c6055dbdbd6f9a6c38ead749bb44989a5412a074
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
26 use Wikimedia\ScopedCallback
;
29 * Basic database interface for live and lazy-loaded relation database handles
31 * @note: IDatabase and DBConnRef should be updated to reflect any changes
35 /** @var int Callback triggered immediately due to no active transaction */
36 const TRIGGER_IDLE
= 1;
37 /** @var int Callback triggered by COMMIT */
38 const TRIGGER_COMMIT
= 2;
39 /** @var int Callback triggered by ROLLBACK */
40 const TRIGGER_ROLLBACK
= 3;
42 /** @var string Transaction is requested by regular caller outside of the DB layer */
43 const TRANSACTION_EXPLICIT
= '';
44 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
45 const TRANSACTION_INTERNAL
= 'implicit';
47 /** @var string Transaction operation comes from service managing all DBs */
48 const FLUSHING_ALL_PEERS
= 'flush';
49 /** @var string Transaction operation comes from the database class internally */
50 const FLUSHING_INTERNAL
= 'flush';
52 /** @var string Do not remember the prior flags */
53 const REMEMBER_NOTHING
= '';
54 /** @var string Remember the prior flags */
55 const REMEMBER_PRIOR
= 'remember';
56 /** @var string Restore to the prior flag state */
57 const RESTORE_PRIOR
= 'prior';
58 /** @var string Restore to the initial flag state */
59 const RESTORE_INITIAL
= 'initial';
61 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
62 const ESTIMATE_TOTAL
= 'total';
63 /** @var string Estimate time to apply (scanning, applying) */
64 const ESTIMATE_DB_APPLY
= 'apply';
66 /** @var int Combine list with comma delimeters */
68 /** @var int Combine list with AND clauses */
70 /** @var int Convert map into a SET clause */
72 /** @var int Treat as field name and do not apply value escaping */
74 /** @var int Combine list with OR clauses */
77 /** @var int Enable debug logging */
79 /** @var int Disable query buffering (only one result set can be iterated at a time) */
80 const DBO_NOBUFFER
= 2;
81 /** @var int Ignore query errors (internal use only!) */
83 /** @var int Autoatically start transaction on first query (work with ILoadBalancer rounds) */
85 /** @var int Use DBO_TRX in non-CLI mode */
86 const DBO_DEFAULT
= 16;
87 /** @var int Use DB persistent connections if possible */
88 const DBO_PERSISTENT
= 32;
89 /** @var int DBA session mode; mostly for Oracle */
90 const DBO_SYSDBA
= 64;
91 /** @var int Schema file mode; mostly for Oracle */
92 const DBO_DDLMODE
= 128;
93 /** @var int Enable SSL/TLS in connection protocol */
95 /** @var int Enable compression in connection protocol */
96 const DBO_COMPRESS
= 512;
99 * A string describing the current software version, and possibly
100 * other details in a user-friendly way. Will be listed on Special:Version, etc.
101 * Use getServerVersion() to get machine-friendly information.
103 * @return string Version information from the database server
105 public function getServerInfo();
108 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
110 * Unbuffered queries are very troublesome in MySQL:
112 * - If another query is executed while the first query is being read
113 * out, the first query is killed. This means you can't call normal
114 * Database functions while you are reading an unbuffered query result
115 * from a normal Database connection.
117 * - Unbuffered queries cause the MySQL server to use large amounts of
118 * memory and to hold broad locks which block other queries.
120 * If you want to limit client-side memory, it's almost always better to
121 * split up queries into batches using a LIMIT clause than to switch off
124 * @param null|bool $buffer
125 * @return null|bool The previous value of the flag
127 public function bufferResults( $buffer = null );
130 * Gets the current transaction level.
132 * Historically, transactions were allowed to be "nested". This is no
133 * longer supported, so this function really only returns a boolean.
135 * @return int The previous value
137 public function trxLevel();
140 * Get the UNIX timestamp of the time that the transaction was established
142 * This can be used to reason about the staleness of SELECT data
143 * in REPEATABLE-READ transaction isolation level.
145 * @return float|null Returns null if there is not active transaction
148 public function trxTimestamp();
151 * @return bool Whether an explicit transaction or atomic sections are still open
154 public function explicitTrxActive();
157 * Get/set the table prefix.
158 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
159 * @return string The previous table prefix.
161 public function tablePrefix( $prefix = null );
164 * Get/set the db schema.
165 * @param string $schema The database schema to set, or omitted to leave it unchanged.
166 * @return string The previous db schema.
168 public function dbSchema( $schema = null );
171 * Get properties passed down from the server info array of the load
174 * @param string $name The entry of the info array to get, or null to get the
177 * @return array|mixed|null
179 public function getLBInfo( $name = null );
182 * Set the LB info array, or a member of it. If called with one parameter,
183 * the LB info array is set to that parameter. If it is called with two
184 * parameters, the member with the given name is set to the given value.
186 * @param string $name
187 * @param array $value
189 public function setLBInfo( $name, $value = null );
192 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
194 * @param IDatabase $conn
197 public function setLazyMasterHandle( IDatabase
$conn );
200 * Returns true if this database does an implicit sort when doing GROUP BY
204 public function implicitGroupby();
207 * Returns true if this database does an implicit order by when the column has an index
208 * For example: SELECT page_title FROM page LIMIT 1
212 public function implicitOrderby();
215 * Return the last query that went through IDatabase::query()
218 public function lastQuery();
221 * Returns true if the connection may have been used for write queries.
