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 namespace Wikimedia\Rdbms
;
28 use Wikimedia\ScopedCallback
;
30 use DBConnectionError
;
31 use DBUnexpectedError
;
35 use UnexpectedValueException
;
39 * Basic database interface for live and lazy-loaded relation database handles
41 * @note: IDatabase and DBConnRef should be updated to reflect any changes
45 /** @var int Callback triggered immediately due to no active transaction */
46 const TRIGGER_IDLE
= 1;
47 /** @var int Callback triggered by COMMIT */
48 const TRIGGER_COMMIT
= 2;
49 /** @var int Callback triggered by ROLLBACK */
50 const TRIGGER_ROLLBACK
= 3;
52 /** @var string Transaction is requested by regular caller outside of the DB layer */
53 const TRANSACTION_EXPLICIT
= '';
54 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
55 const TRANSACTION_INTERNAL
= 'implicit';
57 /** @var string Transaction operation comes from service managing all DBs */
58 const FLUSHING_ALL_PEERS
= 'flush';
59 /** @var string Transaction operation comes from the database class internally */
60 const FLUSHING_INTERNAL
= 'flush';
62 /** @var string Do not remember the prior flags */
63 const REMEMBER_NOTHING
= '';
64 /** @var string Remember the prior flags */
65 const REMEMBER_PRIOR
= 'remember';
66 /** @var string Restore to the prior flag state */
67 const RESTORE_PRIOR
= 'prior';
68 /** @var string Restore to the initial flag state */
69 const RESTORE_INITIAL
= 'initial';
71 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
72 const ESTIMATE_TOTAL
= 'total';
73 /** @var string Estimate time to apply (scanning, applying) */
74 const ESTIMATE_DB_APPLY
= 'apply';
76 /** @var int Combine list with comma delimeters */
78 /** @var int Combine list with AND clauses */
80 /** @var int Convert map into a SET clause */
82 /** @var int Treat as field name and do not apply value escaping */
84 /** @var int Combine list with OR clauses */
87 /** @var int Enable debug logging */
89 /** @var int Disable query buffering (only one result set can be iterated at a time) */
90 const DBO_NOBUFFER
= 2;
91 /** @var int Ignore query errors (internal use only!) */
93 /** @var int Autoatically start transaction on first query (work with ILoadBalancer rounds) */
95 /** @var int Use DBO_TRX in non-CLI mode */
96 const DBO_DEFAULT
= 16;
97 /** @var int Use DB persistent connections if possible */
98 const DBO_PERSISTENT
= 32;
99 /** @var int DBA session mode; mostly for Oracle */
100 const DBO_SYSDBA
= 64;
101 /** @var int Schema file mode; mostly for Oracle */
102 const DBO_DDLMODE
= 128;
103 /** @var int Enable SSL/TLS in connection protocol */
105 /** @var int Enable compression in connection protocol */
106 const DBO_COMPRESS
= 512;
109 * A string describing the current software version, and possibly
110 * other details in a user-friendly way. Will be listed on Special:Version, etc.
111 * Use getServerVersion() to get machine-friendly information.
113 * @return string Version information from the database server
115 public function getServerInfo();
118 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
120 * Unbuffered queries are very troublesome in MySQL:
122 * - If another query is executed while the first query is being read
123 * out, the first query is killed. This means you can't call normal
124 * Database functions while you are reading an unbuffered query result
125 * from a normal Database connection.
127 * - Unbuffered queries cause the MySQL server to use large amounts of
128 * memory and to hold broad locks which block other queries.
130 * If you want to limit client-side memory, it's almost always better to
131 * split up queries into batches using a LIMIT clause than to switch off
134 * @param null|bool $buffer
135 * @return null|bool The previous value of the flag
137 public function bufferResults( $buffer = null );
140 * Gets the current transaction level.
142 * Historically, transactions were allowed to be "nested". This is no
143 * longer supported, so this function really only returns a boolean.
145 * @return int The previous value
147 public function trxLevel();
150 * Get the UNIX timestamp of the time that the transaction was established
152 * This can be used to reason about the staleness of SELECT data
153 * in REPEATABLE-READ transaction isolation level.
155 * @return float|null Returns null if there is not active transaction
158 public function trxTimestamp();
161 * @return bool Whether an explicit transaction or atomic sections are still open
164 public function explicitTrxActive();
167 * Get/set the table prefix.
168 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
169 * @return string The previous table prefix.
171 public function tablePrefix( $prefix = null );
174 * Get/set the db schema.
175 * @param string $schema The database schema to set, or omitted to leave it unchanged.
176 * @return string The previous db schema.
178 public function dbSchema( $schema = null );
181 * Get properties passed down from the server info array of the load
184 * @param string $name The entry of the info array to get, or null to get the
187 * @return array|mixed|null
189 public function getLBInfo( $name = null );
192 * Set the LB info array, or a member of it. If called with one parameter,
193 * the LB info array is set to that parameter. If it is called with two
194 * parameters, the member with the given name is set to the given value.
196 * @param string $name
197 * @param array $value
199 public function setLBInfo( $name, $value = null );
202 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
204 * @param IDatabase $conn
207 public function setLazyMasterHandle( IDatabase
$conn );
210 * Returns true if this database does an implicit sort when doing GROUP BY
214 public function implicitGroupby();
217 * Returns true if this database does an implicit order by when the column has an index
218 * For example: SELECT page_title FROM page LIMIT 1
222 public function implicitOrderby();
225 * Return the last query that went through IDatabase::query()
228 public function lastQuery();
231 * Returns true if the connection may have been used for write queries.
