3 * @defgroup Database Database
5 * This file deals with database interface functions
6 * and query specifics/optimisations.
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
21 * http://www.gnu.org/copyleft/gpl.html
28 * Basic database interface for live and lazy-loaded relation database handles
30 * @note: IDatabase and DBConnRef should be updated to reflect any changes
34 /** @var int Callback triggered immediately due to no active transaction */
35 const TRIGGER_IDLE
= 1;
36 /** @var int Callback triggered by COMMIT */
37 const TRIGGER_COMMIT
= 2;
38 /** @var int Callback triggered by ROLLBACK */
39 const TRIGGER_ROLLBACK
= 3;
41 /** @var string Transaction is requested by regular caller outside of the DB layer */
42 const TRANSACTION_EXPLICIT
= '';
43 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
44 const TRANSACTION_INTERNAL
= 'implicit';
46 /** @var string Transaction operation comes from service managing all DBs */
47 const FLUSHING_ALL_PEERS
= 'flush';
48 /** @var string Transaction operation comes from the database class internally */
49 const FLUSHING_INTERNAL
= 'flush';
51 /** @var string Do not remember the prior flags */
52 const REMEMBER_NOTHING
= '';
53 /** @var string Remember the prior flags */
54 const REMEMBER_PRIOR
= 'remember';
55 /** @var string Restore to the prior flag state */
56 const RESTORE_PRIOR
= 'prior';
57 /** @var string Restore to the initial flag state */
58 const RESTORE_INITIAL
= 'initial';
60 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
61 const ESTIMATE_TOTAL
= 'total';
62 /** @var string Estimate time to apply (scanning, applying) */
63 const ESTIMATE_DB_APPLY
= 'apply';
65 /** @var int Combine list with comma delimeters */
67 /** @var int Combine list with AND clauses */
69 /** @var int Convert map into a SET clause */
71 /** @var int Treat as field name and do not apply value escaping */
73 /** @var int Combine list with OR clauses */
76 /** @var int Enable debug logging */
78 /** @var int Disable query buffering (only one result set can be iterated at a time) */
79 const DBO_NOBUFFER
= 2;
80 /** @var int Ignore query errors (internal use only!) */
82 /** @var int Autoatically start transaction on first query (work with ILoadBalancer rounds) */
84 /** @var int Use DBO_TRX in non-CLI mode */
85 const DBO_DEFAULT
= 16;
86 /** @var int Use DB persistent connections if possible */
87 const DBO_PERSISTENT
= 32;
88 /** @var int DBA session mode; mostly for Oracle */
89 const DBO_SYSDBA
= 64;
90 /** @var int Schema file mode; mostly for Oracle */
91 const DBO_DDLMODE
= 128;
92 /** @var int Enable SSL/TLS in connection protocol */
94 /** @var int Enable compression in connection protocol */
95 const DBO_COMPRESS
= 512;
98 * A string describing the current software version, and possibly
99 * other details in a user-friendly way. Will be listed on Special:Version, etc.
100 * Use getServerVersion() to get machine-friendly information.
102 * @return string Version information from the database server
104 public function getServerInfo();
107 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
109 * Unbuffered queries are very troublesome in MySQL:
111 * - If another query is executed while the first query is being read
112 * out, the first query is killed. This means you can't call normal
113 * Database functions while you are reading an unbuffered query result
114 * from a normal Database connection.
116 * - Unbuffered queries cause the MySQL server to use large amounts of
117 * memory and to hold broad locks which block other queries.
119 * If you want to limit client-side memory, it's almost always better to
120 * split up queries into batches using a LIMIT clause than to switch off
123 * @param null|bool $buffer
124 * @return null|bool The previous value of the flag
126 public function bufferResults( $buffer = null );
129 * Gets the current transaction level.
131 * Historically, transactions were allowed to be "nested". This is no
132 * longer supported, so this function really only returns a boolean.
134 * @return int The previous value
136 public function trxLevel();
139 * Get the UNIX timestamp of the time that the transaction was established
141 * This can be used to reason about the staleness of SELECT data
142 * in REPEATABLE-READ transaction isolation level.
144 * @return float|null Returns null if there is not active transaction
147 public function trxTimestamp();
150 * @return bool Whether an explicit transaction or atomic sections are still open
153 public function explicitTrxActive();
156 * Get/set the table prefix.
157 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
158 * @return string The previous table prefix.
160 public function tablePrefix( $prefix = null );
163 * Get/set the db schema.
164 * @param string $schema The database schema to set, or omitted to leave it unchanged.
165 * @return string The previous db schema.
167 public function dbSchema( $schema = null );
170 * Get properties passed down from the server info array of the load
173 * @param string $name The entry of the info array to get, or null to get the
176 * @return array|mixed|null
178 public function getLBInfo( $name = null );
181 * Set the LB info array, or a member of it. If called with one parameter,
182 * the LB info array is set to that parameter. If it is called with two
183 * parameters, the member with the given name is set to the given value.
185 * @param string $name
186 * @param array $value
188 public function setLBInfo( $name, $value = null );
191 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
193 * @param IDatabase $conn
196 public function setLazyMasterHandle( IDatabase
$conn );
199 * Returns true if this database does an implicit sort when doing GROUP BY
203 public function implicitGroupby();
206 * Returns true if this database does an implicit order by when the column has an index
207 * For example: SELECT page_title FROM page LIMIT 1
211 public function implicitOrderby();
214 * Return the last query that went through IDatabase::query()
217 public function lastQuery();
220 * Returns true if the connection may have been used for write queries.
