56eb002303732e8ef027c645cbf8ec6ad9c9d5c2
4 * @defgroup Database Database
6 * This file deals with database interface functions
7 * and query specifics/optimisations.
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write to the Free Software Foundation, Inc.,
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
22 * http://www.gnu.org/copyleft/gpl.html
29 * Basic database interface for live and lazy-loaded DB 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 */
78 * A string describing the current software version, and possibly
79 * other details in a user-friendly way. Will be listed on Special:Version, etc.
80 * Use getServerVersion() to get machine-friendly information.
82 * @return string Version information from the database server
84 public function getServerInfo();
87 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
89 * Unbuffered queries are very troublesome in MySQL:
91 * - If another query is executed while the first query is being read
92 * out, the first query is killed. This means you can't call normal
93 * Database functions while you are reading an unbuffered query result
94 * from a normal Database connection.
96 * - Unbuffered queries cause the MySQL server to use large amounts of
97 * memory and to hold broad locks which block other queries.
99 * If you want to limit client-side memory, it's almost always better to
100 * split up queries into batches using a LIMIT clause than to switch off
103 * @param null|bool $buffer
104 * @return null|bool The previous value of the flag
106 public function bufferResults( $buffer = null );
109 * Gets the current transaction level.
111 * Historically, transactions were allowed to be "nested". This is no
112 * longer supported, so this function really only returns a boolean.
114 * @return int The previous value
116 public function trxLevel();
119 * Get the UNIX timestamp of the time that the transaction was established
121 * This can be used to reason about the staleness of SELECT data
122 * in REPEATABLE-READ transaction isolation level.
124 * @return float|null Returns null if there is not active transaction
127 public function trxTimestamp();
130 * @return bool Whether an explicit transaction or atomic sections are still open
133 public function explicitTrxActive();
136 * Get/set the table prefix.
137 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
138 * @return string The previous table prefix.
140 public function tablePrefix( $prefix = null );
143 * Get/set the db schema.
144 * @param string $schema The database schema to set, or omitted to leave it unchanged.
145 * @return string The previous db schema.
147 public function dbSchema( $schema = null );
150 * Get properties passed down from the server info array of the load
153 * @param string $name The entry of the info array to get, or null to get the
156 * @return array|mixed|null
158 public function getLBInfo( $name = null );
161 * Set the LB info array, or a member of it. If called with one parameter,
162 * the LB info array is set to that parameter. If it is called with two
163 * parameters, the member with the given name is set to the given value.
165 * @param string $name
166 * @param array $value
168 public function setLBInfo( $name, $value = null );
171 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
173 * @param IDatabase $conn
176 public function setLazyMasterHandle( IDatabase
$conn );
179 * Returns true if this database does an implicit sort when doing GROUP BY
183 public function implicitGroupby();
186 * Returns true if this database does an implicit order by when the column has an index
187 * For example: SELECT page_title FROM page LIMIT 1
191 public function implicitOrderby();
194 * Return the last query that went through IDatabase::query()
197 public function lastQuery();
200 * Returns true if the connection may have been used for write queries.
201 * Should return true if unsure.
205 public function doneWrites();
208 * Returns the last time the connection may have been used for write queries.
209 * Should return a timestamp if unsure.
211 * @return int|float UNIX timestamp or false
214 public function lastDoneWrites();
217 * @return bool Whether there is a transaction open with possible write queries
220 public function writesPending();
223 * Returns true if there is a transaction open with possible write
224 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
225 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
229 public function writesOrCallbacksPending();
232 * Get the time spend running write queries for this transaction
234 * High times could be due to scanning, updates, locking, and such
236 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
237 * @return float|bool Returns false if not transaction is active
240 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
243 * Get the list of method names that did write queries for this transaction
248 public function pendingWriteCallers();
251 * Is a connection to the database open?
254 public function isOpen();
257 * Set a flag for this connection
259 * @param int $flag DBO_* constants from Defines.php:
260 * - DBO_DEBUG: output some debug info (same as debug())
261 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
262 * - DBO_TRX: automatically start transactions
263 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
264 * and removes it in command line mode
265 * - DBO_PERSISTENT: use persistant database connection
266 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
268 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
271 * Clear a flag for this connection
273 * @param int $flag DBO_* constants from Defines.php:
274 * - DBO_DEBUG: output some debug info (same as debug())
275 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
276 * - DBO_TRX: automatically start transactions
277 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
278 * and removes it in command line mode
279 * - DBO_PERSISTENT: use persistant database connection
280 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
282 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
285 * Restore the flags to their prior state before the last setFlag/clearFlag call
287 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
290 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
293 * Returns a boolean whether the flag $flag is set for this connection
295 * @param int $flag DBO_* constants from Defines.php:
296 * - DBO_DEBUG: output some debug info (same as debug())
297 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
298 * - DBO_TRX: automatically start transactions
299 * - DBO_PERSISTENT: use persistant database connection
302 public function getFlag( $flag );
305 * General read-only accessor
307 * @param string $name
310 public function getProperty( $name );
315 public function getDomainID();
318 * Alias for getDomainID()
322 public function getWikiID();
325 * Get the type of the DBMS, as it appears in $wgDBtype.