232 * Should return true if unsure.
236 public function doneWrites();
239 * Returns the last time the connection may have been used for write queries.
240 * Should return a timestamp if unsure.
242 * @return int|float UNIX timestamp or false
245 public function lastDoneWrites();
248 * @return bool Whether there is a transaction open with possible write queries
251 public function writesPending();
254 * Returns true if there is a transaction open with possible write
255 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
256 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
260 public function writesOrCallbacksPending();
263 * Get the time spend running write queries for this transaction
265 * High times could be due to scanning, updates, locking, and such
267 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
268 * @return float|bool Returns false if not transaction is active
271 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
274 * Get the list of method names that did write queries for this transaction
279 public function pendingWriteCallers();
282 * Is a connection to the database open?
285 public function isOpen();
288 * Set a flag for this connection
290 * @param int $flag DBO_* constants from Defines.php:
291 * - DBO_DEBUG: output some debug info (same as debug())
292 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
293 * - DBO_TRX: automatically start transactions
294 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
295 * and removes it in command line mode
296 * - DBO_PERSISTENT: use persistant database connection
297 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
299 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
302 * Clear a flag for this connection
304 * @param int $flag DBO_* constants from Defines.php:
305 * - DBO_DEBUG: output some debug info (same as debug())
306 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
307 * - DBO_TRX: automatically start transactions
308 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
309 * and removes it in command line mode
310 * - DBO_PERSISTENT: use persistant database connection
311 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
313 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
316 * Restore the flags to their prior state before the last setFlag/clearFlag call
318 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
321 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
324 * Returns a boolean whether the flag $flag is set for this connection
326 * @param int $flag DBO_* constants from Defines.php:
327 * - DBO_DEBUG: output some debug info (same as debug())
328 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
329 * - DBO_TRX: automatically start transactions
330 * - DBO_PERSISTENT: use persistant database connection
333 public function getFlag( $flag );
338 public function getDomainID();
341 * Alias for getDomainID()
345 public function getWikiID();
348 * Get the type of the DBMS, as it appears in $wgDBtype.
352 public function getType();
355 * Open a connection to the database. Usually aborts on failure
357 * @param string $server Database server host
358 * @param string $user Database user name
359 * @param string $password Database user password
360 * @param string $dbName Database name
362 * @throws DBConnectionError
364 public function open( $server, $user, $password, $dbName );
367 * Fetch the next row from the given result object, in object form.
368 * Fields can be retrieved with $row->fieldname, with fields acting like
370 * If no more rows are available, false is returned.
372 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
373 * @return stdClass|bool
374 * @throws DBUnexpectedError Thrown if the database returns an error
376 public function fetchObject( $res );
379 * Fetch the next row from the given result object, in associative array
380 * form. Fields are retrieved with $row['fieldname'].
381 * If no more rows are available, false is returned.
383 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
385 * @throws DBUnexpectedError Thrown if the database returns an error
387 public function fetchRow( $res );
390 * Get the number of rows in a result object
392 * @param mixed $res A SQL result
395 public function numRows( $res );
398 * Get the number of fields in a result object
399 * @see https://secure.php.net/mysql_num_fields
401 * @param mixed $res A SQL result
404 public function numFields( $res );
407 * Get a field name in a result object
408 * @see https://secure.php.net/mysql_field_name
410 * @param mixed $res A SQL result
414 public function fieldName( $res, $n );
417 * Get the inserted value of an auto-increment row
419 * The value inserted should be fetched from nextSequenceValue()
422 * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
423 * $dbw->insert( 'page', [ 'page_id' => $id ] );
424 * $id = $dbw->insertId();
428 public function insertId();
431 * Change the position of the cursor in a result object
432 * @see https://secure.php.net/mysql_data_seek
434 * @param mixed $res A SQL result
437 public function dataSeek( $res, $row );
440 * Get the last error number
441 * @see https://secure.php.net/mysql_errno
445 public function lastErrno();
448 * Get a description of the last error
449 * @see https://secure.php.net/mysql_error
453 public function lastError();
456 * mysql_fetch_field() wrapper
457 * Returns false if the field doesn't exist
459 * @param string $table Table name
460 * @param string $field Field name
464 public function fieldInfo( $table, $field );
467 * Get the number of rows affected by the last write query
468 * @see https://secure.php.net/mysql_affected_rows
472 public function affectedRows();
475 * Returns a wikitext link to the DB's website, e.g.,
476 * return "[https://www.mysql.com/ MySQL]";
477 * Should at least contain plain text, if for some reason
478 * your database has no website.
480 * @return string Wikitext of a link to the server software's web site
482 public function getSoftwareLink();
485 * A string describing the current software version, like from
486 * mysql_get_server_info().
488 * @return string Version information from the database server.
490 public function getServerVersion();
493 * Closes a database connection.
494 * if it is open : commits any open transactions
497 * @return bool Operation success. true if already closed.
499 public function close();
502 * @param string $error Fallback error message, used if none is given by DB
503 * @throws DBConnectionError
505 public function reportConnectionError( $error = 'Unknown error' );
508 * Run an SQL query and return the result. Normally throws a DBQueryError
509 * on failure. If errors are ignored, returns false instead.
511 * In new code, the query wrappers select(), insert(), update(), delete(),
512 * etc. should be used where possible, since they give much better DBMS
513 * independence and automatically quote or validate user input in a variety
514 * of contexts. This function is generally only useful for queries which are
515 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
518 * However, the query wrappers themselves should call this function.
