the array key names or in the values of numeric keys.
676 * Escaping of untrusted input used in values of numeric keys should be done via
677 * IDatabase::addQuotes()
679 * @param string|array $options
681 * Optional: Array of query options. Boolean options are specified by
682 * including them in the array as a string value with a numeric key, for
687 * The supported options are:
689 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
690 * with LIMIT can theoretically be used for paging through a result set,
691 * but this is discouraged for performance reasons.
693 * - LIMIT: Integer: return at most this many rows. The rows are sorted
694 * and then the first rows are taken until the limit is reached. LIMIT
695 * is applied to a result set after OFFSET.
697 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
698 * changed until the next COMMIT.
700 * - DISTINCT: Boolean: return only unique result rows.
702 * - GROUP BY: May be either an SQL fragment string naming a field or
703 * expression to group by, or an array of such SQL fragments.
705 * - HAVING: May be either an string containing a HAVING clause or an array of
706 * conditions building the HAVING clause. If an array is given, the conditions
707 * constructed from each element are combined with AND.
709 * - ORDER BY: May be either an SQL fragment giving a field name or
710 * expression to order by, or an array of such SQL fragments.
712 * - USE INDEX: This may be either a string giving the index name to use
713 * for the query, or an array. If it is an associative array, each key
714 * gives the table name (or alias), each value gives the index name to
715 * use for that table. All strings are SQL fragments and so should be
716 * validated by the caller.
718 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
721 * And also the following boolean MySQL extensions, see the MySQL manual
724 * - LOCK IN SHARE MODE
728 * - SQL_BUFFER_RESULT
730 * - SQL_CALC_FOUND_ROWS
735 * @param string|array $join_conds
737 * Optional associative array of table-specific join conditions. In the
738 * most common case, this is unnecessary, since the join condition can be
739 * in $conds. However, it is useful for doing a LEFT JOIN.
741 * The key of the array contains the table name or alias. The value is an
742 * array with two elements, numbered 0 and 1. The first gives the type of
743 * join, the second is the same as the $conds parameter. Thus it can be
744 * an SQL fragment, or an array where the string keys are equality and the
745 * numeric keys are SQL fragments all AND'd together. For example:
747 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
749 * @return IResultWrapper Resulting rows
752 public function select(
753 $table, $vars, $conds = '', $fname = __METHOD__
,
754 $options = [], $join_conds = []
758 * The equivalent of IDatabase::select() except that the constructed SQL
759 * is returned, instead of being immediately executed. This can be useful for
760 * doing UNION queries, where the SQL text of each query is needed. In general,
761 * however, callers outside of Database classes should just use select().
763 * @see IDatabase::select()
765 * @param string|array $table Table name
766 * @param string|array $vars Field names
767 * @param string|array $conds Conditions
768 * @param string $fname Caller function name
769 * @param string|array $options Query options
770 * @param string|array $join_conds Join conditions
771 * @return string SQL query string
773 public function selectSQLText(
774 $table, $vars, $conds = '', $fname = __METHOD__
,
775 $options = [], $join_conds = []
779 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
780 * that a single row object is returned. If the query returns no rows,
783 * @param string|array $table Table name
784 * @param string|array $vars Field names
785 * @param array $conds Conditions
786 * @param string $fname Caller function name
787 * @param string|array $options Query options
788 * @param array|string $join_conds Join conditions
790 * @return stdClass|bool
793 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
794 $options = [], $join_conds = []
798 * Estimate the number of rows in dataset
800 * MySQL allows you to estimate the number of rows that would be returned
801 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
802 * index cardinality statistics, and is notoriously inaccurate, especially
803 * when large numbers of rows have recently been added or deleted.
805 * For DBMSs that don't support fast result size estimation, this function
806 * will actually perform the SELECT COUNT(*).
808 * Takes the same arguments as IDatabase::select().
810 * @param string $table Table name
811 * @param string $var Column for which NULL values are not counted [default "*"]
812 * @param array|string $conds Filters on the table
813 * @param string $fname Function name for profiling
814 * @param array $options Options for select
815 * @param array|string $join_conds Join conditions
816 * @return int Row count
819 public function estimateRowCount(
820 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
824 * Get the number of rows in dataset
826 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
828 * Takes the same arguments as IDatabase::select().