329 public function getType();
332 * Open a connection to the database. Usually aborts on failure
334 * @param string $server Database server host
335 * @param string $user Database user name
336 * @param string $password Database user password
337 * @param string $dbName Database name
339 * @throws DBConnectionError
341 public function open( $server, $user, $password, $dbName );
344 * Fetch the next row from the given result object, in object form.
345 * Fields can be retrieved with $row->fieldname, with fields acting like
347 * If no more rows are available, false is returned.
349 * @param ResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
350 * @return stdClass|bool
351 * @throws DBUnexpectedError Thrown if the database returns an error
353 public function fetchObject( $res );
356 * Fetch the next row from the given result object, in associative array
357 * form. Fields are retrieved with $row['fieldname'].
358 * If no more rows are available, false is returned.
360 * @param ResultWrapper $res Result object as returned from IDatabase::query(), etc.
362 * @throws DBUnexpectedError Thrown if the database returns an error
364 public function fetchRow( $res );
367 * Get the number of rows in a result object
369 * @param mixed $res A SQL result
372 public function numRows( $res );
375 * Get the number of fields in a result object
376 * @see http://www.php.net/mysql_num_fields
378 * @param mixed $res A SQL result
381 public function numFields( $res );
384 * Get a field name in a result object
385 * @see http://www.php.net/mysql_field_name
387 * @param mixed $res A SQL result
391 public function fieldName( $res, $n );
394 * Get the inserted value of an auto-increment row
396 * The value inserted should be fetched from nextSequenceValue()
399 * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
400 * $dbw->insert( 'page', [ 'page_id' => $id ] );
401 * $id = $dbw->insertId();
405 public function insertId();
408 * Change the position of the cursor in a result object
409 * @see http://www.php.net/mysql_data_seek
411 * @param mixed $res A SQL result
414 public function dataSeek( $res, $row );
417 * Get the last error number
418 * @see http://www.php.net/mysql_errno
422 public function lastErrno();
425 * Get a description of the last error
426 * @see http://www.php.net/mysql_error
430 public function lastError();
433 * mysql_fetch_field() wrapper
434 * Returns false if the field doesn't exist
436 * @param string $table Table name
437 * @param string $field Field name
441 public function fieldInfo( $table, $field );
444 * Get the number of rows affected by the last write query
445 * @see http://www.php.net/mysql_affected_rows
449 public function affectedRows();
452 * Returns a wikitext link to the DB's website, e.g.,
453 * return "[http://www.mysql.com/ MySQL]";
454 * Should at least contain plain text, if for some reason
455 * your database has no website.
457 * @return string Wikitext of a link to the server software's web site
459 public function getSoftwareLink();
462 * A string describing the current software version, like from
463 * mysql_get_server_info().
465 * @return string Version information from the database server.
467 public function getServerVersion();
470 * Closes a database connection.
471 * if it is open : commits any open transactions
474 * @return bool Operation success. true if already closed.
476 public function close();
479 * @param string $error Fallback error message, used if none is given by DB
480 * @throws DBConnectionError
482 public function reportConnectionError( $error = 'Unknown error' );
485 * Run an SQL query and return the result. Normally throws a DBQueryError
486 * on failure. If errors are ignored, returns false instead.
488 * In new code, the query wrappers select(), insert(), update(), delete(),
489 * etc. should be used where possible, since they give much better DBMS
490 * independence and automatically quote or validate user input in a variety
491 * of contexts. This function is generally only useful for queries which are
492 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
495 * However, the query wrappers themselves should call this function.
497 * @param string $sql SQL query
498 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
499 * comment (you can use __METHOD__ or add some extra info)
500 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
501 * maybe best to catch the exception instead?
503 * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
504 * for a successful read query, or false on failure if $tempIgnore set
506 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
509 * Report a query error. Log the error, and if neither the object ignore
510 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
512 * @param string $error
515 * @param string $fname
516 * @param bool $tempIgnore
517 * @throws DBQueryError
519 public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
522 * Free a result object returned by query() or select(). It's usually not
523 * necessary to call this, just use unset() or let the variable holding
524 * the result object go out of scope.
526 * @param mixed $res A SQL result
528 public function freeResult( $res );
531 * A SELECT wrapper which returns a single field from a single result row.
533 * Usually throws a DBQueryError on failure. If errors are explicitly
534 * ignored, returns false on failure.
536 * If no result rows are returned from the query, false is returned.
538 * @param string|array $table Table name. See IDatabase::select() for details.
539 * @param string $var The field name to select. This must be a valid SQL
540 * fragment: do not use unvalidated user input.
541 * @param string|array $cond The condition array. See IDatabase::select() for details.
542 * @param string $fname The function name of the caller.
543 * @param string|array $options The query options. See IDatabase::select() for details.
545 * @return bool|mixed The value from the field, or false on failure.
547 public function selectField(
548 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
552 * A SELECT wrapper which returns a list of single field values from result rows.
554 * Usually throws a DBQueryError on failure. If errors are explicitly
555 * ignored, returns false on failure.
557 * If no result rows are returned from the query, false is returned.
559 * @param string|array $table Table name. See IDatabase::select() for details.