520 * @param string $sql SQL query
521 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
522 * comment (you can use __METHOD__ or add some extra info)
523 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
524 * maybe best to catch the exception instead?
526 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
527 * for a successful read query, or false on failure if $tempIgnore set
529 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
532 * Report a query error. Log the error, and if neither the object ignore
533 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
535 * @param string $error
538 * @param string $fname
539 * @param bool $tempIgnore
540 * @throws DBQueryError
542 public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
545 * Free a result object returned by query() or select(). It's usually not
546 * necessary to call this, just use unset() or let the variable holding
547 * the result object go out of scope.
549 * @param mixed $res A SQL result
551 public function freeResult( $res );
554 * A SELECT wrapper which returns a single field from a single result row.
556 * Usually throws a DBQueryError on failure. If errors are explicitly
557 * ignored, returns false on failure.
559 * If no result rows are returned from the query, false is returned.
561 * @param string|array $table Table name. See IDatabase::select() for details.
562 * @param string $var The field name to select. This must be a valid SQL
563 * fragment: do not use unvalidated user input.
564 * @param string|array $cond The condition array. See IDatabase::select() for details.
565 * @param string $fname The function name of the caller.
566 * @param string|array $options The query options. See IDatabase::select() for details.
568 * @return bool|mixed The value from the field, or false on failure.
570 public function selectField(
571 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
575 * A SELECT wrapper which returns a list of single field values from result rows.
577 * Usually throws a DBQueryError on failure. If errors are explicitly
578 * ignored, returns false on failure.
580 * If no result rows are returned from the query, false is returned.
582 * @param string|array $table Table name. See IDatabase::select() for details.
583 * @param string $var The field name to select. This must be a valid SQL
584 * fragment: do not use unvalidated user input.
585 * @param string|array $cond The condition array. See IDatabase::select() for details.
586 * @param string $fname The function name of the caller.
587 * @param string|array $options The query options. See IDatabase::select() for details.
589 * @return bool|array The values from the field, or false on failure
592 public function selectFieldValues(
593 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
597 * Execute a SELECT query constructed using the various parameters provided.
598 * See below for full details of the parameters.
600 * @param string|array $table Table name
601 * @param string|array $vars Field names
602 * @param string|array $conds Conditions
603 * @param string $fname Caller function name
604 * @param array $options Query options
605 * @param array $join_conds Join conditions
608 * @param string|array $table
610 * May be either an array of table names, or a single string holding a table
611 * name. If an array is given, table aliases can be specified, for example:
615 * This includes the user table in the query, with the alias "a" available
616 * for use in field names (e.g. a.user_name).
618 * All of the table names given here are automatically run through
619 * Database::tableName(), which causes the table prefix (if any) to be
620 * added, and various other table name mappings to be performed.
622 * Do not use untrusted user input as a table name. Alias names should
623 * not have characters outside of the Basic multilingual plane.
625 * @param string|array $vars
627 * May be either a field name or an array of field names. The field names
628 * can be complete fragments of SQL, for direct inclusion into the SELECT
629 * query. If an array is given, field aliases can be specified, for example:
631 * [ 'maxrev' => 'MAX(rev_id)' ]
633 * This includes an expression with the alias "maxrev" in the query.
635 * If an expression is given, care must be taken to ensure that it is
638 * Untrusted user input must not be passed to this parameter.
640 * @param string|array $conds
642 * May be either a string containing a single condition, or an array of
643 * conditions. If an array is given, the conditions constructed from each
644 * element are combined with AND.
646 * Array elements may take one of two forms:
648 * - Elements with a numeric key are interpreted as raw SQL fragments.
649 * - Elements with a string key are interpreted as equality conditions,
650 * where the key is the field name.
651 * - If the value of such an array element is a scalar (such as a
652 * string), it will be treated as data and thus quoted appropriately.
653 * If it is null, an IS NULL clause will be added.
654 * - If the value is an array, an IN (...) clause will be constructed
655 * from its non-null elements, and an IS NULL clause will be added
656 * if null is present, such that the field may match any of the
657 * elements in the array. The non-null elements will be quoted.
659 * Note that expressions are often DBMS-dependent in their syntax.
660 * DBMS-independent wrappers are provided for constructing several types of
661 * expression commonly used in condition queries. See:
662 * - IDatabase::buildLike()
663 * - IDatabase::conditional()
665 * Untrusted user input is safe in the values of string keys, however untrusted
666 * input must not be used in the array key names or in the values of numeric keys.
667 * Escaping of untrusted input used in values of numeric keys should be done via
668 * IDatabase::addQuotes()
670 * @param string|array $options
672 * Optional: Array of query options. Boolean options are specified by
673 * including them in the array as a string value with a numeric key, for
678 * The supported options are:
680 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
681 * with LIMIT can theoretically be used for paging through a result set,
682 * but this is discouraged for performance reasons.
684 * - LIMIT: Integer: return at most this many rows. The rows are sorted
685 * and then the first rows are taken until the limit is reached. LIMIT
686 * is applied to a result set after OFFSET.
688 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
689 * changed until the next COMMIT.
691 * - DISTINCT: Boolean: return only unique result rows.
693 * - GROUP BY: May be either an SQL fragment string naming a field or
694 * expression to group by, or an array of such SQL fragments.
696 * - HAVING: May be either an string containing a HAVING clause or an array of
697 * conditions building the HAVING clause. If an array is given, the conditions
698 * constructed from each element are combined with AND.
700 * - ORDER BY: May be either an SQL fragment giving a field name or
701 * expression to order by, or an array of such SQL fragments.