830 * @since 1.27 Added $join_conds parameter
832 * @param array|string $tables Table names
833 * @param string $var Column for which NULL values are not counted [default "*"]
834 * @param array|string $conds Filters on the table
835 * @param string $fname Function name for profiling
836 * @param array $options Options for select
837 * @param array $join_conds Join conditions (since 1.27)
838 * @return int Row count
841 public function selectRowCount(
842 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
846 * Determines whether a field exists in a table
848 * @param string $table Table name
849 * @param string $field Filed to check on that table
850 * @param string $fname Calling function name (optional)
851 * @return bool Whether $table has filed $field
854 public function fieldExists( $table, $field, $fname = __METHOD__
);
857 * Determines whether an index exists
858 * Usually throws a DBQueryError on failure
859 * If errors are explicitly ignored, returns NULL on failure
861 * @param string $table
862 * @param string $index
863 * @param string $fname
867 public function indexExists( $table, $index, $fname = __METHOD__
);
870 * Query whether a given table exists
872 * @param string $table
873 * @param string $fname
877 public function tableExists( $table, $fname = __METHOD__
);
880 * INSERT wrapper, inserts an array into a table.
884 * - A single associative array. The array keys are the field names, and
885 * the values are the values to insert. The values are treated as data
886 * and will be quoted appropriately. If NULL is inserted, this will be
887 * converted to a database NULL.
888 * - An array with numeric keys, holding a list of associative arrays.
889 * This causes a multi-row INSERT on DBMSs that support it. The keys in
890 * each subarray must be identical to each other, and in the same order.
892 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
895 * $options is an array of options, with boolean options encoded as values
896 * with numeric keys, in the same style as $options in
897 * IDatabase::select(). Supported options are:
899 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
900 * any rows which cause duplicate key errors are not inserted. It's
901 * possible to determine how many rows were successfully inserted using
902 * IDatabase::affectedRows().
904 * @param string $table Table name. This will be passed through
905 * Database::tableName().
906 * @param array $a Array of rows to insert
907 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
908 * @param array $options Array of options
913 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
916 * UPDATE wrapper. Takes a condition array and a SET array.
918 * @param string $table Name of the table to UPDATE. This will be passed through
919 * Database::tableName().
920 * @param array $values An array of values to SET. For each array element,
921 * the key gives the field name, and the value gives the data to set
922 * that field to. The data will be quoted by IDatabase::addQuotes().
923 * Values with integer keys form unquoted SET statements, which can be used for
924 * things like "field = field + 1" or similar computed values.
925 * @param array $conds An array of conditions (WHERE). See
926 * IDatabase::select() for the details of the format of condition
927 * arrays. Use '*' to update all rows.
928 * @param string $fname The function name of the caller (from __METHOD__),
929 * for logging and profiling.
930 * @param array $options An array of UPDATE options, can be:
931 * - IGNORE: Ignore unique key conflicts
932 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
936 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
939 * Makes an encoded list of strings from an array
941 * These can be used to make conjunctions or disjunctions on SQL condition strings
942 * derived from an array (see IDatabase::select() $conds documentation).
946 * $sql = $db->makeList( [
948 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
949 * ], $db::LIST_AND );
951 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
953 * @param array $a Containing the data
954 * @param int $mode IDatabase class constant:
955 * - IDatabase::LIST_COMMA: Comma separated, no field names
956 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
957 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
958 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
959 * - IDatabase::LIST_NAMES: Comma separated field names
963 public function makeList( $a, $mode = self
::LIST_COMMA
);
966 * Build a partial where clause from a 2-d array such as used for LinkBatch.
967 * The keys on each level may be either integers or strings.