560 * @param string $var The field name to select. This must be a valid SQL
561 * fragment: do not use unvalidated user input.
562 * @param string|array $cond The condition array. See IDatabase::select() for details.
563 * @param string $fname The function name of the caller.
564 * @param string|array $options The query options. See IDatabase::select() for details.
566 * @return bool|array The values from the field, or false on failure
569 public function selectFieldValues(
570 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
574 * Execute a SELECT query constructed using the various parameters provided.
575 * See below for full details of the parameters.
577 * @param string|array $table Table name
578 * @param string|array $vars Field names
579 * @param string|array $conds Conditions
580 * @param string $fname Caller function name
581 * @param array $options Query options
582 * @param array $join_conds Join conditions
585 * @param string|array $table
587 * May be either an array of table names, or a single string holding a table
588 * name. If an array is given, table aliases can be specified, for example:
592 * This includes the user table in the query, with the alias "a" available
593 * for use in field names (e.g. a.user_name).
595 * All of the table names given here are automatically run through
596 * DatabaseBase::tableName(), which causes the table prefix (if any) to be
597 * added, and various other table name mappings to be performed.
599 * Do not use untrusted user input as a table name. Alias names should
600 * not have characters outside of the Basic multilingual plane.
602 * @param string|array $vars
604 * May be either a field name or an array of field names. The field names
605 * can be complete fragments of SQL, for direct inclusion into the SELECT
606 * query. If an array is given, field aliases can be specified, for example:
608 * [ 'maxrev' => 'MAX(rev_id)' ]
610 * This includes an expression with the alias "maxrev" in the query.
612 * If an expression is given, care must be taken to ensure that it is
615 * Untrusted user input must not be passed to this parameter.
617 * @param string|array $conds
619 * May be either a string containing a single condition, or an array of
620 * conditions. If an array is given, the conditions constructed from each
621 * element are combined with AND.
623 * Array elements may take one of two forms:
625 * - Elements with a numeric key are interpreted as raw SQL fragments.
626 * - Elements with a string key are interpreted as equality conditions,
627 * where the key is the field name.
628 * - If the value of such an array element is a scalar (such as a
629 * string), it will be treated as data and thus quoted appropriately.
630 * If it is null, an IS NULL clause will be added.
631 * - If the value is an array, an IN (...) clause will be constructed
632 * from its non-null elements, and an IS NULL clause will be added
633 * if null is present, such that the field may match any of the
634 * elements in the array. The non-null elements will be quoted.
636 * Note that expressions are often DBMS-dependent in their syntax.
637 * DBMS-independent wrappers are provided for constructing several types of
638 * expression commonly used in condition queries. See:
639 * - IDatabase::buildLike()
640 * - IDatabase::conditional()
642 * Untrusted user input is safe in the values of string keys, however untrusted
643 * input must not be used in the array key names or in the values of numeric keys.
644 * Escaping of untrusted input used in values of numeric keys should be done via
645 * IDatabase::addQuotes()
647 * @param string|array $options
649 * Optional: Array of query options. Boolean options are specified by
650 * including them in the array as a string value with a numeric key, for
655 * The supported options are:
657 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
658 * with LIMIT can theoretically be used for paging through a result set,
659 * but this is discouraged for performance reasons.
661 * - LIMIT: Integer: return at most this many rows. The rows are sorted
662 * and then the first rows are taken until the limit is reached. LIMIT
663 * is applied to a result set after OFFSET.
665 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
666 * changed until the next COMMIT.
668 * - DISTINCT: Boolean: return only unique result rows.
670 * - GROUP BY: May be either an SQL fragment string naming a field or
671 * expression to group by, or an array of such SQL fragments.
673 * - HAVING: May be either an string containing a HAVING clause or an array of
674 * conditions building the HAVING clause. If an array is given, the conditions
675 * constructed from each element are combined with AND.
677 * - ORDER BY: May be either an SQL fragment giving a field name or
678 * expression to order by, or an array of such SQL fragments.
680 * - USE INDEX: This may be either a string giving the index name to use
681 * for the query, or an array. If it is an associative array, each key
682 * gives the table name (or alias), each value gives the index name to
683 * use for that table. All strings are SQL fragments and so should be
684 * validated by the caller.
686 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
689 * And also the following boolean MySQL extensions, see the MySQL manual
692 * - LOCK IN SHARE MODE
696 * - SQL_BUFFER_RESULT
698 * - SQL_CALC_FOUND_ROWS
703 * @param string|array $join_conds
705 * Optional associative array of table-specific join conditions. In the
706 * most common case, this is unnecessary, since the join condition can be
707 * in $conds. However, it is useful for doing a LEFT JOIN.
709 * The key of the array contains the table name or alias. The value is an
710 * array with two elements, numbered 0 and 1. The first gives the type of
711 * join, the second is the same as the $conds parameter. Thus it can be
712 * an SQL fragment, or an array where the string keys are equality and the
713 * numeric keys are SQL fragments all AND'd together. For example:
715 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
717 * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
718 * with no rows in it will be returned. If there was a query error, a
719 * DBQueryError exception will be thrown, except if the "ignore errors"
720 * option was set, in which case false will be returned.