703 * - USE INDEX: This may be either a string giving the index name to use
704 * for the query, or an array. If it is an associative array, each key
705 * gives the table name (or alias), each value gives the index name to
706 * use for that table. All strings are SQL fragments and so should be
707 * validated by the caller.
709 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
712 * And also the following boolean MySQL extensions, see the MySQL manual
715 * - LOCK IN SHARE MODE
719 * - SQL_BUFFER_RESULT
721 * - SQL_CALC_FOUND_ROWS
726 * @param string|array $join_conds
728 * Optional associative array of table-specific join conditions. In the
729 * most common case, this is unnecessary, since the join condition can be
730 * in $conds. However, it is useful for doing a LEFT JOIN.
732 * The key of the array contains the table name or alias. The value is an
733 * array with two elements, numbered 0 and 1. The first gives the type of
734 * join, the second is the same as the $conds parameter. Thus it can be
735 * an SQL fragment, or an array where the string keys are equality and the
736 * numeric keys are SQL fragments all AND'd together. For example:
738 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
740 * @return IResultWrapper|bool If the query returned no rows, a IResultWrapper
741 * with no rows in it will be returned. If there was a query error, a
742 * DBQueryError exception will be thrown, except if the "ignore errors"
743 * option was set, in which case false will be returned.
745 public function select(
746 $table, $vars, $conds = '', $fname = __METHOD__
,
747 $options = [], $join_conds = []
751 * The equivalent of IDatabase::select() except that the constructed SQL
752 * is returned, instead of being immediately executed. This can be useful for
753 * doing UNION queries, where the SQL text of each query is needed. In general,
754 * however, callers outside of Database classes should just use select().
756 * @param string|array $table Table name
757 * @param string|array $vars Field names
758 * @param string|array $conds Conditions
759 * @param string $fname Caller function name
760 * @param string|array $options Query options
761 * @param string|array $join_conds Join conditions
763 * @return string SQL query string.
764 * @see IDatabase::select()
766 public function selectSQLText(
767 $table, $vars, $conds = '', $fname = __METHOD__
,
768 $options = [], $join_conds = []
772 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
773 * that a single row object is returned. If the query returns no rows,
776 * @param string|array $table Table name
777 * @param string|array $vars Field names
778 * @param array $conds Conditions
779 * @param string $fname Caller function name
780 * @param string|array $options Query options
781 * @param array|string $join_conds Join conditions
783 * @return stdClass|bool
785 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
786 $options = [], $join_conds = []
790 * Estimate the number of rows in dataset
792 * MySQL allows you to estimate the number of rows that would be returned
793 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
794 * index cardinality statistics, and is notoriously inaccurate, especially
795 * when large numbers of rows have recently been added or deleted.
797 * For DBMSs that don't support fast result size estimation, this function
798 * will actually perform the SELECT COUNT(*).
800 * Takes the same arguments as IDatabase::select().
802 * @param string $table Table name
803 * @param string $vars Unused
804 * @param array|string $conds Filters on the table
805 * @param string $fname Function name for profiling
806 * @param array $options Options for select
807 * @return int Row count
809 public function estimateRowCount(
810 $table, $vars = '*', $conds = '', $fname = __METHOD__
, $options = []
814 * Get the number of rows in dataset
816 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
818 * Takes the same arguments as IDatabase::select().
820 * @since 1.27 Added $join_conds parameter
822 * @param array|string $tables Table names
823 * @param string $vars Unused
824 * @param array|string $conds Filters on the table
825 * @param string $fname Function name for profiling
826 * @param array $options Options for select
827 * @param array $join_conds Join conditions (since 1.27)
828 * @return int Row count
830 public function selectRowCount(
831 $tables, $vars = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
835 * Determines whether a field exists in a table
837 * @param string $table Table name
838 * @param string $field Filed to check on that table
839 * @param string $fname Calling function name (optional)
840 * @return bool Whether $table has filed $field
842 public function fieldExists( $table, $field, $fname = __METHOD__
);
845 * Determines whether an index exists
846 * Usually throws a DBQueryError on failure
847 * If errors are explicitly ignored, returns NULL on failure
849 * @param string $table
850 * @param string $index
851 * @param string $fname
854 public function indexExists( $table, $index, $fname = __METHOD__
);
857 * Query whether a given table exists
859 * @param string $table
860 * @param string $fname
863 public function tableExists( $table, $fname = __METHOD__
);
866 * Determines if a given index is unique
868 * @param string $table
869 * @param string $index
873 public function indexUnique( $table, $index );
876 * INSERT wrapper, inserts an array into a table.
880 * - A single associative array. The array keys are the field names, and
881 * the values are the values to insert. The values are treated as data
882 * and will be quoted appropriately. If NULL is inserted, this will be
883 * converted to a database NULL.
884 * - An array with numeric keys, holding a list of associative arrays.
885 * This causes a multi-row INSERT on DBMSs that support it. The keys in
886 * each subarray must be identical to each other, and in the same order.
888 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
891 * $options is an array of options, with boolean options encoded as values
892 * with numeric keys, in the same style as $options in
893 * IDatabase::select(). Supported options are:
895 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
896 * any rows which cause duplicate key errors are not inserted. It's
897 * possible to determine how many rows were successfully inserted using
898 * IDatabase::affectedRows().
900 * @param string $table Table name. This will be passed through
901 * Database::tableName().
902 * @param array $a Array of rows to insert
903 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
904 * @param array $options Array of options
908 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
911 * UPDATE wrapper. Takes a condition array and a SET array.