222 * Should return true if unsure.
226 public function doneWrites();
229 * Returns the last time the connection may have been used for write queries.
230 * Should return a timestamp if unsure.
232 * @return int|float UNIX timestamp or false
235 public function lastDoneWrites();
238 * @return bool Whether there is a transaction open with possible write queries
241 public function writesPending();
244 * Returns true if there is a transaction open with possible write
245 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
246 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
250 public function writesOrCallbacksPending();
253 * Get the time spend running write queries for this transaction
255 * High times could be due to scanning, updates, locking, and such
257 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
258 * @return float|bool Returns false if not transaction is active
261 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
264 * Get the list of method names that did write queries for this transaction
269 public function pendingWriteCallers();
272 * Is a connection to the database open?
275 public function isOpen();
278 * Set a flag for this connection
280 * @param int $flag DBO_* constants from Defines.php:
281 * - DBO_DEBUG: output some debug info (same as debug())
282 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
283 * - DBO_TRX: automatically start transactions
284 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
285 * and removes it in command line mode
286 * - DBO_PERSISTENT: use persistant database connection
287 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
289 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
292 * Clear a flag for this connection
294 * @param int $flag DBO_* constants from Defines.php:
295 * - DBO_DEBUG: output some debug info (same as debug())
296 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
297 * - DBO_TRX: automatically start transactions
298 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
299 * and removes it in command line mode
300 * - DBO_PERSISTENT: use persistant database connection
301 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
303 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
306 * Restore the flags to their prior state before the last setFlag/clearFlag call
308 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
311 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
314 * Returns a boolean whether the flag $flag is set 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_PERSISTENT: use persistant database connection
323 public function getFlag( $flag );
328 public function getDomainID();
331 * Alias for getDomainID()
335 public function getWikiID();
338 * Get the type of the DBMS, as it appears in $wgDBtype.
342 public function getType();
345 * Open a connection to the database. Usually aborts on failure
347 * @param string $server Database server host
348 * @param string $user Database user name
349 * @param string $password Database user password
350 * @param string $dbName Database name
352 * @throws DBConnectionError
354 public function open( $server, $user, $password, $dbName );
357 * Fetch the next row from the given result object, in object form.
358 * Fields can be retrieved with $row->fieldname, with fields acting like
360 * If no more rows are available, false is returned.
362 * @param ResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
363 * @return stdClass|bool
364 * @throws DBUnexpectedError Thrown if the database returns an error
366 public function fetchObject( $res );
369 * Fetch the next row from the given result object, in associative array
370 * form. Fields are retrieved with $row['fieldname'].
371 * If no more rows are available, false is returned.
373 * @param ResultWrapper $res Result object as returned from IDatabase::query(), etc.
375 * @throws DBUnexpectedError Thrown if the database returns an error
377 public function fetchRow( $res );
380 * Get the number of rows in a result object
382 * @param mixed $res A SQL result
385 public function numRows( $res );
388 * Get the number of fields in a result object
389 * @see https://secure.php.net/mysql_num_fields
391 * @param mixed $res A SQL result
394 public function numFields( $res );
397 * Get a field name in a result object
398 * @see https://secure.php.net/mysql_field_name
400 * @param mixed $res A SQL result
404 public function fieldName( $res, $n );
407 * Get the inserted value of an auto-increment row
409 * The value inserted should be fetched from nextSequenceValue()
412 * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
413 * $dbw->insert( 'page', [ 'page_id' => $id ] );
414 * $id = $dbw->insertId();
418 public function insertId();
421 * Change the position of the cursor in a result object
422 * @see https://secure.php.net/mysql_data_seek
424 * @param mixed $res A SQL result
427 public function dataSeek( $res, $row );
430 * Get the last error number
431 * @see https://secure.php.net/mysql_errno
435 public function lastErrno();
438 * Get a description of the last error
439 * @see https://secure.php.net/mysql_error
443 public function lastError();
446 * mysql_fetch_field() wrapper
447 * Returns false if the field doesn't exist
449 * @param string $table Table name
450 * @param string $field Field name
454 public function fieldInfo( $table, $field );
457 * Get the number of rows affected by the last write query
458 * @see https://secure.php.net/mysql_affected_rows
462 public function affectedRows();
465 * Returns a wikitext link to the DB's website, e.g.,
466 * return "[https://www.mysql.com/ MySQL]";
467 * Should at least contain plain text, if for some reason
468 * your database has no website.
470 * @return string Wikitext of a link to the server software's web site
472 public function getSoftwareLink();
475 * A string describing the current software version, like from
476 * mysql_get_server_info().
478 * @return string Version information from the database server.
480 public function getServerVersion();
483 * Closes a database connection.
484 * if it is open : commits any open transactions
487 * @return bool Operation success. true if already closed.
489 public function close();
492 * @param string $error Fallback error message, used if none is given by DB
493 * @throws DBConnectionError
495 public function reportConnectionError( $error = 'Unknown error' );
498 * Run an SQL query and return the result. Normally throws a DBQueryError
499 * on failure. If errors are ignored, returns false instead.
501 * In new code, the query wrappers select(), insert(), update(), delete(),
502 * etc. should be used where possible, since they give much better DBMS
503 * independence and automatically quote or validate user input in a variety
504 * of contexts. This function is generally only useful for queries which are
505 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
508 * However, the query wrappers themselves should call this function.
510 * @param string $sql SQL query
511 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
512 * comment (you can use __METHOD__ or add some extra info)
513 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
514 * maybe best to catch the exception instead?