969 * @param array $data Organized as 2-d
970 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
971 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
972 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
973 * @return string|bool SQL fragment, or false if no items in array
975 public function makeWhereFrom2d( $data, $baseKey, $subKey );
978 * Return aggregated value alias
980 * @param array $valuedata
981 * @param string $valuename
985 public function aggregateValue( $valuedata, $valuename = 'value' );
988 * @param string $field
991 public function bitNot( $field );
994 * @param string $fieldLeft
995 * @param string $fieldRight
998 public function bitAnd( $fieldLeft, $fieldRight );
1001 * @param string $fieldLeft
1002 * @param string $fieldRight
1005 public function bitOr( $fieldLeft, $fieldRight );
1008 * Build a concatenation list to feed into a SQL query
1009 * @param array $stringList List of raw SQL expressions; caller is
1010 * responsible for any quoting
1013 public function buildConcat( $stringList );
1016 * Build a GROUP_CONCAT or equivalent statement for a query.
1018 * This is useful for combining a field for several rows into a single string.
1019 * NULL values will not appear in the output, duplicated values will appear,
1020 * and the resulting delimiter-separated values have no defined sort order.
1021 * Code using the results may need to use the PHP unique() or sort() methods.
1023 * @param string $delim Glue to bind the results together
1024 * @param string|array $table Table name
1025 * @param string $field Field name
1026 * @param string|array $conds Conditions
1027 * @param string|array $join_conds Join conditions
1028 * @return string SQL text
1031 public function buildGroupConcatField(
1032 $delim, $table, $field, $conds = '', $join_conds = []
1036 * Build a SUBSTRING function.
1038 * Behavior for non-ASCII values is undefined.
1040 * @param string $input Field name
1041 * @param int $startPosition Positive integer
1042 * @param int|null $length Non-negative integer length or null for no limit
1043 * @throws InvalidArgumentException
1044 * @return string SQL text
1047 public function buildSubString( $input, $startPosition, $length = null );
1050 * @param string $field Field or column to cast
1054 public function buildStringCast( $field );
1057 * @param string $field Field or column to cast
1061 public function buildIntegerCast( $field );
1064 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1066 * @see IDatabase::selectSQLText()
1068 * @param string|array $table Table name
1069 * @param string|array $vars Field names
1070 * @param string|array $conds Conditions
1071 * @param string $fname Caller function name
1072 * @param string|array $options Query options
1073 * @param string|array $join_conds Join conditions
1077 public function buildSelectSubquery(
1078 $table, $vars, $conds = '', $fname = __METHOD__
,
1079 $options = [], $join_conds = []
1083 * Returns true if DBs are assumed to be on potentially different servers
1085 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1086 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1087 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1088 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1093 public function databasesAreIndependent();
1096 * Change the current database
1099 * @return bool Success or failure
1100 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1102 public function selectDB( $db );
1105 * Get the current DB name
1108 public function getDBname();
1111 * Get the server hostname or IP address
1114 public function getServer();
1117 * Adds quotes and backslashes.
1119 * @param string|int|null|bool|Blob $s
1120 * @return string|int
1122 public function addQuotes( $s );
1125 * LIKE statement wrapper, receives a variable-length argument list with
1126 * parts of pattern to match containing either string literals that will be
1127 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1128 * the function could be provided with an array of aforementioned
1131 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1132 * a LIKE clause that searches for subpages of 'My page title'.
1134 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1135 * $query .= $dbr->buildLike( $pattern );
1138 * @return string Fully built LIKE statement
1140 public function buildLike();
1143 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1147 public function anyChar();
1150 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1154 public function anyString();
1157 * Deprecated method, calls should be removed.
1159 * This was formerly used for PostgreSQL and Oracle to handle
1160 * self::insertId() auto-incrementing fields. It is no longer necessary
1161 * since DatabasePostgres::insertId() has been reimplemented using
1162 * `lastval()` and Oracle has been reimplemented using triggers.
1164 * Implementations should return null if inserting `NULL` into an
1165 * auto-incrementing field works, otherwise it should return an instance of
1166 * NextSequenceValue and filter it on calls to relevant methods.
1168 * @deprecated since 1.30, no longer needed
1169 * @param string $seqName
1170 * @return null|NextSequenceValue
1172 public function nextSequenceValue( $seqName );
1175 * REPLACE query wrapper.
1177 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1178 * except that when there is a duplicate key error, the old row is deleted
1179 * and the new row is inserted in its place.
1181 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1182 * perform the delete, we need to know what the unique indexes are so that
1183 * we know how to find the conflicting rows.
1185 * It may be more efficient to leave off unique indexes which are unlikely
1186 * to collide. However if you do this, you run the risk of encountering
1187 * errors which wouldn't have occurred in MySQL.