913 * @param string $table Name of the table to UPDATE. This will be passed through
914 * Database::tableName().
915 * @param array $values An array of values to SET. For each array element,
916 * the key gives the field name, and the value gives the data to set
917 * that field to. The data will be quoted by IDatabase::addQuotes().
918 * Values with integer keys form unquoted SET statements, which can be used for
919 * things like "field = field + 1" or similar computed values.
920 * @param array $conds An array of conditions (WHERE). See
921 * IDatabase::select() for the details of the format of condition
922 * arrays. Use '*' to update all rows.
923 * @param string $fname The function name of the caller (from __METHOD__),
924 * for logging and profiling.
925 * @param array $options An array of UPDATE options, can be:
926 * - IGNORE: Ignore unique key conflicts
927 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
930 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
933 * Makes an encoded list of strings from an array
935 * These can be used to make conjunctions or disjunctions on SQL condition strings
936 * derived from an array (see IDatabase::select() $conds documentation).
940 * $sql = $db->makeList( [
942 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
943 * ], $db::LIST_AND );
945 * This would set $sql to "rev_user = '$id' AND (rev_minor = '1' OR rev_len < '500')"
947 * @param array $a Containing the data
948 * @param int $mode IDatabase class constant:
949 * - IDatabase::LIST_COMMA: Comma separated, no field names
950 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
951 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
952 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
953 * - IDatabase::LIST_NAMES: Comma separated field names
957 public function makeList( $a, $mode = self
::LIST_COMMA
);
960 * Build a partial where clause from a 2-d array such as used for LinkBatch.
961 * The keys on each level may be either integers or strings.
963 * @param array $data Organized as 2-d
964 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
965 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
966 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
967 * @return string|bool SQL fragment, or false if no items in array
969 public function makeWhereFrom2d( $data, $baseKey, $subKey );
972 * Return aggregated value alias
974 * @param array $valuedata
975 * @param string $valuename
979 public function aggregateValue( $valuedata, $valuename = 'value' );
982 * @param string $field
985 public function bitNot( $field );
988 * @param string $fieldLeft
989 * @param string $fieldRight
992 public function bitAnd( $fieldLeft, $fieldRight );
995 * @param string $fieldLeft
996 * @param string $fieldRight
999 public function bitOr( $fieldLeft, $fieldRight );
1002 * Build a concatenation list to feed into a SQL query
1003 * @param array $stringList List of raw SQL expressions; caller is
1004 * responsible for any quoting
1007 public function buildConcat( $stringList );
1010 * Build a GROUP_CONCAT or equivalent statement for a query.
1012 * This is useful for combining a field for several rows into a single string.
1013 * NULL values will not appear in the output, duplicated values will appear,
1014 * and the resulting delimiter-separated values have no defined sort order.
1015 * Code using the results may need to use the PHP unique() or sort() methods.
1017 * @param string $delim Glue to bind the results together
1018 * @param string|array $table Table name
1019 * @param string $field Field name
1020 * @param string|array $conds Conditions
1021 * @param string|array $join_conds Join conditions
1022 * @return string SQL text
1025 public function buildGroupConcatField(
1026 $delim, $table, $field, $conds = '', $join_conds = []
1030 * @param string $field Field or column to cast
1034 public function buildStringCast( $field );
1037 * Change the current database
1040 * @return bool Success or failure
1042 public function selectDB( $db );
1045 * Get the current DB name
1048 public function getDBname();
1051 * Get the server hostname or IP address
1054 public function getServer();
1057 * Adds quotes and backslashes.
1059 * @param string|int|null|bool|Blob $s
1060 * @return string|int
1062 public function addQuotes( $s );
1065 * LIKE statement wrapper, receives a variable-length argument list with
1066 * parts of pattern to match containing either string literals that will be
1067 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1068 * the function could be provided with an array of aforementioned
1071 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1072 * a LIKE clause that searches for subpages of 'My page title'.
1074 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1075 * $query .= $dbr->buildLike( $pattern );
1078 * @return string Fully built LIKE statement
1080 public function buildLike();
1083 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1087 public function anyChar();
1090 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1094 public function anyString();
1097 * Returns an appropriately quoted sequence value for inserting a new row.
1098 * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1099 * subclass will return an integer, and save the value for insertId()
1101 * Any implementation of this function should *not* involve reusing
1102 * sequence numbers created for rolled-back transactions.
1103 * See https://bugs.mysql.com/bug.php?id=30767 for details.
1104 * @param string $seqName
1107 public function nextSequenceValue( $seqName );
1110 * REPLACE query wrapper.
1112 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1113 * except that when there is a duplicate key error, the old row is deleted
1114 * and the new row is inserted in its place.
1116 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1117 * perform the delete, we need to know what the unique indexes are so that
1118 * we know how to find the conflicting rows.
1120 * It may be more efficient to leave off unique indexes which are unlikely
1121 * to collide. However if you do this, you run the risk of encountering
1122 * errors which wouldn't have occurred in MySQL.
1124 * @param string $table The table to replace the row(s) in.
1125 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1126 * a field name or an array of field names
1127 * @param array $rows Can be either a single row to insert, or multiple rows,
1128 * in the same format as for IDatabase::insert()
1129 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1131 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1134 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1136 * This updates any conflicting rows (according to the unique indexes) using
1137 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1139 * $rows may be either:
1140 * - A single associative array. The array keys are the field names, and
1141 * the values are the values to insert. The values are treated as data
1142 * and will be quoted appropriately. If NULL is inserted, this will be
1143 * converted to a database NULL.
1144 * - An array with numeric keys, holding a list of associative arrays.