516 * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
517 * for a successful read query, or false on failure if $tempIgnore set
519 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
522 * Report a query error. Log the error, and if neither the object ignore
523 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
525 * @param string $error
528 * @param string $fname
529 * @param bool $tempIgnore
530 * @throws DBQueryError
532 public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
535 * Free a result object returned by query() or select(). It's usually not
536 * necessary to call this, just use unset() or let the variable holding
537 * the result object go out of scope.
539 * @param mixed $res A SQL result
541 public function freeResult( $res );
544 * A SELECT wrapper which returns a single field from a single result row.
546 * Usually throws a DBQueryError on failure. If errors are explicitly
547 * ignored, returns false on failure.
549 * If no result rows are returned from the query, false is returned.
551 * @param string|array $table Table name. See IDatabase::select() for details.
552 * @param string $var The field name to select. This must be a valid SQL
553 * fragment: do not use unvalidated user input.
554 * @param string|array $cond The condition array. See IDatabase::select() for details.
555 * @param string $fname The function name of the caller.
556 * @param string|array $options The query options. See IDatabase::select() for details.
558 * @return bool|mixed The value from the field, or false on failure.
560 public function selectField(
561 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
565 * A SELECT wrapper which returns a list of single field values from result rows.
567 * Usually throws a DBQueryError on failure. If errors are explicitly
568 * ignored, returns false on failure.
570 * If no result rows are returned from the query, false is returned.
572 * @param string|array $table Table name. See IDatabase::select() for details.
573 * @param string $var The field name to select. This must be a valid SQL
574 * fragment: do not use unvalidated user input.
575 * @param string|array $cond The condition array. See IDatabase::select() for details.
576 * @param string $fname The function name of the caller.
577 * @param string|array $options The query options. See IDatabase::select() for details.
579 * @return bool|array The values from the field, or false on failure
582 public function selectFieldValues(
583 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
587 * Execute a SELECT query constructed using the various parameters provided.
588 * See below for full details of the parameters.
590 * @param string|array $table Table name
591 * @param string|array $vars Field names
592 * @param string|array $conds Conditions
593 * @param string $fname Caller function name
594 * @param array $options Query options
595 * @param array $join_conds Join conditions
598 * @param string|array $table
600 * May be either an array of table names, or a single string holding a table
601 * name. If an array is given, table aliases can be specified, for example:
605 * This includes the user table in the query, with the alias "a" available
606 * for use in field names (e.g. a.user_name).
608 * All of the table names given here are automatically run through
609 * Database::tableName(), which causes the table prefix (if any) to be
610 * added, and various other table name mappings to be performed.
612 * Do not use untrusted user input as a table name. Alias names should
613 * not have characters outside of the Basic multilingual plane.
615 * @param string|array $vars
617 * May be either a field name or an array of field names. The field names
618 * can be complete fragments of SQL, for direct inclusion into the SELECT
619 * query. If an array is given, field aliases can be specified, for example:
621 * [ 'maxrev' => 'MAX(rev_id)' ]
623 * This includes an expression with the alias "maxrev" in the query.
625 * If an expression is given, care must be taken to ensure that it is
628 * Untrusted user input must not be passed to this parameter.
630 * @param string|array $conds
632 * May be either a string containing a single condition, or an array of
633 * conditions. If an array is given, the conditions constructed from each
634 * element are combined with AND.
636 * Array elements may take one of two forms:
638 * - Elements with a numeric key are interpreted as raw SQL fragments.
639 * - Elements with a string key are interpreted as equality conditions,
640 * where the key is the field name.
641 * - If the value of such an array element is a scalar (such as a
642 * string), it will be treated as data and thus quoted appropriately.
643 * If it is null, an IS NULL clause will be added.
644 * - If the value is an array, an IN (...) clause will be constructed
645 * from its non-null elements, and an IS NULL clause will be added
646 * if null is present, such that the field may match any of the
647 * elements in the array. The non-null elements will be quoted.
649 * Note that expressions are often DBMS-dependent in their syntax.
650 * DBMS-independent wrappers are provided for constructing several types of
651 * expression commonly used in condition queries. See:
652 * - IDatabase::buildLike()
653 * - IDatabase::conditional()
655 * Untrusted user input is safe in the values of string keys, however untrusted
656 * input must not be used in the array key names or in the values of numeric keys.
657 * Escaping of untrusted input used in values of numeric keys should be done via
658 * IDatabase::addQuotes()
660 * @param string|array $options
662 * Optional: Array of query options. Boolean options are specified by
663 * including them in the array as a string value with a numeric key, for
668 * The supported options are:
670 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
671 * with LIMIT can theoretically be used for paging through a result set,
672 * but this is discouraged for performance reasons.
674 * - LIMIT: Integer: return at most this many rows. The rows are sorted
675 * and then the first rows are taken until the limit is reached. LIMIT
676 * is applied to a result set after OFFSET.
678 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
679 * changed until the next COMMIT.
681 * - DISTINCT: Boolean: return only unique result rows.
683 * - GROUP BY: May be either an SQL fragment string naming a field or
684 * expression to group by, or an array of such SQL fragments.
686 * - HAVING: May be either an string containing a HAVING clause or an array of
687 * conditions building the HAVING clause. If an array is given, the conditions
688 * constructed from each element are combined with AND.
690 * - ORDER BY: May be either an SQL fragment giving a field name or
691 * expression to order by, or an array of such SQL fragments.