1189 * @param string $table The table to replace the row(s) in.
1190 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1191 * a field name or an array of field names
1192 * @param array $rows Can be either a single row to insert, or multiple rows,
1193 * in the same format as for IDatabase::insert()
1194 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1197 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1200 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1202 * This updates any conflicting rows (according to the unique indexes) using
1203 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1205 * $rows may be either:
1206 * - A single associative array. The array keys are the field names, and
1207 * the values are the values to insert. The values are treated as data
1208 * and will be quoted appropriately. If NULL is inserted, this will be
1209 * converted to a database NULL.
1210 * - An array with numeric keys, holding a list of associative arrays.
1211 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1212 * each subarray must be identical to each other, and in the same order.
1214 * It may be more efficient to leave off unique indexes which are unlikely
1215 * to collide. However if you do this, you run the risk of encountering
1216 * errors which wouldn't have occurred in MySQL.
1218 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1223 * @param string $table Table name. This will be passed through Database::tableName().
1224 * @param array $rows A single row or list of rows to insert
1225 * @param array $uniqueIndexes List of single field names or field name tuples
1226 * @param array $set An array of values to SET. For each array element, the
1227 * key gives the field name, and the value gives the data to set that
1228 * field to. The data will be quoted by IDatabase::addQuotes().
1229 * Values with integer keys form unquoted SET statements, which can be used for
1230 * things like "field = field + 1" or similar computed values.
1231 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1235 public function upsert(
1236 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1240 * DELETE where the condition is a join.
1242 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1243 * we use sub-selects
1245 * For safety, an empty $conds will not delete everything. If you want to
1246 * delete all rows where the join condition matches, set $conds='*'.
1248 * DO NOT put the join condition in $conds.
1250 * @param string $delTable The table to delete from.
1251 * @param string $joinTable The other table.
1252 * @param string $delVar The variable to join on, in the first table.
1253 * @param string $joinVar The variable to join on, in the second table.
1254 * @param array $conds Condition array of field names mapped to variables,
1255 * ANDed together in the WHERE clause
1256 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1259 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1264 * DELETE query wrapper.
1266 * @param string $table Table name
1267 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1268 * for the format. Use $conds == "*" to delete all rows
1269 * @param string $fname Name of the calling function
1270 * @throws DBUnexpectedError
1271 * @return bool|IResultWrapper
1274 public function delete( $table, $conds, $fname = __METHOD__
);
1277 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1278 * into another table.
1280 * @warning If the insert will use an auto-increment or sequence to
1281 * determine the value of a column, this may break replication on
1282 * databases using statement-based replication if the SELECT is not
1283 * deterministically ordered.
1285 * @param string $destTable The table name to insert into
1286 * @param string|array $srcTable May be either a table name, or an array of table names
1287 * to include in a join.
1289 * @param array $varMap Must be an associative array of the form
1290 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1291 * rather than field names, but strings should be quoted with
1292 * IDatabase::addQuotes()
1294 * @param array $conds Condition array. See $conds in IDatabase::select() for
1295 * the details of the format of condition arrays. May be "*" to copy the
1298 * @param string $fname The function name of the caller, from __METHOD__
1300 * @param array $insertOptions Options for the INSERT part of the query, see
1301 * IDatabase::insert() for details. Also, one additional option is
1302 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1303 * an auto-increment or sequence to determine any column values.
1304 * @param array $selectOptions Options for the SELECT part of the query, see
1305 * IDatabase::select() for details.
1306 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1307 * IDatabase::select() for details.
1312 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1313 $fname = __METHOD__
,
1314 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1318 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1319 * within the UNION construct.
1322 public function unionSupportsOrderAndLimit();
1325 * Construct a UNION query
1326 * This is used for providing overload point for other DB abstractions
1327 * not compatible with the MySQL syntax.
1328 * @param array $sqls SQL statements to combine
1329 * @param bool $all Use UNION ALL
1330 * @return string SQL fragment
1332 public function unionQueries( $sqls, $all );
1335 * Construct a UNION query for permutations of conditions
1337 * Databases sometimes have trouble with queries that have multiple values
1338 * for multiple condition parameters combined with limits and ordering.