1145 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1146 * each subarray must be identical to each other, and in the same order.
1148 * It may be more efficient to leave off unique indexes which are unlikely
1149 * to collide. However if you do this, you run the risk of encountering
1150 * errors which wouldn't have occurred in MySQL.
1152 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1157 * @param string $table Table name. This will be passed through Database::tableName().
1158 * @param array $rows A single row or list of rows to insert
1159 * @param array $uniqueIndexes List of single field names or field name tuples
1160 * @param array $set An array of values to SET. For each array element, the
1161 * key gives the field name, and the value gives the data to set that
1162 * field to. The data will be quoted by IDatabase::addQuotes().
1163 * Values with integer keys form unquoted SET statements, which can be used for
1164 * things like "field = field + 1" or similar computed values.
1165 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1169 public function upsert(
1170 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1174 * DELETE where the condition is a join.
1176 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1177 * we use sub-selects
1179 * For safety, an empty $conds will not delete everything. If you want to
1180 * delete all rows where the join condition matches, set $conds='*'.
1182 * DO NOT put the join condition in $conds.
1184 * @param string $delTable The table to delete from.
1185 * @param string $joinTable The other table.
1186 * @param string $delVar The variable to join on, in the first table.
1187 * @param string $joinVar The variable to join on, in the second table.
1188 * @param array $conds Condition array of field names mapped to variables,
1189 * ANDed together in the WHERE clause
1190 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1191 * @throws DBUnexpectedError
1193 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1198 * DELETE query wrapper.
1200 * @param string $table Table name
1201 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1202 * for the format. Use $conds == "*" to delete all rows
1203 * @param string $fname Name of the calling function
1204 * @throws DBUnexpectedError
1205 * @return bool|IResultWrapper
1207 public function delete( $table, $conds, $fname = __METHOD__
);
1210 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1211 * into another table.
1213 * @param string $destTable The table name to insert into
1214 * @param string|array $srcTable May be either a table name, or an array of table names
1215 * to include in a join.
1217 * @param array $varMap Must be an associative array of the form
1218 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1219 * rather than field names, but strings should be quoted with
1220 * IDatabase::addQuotes()
1222 * @param array $conds Condition array. See $conds in IDatabase::select() for
1223 * the details of the format of condition arrays. May be "*" to copy the
1226 * @param string $fname The function name of the caller, from __METHOD__
1228 * @param array $insertOptions Options for the INSERT part of the query, see
1229 * IDatabase::insert() for details.
1230 * @param array $selectOptions Options for the SELECT part of the query, see
1231 * IDatabase::select() for details.
1233 * @return IResultWrapper
1235 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1236 $fname = __METHOD__
,
1237 $insertOptions = [], $selectOptions = []
1241 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1242 * within the UNION construct.
1245 public function unionSupportsOrderAndLimit();
1248 * Construct a UNION query
1249 * This is used for providing overload point for other DB abstractions
1250 * not compatible with the MySQL syntax.
1251 * @param array $sqls SQL statements to combine
1252 * @param bool $all Use UNION ALL
1253 * @return string SQL fragment
1255 public function unionQueries( $sqls, $all );
1258 * Returns an SQL expression for a simple conditional. This doesn't need
1259 * to be overridden unless CASE isn't supported in your DBMS.
1261 * @param string|array $cond SQL expression which will result in a boolean value
1262 * @param string $trueVal SQL expression to return if true
1263 * @param string $falseVal SQL expression to return if false
1264 * @return string SQL fragment
1266 public function conditional( $cond, $trueVal, $falseVal );
1269 * Returns a comand for str_replace function in SQL query.
1270 * Uses REPLACE() in MySQL
1272 * @param string $orig Column to modify
1273 * @param string $old Column to seek
1274 * @param string $new Column to replace with
1278 public function strreplace( $orig, $old, $new );
1281 * Determines how long the server has been up
1285 public function getServerUptime();
1288 * Determines if the last failure was due to a deadlock
1292 public function wasDeadlock();
1295 * Determines if the last failure was due to a lock timeout
1299 public function wasLockTimeout();
1302 * Determines if the last query error was due to a dropped connection and should
1303 * be dealt with by pinging the connection and reissuing the query.
1307 public function wasErrorReissuable();
1310 * Determines if the last failure was due to the database being read-only.
1314 public function wasReadOnlyError();
1317 * Wait for the replica DB to catch up to a given master position
1319 * @param DBMasterPos $pos
1320 * @param int $timeout The maximum number of seconds to wait for synchronisation
1321 * @return int|null Zero if the replica DB was past that position already,
1322 * greater than zero if we waited for some period of time, less than
1323 * zero if it timed out, and null on error
1325 public function masterPosWait( DBMasterPos
$pos, $timeout );
1328 * Get the replication position of this replica DB
1330 * @return DBMasterPos|bool False if this is not a replica DB.
1332 public function getReplicaPos();
1335 * Get the position of this master
1337 * @return DBMasterPos|bool False if this is not a master
1339 public function getMasterPos();
1342 * @return bool Whether the DB is marked as read-only server-side
1345 public function serverIsReadOnly();
1348 * Run a callback as soon as the current transaction commits or rolls back.
1349 * An error is thrown if no transaction is pending. Queries in the function will run in
1350 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1353 * This is useful for combining cooperative locks and DB transactions.
1355 * The callback takes one argument:
1356 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1358 * @param callable $callback
1359 * @param string $fname Caller name
1363 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1366 * Run a callback as soon as there is no transaction pending.
1367 * If there is a transaction and it is rolled back, then the callback is cancelled.