722 public function select(
723 $table, $vars, $conds = '', $fname = __METHOD__
,
724 $options = [], $join_conds = []
728 * The equivalent of IDatabase::select() except that the constructed SQL
729 * is returned, instead of being immediately executed. This can be useful for
730 * doing UNION queries, where the SQL text of each query is needed. In general,
731 * however, callers outside of Database classes should just use select().
733 * @param string|array $table Table name
734 * @param string|array $vars Field names
735 * @param string|array $conds Conditions
736 * @param string $fname Caller function name
737 * @param string|array $options Query options
738 * @param string|array $join_conds Join conditions
740 * @return string SQL query string.
741 * @see IDatabase::select()
743 public function selectSQLText(
744 $table, $vars, $conds = '', $fname = __METHOD__
,
745 $options = [], $join_conds = []
749 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
750 * that a single row object is returned. If the query returns no rows,
753 * @param string|array $table Table name
754 * @param string|array $vars Field names
755 * @param array $conds Conditions
756 * @param string $fname Caller function name
757 * @param string|array $options Query options
758 * @param array|string $join_conds Join conditions
760 * @return stdClass|bool
762 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
763 $options = [], $join_conds = []
767 * Estimate the number of rows in dataset
769 * MySQL allows you to estimate the number of rows that would be returned
770 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
771 * index cardinality statistics, and is notoriously inaccurate, especially
772 * when large numbers of rows have recently been added or deleted.
774 * For DBMSs that don't support fast result size estimation, this function
775 * will actually perform the SELECT COUNT(*).
777 * Takes the same arguments as IDatabase::select().
779 * @param string $table Table name
780 * @param string $vars Unused
781 * @param array|string $conds Filters on the table
782 * @param string $fname Function name for profiling
783 * @param array $options Options for select
784 * @return int Row count
786 public function estimateRowCount(
787 $table, $vars = '*', $conds = '', $fname = __METHOD__
, $options = []
791 * Get the number of rows in dataset
793 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
795 * Takes the same arguments as IDatabase::select().
797 * @since 1.27 Added $join_conds parameter
799 * @param array|string $tables Table names
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 * @param array $join_conds Join conditions (since 1.27)
805 * @return int Row count
807 public function selectRowCount(
808 $tables, $vars = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
812 * Determines whether a field exists in a table
814 * @param string $table Table name
815 * @param string $field Filed to check on that table
816 * @param string $fname Calling function name (optional)
817 * @return bool Whether $table has filed $field
819 public function fieldExists( $table, $field, $fname = __METHOD__
);
822 * Determines whether an index exists
823 * Usually throws a DBQueryError on failure
824 * If errors are explicitly ignored, returns NULL on failure
826 * @param string $table
827 * @param string $index
828 * @param string $fname
831 public function indexExists( $table, $index, $fname = __METHOD__
);
834 * Query whether a given table exists
836 * @param string $table
837 * @param string $fname
840 public function tableExists( $table, $fname = __METHOD__
);
843 * Determines if a given index is unique
845 * @param string $table
846 * @param string $index
850 public function indexUnique( $table, $index );
853 * INSERT wrapper, inserts an array into a table.
857 * - A single associative array. The array keys are the field names, and
858 * the values are the values to insert. The values are treated as data
859 * and will be quoted appropriately. If NULL is inserted, this will be
860 * converted to a database NULL.
861 * - An array with numeric keys, holding a list of associative arrays.
862 * This causes a multi-row INSERT on DBMSs that support it. The keys in
863 * each subarray must be identical to each other, and in the same order.
865 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
868 * $options is an array of options, with boolean options encoded as values
869 * with numeric keys, in the same style as $options in
870 * IDatabase::select(). Supported options are:
872 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
873 * any rows which cause duplicate key errors are not inserted. It's
874 * possible to determine how many rows were successfully inserted using
875 * IDatabase::affectedRows().
877 * @param string $table Table name. This will be passed through
878 * DatabaseBase::tableName().
879 * @param array $a Array of rows to insert
880 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
881 * @param array $options Array of options
885 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
888 * UPDATE wrapper. Takes a condition array and a SET array.
890 * @param string $table Name of the table to UPDATE. This will be passed through
891 * DatabaseBase::tableName().
892 * @param array $values An array of values to SET. For each array element,
893 * the key gives the field name, and the value gives the data to set
894 * that field to. The data will be quoted by IDatabase::addQuotes().
895 * @param array $conds An array of conditions (WHERE). See
896 * IDatabase::select() for the details of the format of condition
897 * arrays. Use '*' to update all rows.
898 * @param string $fname The function name of the caller (from __METHOD__),
899 * for logging and profiling.
900 * @param array $options An array of UPDATE options, can be:
901 * - IGNORE: Ignore unique key conflicts
902 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
905 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
908 * Makes an encoded list of strings from an array
910 * These can be used to make conjunctions or disjunctions on SQL condition strings
911 * derived from an array (see IDatabase::select() $conds documentation).