693 * - USE INDEX: This may be either a string giving the index name to use
694 * for the query, or an array. If it is an associative array, each key
695 * gives the table name (or alias), each value gives the index name to
696 * use for that table. All strings are SQL fragments and so should be
697 * validated by the caller.
699 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
702 * And also the following boolean MySQL extensions, see the MySQL manual
705 * - LOCK IN SHARE MODE
709 * - SQL_BUFFER_RESULT
711 * - SQL_CALC_FOUND_ROWS
716 * @param string|array $join_conds
718 * Optional associative array of table-specific join conditions. In the
719 * most common case, this is unnecessary, since the join condition can be
720 * in $conds. However, it is useful for doing a LEFT JOIN.
722 * The key of the array contains the table name or alias. The value is an
723 * array with two elements, numbered 0 and 1. The first gives the type of
724 * join, the second is the same as the $conds parameter. Thus it can be
725 * an SQL fragment, or an array where the string keys are equality and the
726 * numeric keys are SQL fragments all AND'd together. For example:
728 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
730 * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
731 * with no rows in it will be returned. If there was a query error, a
732 * DBQueryError exception will be thrown, except if the "ignore errors"
733 * option was set, in which case false will be returned.
735 public function select(
736 $table, $vars, $conds = '', $fname = __METHOD__
,
737 $options = [], $join_conds = []
741 * The equivalent of IDatabase::select() except that the constructed SQL
742 * is returned, instead of being immediately executed. This can be useful for
743 * doing UNION queries, where the SQL text of each query is needed. In general,
744 * however, callers outside of Database classes should just use select().
746 * @param string|array $table Table name
747 * @param string|array $vars Field names
748 * @param string|array $conds Conditions
749 * @param string $fname Caller function name
750 * @param string|array $options Query options
751 * @param string|array $join_conds Join conditions
753 * @return string SQL query string.
754 * @see IDatabase::select()
756 public function selectSQLText(
757 $table, $vars, $conds = '', $fname = __METHOD__
,
758 $options = [], $join_conds = []
762 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
763 * that a single row object is returned. If the query returns no rows,
766 * @param string|array $table Table name
767 * @param string|array $vars Field names
768 * @param array $conds Conditions
769 * @param string $fname Caller function name
770 * @param string|array $options Query options
771 * @param array|string $join_conds Join conditions
773 * @return stdClass|bool
775 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
776 $options = [], $join_conds = []
780 * Estimate the number of rows in dataset
782 * MySQL allows you to estimate the number of rows that would be returned
783 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
784 * index cardinality statistics, and is notoriously inaccurate, especially
785 * when large numbers of rows have recently been added or deleted.
787 * For DBMSs that don't support fast result size estimation, this function
788 * will actually perform the SELECT COUNT(*).
790 * Takes the same arguments as IDatabase::select().
792 * @param string $table Table name
793 * @param string $vars Unused
794 * @param array|string $conds Filters on the table
795 * @param string $fname Function name for profiling
796 * @param array $options Options for select
797 * @return int Row count
799 public function estimateRowCount(
800 $table, $vars = '*', $conds = '', $fname = __METHOD__
, $options = []
804 * Get the number of rows in dataset
806 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
808 * Takes the same arguments as IDatabase::select().
810 * @since 1.27 Added $join_conds parameter
812 * @param array|string $tables Table names
813 * @param string $vars Unused
814 * @param array|string $conds Filters on the table
815 * @param string $fname Function name for profiling
816 * @param array $options Options for select
817 * @param array $join_conds Join conditions (since 1.27)
818 * @return int Row count
820 public function selectRowCount(
821 $tables, $vars = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
825 * Determines whether a field exists in a table
827 * @param string $table Table name
828 * @param string $field Filed to check on that table
829 * @param string $fname Calling function name (optional)
830 * @return bool Whether $table has filed $field
832 public function fieldExists( $table, $field, $fname = __METHOD__
);
835 * Determines whether an index exists
836 * Usually throws a DBQueryError on failure
837 * If errors are explicitly ignored, returns NULL on failure
839 * @param string $table
840 * @param string $index
841 * @param string $fname
844 public function indexExists( $table, $index, $fname = __METHOD__
);
847 * Query whether a given table exists
849 * @param string $table
850 * @param string $fname
853 public function tableExists( $table, $fname = __METHOD__
);
856 * Determines if a given index is unique
858 * @param string $table
859 * @param string $index
863 public function indexUnique( $table, $index );
866 * INSERT wrapper, inserts an array into a table.
870 * - A single associative array. The array keys are the field names, and
871 * the values are the values to insert. The values are treated as data
872 * and will be quoted appropriately. If NULL is inserted, this will be
873 * converted to a database NULL.
874 * - An array with numeric keys, holding a list of associative arrays.
875 * This causes a multi-row INSERT on DBMSs that support it. The keys in
876 * each subarray must be identical to each other, and in the same order.
878 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
881 * $options is an array of options, with boolean options encoded as values
882 * with numeric keys, in the same style as $options in
883 * IDatabase::select(). Supported options are:
885 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
886 * any rows which cause duplicate key errors are not inserted. It's
887 * possible to determine how many rows were successfully inserted using
888 * IDatabase::affectedRows().
890 * @param string $table Table name. This will be passed through
891 * Database::tableName().
892 * @param array $a Array of rows to insert
893 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
894 * @param array $options Array of options
898 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
901 * UPDATE wrapper. Takes a condition array and a SET array.