1339 * This method constructs queries for the Cartesian product of the
1340 * conditions and unions them all together.
1342 * @see IDatabase::select()
1344 * @param string|array $table Table name
1345 * @param string|array $vars Field names
1346 * @param array $permute_conds Conditions for the Cartesian product. Keys
1347 * are field names, values are arrays of the possible values for that
1349 * @param string|array $extra_conds Additional conditions to include in the
1351 * @param string $fname Caller function name
1352 * @param string|array $options Query options. In addition to the options
1353 * recognized by IDatabase::select(), the following may be used:
1354 * - NOTALL: Set to use UNION instead of UNION ALL.
1355 * - INNER ORDER BY: If specified and supported, subqueries will use this
1356 * instead of ORDER BY.
1357 * @param string|array $join_conds Join conditions
1358 * @return string SQL query string.
1360 public function unionConditionPermutations(
1361 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1362 $options = [], $join_conds = []
1366 * Returns an SQL expression for a simple conditional. This doesn't need
1367 * to be overridden unless CASE isn't supported in your DBMS.
1369 * @param string|array $cond SQL expression which will result in a boolean value
1370 * @param string $trueVal SQL expression to return if true
1371 * @param string $falseVal SQL expression to return if false
1372 * @return string SQL fragment
1374 public function conditional( $cond, $trueVal, $falseVal );
1377 * Returns a command for str_replace function in SQL query.
1378 * Uses REPLACE() in MySQL
1380 * @param string $orig Column to modify
1381 * @param string $old Column to seek
1382 * @param string $new Column to replace with
1386 public function strreplace( $orig, $old, $new );
1389 * Determines how long the server has been up
1394 public function getServerUptime();
1397 * Determines if the last failure was due to a deadlock
1399 * Note that during a deadlock, the prior transaction will have been lost
1403 public function wasDeadlock();
1406 * Determines if the last failure was due to a lock timeout
1408 * Note that during a lock wait timeout, the prior transaction will have been lost
1412 public function wasLockTimeout();
1415 * Determines if the last query error was due to a dropped connection
1417 * Note that during a connection loss, the prior transaction will have been lost
1422 public function wasConnectionLoss();
1425 * Determines if the last failure was due to the database being read-only.
1429 public function wasReadOnlyError();
1432 * Determines if the last query error was due to something outside of the query itself
1434 * Note that the transaction may have been lost, discarding prior writes and results
1438 public function wasErrorReissuable();
1441 * Wait for the replica DB to catch up to a given master position
1443 * @param DBMasterPos $pos
1444 * @param int $timeout The maximum number of seconds to wait for synchronisation
1445 * @return int|null Zero if the replica DB was past that position already,
1446 * greater than zero if we waited for some period of time, less than
1447 * zero if it timed out, and null on error
1450 public function masterPosWait( DBMasterPos
$pos, $timeout );
1453 * Get the replication position of this replica DB
1455 * @return DBMasterPos|bool False if this is not a replica DB
1458 public function getReplicaPos();
1461 * Get the position of this master
1463 * @return DBMasterPos|bool False if this is not a master
1466 public function getMasterPos();
1469 * @return bool Whether the DB is marked as read-only server-side
1472 public function serverIsReadOnly();
1475 * Run a callback as soon as the current transaction commits or rolls back.
1476 * An error is thrown if no transaction is pending. Queries in the function will run in
1477 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1480 * This is useful for combining cooperative locks and DB transactions.
1482 * The callback takes one argument:
1483 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1485 * @param callable $callback
1486 * @param string $fname Caller name
1490 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1493 * Run a callback as soon as there is no transaction pending.
1494 * If there is a transaction and it is rolled back, then the callback is cancelled.
1496 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1497 * of the round, just after all peer transactions COMMIT. If the transaction round
1498 * is rolled back, then the callback is cancelled.
1500 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1501 * Callbacks must commit any transactions that they begin.
1503 * This is useful for updates to different systems or when separate transactions are needed.
1504 * For example, one might want to enqueue jobs into a system outside the database, but only
1505 * after the database is updated so that the jobs will see the data when they actually run.