221 * Should return true if unsure.
225 public function doneWrites();
228 * Returns the last time the connection may have been used for write queries.
229 * Should return a timestamp if unsure.
231 * @return int|float UNIX timestamp or false
234 public function lastDoneWrites();
237 * @return bool Whether there is a transaction open with possible write queries
240 public function writesPending();
243 * Returns true if there is a transaction open with possible write
244 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
245 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
249 public function writesOrCallbacksPending();
252 * Get the time spend running write queries for this transaction
254 * High times could be due to scanning, updates, locking, and such
256 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
257 * @return float|bool Returns false if not transaction is active
260 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
263 * Get the list of method names that did write queries for this transaction
268 public function pendingWriteCallers();
271 * Is a connection to the database open?
274 public function isOpen();
277 * Set a flag for this connection
279 * @param int $flag DBO_* constants from Defines.php:
280 * - DBO_DEBUG: output some debug info (same as debug())
281 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
282 * - DBO_TRX: automatically start transactions
283 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
284 * and removes it in command line mode
285 * - DBO_PERSISTENT: use persistant database connection
286 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
288 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
291 * Clear a flag for this connection
293 * @param int $flag DBO_* constants from Defines.php:
294 * - DBO_DEBUG: output some debug info (same as debug())
295 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
296 * - DBO_TRX: automatically start transactions
297 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
298 * and removes it in command line mode
299 * - DBO_PERSISTENT: use persistant database connection
300 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
302 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
305 * Restore the flags to their prior state before the last setFlag/clearFlag call
307 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
310 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
313 * Returns a boolean whether the flag $flag is set 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_PERSISTENT: use persistant database connection
322 public function getFlag( $flag );
325 * General read-only accessor
327 * @param string $name
330 public function getProperty( $name );
335 public function getDomainID();
338 * Alias for getDomainID()
342 public function getWikiID();
345 * Get the type of the DBMS, as it appears in $wgDBtype.
349 public function getType();
352 * Open a connection to the database. Usually aborts on failure
354 * @param string $server Database server host
355 * @param string $user Database user name
356 * @param string $password Database user password
357 * @param string $dbName Database name
359 * @throws DBConnectionError
361 public function open( $server, $user, $password, $dbName );
364 * Fetch the next row from the given result object, in object form.
365 * Fields can be retrieved with $row->fieldname, with fields acting like
367 * If no more rows are available, false is returned.
369 * @param ResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
370 * @return stdClass|bool
371 * @throws DBUnexpectedError Thrown if the database returns an error
373 public function fetchObject( $res );
376 * Fetch the next row from the given result object, in associative array
377 * form. Fields are retrieved with $row['fieldname'].
378 * If no more rows are available, false is returned.
380 * @param ResultWrapper $res Result object as returned from IDatabase::query(), etc.
382 * @throws DBUnexpectedError Thrown if the database returns an error
384 public function fetchRow( $res );
387 * Get the number of rows in a result object
389 * @param mixed $res A SQL result
392 public function numRows( $res );
395 * Get the number of fields in a result object
396 * @see http://www.php.net/mysql_num_fields
398 * @param mixed $res A SQL result
401 public function numFields( $res );
404 * Get a field name in a result object
405 * @see http://www.php.net/mysql_field_name
407 * @param mixed $res A SQL result
411 public function fieldName( $res, $n );
414 * Get the inserted value of an auto-increment row
416 * The value inserted should be fetched from nextSequenceValue()
419 * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
420 * $dbw->insert( 'page', [ 'page_id' => $id ] );
421 * $id = $dbw->insertId();
425 public function insertId();
428 * Change the position of the cursor in a result object
429 * @see http://www.php.net/mysql_data_seek
431 * @param mixed $res A SQL result
434 public function dataSeek( $res, $row );
437 * Get the last error number
438 * @see http://www.php.net/mysql_errno
442 public function lastErrno();
445 * Get a description of the last error
446 * @see http://www.php.net/mysql_error
450 public function lastError();
453 * mysql_fetch_field() wrapper
454 * Returns false if the field doesn't exist
456 * @param string $table Table name
457 * @param string $field Field name
461 public function fieldInfo( $table, $field );
464 * Get the number of rows affected by the last write query
465 * @see http://www.php.net/mysql_affected_rows
469 public function affectedRows();
472 * Returns a wikitext link to the DB's website, e.g.,
473 * return "[http://www.mysql.com/ MySQL]";
474 * Should at least contain plain text, if for some reason
475 * your database has no website.
477 * @return string Wikitext of a link to the server software's web site
479 public function getSoftwareLink();
482 * A string describing the current software version, like from
483 * mysql_get_server_info().
485 * @return string Version information from the database server.
487 public function getServerVersion();
490 * Closes a database connection.
491 * if it is open : commits any open transactions
494 * @return bool Operation success. true if already closed.
496 public function close();
499 * @param string $error Fallback error message, used if none is given by DB
500 * @throws DBConnectionError
502 public function reportConnectionError( $error = 'Unknown error' );
505 * Run an SQL query and return the result. Normally throws a DBQueryError
506 * on failure. If errors are ignored, returns false instead.
508 * In new code, the query wrappers select(), insert(), update(), delete(),
509 * etc. should be used where possible, since they give much better DBMS
510 * independence and automatically quote or validate user input in a variety
511 * of contexts. This function is generally only useful for queries which are
512 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
515 * However, the query wrappers themselves should call this function.