903 * @param string $table Name of the table to UPDATE. This will be passed through
904 * Database::tableName().
905 * @param array $values An array of values to SET. For each array element,
906 * the key gives the field name, and the value gives the data to set
907 * that field to. The data will be quoted by IDatabase::addQuotes().
908 * @param array $conds An array of conditions (WHERE). See
909 * IDatabase::select() for the details of the format of condition
910 * arrays. Use '*' to update all rows.
911 * @param string $fname The function name of the caller (from __METHOD__),
912 * for logging and profiling.
913 * @param array $options An array of UPDATE options, can be:
914 * - IGNORE: Ignore unique key conflicts
915 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
918 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
921 * Makes an encoded list of strings from an array
923 * These can be used to make conjunctions or disjunctions on SQL condition strings
924 * derived from an array (see IDatabase::select() $conds documentation).
928 * $sql = $db->makeList( [
930 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
931 * ], $db::LIST_AND );
933 * This would set $sql to "rev_user = '$id' AND (rev_minor = '1' OR rev_len < '500')"
935 * @param array $a Containing the data
936 * @param int $mode IDatabase class constant:
937 * - IDatabase::LIST_COMMA: Comma separated, no field names
938 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
939 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
940 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
941 * - IDatabase::LIST_NAMES: Comma separated field names
945 public function makeList( $a, $mode = self
::LIST_COMMA
);
948 * Build a partial where clause from a 2-d array such as used for LinkBatch.
949 * The keys on each level may be either integers or strings.
951 * @param array $data Organized as 2-d
952 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
953 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
954 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
955 * @return string|bool SQL fragment, or false if no items in array
957 public function makeWhereFrom2d( $data, $baseKey, $subKey );
960 * Return aggregated value alias
962 * @param array $valuedata
963 * @param string $valuename
967 public function aggregateValue( $valuedata, $valuename = 'value' );
970 * @param string $field
973 public function bitNot( $field );
976 * @param string $fieldLeft
977 * @param string $fieldRight
980 public function bitAnd( $fieldLeft, $fieldRight );
983 * @param string $fieldLeft
984 * @param string $fieldRight
987 public function bitOr( $fieldLeft, $fieldRight );
990 * Build a concatenation list to feed into a SQL query
991 * @param array $stringList List of raw SQL expressions; caller is
992 * responsible for any quoting
995 public function buildConcat( $stringList );
998 * Build a GROUP_CONCAT or equivalent statement for a query.
1000 * This is useful for combining a field for several rows into a single string.
1001 * NULL values will not appear in the output, duplicated values will appear,
1002 * and the resulting delimiter-separated values have no defined sort order.
1003 * Code using the results may need to use the PHP unique() or sort() methods.
1005 * @param string $delim Glue to bind the results together
1006 * @param string|array $table Table name
1007 * @param string $field Field name
1008 * @param string|array $conds Conditions
1009 * @param string|array $join_conds Join conditions
1010 * @return string SQL text
1013 public function buildGroupConcatField(
1014 $delim, $table, $field, $conds = '', $join_conds = []
1018 * @param string $field Field or column to cast
1022 public function buildStringCast( $field );
1025 * Change the current database
1028 * @return bool Success or failure
1030 public function selectDB( $db );
1033 * Get the current DB name
1036 public function getDBname();
1039 * Get the server hostname or IP address
1042 public function getServer();
1045 * Adds quotes and backslashes.
1047 * @param string|int|null|bool|Blob $s
1048 * @return string|int
1050 public function addQuotes( $s );
1053 * LIKE statement wrapper, receives a variable-length argument list with
1054 * parts of pattern to match containing either string literals that will be
1055 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1056 * the function could be provided with an array of aforementioned
1059 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1060 * a LIKE clause that searches for subpages of 'My page title'.
1062 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1063 * $query .= $dbr->buildLike( $pattern );
1066 * @return string Fully built LIKE statement
1068 public function buildLike();
1071 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1075 public function anyChar();
1078 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1082 public function anyString();
1085 * Returns an appropriately quoted sequence value for inserting a new row.
1086 * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1087 * subclass will return an integer, and save the value for insertId()
1089 * Any implementation of this function should *not* involve reusing
1090 * sequence numbers created for rolled-back transactions.
1091 * See https://bugs.mysql.com/bug.php?id=30767 for details.
1092 * @param string $seqName
1095 public function nextSequenceValue( $seqName );
1098 * REPLACE query wrapper.
1100 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1101 * except that when there is a duplicate key error, the old row is deleted
1102 * and the new row is inserted in its place.
1104 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1105 * perform the delete, we need to know what the unique indexes are so that
1106 * we know how to find the conflicting rows.
1108 * It may be more efficient to leave off unique indexes which are unlikely
1109 * to collide. However if you do this, you run the risk of encountering
1110 * errors which wouldn't have occurred in MySQL.
1112 * @param string $table The table to replace the row(s) in.
1113 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1114 * a field name or an array of field names
1115 * @param array $rows Can be either a single row to insert, or multiple rows,
1116 * in the same format as for IDatabase::insert()
1117 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1119 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1122 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1124 * This updates any conflicting rows (according to the unique indexes) using
1125 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1127 * $rows may be either:
1128 * - A single associative array. The array keys are the field names, and
1129 * the values are the values to insert. The values are treated as data
1130 * and will be quoted appropriately. If NULL is inserted, this will be
1131 * converted to a database NULL.
1132 * - An array with numeric keys, holding a list of associative arrays.
