3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
16 * http://www.gnu.org/copyleft/gpl.html
20 namespace Wikimedia\Rdbms
;
22 use InvalidArgumentException
;
23 use Wikimedia\ScopedCallback
;
25 use UnexpectedValueException
;
29 * @defgroup Database Database
30 * This group deals with database interface functions
31 * and query specifics/optimisations.
34 * Basic database interface for live and lazy-loaded relation database handles
36 * @note: IDatabase and DBConnRef should be updated to reflect any changes
40 /** @var int Callback triggered immediately due to no active transaction */
41 const TRIGGER_IDLE
= 1;
42 /** @var int Callback triggered by COMMIT */
43 const TRIGGER_COMMIT
= 2;
44 /** @var int Callback triggered by ROLLBACK */
45 const TRIGGER_ROLLBACK
= 3;
47 /** @var string Transaction is requested by regular caller outside of the DB layer */
48 const TRANSACTION_EXPLICIT
= '';
49 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
50 const TRANSACTION_INTERNAL
= 'implicit';
52 /** @var string Transaction operation comes from service managing all DBs */
53 const FLUSHING_ALL_PEERS
= 'flush';
54 /** @var string Transaction operation comes from the database class internally */
55 const FLUSHING_INTERNAL
= 'flush';
57 /** @var string Do not remember the prior flags */
58 const REMEMBER_NOTHING
= '';
59 /** @var string Remember the prior flags */
60 const REMEMBER_PRIOR
= 'remember';
61 /** @var string Restore to the prior flag state */
62 const RESTORE_PRIOR
= 'prior';
63 /** @var string Restore to the initial flag state */
64 const RESTORE_INITIAL
= 'initial';
66 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
67 const ESTIMATE_TOTAL
= 'total';
68 /** @var string Estimate time to apply (scanning, applying) */
69 const ESTIMATE_DB_APPLY
= 'apply';
71 /** @var int Combine list with comma delimeters */
73 /** @var int Combine list with AND clauses */
75 /** @var int Convert map into a SET clause */
77 /** @var int Treat as field name and do not apply value escaping */
79 /** @var int Combine list with OR clauses */
82 /** @var int Enable debug logging */
84 /** @var int Disable query buffering (only one result set can be iterated at a time) */
85 const DBO_NOBUFFER
= 2;
86 /** @var int Ignore query errors (internal use only!) */
88 /** @var int Autoatically start transaction on first query (work with ILoadBalancer rounds) */
90 /** @var int Use DBO_TRX in non-CLI mode */
91 const DBO_DEFAULT
= 16;
92 /** @var int Use DB persistent connections if possible */
93 const DBO_PERSISTENT
= 32;
94 /** @var int DBA session mode; mostly for Oracle */
95 const DBO_SYSDBA
= 64;
96 /** @var int Schema file mode; mostly for Oracle */
97 const DBO_DDLMODE
= 128;
98 /** @var int Enable SSL/TLS in connection protocol */
100 /** @var int Enable compression in connection protocol */
101 const DBO_COMPRESS
= 512;
104 * A string describing the current software version, and possibly
105 * other details in a user-friendly way. Will be listed on Special:Version, etc.
106 * Use getServerVersion() to get machine-friendly information.
108 * @return string Version information from the database server
110 public function getServerInfo();
113 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
115 * Unbuffered queries are very troublesome in MySQL:
117 * - If another query is executed while the first query is being read
118 * out, the first query is killed. This means you can't call normal
119 * Database functions while you are reading an unbuffered query result
120 * from a normal Database connection.
122 * - Unbuffered queries cause the MySQL server to use large amounts of
123 * memory and to hold broad locks which block other queries.
125 * If you want to limit client-side memory, it's almost always better to
126 * split up queries into batches using a LIMIT clause than to switch off
129 * @param null|bool $buffer
130 * @return null|bool The previous value of the flag
132 public function bufferResults( $buffer = null );
135 * Gets the current transaction level.
137 * Historically, transactions were allowed to be "nested". This is no
138 * longer supported, so this function really only returns a boolean.
140 * @return int The previous value
142 public function trxLevel();
145 * Get the UNIX timestamp of the time that the transaction was established
147 * This can be used to reason about the staleness of SELECT data
148 * in REPEATABLE-READ transaction isolation level.
150 * @return float|null Returns null if there is not active transaction
153 public function trxTimestamp();
156 * @return bool Whether an explicit transaction or atomic sections are still open
159 public function explicitTrxActive();
162 * Get/set the table prefix.
163 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
164 * @return string The previous table prefix.
166 public function tablePrefix( $prefix = null );
169 * Get/set the db schema.
170 * @param string $schema The database schema to set, or omitted to leave it unchanged.
171 * @return string The previous db schema.
173 public function dbSchema( $schema = null );
176 * Get properties passed down from the server info array of the load
179 * @param string $name The entry of the info array to get, or null to get the
182 * @return array|mixed|null
184 public function getLBInfo( $name = null );
187 * Set the LB info array, or a member of it. If called with one parameter,
188 * the LB info array is set to that parameter. If it is called with two
189 * parameters, the member with the given name is set to the given value.
191 * @param string $name
192 * @param array $value
194 public function setLBInfo( $name, $value = null );
197 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
199 * @param IDatabase $conn
202 public function setLazyMasterHandle( IDatabase
$conn );
205 * Returns true if this database does an implicit sort when doing GROUP BY
208 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
210 public function implicitGroupby();
213 * Returns true if this database does an implicit order by when the column has an index
214 * For example: SELECT page_title FROM page LIMIT 1
218 public function implicitOrderby();
221 * Return the last query that went through IDatabase::query()
224 public function lastQuery();
227 * Returns true if the connection may have been used for write queries.