517 * @param string $sql SQL query
518 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
519 * comment (you can use __METHOD__ or add some extra info)
520 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
521 * maybe best to catch the exception instead?
523 * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
524 * for a successful read query, or false on failure if $tempIgnore set
526 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
529 * Report a query error. Log the error, and if neither the object ignore
530 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
532 * @param string $error
535 * @param string $fname
536 * @param bool $tempIgnore
537 * @throws DBQueryError
539 public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
542 * Free a result object returned by query() or select(). It's usually not
543 * necessary to call this, just use unset() or let the variable holding
544 * the result object go out of scope.
546 * @param mixed $res A SQL result
548 public function freeResult( $res );
551 * A SELECT wrapper which returns a single field from a single result row.
553 * Usually throws a DBQueryError on failure. If errors are explicitly
554 * ignored, returns false on failure.
556 * If no result rows are returned from the query, false is returned.
558 * @param string|array $table Table name. See IDatabase::select() for details.
559 * @param string $var The field name to select. This must be a valid SQL
560 * fragment: do not use unvalidated user input.
561 * @param string|array $cond The condition array. See IDatabase::select() for details.
562 * @param string $fname The function name of the caller.
563 * @param string|array $options The query options. See IDatabase::select() for details.
565 * @return bool|mixed The value from the field, or false on failure.
567 public function selectField(
568 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
572 * A SELECT wrapper which returns a list of single field values from result rows.
574 * Usually throws a DBQueryError on failure. If errors are explicitly
575 * ignored, returns false on failure.
577 * If no result rows are returned from the query, false is returned.
579 * @param string|array $table Table name. See IDatabase::select() for details.
580 * @param string $var The field name to select. This must be a valid SQL
581 * fragment: do not use unvalidated user input.
582 * @param string|array $cond The condition array. See IDatabase::select() for details.
583 * @param string $fname The function name of the caller.
584 * @param string|array $options The query options. See IDatabase::select() for details.
586 * @return bool|array The values from the field, or false on failure
589 public function selectFieldValues(
590 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
594 * Execute a SELECT query constructed using the various parameters provided.
595 * See below for full details of the parameters.
597 * @param string|array $table Table name
598 * @param string|array $vars Field names
599 * @param string|array $conds Conditions
600 * @param string $fname Caller function name
601 * @param array $options Query options
602 * @param array $join_conds Join conditions
605 * @param string|array $table
607 * May be either an array of table names, or a single string holding a table
608 * name. If an array is given, table aliases can be specified, for example:
612 * This includes the user table in the query, with the alias "a" available
613 * for use in field names (e.g. a.user_name).
615 * All of the table names given here are automatically run through
616 * Database::tableName(), which causes the table prefix (if any) to be
617 * added, and various other table name mappings to be performed.
619 * Do not use untrusted user input as a table name. Alias names should
620 * not have characters outside of the Basic multilingual plane.
622 * @param string|array $vars
624 * May be either a field name or an array of field names. The field names
625 * can be complete fragments of SQL, for direct inclusion into the SELECT
626 * query. If an array is given, field aliases can be specified, for example:
628 * [ 'maxrev' => 'MAX(rev_id)' ]
630 * This includes an expression with the alias "maxrev" in the query.
632 * If an expression is given, care must be taken to ensure that it is
635 * Untrusted user input must not be passed to this parameter.
637 * @param string|array $conds
639 * May be either a string containing a single condition, or an array of
640 * conditions. If an array is given, the conditions constructed from each
641 * element are combined with AND.
643 * Array elements may take one of two forms:
645 * - Elements with a numeric key are interpreted as raw SQL fragments.
646 * - Elements with a string key are interpreted as equality conditions,
647 * where the key is the field name.
648 * - If the value of such an array element is a scalar (such as a
649 * string), it will be treated as data and thus quoted appropriately.
650 * If it is null, an IS NULL clause will be added.
651 * - If the value is an array, an IN (...) clause will be constructed
652 * from its non-null elements, and an IS NULL clause will be added
653 * if null is present, such that the field may match any of the
654 * elements in the array. The non-null elements will be quoted.
656 * Note that expressions are often DBMS-dependent in their syntax.
657 * DBMS-independent wrappers are provided for constructing several types of
658 * expression commonly used in condition queries. See:
659 * - IDatabase::buildLike()
660 * - IDatabase::conditional()
662 * Untrusted user input is safe in the values of string keys, however untrusted
663 * input must not be used in the array key names or in the values of numeric keys.
664 * Escaping of untrusted input used in values of numeric keys should be done via
665 * IDatabase::addQuotes()
667 * @param string|array $options
669 * Optional: Array of query options. Boolean options are specified by
670 * including them in the array as a string value with a numeric key, for
675 * The supported options are:
677 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
678 * with LIMIT can theoretically be used for paging through a result set,
679 * but this is discouraged for performance reasons.
681 * - LIMIT: Integer: return at most this many rows. The rows are sorted
682 * and then the first rows are taken until the limit is reached. LIMIT
683 * is applied to a result set after OFFSET.
685 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
686 * changed until the next COMMIT.
688 * - DISTINCT: Boolean: return only unique result rows.
690 * - GROUP BY: May be either an SQL fragment string naming a field or
691 * expression to group by, or an array of such SQL fragments.
693 * - HAVING: May be either an string containing a HAVING clause or an array of
694 * conditions building the HAVING clause. If an array is given, the conditions
695 * constructed from each element are combined with AND.