1506 * It can also be used for updates that easily suffer from lock timeouts and deadlocks,
1507 * but where atomicity is not essential.
1509 * Updates will execute in the order they were enqueued.
1511 * The callback takes one argument:
1512 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1514 * @param callable $callback
1515 * @param string $fname Caller name
1518 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1521 * Run a callback before the current transaction commits or now if there is none.
1522 * If there is a transaction and it is rolled back, then the callback is cancelled.
1524 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1525 * of the round, just before all peer transactions COMMIT. If the transaction round
1526 * is rolled back, then the callback is cancelled.
1528 * Callbacks must not start nor commit any transactions. If no transaction is active,
1529 * then a transaction will wrap the callback.
1531 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1532 * but where atomicity is strongly desired for these updates and some related updates.
1534 * Updates will execute in the order they were enqueued.
1536 * @param callable $callback
1537 * @param string $fname Caller name
1540 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1543 * Run a callback each time any transaction commits or rolls back
1545 * The callback takes two arguments:
1546 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1547 * - This IDatabase object
1548 * Callbacks must commit any transactions that they begin.
1550 * Registering a callback here will not affect writesOrCallbacks() pending
1552 * @param string $name Callback name
1553 * @param callable|null $callback Use null to unset a listener
1557 public function setTransactionListener( $name, callable
$callback = null );
1560 * Begin an atomic section of statements
1562 * If a transaction has been started already, (optionally) sets a savepoint
1563 * and tracks the given section name to make sure the transaction is not
1564 * committed pre-maturely. This function can be used in layers (with
1565 * sub-sections), so use a stack to keep track of the different atomic
1566 * sections. If there is no transaction, one is started implicitly.
1568 * The goal of this function is to create an atomic section of SQL queries
1569 * without having to start a new transaction if it already exists.
1571 * All atomic levels *must* be explicitly closed using IDatabase::endAtomic()
1572 * or IDatabase::cancelAtomic(), and any database transactions cannot be
1573 * began or committed until all atomic levels are closed. There is no such
1574 * thing as implicitly opening or closing an atomic section.
1577 * @param string $fname
1578 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1579 * savepoint and enable self::cancelAtomic() for this section.
1580 * @return AtomicSectionIdentifier section ID token
1583 public function startAtomic( $fname = __METHOD__
, $cancelable = self
::ATOMIC_NOT_CANCELABLE
);
1586 * Ends an atomic section of SQL statements
1588 * Ends the next section of atomic SQL statements and commits the transaction
1592 * @see IDatabase::startAtomic
1593 * @param string $fname
1596 public function endAtomic( $fname = __METHOD__
);
1599 * Cancel an atomic section of SQL statements
1601 * This will roll back only the statements executed since the start of the
1602 * most recent atomic section, and close that section. If a transaction was
1603 * open before the corresponding startAtomic() call, any statements before
1604 * that call are *not* rolled back and the transaction remains open. If the
1605 * corresponding startAtomic() implicitly started a transaction, that
1606 * transaction is rolled back.
1608 * Note that a call to IDatabase::rollback() will also roll back any open
1611 * @note As a micro-optimization to save a few DB calls, this method may only
1612 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1614 * @see IDatabase::startAtomic
1615 * @param string $fname
1616 * @param AtomicSectionIdentifier $sectionId Section ID from startAtomic();
1617 * passing this enables cancellation of unclosed nested sections [optional]
1620 public function cancelAtomic( $fname = __METHOD__
, AtomicSectionIdentifier
$sectionId = null );
1623 * Run a callback to do an atomic set of updates for this database
1625 * The $callback takes the following arguments:
1626 * - This database object
1627 * - The value of $fname
1629 * If any exception occurs in the callback, then cancelAtomic() will be
1630 * called to back out any statements executed by the callback and the error
1631 * will be re-thrown. It may also be that the cancel itself fails with an
1632 * exception before then. In any case, such errors are expected to
1633 * terminate the request, without any outside caller attempting to catch
1634 * errors and commit anyway.
1636 * This can be an alternative to explicit startAtomic()/endAtomic()/cancelAtomic() calls.