915 * $sql = $db->makeList( [
917 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
918 * ], $db::LIST_AND );
920 * This would set $sql to "rev_user = '$id' AND (rev_minor = '1' OR rev_len < '500')"
922 * @param array $a Containing the data
923 * @param int $mode IDatabase class constant:
924 * - IDatabase::LIST_COMMA: Comma separated, no field names
925 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
926 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
927 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
928 * - IDatabase::LIST_NAMES: Comma separated field names
932 public function makeList( $a, $mode = self
::LIST_COMMA
);
935 * Build a partial where clause from a 2-d array such as used for LinkBatch.
936 * The keys on each level may be either integers or strings.
938 * @param array $data Organized as 2-d
939 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
940 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
941 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
942 * @return string|bool SQL fragment, or false if no items in array
944 public function makeWhereFrom2d( $data, $baseKey, $subKey );
947 * Return aggregated value alias
949 * @param array $valuedata
950 * @param string $valuename
954 public function aggregateValue( $valuedata, $valuename = 'value' );
957 * @param string $field
960 public function bitNot( $field );
963 * @param string $fieldLeft
964 * @param string $fieldRight
967 public function bitAnd( $fieldLeft, $fieldRight );
970 * @param string $fieldLeft
971 * @param string $fieldRight
974 public function bitOr( $fieldLeft, $fieldRight );
977 * Build a concatenation list to feed into a SQL query
978 * @param array $stringList List of raw SQL expressions; caller is
979 * responsible for any quoting
982 public function buildConcat( $stringList );
985 * Build a GROUP_CONCAT or equivalent statement for a query.
987 * This is useful for combining a field for several rows into a single string.
988 * NULL values will not appear in the output, duplicated values will appear,
989 * and the resulting delimiter-separated values have no defined sort order.
990 * Code using the results may need to use the PHP unique() or sort() methods.
992 * @param string $delim Glue to bind the results together
993 * @param string|array $table Table name
994 * @param string $field Field name
995 * @param string|array $conds Conditions
996 * @param string|array $join_conds Join conditions
997 * @return string SQL text
1000 public function buildGroupConcatField(
1001 $delim, $table, $field, $conds = '', $join_conds = []
1005 * @param string $field Field or column to cast
1009 public function buildStringCast( $field );
1012 * Change the current database
1015 * @return bool Success or failure
1017 public function selectDB( $db );
1020 * Get the current DB name
1023 public function getDBname();
1026 * Get the server hostname or IP address
1029 public function getServer();
1032 * Adds quotes and backslashes.
1034 * @param string|int|null|bool|Blob $s
1035 * @return string|int
1037 public function addQuotes( $s );
1040 * LIKE statement wrapper, receives a variable-length argument list with
1041 * parts of pattern to match containing either string literals that will be
1042 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1043 * the function could be provided with an array of aforementioned
1046 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1047 * a LIKE clause that searches for subpages of 'My page title'.
1049 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1050 * $query .= $dbr->buildLike( $pattern );
1053 * @return string Fully built LIKE statement
1055 public function buildLike();
1058 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1062 public function anyChar();
1065 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1069 public function anyString();
1072 * Returns an appropriately quoted sequence value for inserting a new row.
1073 * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1074 * subclass will return an integer, and save the value for insertId()
1076 * Any implementation of this function should *not* involve reusing
1077 * sequence numbers created for rolled-back transactions.
1078 * See http://bugs.mysql.com/bug.php?id=30767 for details.
1079 * @param string $seqName
1082 public function nextSequenceValue( $seqName );
1085 * REPLACE query wrapper.
1087 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1088 * except that when there is a duplicate key error, the old row is deleted
1089 * and the new row is inserted in its place.
1091 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1092 * perform the delete, we need to know what the unique indexes are so that
1093 * we know how to find the conflicting rows.
1095 * It may be more efficient to leave off unique indexes which are unlikely
1096 * to collide. However if you do this, you run the risk of encountering
1097 * errors which wouldn't have occurred in MySQL.
1099 * @param string $table The table to replace the row(s) in.
1100 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1101 * a field name or an array of field names
1102 * @param array $rows Can be either a single row to insert, or multiple rows,
1103 * in the same format as for IDatabase::insert()
1104 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1106 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1109 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1111 * This updates any conflicting rows (according to the unique indexes) using
1112 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1114 * $rows may be either:
1115 * - A single associative array. The array keys are the field names, and
1116 * the values are the values to insert. The values are treated as data
1117 * and will be quoted appropriately. If NULL is inserted, this will be
1118 * converted to a database NULL.
1119 * - An array with numeric keys, holding a list of associative arrays.
1120 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1121 * each subarray must be identical to each other, and in the same order.
1123 * It may be more efficient to leave off unique indexes which are unlikely
1124 * to collide. However if you do this, you run the risk of encountering
1125 * errors which wouldn't have occurred in MySQL.
1127 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1132 * @param string $table Table name. This will be passed through DatabaseBase::tableName().
1133 * @param array $rows A single row or list of rows to insert
1134 * @param array $uniqueIndexes List of single field names or field name tuples
1135 * @param array $set An array of values to SET. For each array element, the
1136 * key gives the field name, and the value gives the data to set that
1137 * field to. The data will be quoted by IDatabase::addQuotes().
1138 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1142 public function upsert(
1143 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1147 * DELETE where the condition is a join.
1149 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1150 * we use sub-selects
1152 * For safety, an empty $conds will not delete everything. If you want to
1153 * delete all rows where the join condition matches, set $conds='*'.