697 * - ORDER BY: May be either an SQL fragment giving a field name or
698 * expression to order by, or an array of such SQL fragments.
700 * - USE INDEX: This may be either a string giving the index name to use
701 * for the query, or an array. If it is an associative array, each key
702 * gives the table name (or alias), each value gives the index name to
703 * use for that table. All strings are SQL fragments and so should be
704 * validated by the caller.
706 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
709 * And also the following boolean MySQL extensions, see the MySQL manual
712 * - LOCK IN SHARE MODE
716 * - SQL_BUFFER_RESULT
718 * - SQL_CALC_FOUND_ROWS
723 * @param string|array $join_conds
725 * Optional associative array of table-specific join conditions. In the
726 * most common case, this is unnecessary, since the join condition can be
727 * in $conds. However, it is useful for doing a LEFT JOIN.
729 * The key of the array contains the table name or alias. The value is an
730 * array with two elements, numbered 0 and 1. The first gives the type of
731 * join, the second is the same as the $conds parameter. Thus it can be
732 * an SQL fragment, or an array where the string keys are equality and the
733 * numeric keys are SQL fragments all AND'd together. For example:
735 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
737 * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
738 * with no rows in it will be returned. If there was a query error, a
739 * DBQueryError exception will be thrown, except if the "ignore errors"
740 * option was set, in which case false will be returned.
742 public function select(
743 $table, $vars, $conds = '', $fname = __METHOD__
,
744 $options = [], $join_conds = []
748 * The equivalent of IDatabase::select() except that the constructed SQL
749 * is returned, instead of being immediately executed. This can be useful for
750 * doing UNION queries, where the SQL text of each query is needed. In general,
751 * however, callers outside of Database classes should just use select().
753 * @param string|array $table Table name
754 * @param string|array $vars Field names
755 * @param string|array $conds Conditions
756 * @param string $fname Caller function name
757 * @param string|array $options Query options
758 * @param string|array $join_conds Join conditions
760 * @return string SQL query string.
761 * @see IDatabase::select()
763 public function selectSQLText(
764 $table, $vars, $conds = '', $fname = __METHOD__
,
765 $options = [], $join_conds = []
769 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
770 * that a single row object is returned. If the query returns no rows,
773 * @param string|array $table Table name
774 * @param string|array $vars Field names
775 * @param array $conds Conditions
776 * @param string $fname Caller function name
777 * @param string|array $options Query options
778 * @param array|string $join_conds Join conditions
780 * @return stdClass|bool
782 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
783 $options = [], $join_conds = []
787 * Estimate the number of rows in dataset
789 * MySQL allows you to estimate the number of rows that would be returned
790 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
791 * index cardinality statistics, and is notoriously inaccurate, especially
792 * when large numbers of rows have recently been added or deleted.
794 * For DBMSs that don't support fast result size estimation, this function
795 * will actually perform the SELECT COUNT(*).
797 * Takes the same arguments as IDatabase::select().
799 * @param string $table Table name
800 * @param string $vars Unused
801 * @param array|string $conds Filters on the table
802 * @param string $fname Function name for profiling
803 * @param array $options Options for select
804 * @return int Row count
806 public function estimateRowCount(
807 $table, $vars = '*', $conds = '', $fname = __METHOD__
, $options = []
811 * Get the number of rows in dataset
813 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
815 * Takes the same arguments as IDatabase::select().
817 * @since 1.27 Added $join_conds parameter
819 * @param array|string $tables Table names
820 * @param string $vars Unused
821 * @param array|string $conds Filters on the table
822 * @param string $fname Function name for profiling
823 * @param array $options Options for select
824 * @param array $join_conds Join conditions (since 1.27)
825 * @return int Row count
827 public function selectRowCount(
828 $tables, $vars = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
832 * Determines whether a field exists in a table
834 * @param string $table Table name
835 * @param string $field Filed to check on that table
836 * @param string $fname Calling function name (optional)
837 * @return bool Whether $table has filed $field
839 public function fieldExists( $table, $field, $fname = __METHOD__
);
842 * Determines whether an index exists
843 * Usually throws a DBQueryError on failure
844 * If errors are explicitly ignored, returns NULL on failure
846 * @param string $table
847 * @param string $index
848 * @param string $fname
851 public function indexExists( $table, $index, $fname = __METHOD__
);
854 * Query whether a given table exists
856 * @param string $table
857 * @param string $fname
860 public function tableExists( $table, $fname = __METHOD__
);
863 * Determines if a given index is unique
865 * @param string $table
866 * @param string $index
870 public function indexUnique( $table, $index );
873 * INSERT wrapper, inserts an array into a table.
877 * - A single associative array. The array keys are the field names, and
878 * the values are the values to insert. The values are treated as data
879 * and will be quoted appropriately. If NULL is inserted, this will be
880 * converted to a database NULL.
881 * - An array with numeric keys, holding a list of associative arrays.
882 * This causes a multi-row INSERT on DBMSs that support it. The keys in
883 * each subarray must be identical to each other, and in the same order.
885 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
888 * $options is an array of options, with boolean options encoded as values
889 * with numeric keys, in the same style as $options in
890 * IDatabase::select(). Supported options are:
892 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
893 * any rows which cause duplicate key errors are not inserted. It's
894 * possible to determine how many rows were successfully inserted using
895 * IDatabase::affectedRows().
897 * @param string $table Table name. This will be passed through
898 * Database::tableName().
899 * @param array $a Array of rows to insert
900 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
901 * @param array $options Array of options
905 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
908 * UPDATE wrapper. Takes a condition array and a SET array.