1638 * @see Database::startAtomic
1639 * @see Database::endAtomic
1640 * @see Database::cancelAtomic
1642 * @param string $fname Caller name (usually __METHOD__)
1643 * @param callable $callback Callback that issues DB updates
1644 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1645 * savepoint and enable self::cancelAtomic() for this section.
1646 * @return mixed $res Result of the callback (since 1.28)
1648 * @throws RuntimeException
1649 * @throws UnexpectedValueException
1650 * @since 1.27; prior to 1.31 this did a rollback() instead of
1651 * cancelAtomic(), and assumed no callers up the stack would ever try to
1652 * catch the exception.
1654 public function doAtomicSection(
1655 $fname, callable
$callback, $cancelable = self
::ATOMIC_NOT_CANCELABLE
1659 * Begin a transaction. If a transaction is already in progress,
1660 * that transaction will be committed before the new transaction is started.
1662 * Only call this from code with outer transcation scope.
1663 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1664 * Nesting of transactions is not supported.
1666 * Note that when the DBO_TRX flag is set (which is usually the case for web
1667 * requests, but not for maintenance scripts), any previous database query
1668 * will have started a transaction automatically.
1670 * Nesting of transactions is not supported. Attempts to nest transactions
1671 * will cause a warning, unless the current transaction was started
1672 * automatically because of the DBO_TRX flag.
1674 * @param string $fname Calling function name
1675 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1678 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1681 * Commits a transaction previously started using begin().
1682 * If no transaction is in progress, a warning is issued.
1684 * Only call this from code with outer transcation scope.
1685 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1686 * Nesting of transactions is not supported.
1688 * @param string $fname
1689 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1690 * constant to disable warnings about explicitly committing implicit transactions,
1691 * or calling commit when no transaction is in progress.
1693 * This will trigger an exception if there is an ongoing explicit transaction.
1695 * Only set the flush flag if you are sure that these warnings are not applicable,
1696 * and no explicit transactions are open.
1700 public function commit( $fname = __METHOD__
, $flush = '' );
1703 * Rollback a transaction previously started using begin().
1704 * If no transaction is in progress, a warning is issued.
1706 * Only call this from code with outer transcation scope.
1707 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1708 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1709 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1710 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1712 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1714 * @param string $fname Calling function name
1715 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1716 * constant to disable warnings about calling rollback when no transaction is in
1717 * progress. This will silently break any ongoing explicit transaction. Only set the
1718 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1720 * @since 1.23 Added $flush parameter
1722 public function rollback( $fname = __METHOD__
, $flush = '' );
1725 * Commit any transaction but error out if writes or callbacks are pending
1727 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1728 * see a new point-in-time of the database. This is useful when one of many transaction
1729 * rounds finished and significant time will pass in the script's lifetime. It is also
1730 * useful to call on a replica DB after waiting on replication to catch up to the master.
1732 * @param string $fname Calling function name
1736 public function flushSnapshot( $fname = __METHOD__
);
1739 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1740 * to the format used for inserting into timestamp fields in this DBMS.
1742 * The result is unquoted, and needs to be passed through addQuotes()
1743 * before it can be included in raw SQL.
1745 * @param string|int $ts
1749 public function timestamp( $ts = 0 );
1752 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1753 * to the format used for inserting into timestamp fields in this DBMS. If
1754 * NULL is input, it is passed through, allowing NULL values to be inserted
1755 * into timestamp fields.
1757 * The result is unquoted, and needs to be passed through addQuotes()
1758 * before it can be included in raw SQL.
1760 * @param string|int $ts
1764 public function timestampOrNull( $ts = null );
1767 * Ping the server and try to reconnect if it there is no connection
1769 * @param float|null &$rtt Value to store the estimated RTT [optional]
1770 * @return bool Success or failure
1772 public function ping( &$rtt = null );
1775 * Get the amount of replication lag for this database server
1777 * Callers should avoid using this method while a transaction is active
1779 * @return int|bool Database replication lag in seconds or false on error
1782 public function getLag();
1785 * Get the replica DB lag when the current transaction started
1786 * or a general lag estimate if not transaction is active
1788 * This is useful when transactions might use snapshot isolation
1789 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1790 * is this lag plus transaction duration. If they don't, it is still
1791 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1792 * indication of the staleness of subsequent reads.