1368 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1369 * Callbacks must commit any transactions that they begin.
1371 * This is useful for updates to different systems or when separate transactions are needed.
1372 * For example, one might want to enqueue jobs into a system outside the database, but only
1373 * after the database is updated so that the jobs will see the data when they actually run.
1374 * It can also be used for updates that easily cause deadlocks if locks are held too long.
1376 * Updates will execute in the order they were enqueued.
1378 * The callback takes one argument:
1379 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1381 * @param callable $callback
1382 * @param string $fname Caller name
1385 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1388 * Run a callback before the current transaction commits or now if there is none.
1389 * If there is a transaction and it is rolled back, then the callback is cancelled.
1390 * Callbacks must not start nor commit any transactions. If no transaction is active,
1391 * then a transaction will wrap the callback.
1393 * This is useful for updates that easily cause deadlocks if locks are held too long
1394 * but where atomicity is strongly desired for these updates and some related updates.
1396 * Updates will execute in the order they were enqueued.
1398 * @param callable $callback
1399 * @param string $fname Caller name
1402 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1405 * Run a callback each time any transaction commits or rolls back
1407 * The callback takes two arguments:
1408 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1409 * - This IDatabase object
1410 * Callbacks must commit any transactions that they begin.
1412 * Registering a callback here will not affect writesOrCallbacks() pending
1414 * @param string $name Callback name
1415 * @param callable|null $callback Use null to unset a listener
1419 public function setTransactionListener( $name, callable
$callback = null );
1422 * Begin an atomic section of statements
1424 * If a transaction has been started already, just keep track of the given
1425 * section name to make sure the transaction is not committed pre-maturely.
1426 * This function can be used in layers (with sub-sections), so use a stack
1427 * to keep track of the different atomic sections. If there is no transaction,
1428 * start one implicitly.
1430 * The goal of this function is to create an atomic section of SQL queries
1431 * without having to start a new transaction if it already exists.
1433 * All atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1434 * and any database transactions cannot be began or committed until all atomic
1435 * levels are closed. There is no such thing as implicitly opening or closing
1436 * an atomic section.
1439 * @param string $fname
1442 public function startAtomic( $fname = __METHOD__
);
1445 * Ends an atomic section of SQL statements
1447 * Ends the next section of atomic SQL statements and commits the transaction
1451 * @see IDatabase::startAtomic
1452 * @param string $fname
1455 public function endAtomic( $fname = __METHOD__
);
1458 * Run a callback to do an atomic set of updates for this database
1460 * The $callback takes the following arguments:
1461 * - This database object
1462 * - The value of $fname
1464 * If any exception occurs in the callback, then rollback() will be called and the error will
1465 * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1466 * In any case, such errors are expected to terminate the request, without any outside caller
1467 * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1468 * atomic section and uncommitted updates, which trashes the current request, requiring an
1469 * error to be displayed.
1471 * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1473 * @see Database::startAtomic
1474 * @see Database::endAtomic
1476 * @param string $fname Caller name (usually __METHOD__)
1477 * @param callable $callback Callback that issues DB updates
1478 * @return mixed $res Result of the callback (since 1.28)
1480 * @throws RuntimeException
1481 * @throws UnexpectedValueException
1484 public function doAtomicSection( $fname, callable
$callback );
1487 * Begin a transaction. If a transaction is already in progress,
1488 * that transaction will be committed before the new transaction is started.
1490 * Only call this from code with outer transcation scope.
1491 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1492 * Nesting of transactions is not supported.
1494 * Note that when the DBO_TRX flag is set (which is usually the case for web
1495 * requests, but not for maintenance scripts), any previous database query
1496 * will have started a transaction automatically.
1498 * Nesting of transactions is not supported. Attempts to nest transactions
1499 * will cause a warning, unless the current transaction was started
1500 * automatically because of the DBO_TRX flag.
1502 * @param string $fname Calling function name
1503 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1506 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1509 * Commits a transaction previously started using begin().
1510 * If no transaction is in progress, a warning is issued.
1512 * Only call this from code with outer transcation scope.
1513 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1514 * Nesting of transactions is not supported.
1516 * @param string $fname
1517 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1518 * constant to disable warnings about explicitly committing implicit transactions,
1519 * or calling commit when no transaction is in progress.
1521 * This will trigger an exception if there is an ongoing explicit transaction.
1523 * Only set the flush flag if you are sure that these warnings are not applicable,
1524 * and no explicit transactions are open.
1526 * @throws DBUnexpectedError
1528 public function commit( $fname = __METHOD__
, $flush = '' );
1531 * Rollback a transaction previously started using begin().
1532 * If no transaction is in progress, a warning is issued.
1534 * Only call this from code with outer transcation scope.
1535 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1536 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1537 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1538 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1540 * @param string $fname Calling function name
1541 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1542 * constant to disable warnings about calling rollback when no transaction is in
1543 * progress. This will silently break any ongoing explicit transaction. Only set the
1544 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1545 * @throws DBUnexpectedError
1546 * @since 1.23 Added $flush parameter
1548 public function rollback( $fname = __METHOD__
, $flush = '' );
1551 * Commit any transaction but error out if writes or callbacks are pending
1553 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1554 * see a new point-in-time of the database. This is useful when one of many transaction
1555 * rounds finished and significant time will pass in the script's lifetime. It is also
1556 * useful to call on a replica DB after waiting on replication to catch up to the master.