910 * @param string $table Name of the table to UPDATE. This will be passed through
911 * Database::tableName().
912 * @param array $values An array of values to SET. For each array element,
913 * the key gives the field name, and the value gives the data to set
914 * that field to. The data will be quoted by IDatabase::addQuotes().
915 * @param array $conds An array of conditions (WHERE). See
916 * IDatabase::select() for the details of the format of condition
917 * arrays. Use '*' to update all rows.
918 * @param string $fname The function name of the caller (from __METHOD__),
919 * for logging and profiling.
920 * @param array $options An array of UPDATE options, can be:
921 * - IGNORE: Ignore unique key conflicts
922 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
925 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
928 * Makes an encoded list of strings from an array
930 * These can be used to make conjunctions or disjunctions on SQL condition strings
931 * derived from an array (see IDatabase::select() $conds documentation).
935 * $sql = $db->makeList( [
937 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
938 * ], $db::LIST_AND );
940 * This would set $sql to "rev_user = '$id' AND (rev_minor = '1' OR rev_len < '500')"
942 * @param array $a Containing the data
943 * @param int $mode IDatabase class constant:
944 * - IDatabase::LIST_COMMA: Comma separated, no field names
945 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
946 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
947 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
948 * - IDatabase::LIST_NAMES: Comma separated field names
952 public function makeList( $a, $mode = self
::LIST_COMMA
);
955 * Build a partial where clause from a 2-d array such as used for LinkBatch.
956 * The keys on each level may be either integers or strings.
958 * @param array $data Organized as 2-d
959 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
960 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
961 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
962 * @return string|bool SQL fragment, or false if no items in array
964 public function makeWhereFrom2d( $data, $baseKey, $subKey );
967 * Return aggregated value alias
969 * @param array $valuedata
970 * @param string $valuename
974 public function aggregateValue( $valuedata, $valuename = 'value' );
977 * @param string $field
980 public function bitNot( $field );
983 * @param string $fieldLeft
984 * @param string $fieldRight
987 public function bitAnd( $fieldLeft, $fieldRight );
990 * @param string $fieldLeft
991 * @param string $fieldRight
994 public function bitOr( $fieldLeft, $fieldRight );
997 * Build a concatenation list to feed into a SQL query
998 * @param array $stringList List of raw SQL expressions; caller is
999 * responsible for any quoting
1002 public function buildConcat( $stringList );
1005 * Build a GROUP_CONCAT or equivalent statement for a query.
1007 * This is useful for combining a field for several rows into a single string.
1008 * NULL values will not appear in the output, duplicated values will appear,
1009 * and the resulting delimiter-separated values have no defined sort order.
1010 * Code using the results may need to use the PHP unique() or sort() methods.
1012 * @param string $delim Glue to bind the results together
1013 * @param string|array $table Table name
1014 * @param string $field Field name
1015 * @param string|array $conds Conditions
1016 * @param string|array $join_conds Join conditions
1017 * @return string SQL text
1020 public function buildGroupConcatField(
1021 $delim, $table, $field, $conds = '', $join_conds = []
1025 * @param string $field Field or column to cast
1029 public function buildStringCast( $field );
1032 * Change the current database
1035 * @return bool Success or failure
1037 public function selectDB( $db );
1040 * Get the current DB name
1043 public function getDBname();
1046 * Get the server hostname or IP address
1049 public function getServer();
1052 * Adds quotes and backslashes.
1054 * @param string|int|null|bool|Blob $s
1055 * @return string|int
1057 public function addQuotes( $s );
1060 * LIKE statement wrapper, receives a variable-length argument list with
1061 * parts of pattern to match containing either string literals that will be
1062 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1063 * the function could be provided with an array of aforementioned
1066 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1067 * a LIKE clause that searches for subpages of 'My page title'.
1069 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1070 * $query .= $dbr->buildLike( $pattern );
1073 * @return string Fully built LIKE statement
1075 public function buildLike();
1078 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1082 public function anyChar();
1085 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1089 public function anyString();
1092 * Returns an appropriately quoted sequence value for inserting a new row.
1093 * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1094 * subclass will return an integer, and save the value for insertId()
1096 * Any implementation of this function should *not* involve reusing
1097 * sequence numbers created for rolled-back transactions.
1098 * See http://bugs.mysql.com/bug.php?id=30767 for details.
1099 * @param string $seqName
1102 public function nextSequenceValue( $seqName );
1105 * REPLACE query wrapper.
1107 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1108 * except that when there is a duplicate key error, the old row is deleted
1109 * and the new row is inserted in its place.
1111 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1112 * perform the delete, we need to know what the unique indexes are so that
1113 * we know how to find the conflicting rows.
1115 * It may be more efficient to leave off unique indexes which are unlikely
1116 * to collide. However if you do this, you run the risk of encountering
1117 * errors which wouldn't have occurred in MySQL.
1119 * @param string $table The table to replace the row(s) in.
1120 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1121 * a field name or an array of field names
1122 * @param array $rows Can be either a single row to insert, or multiple rows,
1123 * in the same format as for IDatabase::insert()
1124 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1126 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1129 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1131 * This updates any conflicting rows (according to the unique indexes) using
1132 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1134 * $rows may be either:
1135 * - A single associative array. The array keys are the field names, and
1136 * the values are the values to insert. The values are treated as data
1137 * and will be quoted appropriately. If NULL is inserted, this will be
1138 * converted to a database NULL.