1133 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1134 * each subarray must be identical to each other, and in the same order.
1136 * It may be more efficient to leave off unique indexes which are unlikely
1137 * to collide. However if you do this, you run the risk of encountering
1138 * errors which wouldn't have occurred in MySQL.
1140 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1145 * @param string $table Table name. This will be passed through Database::tableName().
1146 * @param array $rows A single row or list of rows to insert
1147 * @param array $uniqueIndexes List of single field names or field name tuples
1148 * @param array $set An array of values to SET. For each array element, the
1149 * key gives the field name, and the value gives the data to set that
1150 * field to. The data will be quoted by IDatabase::addQuotes().
1151 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1155 public function upsert(
1156 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1160 * DELETE where the condition is a join.
1162 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1163 * we use sub-selects
1165 * For safety, an empty $conds will not delete everything. If you want to
1166 * delete all rows where the join condition matches, set $conds='*'.
1168 * DO NOT put the join condition in $conds.
1170 * @param string $delTable The table to delete from.
1171 * @param string $joinTable The other table.
1172 * @param string $delVar The variable to join on, in the first table.
1173 * @param string $joinVar The variable to join on, in the second table.
1174 * @param array $conds Condition array of field names mapped to variables,
1175 * ANDed together in the WHERE clause
1176 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1177 * @throws DBUnexpectedError
1179 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1184 * DELETE query wrapper.
1186 * @param string $table Table name
1187 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1188 * for the format. Use $conds == "*" to delete all rows
1189 * @param string $fname Name of the calling function
1190 * @throws DBUnexpectedError
1191 * @return bool|ResultWrapper
1193 public function delete( $table, $conds, $fname = __METHOD__
);
1196 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1197 * into another table.
1199 * @param string $destTable The table name to insert into
1200 * @param string|array $srcTable May be either a table name, or an array of table names
1201 * to include in a join.
1203 * @param array $varMap Must be an associative array of the form
1204 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1205 * rather than field names, but strings should be quoted with
1206 * IDatabase::addQuotes()
1208 * @param array $conds Condition array. See $conds in IDatabase::select() for
1209 * the details of the format of condition arrays. May be "*" to copy the
1212 * @param string $fname The function name of the caller, from __METHOD__
1214 * @param array $insertOptions Options for the INSERT part of the query, see
1215 * IDatabase::insert() for details.
1216 * @param array $selectOptions Options for the SELECT part of the query, see
1217 * IDatabase::select() for details.
1219 * @return ResultWrapper
1221 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1222 $fname = __METHOD__
,
1223 $insertOptions = [], $selectOptions = []
1227 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1228 * within the UNION construct.
1231 public function unionSupportsOrderAndLimit();
1234 * Construct a UNION query
1235 * This is used for providing overload point for other DB abstractions
1236 * not compatible with the MySQL syntax.
1237 * @param array $sqls SQL statements to combine
1238 * @param bool $all Use UNION ALL
1239 * @return string SQL fragment
1241 public function unionQueries( $sqls, $all );
1244 * Returns an SQL expression for a simple conditional. This doesn't need
1245 * to be overridden unless CASE isn't supported in your DBMS.
1247 * @param string|array $cond SQL expression which will result in a boolean value
1248 * @param string $trueVal SQL expression to return if true
1249 * @param string $falseVal SQL expression to return if false
1250 * @return string SQL fragment
1252 public function conditional( $cond, $trueVal, $falseVal );
1255 * Returns a comand for str_replace function in SQL query.
1256 * Uses REPLACE() in MySQL
1258 * @param string $orig Column to modify
1259 * @param string $old Column to seek
1260 * @param string $new Column to replace with
1264 public function strreplace( $orig, $old, $new );
1267 * Determines how long the server has been up
1271 public function getServerUptime();
1274 * Determines if the last failure was due to a deadlock
1278 public function wasDeadlock();
1281 * Determines if the last failure was due to a lock timeout
1285 public function wasLockTimeout();
1288 * Determines if the last query error was due to a dropped connection and should
1289 * be dealt with by pinging the connection and reissuing the query.
1293 public function wasErrorReissuable();
1296 * Determines if the last failure was due to the database being read-only.
1300 public function wasReadOnlyError();
1303 * Wait for the replica DB to catch up to a given master position
1305 * @param DBMasterPos $pos
1306 * @param int $timeout The maximum number of seconds to wait for synchronisation
1307 * @return int|null Zero if the replica DB was past that position already,
1308 * greater than zero if we waited for some period of time, less than
1309 * zero if it timed out, and null on error
1311 public function masterPosWait( DBMasterPos
$pos, $timeout );
1314 * Get the replication position of this replica DB
1316 * @return DBMasterPos|bool False if this is not a replica DB.
1318 public function getReplicaPos();
1321 * Get the position of this master
1323 * @return DBMasterPos|bool False if this is not a master
1325 public function getMasterPos();
1328 * @return bool Whether the DB is marked as read-only server-side
1331 public function serverIsReadOnly();
1334 * Run a callback as soon as the current transaction commits or rolls back.
1335 * An error is thrown if no transaction is pending. Queries in the function will run in
1336 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1339 * This is useful for combining cooperative locks and DB transactions.
1341 * The callback takes one argument:
1342 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1344 * @param callable $callback
1345 * @param string $fname Caller name
1349 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1352 * Run a callback as soon as there is no transaction pending.
1353 * If there is a transaction and it is rolled back, then the callback is cancelled.
1354 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1355 * Callbacks must commit any transactions that they begin.