1558 * @param string $fname Calling function name
1559 * @throws DBUnexpectedError
1562 public function flushSnapshot( $fname = __METHOD__
);
1565 * List all tables on the database
1567 * @param string $prefix Only show tables with this prefix, e.g. mw_
1568 * @param string $fname Calling function name
1572 public function listTables( $prefix = null, $fname = __METHOD__
);
1575 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1576 * to the format used for inserting into timestamp fields in this DBMS.
1578 * The result is unquoted, and needs to be passed through addQuotes()
1579 * before it can be included in raw SQL.
1581 * @param string|int $ts
1585 public function timestamp( $ts = 0 );
1588 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1589 * to the format used for inserting into timestamp fields in this DBMS. If
1590 * NULL is input, it is passed through, allowing NULL values to be inserted
1591 * into timestamp fields.
1593 * The result is unquoted, and needs to be passed through addQuotes()
1594 * before it can be included in raw SQL.
1596 * @param string|int $ts
1600 public function timestampOrNull( $ts = null );
1603 * Ping the server and try to reconnect if it there is no connection
1605 * @param float|null &$rtt Value to store the estimated RTT [optional]
1606 * @return bool Success or failure
1608 public function ping( &$rtt = null );
1611 * Get replica DB lag. Currently supported only by MySQL.
1613 * Note that this function will generate a fatal error on many
1614 * installations. Most callers should use LoadBalancer::safeGetLag()
1617 * @return int|bool Database replication lag in seconds or false on error
1619 public function getLag();
1622 * Get the replica DB lag when the current transaction started
1623 * or a general lag estimate if not transaction is active
1625 * This is useful when transactions might use snapshot isolation
1626 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1627 * is this lag plus transaction duration. If they don't, it is still
1628 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1629 * indication of the staleness of subsequent reads.
1631 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1634 public function getSessionLagStatus();
1637 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1641 public function maxListLen();
1644 * Some DBMSs have a special format for inserting into blob fields, they
1645 * don't allow simple quoted strings to be inserted. To insert into such
1646 * a field, pass the data through this function before passing it to
1647 * IDatabase::insert().
1650 * @return string|Blob
1652 public function encodeBlob( $b );
1655 * Some DBMSs return a special placeholder object representing blob fields
1656 * in result objects. Pass the object through this function to return the
1659 * @param string|Blob $b
1662 public function decodeBlob( $b );
1665 * Override database's default behavior. $options include:
1666 * 'connTimeout' : Set the connection timeout value in seconds.
1667 * May be useful for very long batch queries such as
1668 * full-wiki dumps, where a single query reads out over
1671 * @param array $options
1674 public function setSessionOptions( array $options );
1677 * Set variables to be used in sourceFile/sourceStream, in preference to the
1678 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1679 * all. If it's set to false, $GLOBALS will be used.
1681 * @param bool|array $vars Mapping variable name to value.
1683 public function setSchemaVars( $vars );
1686 * Check to see if a named lock is available (non-blocking)
1688 * @param string $lockName Name of lock to poll
1689 * @param string $method Name of method calling us
1693 public function lockIsFree( $lockName, $method );
1696 * Acquire a named lock
1698 * Named locks are not related to transactions
1700 * @param string $lockName Name of lock to aquire
1701 * @param string $method Name of the calling method
1702 * @param int $timeout Acquisition timeout in seconds
1705 public function lock( $lockName, $method, $timeout = 5 );
1710 * Named locks are not related to transactions
1712 * @param string $lockName Name of lock to release
1713 * @param string $method Name of the calling method
1715 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1716 * by this thread (in which case the lock is not released), and NULL if the named
1717 * lock did not exist
1719 public function unlock( $lockName, $method );
1722 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1724 * Only call this from outer transcation scope and when only one DB will be affected.
1725 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1727 * This is suitiable for transactions that need to be serialized using cooperative locks,
1728 * where each transaction can see each others' changes. Any transaction is flushed to clear
1729 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1730 * the lock will be released unless a transaction is active. If one is active, then the lock
1731 * will be released when it either commits or rolls back.
1733 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1735 * @param string $lockKey Name of lock to release
1736 * @param string $fname Name of the calling method
1737 * @param int $timeout Acquisition timeout in seconds
1738 * @return ScopedCallback|null
1739 * @throws DBUnexpectedError
1742 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1745 * Check to see if a named lock used by lock() use blocking queues
1750 public function namedLocksEnqueue();
1753 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1754 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1755 * because "i" sorts after all numbers.
1759 public function getInfinity();
1762 * Encode an expiry time into the DBMS dependent format
1764 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1767 public function encodeExpiry( $expiry );
1770 * Decode an expiry time into a DBMS independent format
1772 * @param string $expiry DB timestamp field value for expiry
1773 * @param int $format TS_* constant, defaults to TS_MW
1776 public function decodeExpiry( $expiry, $format = TS_MW
);
1779 * Allow or deny "big selects" for this session only. This is done by setting
1780 * the sql_big_selects session variable.
1782 * This is a MySQL-specific feature.
1784 * @param bool|string $value True for allow, false for deny, or "default" to
1785 * restore the initial value
1787 public function setBigSelects( $value = true );
1790 * @return bool Whether this DB is read-only
1793 public function isReadOnly();
1796 * Make certain table names use their own database, schema, and table prefix
1797 * when passed into SQL queries pre-escaped and without a qualified database name
1799 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1800 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1802 * Calling this twice will completely clear any old table aliases. Also, note that
1803 * callers are responsible for making sure the schemas and databases actually exist.
1805 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1808 public function setTableAliases( array $aliases );
1811 class_alias( IDatabase
::class, 'IDatabase' );