1139 * - An array with numeric keys, holding a list of associative arrays.
1140 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1141 * each subarray must be identical to each other, and in the same order.
1143 * It may be more efficient to leave off unique indexes which are unlikely
1144 * to collide. However if you do this, you run the risk of encountering
1145 * errors which wouldn't have occurred in MySQL.
1147 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1152 * @param string $table Table name. This will be passed through Database::tableName().
1153 * @param array $rows A single row or list of rows to insert
1154 * @param array $uniqueIndexes List of single field names or field name tuples
1155 * @param array $set An array of values to SET. For each array element, the
1156 * key gives the field name, and the value gives the data to set that
1157 * field to. The data will be quoted by IDatabase::addQuotes().
1158 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1162 public function upsert(
1163 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1167 * DELETE where the condition is a join.
1169 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1170 * we use sub-selects
1172 * For safety, an empty $conds will not delete everything. If you want to
1173 * delete all rows where the join condition matches, set $conds='*'.
1175 * DO NOT put the join condition in $conds.
1177 * @param string $delTable The table to delete from.
1178 * @param string $joinTable The other table.
1179 * @param string $delVar The variable to join on, in the first table.
1180 * @param string $joinVar The variable to join on, in the second table.
1181 * @param array $conds Condition array of field names mapped to variables,
1182 * ANDed together in the WHERE clause
1183 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1184 * @throws DBUnexpectedError
1186 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1191 * DELETE query wrapper.
1193 * @param array $table Table name
1194 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1195 * for the format. Use $conds == "*" to delete all rows
1196 * @param string $fname Name of the calling function
1197 * @throws DBUnexpectedError
1198 * @return bool|ResultWrapper
1200 public function delete( $table, $conds, $fname = __METHOD__
);
1203 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1204 * into another table.
1206 * @param string $destTable The table name to insert into
1207 * @param string|array $srcTable May be either a table name, or an array of table names
1208 * to include in a join.
1210 * @param array $varMap Must be an associative array of the form
1211 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1212 * rather than field names, but strings should be quoted with
1213 * IDatabase::addQuotes()
1215 * @param array $conds Condition array. See $conds in IDatabase::select() for
1216 * the details of the format of condition arrays. May be "*" to copy the
1219 * @param string $fname The function name of the caller, from __METHOD__
1221 * @param array $insertOptions Options for the INSERT part of the query, see
1222 * IDatabase::insert() for details.
1223 * @param array $selectOptions Options for the SELECT part of the query, see
1224 * IDatabase::select() for details.
1226 * @return ResultWrapper
1228 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1229 $fname = __METHOD__
,
1230 $insertOptions = [], $selectOptions = []
1234 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1235 * within the UNION construct.
1238 public function unionSupportsOrderAndLimit();
1241 * Construct a UNION query
1242 * This is used for providing overload point for other DB abstractions
1243 * not compatible with the MySQL syntax.
1244 * @param array $sqls SQL statements to combine
1245 * @param bool $all Use UNION ALL
1246 * @return string SQL fragment
1248 public function unionQueries( $sqls, $all );
1251 * Returns an SQL expression for a simple conditional. This doesn't need
1252 * to be overridden unless CASE isn't supported in your DBMS.
1254 * @param string|array $cond SQL expression which will result in a boolean value
1255 * @param string $trueVal SQL expression to return if true
1256 * @param string $falseVal SQL expression to return if false
1257 * @return string SQL fragment
1259 public function conditional( $cond, $trueVal, $falseVal );
1262 * Returns a comand for str_replace function in SQL query.
1263 * Uses REPLACE() in MySQL
1265 * @param string $orig Column to modify
1266 * @param string $old Column to seek
1267 * @param string $new Column to replace with
1271 public function strreplace( $orig, $old, $new );
1274 * Determines how long the server has been up
1278 public function getServerUptime();
1281 * Determines if the last failure was due to a deadlock
1285 public function wasDeadlock();
1288 * Determines if the last failure was due to a lock timeout
1292 public function wasLockTimeout();
1295 * Determines if the last query error was due to a dropped connection and should
1296 * be dealt with by pinging the connection and reissuing the query.
1300 public function wasErrorReissuable();
1303 * Determines if the last failure was due to the database being read-only.
1307 public function wasReadOnlyError();
1310 * Wait for the replica DB to catch up to a given master position
1312 * @param DBMasterPos $pos
1313 * @param int $timeout The maximum number of seconds to wait for synchronisation
1314 * @return int|null Zero if the replica DB was past that position already,
1315 * greater than zero if we waited for some period of time, less than
1316 * zero if it timed out, and null on error
1318 public function masterPosWait( DBMasterPos
$pos, $timeout );
1321 * Get the replication position of this replica DB
1323 * @return DBMasterPos|bool False if this is not a replica DB.
1325 public function getReplicaPos();
1328 * Get the position of this master
1330 * @return DBMasterPos|bool False if this is not a master
1332 public function getMasterPos();
1335 * @return bool Whether the DB is marked as read-only server-side
1338 public function serverIsReadOnly();
1341 * Run a callback as soon as the current transaction commits or rolls back.
1342 * An error is thrown if no transaction is pending. Queries in the function will run in
1343 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1346 * This is useful for combining cooperative locks and DB transactions.
1348 * The callback takes one argument:
1349 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1351 * @param callable $callback
1352 * @param string $fname Caller name
1356 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1359 * Run a callback as soon as there is no transaction pending.
1360 * If there is a transaction and it is rolled back, then the callback is cancelled.