1357 * This is useful for updates to different systems or when separate transactions are needed.
1358 * For example, one might want to enqueue jobs into a system outside the database, but only
1359 * after the database is updated so that the jobs will see the data when they actually run.
1360 * It can also be used for updates that easily cause deadlocks if locks are held too long.
1362 * Updates will execute in the order they were enqueued.
1364 * The callback takes one argument:
1365 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1367 * @param callable $callback
1368 * @param string $fname Caller name
1371 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1374 * Run a callback before the current transaction commits or now if there is none.
1375 * If there is a transaction and it is rolled back, then the callback is cancelled.
1376 * Callbacks must not start nor commit any transactions. If no transaction is active,
1377 * then a transaction will wrap the callback.
1379 * This is useful for updates that easily cause deadlocks if locks are held too long
1380 * but where atomicity is strongly desired for these updates and some related updates.
1382 * Updates will execute in the order they were enqueued.
1384 * @param callable $callback
1385 * @param string $fname Caller name
1388 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1391 * Run a callback each time any transaction commits or rolls back
1393 * The callback takes two arguments:
1394 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1395 * - This IDatabase object
1396 * Callbacks must commit any transactions that they begin.
1398 * Registering a callback here will not affect writesOrCallbacks() pending
1400 * @param string $name Callback name
1401 * @param callable|null $callback Use null to unset a listener
1405 public function setTransactionListener( $name, callable
$callback = null );
1408 * Begin an atomic section of statements
1410 * If a transaction has been started already, just keep track of the given
1411 * section name to make sure the transaction is not committed pre-maturely.
1412 * This function can be used in layers (with sub-sections), so use a stack
1413 * to keep track of the different atomic sections. If there is no transaction,
1414 * start one implicitly.
1416 * The goal of this function is to create an atomic section of SQL queries
1417 * without having to start a new transaction if it already exists.
1419 * All atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1420 * and any database transactions cannot be began or committed until all atomic
1421 * levels are closed. There is no such thing as implicitly opening or closing
1422 * an atomic section.
1425 * @param string $fname
1428 public function startAtomic( $fname = __METHOD__
);
1431 * Ends an atomic section of SQL statements
1433 * Ends the next section of atomic SQL statements and commits the transaction
1437 * @see IDatabase::startAtomic
1438 * @param string $fname
1441 public function endAtomic( $fname = __METHOD__
);
1444 * Run a callback to do an atomic set of updates for this database
1446 * The $callback takes the following arguments:
1447 * - This database object
1448 * - The value of $fname
1450 * If any exception occurs in the callback, then rollback() will be called and the error will
1451 * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1452 * In any case, such errors are expected to terminate the request, without any outside caller
1453 * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1454 * atomic section and uncommitted updates, which trashes the current request, requiring an
1455 * error to be displayed.
1457 * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1459 * @see Database::startAtomic
1460 * @see Database::endAtomic
1462 * @param string $fname Caller name (usually __METHOD__)
1463 * @param callable $callback Callback that issues DB updates
1464 * @return mixed $res Result of the callback (since 1.28)
1466 * @throws RuntimeException
1467 * @throws UnexpectedValueException
1470 public function doAtomicSection( $fname, callable
$callback );
1473 * Begin a transaction. If a transaction is already in progress,
1474 * that transaction will be committed before the new transaction is started.
1476 * Only call this from code with outer transcation scope.
1477 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1478 * Nesting of transactions is not supported.
1480 * Note that when the DBO_TRX flag is set (which is usually the case for web
1481 * requests, but not for maintenance scripts), any previous database query
1482 * will have started a transaction automatically.
1484 * Nesting of transactions is not supported. Attempts to nest transactions
1485 * will cause a warning, unless the current transaction was started
1486 * automatically because of the DBO_TRX flag.
1488 * @param string $fname Calling function name
1489 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1492 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1495 * Commits a transaction previously started using begin().
1496 * If no transaction is in progress, a warning is issued.
1498 * Only call this from code with outer transcation scope.
1499 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1500 * Nesting of transactions is not supported.
1502 * @param string $fname
1503 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1504 * constant to disable warnings about explicitly committing implicit transactions,
1505 * or calling commit when no transaction is in progress.
1507 * This will trigger an exception if there is an ongoing explicit transaction.
1509 * Only set the flush flag if you are sure that these warnings are not applicable,
1510 * and no explicit transactions are open.
1512 * @throws DBUnexpectedError
1514 public function commit( $fname = __METHOD__
, $flush = '' );
1517 * Rollback a transaction previously started using begin().
1518 * If no transaction is in progress, a warning is issued.
1520 * Only call this from code with outer transcation scope.
1521 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1522 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1523 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1524 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1526 * @param string $fname Calling function name
1527 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1528 * constant to disable warnings about calling rollback when no transaction is in
1529 * progress. This will silently break any ongoing explicit transaction. Only set the
1530 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1531 * @throws DBUnexpectedError
1532 * @since 1.23 Added $flush parameter
1534 public function rollback( $fname = __METHOD__
, $flush = '' );
1537 * Commit any transaction but error out if writes or callbacks are pending
1539 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1540 * see a new point-in-time of the database. This is useful when one of many transaction
1541 * rounds finished and significant time will pass in the script's lifetime. It is also
1542 * useful to call on a replica DB after waiting on replication to catch up to the master.