1155 * DO NOT put the join condition in $conds.
1157 * @param string $delTable The table to delete from.
1158 * @param string $joinTable The other table.
1159 * @param string $delVar The variable to join on, in the first table.
1160 * @param string $joinVar The variable to join on, in the second table.
1161 * @param array $conds Condition array of field names mapped to variables,
1162 * ANDed together in the WHERE clause
1163 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1164 * @throws DBUnexpectedError
1166 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1171 * DELETE query wrapper.
1173 * @param array $table Table name
1174 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1175 * for the format. Use $conds == "*" to delete all rows
1176 * @param string $fname Name of the calling function
1177 * @throws DBUnexpectedError
1178 * @return bool|ResultWrapper
1180 public function delete( $table, $conds, $fname = __METHOD__
);
1183 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1184 * into another table.
1186 * @param string $destTable The table name to insert into
1187 * @param string|array $srcTable May be either a table name, or an array of table names
1188 * to include in a join.
1190 * @param array $varMap Must be an associative array of the form
1191 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1192 * rather than field names, but strings should be quoted with
1193 * IDatabase::addQuotes()
1195 * @param array $conds Condition array. See $conds in IDatabase::select() for
1196 * the details of the format of condition arrays. May be "*" to copy the
1199 * @param string $fname The function name of the caller, from __METHOD__
1201 * @param array $insertOptions Options for the INSERT part of the query, see
1202 * IDatabase::insert() for details.
1203 * @param array $selectOptions Options for the SELECT part of the query, see
1204 * IDatabase::select() for details.
1206 * @return ResultWrapper
1208 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1209 $fname = __METHOD__
,
1210 $insertOptions = [], $selectOptions = []
1214 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1215 * within the UNION construct.
1218 public function unionSupportsOrderAndLimit();
1221 * Construct a UNION query
1222 * This is used for providing overload point for other DB abstractions
1223 * not compatible with the MySQL syntax.
1224 * @param array $sqls SQL statements to combine
1225 * @param bool $all Use UNION ALL
1226 * @return string SQL fragment
1228 public function unionQueries( $sqls, $all );
1231 * Returns an SQL expression for a simple conditional. This doesn't need
1232 * to be overridden unless CASE isn't supported in your DBMS.
1234 * @param string|array $cond SQL expression which will result in a boolean value
1235 * @param string $trueVal SQL expression to return if true
1236 * @param string $falseVal SQL expression to return if false
1237 * @return string SQL fragment
1239 public function conditional( $cond, $trueVal, $falseVal );
1242 * Returns a comand for str_replace function in SQL query.
1243 * Uses REPLACE() in MySQL
1245 * @param string $orig Column to modify
1246 * @param string $old Column to seek
1247 * @param string $new Column to replace with
1251 public function strreplace( $orig, $old, $new );
1254 * Determines how long the server has been up
1258 public function getServerUptime();
1261 * Determines if the last failure was due to a deadlock
1265 public function wasDeadlock();
1268 * Determines if the last failure was due to a lock timeout
1272 public function wasLockTimeout();
1275 * Determines if the last query error was due to a dropped connection and should
1276 * be dealt with by pinging the connection and reissuing the query.
1280 public function wasErrorReissuable();
1283 * Determines if the last failure was due to the database being read-only.
1287 public function wasReadOnlyError();
1290 * Wait for the replica DB to catch up to a given master position
1292 * @param DBMasterPos $pos
1293 * @param int $timeout The maximum number of seconds to wait for synchronisation
1294 * @return int|null Zero if the replica DB was past that position already,
1295 * greater than zero if we waited for some period of time, less than
1296 * zero if it timed out, and null on error
1298 public function masterPosWait( DBMasterPos
$pos, $timeout );
1301 * Get the replication position of this replica DB
1303 * @return DBMasterPos|bool False if this is not a replica DB.
1305 public function getSlavePos();
1308 * Get the position of this master
1310 * @return DBMasterPos|bool False if this is not a master
1312 public function getMasterPos();
1315 * @return bool Whether the DB is marked as read-only server-side
1318 public function serverIsReadOnly();
1321 * Run a callback as soon as the current transaction commits or rolls back.
1322 * An error is thrown if no transaction is pending. Queries in the function will run in
1323 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1326 * This is useful for combining cooperative locks and DB transactions.
1328 * The callback takes one argument:
1329 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1331 * @param callable $callback
1332 * @param string $fname Caller name
1336 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1339 * Run a callback as soon as there is no transaction pending.
1340 * If there is a transaction and it is rolled back, then the callback is cancelled.
1341 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1342 * Callbacks must commit any transactions that they begin.
1344 * This is useful for updates to different systems or when separate transactions are needed.
1345 * For example, one might want to enqueue jobs into a system outside the database, but only
1346 * after the database is updated so that the jobs will see the data when they actually run.
1347 * It can also be used for updates that easily cause deadlocks if locks are held too long.
1349 * Updates will execute in the order they were enqueued.
1351 * The callback takes one argument:
1352 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1354 * @param callable $callback
1355 * @param string $fname Caller name
1358 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1361 * Run a callback before the current transaction commits or now if there is none.