1361 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1362 * Callbacks must commit any transactions that they begin.
1364 * This is useful for updates to different systems or when separate transactions are needed.
1365 * For example, one might want to enqueue jobs into a system outside the database, but only
1366 * after the database is updated so that the jobs will see the data when they actually run.
1367 * It can also be used for updates that easily cause deadlocks if locks are held too long.
1369 * Updates will execute in the order they were enqueued.
1371 * The callback takes one argument:
1372 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1374 * @param callable $callback
1375 * @param string $fname Caller name
1378 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1381 * Run a callback before the current transaction commits or now if there is none.
1382 * If there is a transaction and it is rolled back, then the callback is cancelled.
1383 * Callbacks must not start nor commit any transactions. If no transaction is active,
1384 * then a transaction will wrap the callback.
1386 * This is useful for updates that easily cause deadlocks if locks are held too long
1387 * but where atomicity is strongly desired for these updates and some related updates.
1389 * Updates will execute in the order they were enqueued.
1391 * @param callable $callback
1392 * @param string $fname Caller name
1395 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1398 * Run a callback each time any transaction commits or rolls back
1400 * The callback takes two arguments:
1401 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1402 * - This IDatabase object
1403 * Callbacks must commit any transactions that they begin.
1405 * Registering a callback here will not affect writesOrCallbacks() pending
1407 * @param string $name Callback name
1408 * @param callable|null $callback Use null to unset a listener
1412 public function setTransactionListener( $name, callable
$callback = null );
1415 * Begin an atomic section of statements
1417 * If a transaction has been started already, just keep track of the given
1418 * section name to make sure the transaction is not committed pre-maturely.
1419 * This function can be used in layers (with sub-sections), so use a stack
1420 * to keep track of the different atomic sections. If there is no transaction,
1421 * start one implicitly.
1423 * The goal of this function is to create an atomic section of SQL queries
1424 * without having to start a new transaction if it already exists.
1426 * All atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1427 * and any database transactions cannot be began or committed until all atomic
1428 * levels are closed. There is no such thing as implicitly opening or closing
1429 * an atomic section.
1432 * @param string $fname
1435 public function startAtomic( $fname = __METHOD__
);
1438 * Ends an atomic section of SQL statements
1440 * Ends the next section of atomic SQL statements and commits the transaction
1444 * @see IDatabase::startAtomic
1445 * @param string $fname
1448 public function endAtomic( $fname = __METHOD__
);
1451 * Run a callback to do an atomic set of updates for this database
1453 * The $callback takes the following arguments:
1454 * - This database object
1455 * - The value of $fname
1457 * If any exception occurs in the callback, then rollback() will be called and the error will
1458 * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1459 * In any case, such errors are expected to terminate the request, without any outside caller
1460 * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1461 * atomic section and uncommitted updates, which trashes the current request, requiring an
1462 * error to be displayed.
1464 * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1466 * @see Database::startAtomic
1467 * @see Database::endAtomic
1469 * @param string $fname Caller name (usually __METHOD__)
1470 * @param callable $callback Callback that issues DB updates
1471 * @return mixed $res Result of the callback (since 1.28)
1473 * @throws RuntimeException
1474 * @throws UnexpectedValueException
1477 public function doAtomicSection( $fname, callable
$callback );
1480 * Begin a transaction. If a transaction is already in progress,
1481 * that transaction will be committed before the new transaction is started.
1483 * Only call this from code with outer transcation scope.
1484 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1485 * Nesting of transactions is not supported.
1487 * Note that when the DBO_TRX flag is set (which is usually the case for web
1488 * requests, but not for maintenance scripts), any previous database query
1489 * will have started a transaction automatically.
1491 * Nesting of transactions is not supported. Attempts to nest transactions
1492 * will cause a warning, unless the current transaction was started
1493 * automatically because of the DBO_TRX flag.
1495 * @param string $fname Calling function name
1496 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1499 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1502 * Commits a transaction previously started using begin().
1503 * If no transaction is in progress, a warning is issued.
1505 * Only call this from code with outer transcation scope.
1506 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1507 * Nesting of transactions is not supported.
1509 * @param string $fname
1510 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1511 * constant to disable warnings about explicitly committing implicit transactions,
1512 * or calling commit when no transaction is in progress.
1514 * This will trigger an exception if there is an ongoing explicit transaction.
1516 * Only set the flush flag if you are sure that these warnings are not applicable,
1517 * and no explicit transactions are open.
1519 * @throws DBUnexpectedError
1521 public function commit( $fname = __METHOD__
, $flush = '' );
1524 * Rollback a transaction previously started using begin().
1525 * If no transaction is in progress, a warning is issued.
1527 * Only call this from code with outer transcation scope.
1528 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1529 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1530 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1531 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1533 * @param string $fname Calling function name
1534 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1535 * constant to disable warnings about calling rollback when no transaction is in
1536 * progress. This will silently break any ongoing explicit transaction. Only set the
1537 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1538 * @throws DBUnexpectedError
1539 * @since 1.23 Added $flush parameter
1541 public function rollback( $fname = __METHOD__
, $flush = '' );
1544 * Commit any transaction but error out if writes or callbacks are pending
1546 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1547 * see a new point-in-time of the database. This is useful when one of many transaction
1548 * rounds finished and significant time will pass in the script's lifetime. It is also
1549 * useful to call on a replica DB after waiting on replication to catch up to the master.