1544 * @param string $fname Calling function name
1545 * @throws DBUnexpectedError
1548 public function flushSnapshot( $fname = __METHOD__
);
1551 * List all tables on the database
1553 * @param string $prefix Only show tables with this prefix, e.g. mw_
1554 * @param string $fname Calling function name
1558 public function listTables( $prefix = null, $fname = __METHOD__
);
1561 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1562 * to the format used for inserting into timestamp fields in this DBMS.
1564 * The result is unquoted, and needs to be passed through addQuotes()
1565 * before it can be included in raw SQL.
1567 * @param string|int $ts
1571 public function timestamp( $ts = 0 );
1574 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1575 * to the format used for inserting into timestamp fields in this DBMS. If
1576 * NULL is input, it is passed through, allowing NULL values to be inserted
1577 * into timestamp fields.
1579 * The result is unquoted, and needs to be passed through addQuotes()
1580 * before it can be included in raw SQL.
1582 * @param string|int $ts
1586 public function timestampOrNull( $ts = null );
1589 * Ping the server and try to reconnect if it there is no connection
1591 * @param float|null &$rtt Value to store the estimated RTT [optional]
1592 * @return bool Success or failure
1594 public function ping( &$rtt = null );
1597 * Get replica DB lag. Currently supported only by MySQL.
1599 * Note that this function will generate a fatal error on many
1600 * installations. Most callers should use LoadBalancer::safeGetLag()
1603 * @return int|bool Database replication lag in seconds or false on error
1605 public function getLag();
1608 * Get the replica DB lag when the current transaction started
1609 * or a general lag estimate if not transaction is active
1611 * This is useful when transactions might use snapshot isolation
1612 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1613 * is this lag plus transaction duration. If they don't, it is still
1614 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1615 * indication of the staleness of subsequent reads.
1617 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1620 public function getSessionLagStatus();
1623 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1627 public function maxListLen();
1630 * Some DBMSs have a special format for inserting into blob fields, they
1631 * don't allow simple quoted strings to be inserted. To insert into such
1632 * a field, pass the data through this function before passing it to
1633 * IDatabase::insert().
1636 * @return string|Blob
1638 public function encodeBlob( $b );
1641 * Some DBMSs return a special placeholder object representing blob fields
1642 * in result objects. Pass the object through this function to return the
1645 * @param string|Blob $b
1648 public function decodeBlob( $b );
1651 * Override database's default behavior. $options include:
1652 * 'connTimeout' : Set the connection timeout value in seconds.
1653 * May be useful for very long batch queries such as
1654 * full-wiki dumps, where a single query reads out over
1657 * @param array $options
1660 public function setSessionOptions( array $options );
1663 * Set variables to be used in sourceFile/sourceStream, in preference to the
1664 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1665 * all. If it's set to false, $GLOBALS will be used.
1667 * @param bool|array $vars Mapping variable name to value.
1669 public function setSchemaVars( $vars );
1672 * Check to see if a named lock is available (non-blocking)
1674 * @param string $lockName Name of lock to poll
1675 * @param string $method Name of method calling us
1679 public function lockIsFree( $lockName, $method );
1682 * Acquire a named lock
1684 * Named locks are not related to transactions
1686 * @param string $lockName Name of lock to aquire
1687 * @param string $method Name of the calling method
1688 * @param int $timeout Acquisition timeout in seconds
1691 public function lock( $lockName, $method, $timeout = 5 );
1696 * Named locks are not related to transactions
1698 * @param string $lockName Name of lock to release
1699 * @param string $method Name of the calling method
1701 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1702 * by this thread (in which case the lock is not released), and NULL if the named
1703 * lock did not exist
1705 public function unlock( $lockName, $method );
1708 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1710 * Only call this from outer transcation scope and when only one DB will be affected.
1711 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1713 * This is suitiable for transactions that need to be serialized using cooperative locks,
1714 * where each transaction can see each others' changes. Any transaction is flushed to clear
1715 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1716 * the lock will be released unless a transaction is active. If one is active, then the lock
1717 * will be released when it either commits or rolls back.
1719 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1721 * @param string $lockKey Name of lock to release
1722 * @param string $fname Name of the calling method
1723 * @param int $timeout Acquisition timeout in seconds
1724 * @return ScopedCallback|null
1725 * @throws DBUnexpectedError
1728 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1731 * Check to see if a named lock used by lock() use blocking queues
1736 public function namedLocksEnqueue();
1739 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1740 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1741 * because "i" sorts after all numbers.
1745 public function getInfinity();
1748 * Encode an expiry time into the DBMS dependent format
1750 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1753 public function encodeExpiry( $expiry );
1756 * Decode an expiry time into a DBMS independent format
1758 * @param string $expiry DB timestamp field value for expiry
1759 * @param int $format TS_* constant, defaults to TS_MW
1762 public function decodeExpiry( $expiry, $format = TS_MW
);
1765 * Allow or deny "big selects" for this session only. This is done by setting
1766 * the sql_big_selects session variable.
1768 * This is a MySQL-specific feature.
1770 * @param bool|string $value True for allow, false for deny, or "default" to
1771 * restore the initial value
1773 public function setBigSelects( $value = true );
1776 * @return bool Whether this DB is read-only
1779 public function isReadOnly();
1782 * Make certain table names use their own database, schema, and table prefix
1783 * when passed into SQL queries pre-escaped and without a qualified database name
1785 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1786 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1788 * Calling this twice will completely clear any old table aliases. Also, note that
1789 * callers are responsible for making sure the schemas and databases actually exist.
1791 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1794 public function setTableAliases( array $aliases );