1362 * If there is a transaction and it is rolled back, then the callback is cancelled.
1363 * Callbacks must not start nor commit any transactions. If no transaction is active,
1364 * then a transaction will wrap the callback.
1366 * This is useful for updates that easily cause deadlocks if locks are held too long
1367 * but where atomicity is strongly desired for these updates and some related updates.
1369 * Updates will execute in the order they were enqueued.
1371 * @param callable $callback
1372 * @param string $fname Caller name
1375 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1378 * Run a callback each time any transaction commits or rolls back
1380 * The callback takes two arguments:
1381 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1382 * - This IDatabase object
1383 * Callbacks must commit any transactions that they begin.
1385 * Registering a callback here will not affect writesOrCallbacks() pending
1387 * @param string $name Callback name
1388 * @param callable|null $callback Use null to unset a listener
1392 public function setTransactionListener( $name, callable
$callback = null );
1395 * Begin an atomic section of statements
1397 * If a transaction has been started already, just keep track of the given
1398 * section name to make sure the transaction is not committed pre-maturely.
1399 * This function can be used in layers (with sub-sections), so use a stack
1400 * to keep track of the different atomic sections. If there is no transaction,
1401 * start one implicitly.
1403 * The goal of this function is to create an atomic section of SQL queries
1404 * without having to start a new transaction if it already exists.
1406 * All atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1407 * and any database transactions cannot be began or committed until all atomic
1408 * levels are closed. There is no such thing as implicitly opening or closing
1409 * an atomic section.
1412 * @param string $fname
1415 public function startAtomic( $fname = __METHOD__
);
1418 * Ends an atomic section of SQL statements
1420 * Ends the next section of atomic SQL statements and commits the transaction
1424 * @see IDatabase::startAtomic
1425 * @param string $fname
1428 public function endAtomic( $fname = __METHOD__
);
1431 * Run a callback to do an atomic set of updates for this database
1433 * The $callback takes the following arguments:
1434 * - This database object
1435 * - The value of $fname
1437 * If any exception occurs in the callback, then rollback() will be called and the error will
1438 * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1439 * In any case, such errors are expected to terminate the request, without any outside caller
1440 * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1441 * atomic section and uncommitted updates, which trashes the current request, requiring an
1442 * error to be displayed.
1444 * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1446 * @see DatabaseBase::startAtomic
1447 * @see DatabaseBase::endAtomic
1449 * @param string $fname Caller name (usually __METHOD__)
1450 * @param callable $callback Callback that issues DB updates
1451 * @return mixed $res Result of the callback (since 1.28)
1453 * @throws RuntimeException
1454 * @throws UnexpectedValueException
1457 public function doAtomicSection( $fname, callable
$callback );
1460 * Begin a transaction. If a transaction is already in progress,
1461 * that transaction will be committed before the new transaction is started.
1463 * Only call this from code with outer transcation scope.
1464 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1465 * Nesting of transactions is not supported.
1467 * Note that when the DBO_TRX flag is set (which is usually the case for web
1468 * requests, but not for maintenance scripts), any previous database query
1469 * will have started a transaction automatically.
1471 * Nesting of transactions is not supported. Attempts to nest transactions
1472 * will cause a warning, unless the current transaction was started
1473 * automatically because of the DBO_TRX flag.
1475 * @param string $fname Calling function name
1476 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1479 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1482 * Commits a transaction previously started using begin().
1483 * If no transaction is in progress, a warning is issued.
1485 * Only call this from code with outer transcation scope.
1486 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1487 * Nesting of transactions is not supported.
1489 * @param string $fname
1490 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1491 * constant to disable warnings about explicitly committing implicit transactions,
1492 * or calling commit when no transaction is in progress.
1494 * This will trigger an exception if there is an ongoing explicit transaction.
1496 * Only set the flush flag if you are sure that these warnings are not applicable,
1497 * and no explicit transactions are open.
1499 * @throws DBUnexpectedError
1501 public function commit( $fname = __METHOD__
, $flush = '' );
1504 * Rollback a transaction previously started using begin().
1505 * If no transaction is in progress, a warning is issued.
1507 * Only call this from code with outer transcation scope.
1508 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1509 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1510 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1511 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1513 * @param string $fname Calling function name
1514 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1515 * constant to disable warnings about calling rollback when no transaction is in
1516 * progress. This will silently break any ongoing explicit transaction. Only set the
1517 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1518 * @throws DBUnexpectedError
1519 * @since 1.23 Added $flush parameter
1521 public function rollback( $fname = __METHOD__
, $flush = '' );
1524 * Commit any transaction but error out if writes or callbacks are pending
1526 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1527 * see a new point-in-time of the database. This is useful when one of many transaction
1528 * rounds finished and significant time will pass in the script's lifetime. It is also
1529 * useful to call on a replica DB after waiting on replication to catch up to the master.
1531 * @param string $fname Calling function name
1532 * @throws DBUnexpectedError
1535 public function flushSnapshot( $fname = __METHOD__
);
1538 * List all tables on the database
1540 * @param string $prefix Only show tables with this prefix, e.g. mw_
1541 * @param string $fname Calling function name
1545 public function listTables( $prefix = null, $fname = __METHOD__
);
1548 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1549 * to the format used for inserting into timestamp fields in this DBMS.