1551 * @param string $fname Calling function name
1552 * @throws DBUnexpectedError
1555 public function flushSnapshot( $fname = __METHOD__
);
1558 * List all tables on the database
1560 * @param string $prefix Only show tables with this prefix, e.g. mw_
1561 * @param string $fname Calling function name
1565 public function listTables( $prefix = null, $fname = __METHOD__
);
1568 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1569 * to the format used for inserting into timestamp fields in this DBMS.
1571 * The result is unquoted, and needs to be passed through addQuotes()
1572 * before it can be included in raw SQL.
1574 * @param string|int $ts
1578 public function timestamp( $ts = 0 );
1581 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1582 * to the format used for inserting into timestamp fields in this DBMS. If
1583 * NULL is input, it is passed through, allowing NULL values to be inserted
1584 * into timestamp fields.
1586 * The result is unquoted, and needs to be passed through addQuotes()
1587 * before it can be included in raw SQL.
1589 * @param string|int $ts
1593 public function timestampOrNull( $ts = null );
1596 * Ping the server and try to reconnect if it there is no connection
1598 * @param float|null &$rtt Value to store the estimated RTT [optional]
1599 * @return bool Success or failure
1601 public function ping( &$rtt = null );
1604 * Get replica DB lag. Currently supported only by MySQL.
1606 * Note that this function will generate a fatal error on many
1607 * installations. Most callers should use LoadBalancer::safeGetLag()
1610 * @return int|bool Database replication lag in seconds or false on error
1612 public function getLag();
1615 * Get the replica DB lag when the current transaction started
1616 * or a general lag estimate if not transaction is active
1618 * This is useful when transactions might use snapshot isolation
1619 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1620 * is this lag plus transaction duration. If they don't, it is still
1621 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1622 * indication of the staleness of subsequent reads.
1624 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1627 public function getSessionLagStatus();
1630 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1634 public function maxListLen();
1637 * Some DBMSs have a special format for inserting into blob fields, they
1638 * don't allow simple quoted strings to be inserted. To insert into such
1639 * a field, pass the data through this function before passing it to
1640 * IDatabase::insert().
1645 public function encodeBlob( $b );
1648 * Some DBMSs return a special placeholder object representing blob fields
1649 * in result objects. Pass the object through this function to return the
1652 * @param string|Blob $b
1655 public function decodeBlob( $b );
1658 * Override database's default behavior. $options include:
1659 * 'connTimeout' : Set the connection timeout value in seconds.
1660 * May be useful for very long batch queries such as
1661 * full-wiki dumps, where a single query reads out over
1664 * @param array $options
1667 public function setSessionOptions( array $options );
1670 * Set variables to be used in sourceFile/sourceStream, in preference to the
1671 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1672 * all. If it's set to false, $GLOBALS will be used.
1674 * @param bool|array $vars Mapping variable name to value.
1676 public function setSchemaVars( $vars );
1679 * Check to see if a named lock is available (non-blocking)
1681 * @param string $lockName Name of lock to poll
1682 * @param string $method Name of method calling us
1686 public function lockIsFree( $lockName, $method );
1689 * Acquire a named lock
1691 * Named locks are not related to transactions
1693 * @param string $lockName Name of lock to aquire
1694 * @param string $method Name of the calling method
1695 * @param int $timeout Acquisition timeout in seconds
1698 public function lock( $lockName, $method, $timeout = 5 );
1703 * Named locks are not related to transactions
1705 * @param string $lockName Name of lock to release
1706 * @param string $method Name of the calling method
1708 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1709 * by this thread (in which case the lock is not released), and NULL if the named
1710 * lock did not exist
1712 public function unlock( $lockName, $method );
1715 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1717 * Only call this from outer transcation scope and when only one DB will be affected.
1718 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1720 * This is suitiable for transactions that need to be serialized using cooperative locks,
1721 * where each transaction can see each others' changes. Any transaction is flushed to clear
1722 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1723 * the lock will be released unless a transaction is active. If one is active, then the lock
1724 * will be released when it either commits or rolls back.
1726 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1728 * @param string $lockKey Name of lock to release
1729 * @param string $fname Name of the calling method
1730 * @param int $timeout Acquisition timeout in seconds
1731 * @return ScopedCallback|null
1732 * @throws DBUnexpectedError
1735 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1738 * Check to see if a named lock used by lock() use blocking queues
1743 public function namedLocksEnqueue();
1746 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1747 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1748 * because "i" sorts after all numbers.
1752 public function getInfinity();
1755 * Encode an expiry time into the DBMS dependent format
1757 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1760 public function encodeExpiry( $expiry );
1763 * Decode an expiry time into a DBMS independent format
1765 * @param string $expiry DB timestamp field value for expiry
1766 * @param int $format TS_* constant, defaults to TS_MW
1769 public function decodeExpiry( $expiry, $format = TS_MW
);
1772 * Allow or deny "big selects" for this session only. This is done by setting
1773 * the sql_big_selects session variable.
1775 * This is a MySQL-specific feature.
1777 * @param bool|string $value True for allow, false for deny, or "default" to
1778 * restore the initial value
1780 public function setBigSelects( $value = true );
1783 * @return bool Whether this DB is read-only
1786 public function isReadOnly();
1789 * Make certain table names use their own database, schema, and table prefix
1790 * when passed into SQL queries pre-escaped and without a qualified database name
1792 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1793 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1795 * Calling this twice will completely clear any old table aliases. Also, note that
1796 * callers are responsible for making sure the schemas and databases actually exist.
1798 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1801 public function setTableAliases( array $aliases );