1794 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1798 public function getSessionLagStatus();
1801 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1805 public function maxListLen();
1808 * Some DBMSs have a special format for inserting into blob fields, they
1809 * don't allow simple quoted strings to be inserted. To insert into such
1810 * a field, pass the data through this function before passing it to
1811 * IDatabase::insert().
1814 * @return string|Blob
1816 public function encodeBlob( $b );
1819 * Some DBMSs return a special placeholder object representing blob fields
1820 * in result objects. Pass the object through this function to return the
1823 * @param string|Blob $b
1826 public function decodeBlob( $b );
1829 * Override database's default behavior. $options include:
1830 * 'connTimeout' : Set the connection timeout value in seconds.
1831 * May be useful for very long batch queries such as
1832 * full-wiki dumps, where a single query reads out over
1835 * @param array $options
1839 public function setSessionOptions( array $options );
1842 * Set variables to be used in sourceFile/sourceStream, in preference to the
1843 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1844 * all. If it's set to false, $GLOBALS will be used.
1846 * @param bool|array $vars Mapping variable name to value.
1848 public function setSchemaVars( $vars );
1851 * Check to see if a named lock is not locked by any thread (non-blocking)
1853 * @param string $lockName Name of lock to poll
1854 * @param string $method Name of method calling us
1859 public function lockIsFree( $lockName, $method );
1862 * Acquire a named lock
1864 * Named locks are not related to transactions
1866 * @param string $lockName Name of lock to aquire
1867 * @param string $method Name of the calling method
1868 * @param int $timeout Acquisition timeout in seconds
1872 public function lock( $lockName, $method, $timeout = 5 );
1877 * Named locks are not related to transactions
1879 * @param string $lockName Name of lock to release
1880 * @param string $method Name of the calling method
1882 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1883 * by this thread (in which case the lock is not released), and NULL if the named lock
1888 public function unlock( $lockName, $method );
1891 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1893 * Only call this from outer transcation scope and when only one DB will be affected.
1894 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1896 * This is suitiable for transactions that need to be serialized using cooperative locks,
1897 * where each transaction can see each others' changes. Any transaction is flushed to clear
1898 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1899 * the lock will be released unless a transaction is active. If one is active, then the lock
1900 * will be released when it either commits or rolls back.
1902 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1904 * @param string $lockKey Name of lock to release
1905 * @param string $fname Name of the calling method
1906 * @param int $timeout Acquisition timeout in seconds
1907 * @return ScopedCallback|null
1911 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1914 * Check to see if a named lock used by lock() use blocking queues
1919 public function namedLocksEnqueue();
1922 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1923 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1924 * because "i" sorts after all numbers.
1928 public function getInfinity();
1931 * Encode an expiry time into the DBMS dependent format
1933 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1936 public function encodeExpiry( $expiry );
1939 * Decode an expiry time into a DBMS independent format
1941 * @param string $expiry DB timestamp field value for expiry
1942 * @param int $format TS_* constant, defaults to TS_MW
1945 public function decodeExpiry( $expiry, $format = TS_MW
);
1948 * Allow or deny "big selects" for this session only. This is done by setting
1949 * the sql_big_selects session variable.
1951 * This is a MySQL-specific feature.
1953 * @param bool|string $value True for allow, false for deny, or "default" to
1954 * restore the initial value
1956 public function setBigSelects( $value = true );
1959 * @return bool Whether this DB is read-only
1962 public function isReadOnly();
1965 * Make certain table names use their own database, schema, and table prefix
1966 * when passed into SQL queries pre-escaped and without a qualified database name
1968 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1969 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1971 * Calling this twice will completely clear any old table aliases. Also, note that
1972 * callers are responsible for making sure the schemas and databases actually exist.
1974 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1977 public function setTableAliases( array $aliases );
1980 * Convert certain index names to alternative names before querying the DB
1982 * Note that this applies to indexes regardless of the table they belong to.
1984 * This can be employed when an index was renamed X => Y in code, but the new Y-named
1985 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
1986 * the aliases can be removed, and then the old X-named indexes dropped.
1988 * @param string[] $aliases
1992 public function setIndexAliases( array $aliases );
1995 class_alias( IDatabase
::class, 'IDatabase' );