1551 * The result is unquoted, and needs to be passed through addQuotes()
1552 * before it can be included in raw SQL.
1554 * @param string|int $ts
1558 public function timestamp( $ts = 0 );
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. If
1563 * NULL is input, it is passed through, allowing NULL values to be inserted
1564 * into timestamp fields.
1566 * The result is unquoted, and needs to be passed through addQuotes()
1567 * before it can be included in raw SQL.
1569 * @param string|int $ts
1573 public function timestampOrNull( $ts = null );
1576 * Ping the server and try to reconnect if it there is no connection
1578 * @param float|null &$rtt Value to store the estimated RTT [optional]
1579 * @return bool Success or failure
1581 public function ping( &$rtt = null );
1584 * Get replica DB lag. Currently supported only by MySQL.
1586 * Note that this function will generate a fatal error on many
1587 * installations. Most callers should use LoadBalancer::safeGetLag()
1590 * @return int|bool Database replication lag in seconds or false on error
1592 public function getLag();
1595 * Get the replica DB lag when the current transaction started
1596 * or a general lag estimate if not transaction is active
1598 * This is useful when transactions might use snapshot isolation
1599 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1600 * is this lag plus transaction duration. If they don't, it is still
1601 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1602 * indication of the staleness of subsequent reads.
1604 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1607 public function getSessionLagStatus();
1610 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1614 public function maxListLen();
1617 * Some DBMSs have a special format for inserting into blob fields, they
1618 * don't allow simple quoted strings to be inserted. To insert into such
1619 * a field, pass the data through this function before passing it to
1620 * IDatabase::insert().
1625 public function encodeBlob( $b );
1628 * Some DBMSs return a special placeholder object representing blob fields
1629 * in result objects. Pass the object through this function to return the
1632 * @param string|Blob $b
1635 public function decodeBlob( $b );
1638 * Override database's default behavior. $options include:
1639 * 'connTimeout' : Set the connection timeout value in seconds.
1640 * May be useful for very long batch queries such as
1641 * full-wiki dumps, where a single query reads out over
1644 * @param array $options
1647 public function setSessionOptions( array $options );
1650 * Set variables to be used in sourceFile/sourceStream, in preference to the
1651 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1652 * all. If it's set to false, $GLOBALS will be used.
1654 * @param bool|array $vars Mapping variable name to value.
1656 public function setSchemaVars( $vars );
1659 * Check to see if a named lock is available (non-blocking)
1661 * @param string $lockName Name of lock to poll
1662 * @param string $method Name of method calling us
1666 public function lockIsFree( $lockName, $method );
1669 * Acquire a named lock
1671 * Named locks are not related to transactions
1673 * @param string $lockName Name of lock to aquire
1674 * @param string $method Name of the calling method
1675 * @param int $timeout Acquisition timeout in seconds
1678 public function lock( $lockName, $method, $timeout = 5 );
1683 * Named locks are not related to transactions
1685 * @param string $lockName Name of lock to release
1686 * @param string $method Name of the calling method
1688 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1689 * by this thread (in which case the lock is not released), and NULL if the named
1690 * lock did not exist
1692 public function unlock( $lockName, $method );
1695 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1697 * Only call this from outer transcation scope and when only one DB will be affected.
1698 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1700 * This is suitiable for transactions that need to be serialized using cooperative locks,
1701 * where each transaction can see each others' changes. Any transaction is flushed to clear
1702 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1703 * the lock will be released unless a transaction is active. If one is active, then the lock
1704 * will be released when it either commits or rolls back.
1706 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1708 * @param string $lockKey Name of lock to release
1709 * @param string $fname Name of the calling method
1710 * @param int $timeout Acquisition timeout in seconds
1711 * @return ScopedCallback|null
1712 * @throws DBUnexpectedError
1715 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1718 * Check to see if a named lock used by lock() use blocking queues
1723 public function namedLocksEnqueue();
1726 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1727 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1728 * because "i" sorts after all numbers.
1732 public function getInfinity();
1735 * Encode an expiry time into the DBMS dependent format
1737 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1740 public function encodeExpiry( $expiry );
1743 * Decode an expiry time into a DBMS independent format
1745 * @param string $expiry DB timestamp field value for expiry
1746 * @param int $format TS_* constant, defaults to TS_MW
1749 public function decodeExpiry( $expiry, $format = TS_MW
);
1752 * Allow or deny "big selects" for this session only. This is done by setting
1753 * the sql_big_selects session variable.
1755 * This is a MySQL-specific feature.
1757 * @param bool|string $value True for allow, false for deny, or "default" to
1758 * restore the initial value
1760 public function setBigSelects( $value = true );
1763 * @return bool Whether this DB is read-only
1766 public function isReadOnly();
1769 * Make certain table names use their own database, schema, and table prefix
1770 * when passed into SQL queries pre-escaped and without a qualified database name
1772 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1773 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1775 * Calling this twice will completely clear any old table aliases. Also, note that
1776 * callers are responsible for making sure the schemas and databases actually exist.
1778 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1781 public function setTableAliases( array $aliases );