228 * Should return true if unsure.
231 * @deprecated Since 1.31; use lastDoneWrites()
233 public function doneWrites();
236 * Returns the last time the connection may have been used for write queries.
237 * Should return a timestamp if unsure.
239 * @return int|float UNIX timestamp or false
242 public function lastDoneWrites();
245 * @return bool Whether there is a transaction open with possible write queries
248 public function writesPending();
251 * Returns true if there is a transaction open with possible write
252 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
253 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
257 public function writesOrCallbacksPending();
260 * Get the time spend running write queries for this transaction
262 * High times could be due to scanning, updates, locking, and such
264 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
265 * @return float|bool Returns false if not transaction is active
268 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
271 * Get the list of method names that did write queries for this transaction
276 public function pendingWriteCallers();
279 * Get the number of affected rows from pending write queries
284 public function pendingWriteRowsAffected();
287 * Is a connection to the database open?
290 public function isOpen();
293 * Set a flag 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_DEFAULT: automatically sets DBO_TRX if not in command line mode
300 * and removes it in command line mode
301 * - DBO_PERSISTENT: use persistant database connection
302 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
304 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
307 * Clear a flag for this connection
309 * @param int $flag DBO_* constants from Defines.php:
310 * - DBO_DEBUG: output some debug info (same as debug())
311 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
312 * - DBO_TRX: automatically start transactions
313 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
314 * and removes it in command line mode
315 * - DBO_PERSISTENT: use persistant database connection
316 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
318 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
321 * Restore the flags to their prior state before the last setFlag/clearFlag call
323 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
326 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
329 * Returns a boolean whether the flag $flag is set for this connection
331 * @param int $flag DBO_* constants from Defines.php:
332 * - DBO_DEBUG: output some debug info (same as debug())
333 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
334 * - DBO_TRX: automatically start transactions
335 * - DBO_PERSISTENT: use persistant database connection
338 public function getFlag( $flag );
343 public function getDomainID();
346 * Alias for getDomainID()
351 public function getWikiID();
354 * Get the type of the DBMS, as it appears in $wgDBtype.
358 public function getType();
361 * Open a new connection to the database (closing any existing one)
363 * @param string $server Database server host
364 * @param string $user Database user name
365 * @param string $password Database user password
366 * @param string $dbName Database name
368 * @throws DBConnectionError
370 public function open( $server, $user, $password, $dbName );
373 * Fetch the next row from the given result object, in object form.
374 * Fields can be retrieved with $row->fieldname, with fields acting like
376 * If no more rows are available, false is returned.
378 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
379 * @return stdClass|bool
380 * @throws DBUnexpectedError Thrown if the database returns an error
382 public function fetchObject( $res );
385 * Fetch the next row from the given result object, in associative array
386 * form. Fields are retrieved with $row['fieldname'].
387 * If no more rows are available, false is returned.
389 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
391 * @throws DBUnexpectedError Thrown if the database returns an error
393 public function fetchRow( $res );
396 * Get the number of rows in a result object
398 * @param mixed $res A SQL result
401 public function numRows( $res );
404 * Get the number of fields in a result object
405 * @see https://secure.php.net/mysql_num_fields
407 * @param mixed $res A SQL result
410 public function numFields( $res );
413 * Get a field name in a result object
414 * @see https://secure.php.net/mysql_field_name
416 * @param mixed $res A SQL result
420 public function fieldName( $res, $n );
423 * Get the inserted value of an auto-increment row
425 * This should only be called after an insert that used an auto-incremented
426 * value. If no such insert was previously done in the current database
427 * session, the return value is undefined.
431 public function insertId();
434 * Change the position of the cursor in a result object
435 * @see https://secure.php.net/mysql_data_seek
437 * @param mixed $res A SQL result
440 public function dataSeek( $res, $row );
443 * Get the last error number
444 * @see https://secure.php.net/mysql_errno
448 public function lastErrno();
451 * Get a description of the last error
452 * @see https://secure.php.net/mysql_error
456 public function lastError();
459 * Get the number of rows affected by the last write query
460 * @see https://secure.php.net/mysql_affected_rows
464 public function affectedRows();
467 * Returns a wikitext link to the DB's website, e.g.,
468 * return "[https://www.mysql.com/ MySQL]";
469 * Should at least contain plain text, if for some reason
470 * your database has no website.
472 * @return string Wikitext of a link to the server software's web site
474 public function getSoftwareLink();
477 * A string describing the current software version, like from
478 * mysql_get_server_info().
480 * @return string Version information from the database server.
482 public function getServerVersion();
485 * Close the database connection
487 * This should only be called after any transactions have been resolved,
488 * aside from read-only transactions (assuming no callbacks are registered).
489 * If a transaction is still open anyway, it will be committed if possible.
492 * @return bool Operation success. true if already closed.
494 public function close();
497 * Run an SQL query and return the result. Normally throws a DBQueryError
498 * on failure. If errors are ignored, returns false instead.
500 * If a connection loss is detected, then an attempt to reconnect will be made.
501 * For queries that involve no larger transactions or locks, they will be re-issued
502 * for convenience, provided the connection was re-established.
504 * In new code, the query wrappers select(), insert(), update(), delete(),
505 * etc. should be used where possible, since they give much better DBMS
506 * independence and automatically quote or validate user input in a variety
507 * of contexts. This function is generally only useful for queries which are
508 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
511 * However, the query wrappers themselves should call this function.
513 * @param string $sql SQL query
514 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
515 * comment (you can use __METHOD__ or add some extra info)
516 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
517 * maybe best to catch the exception instead?
518 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
519 * for a successful read query, or false on failure if $tempIgnore set
522 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
525 * Free a result object returned by query() or select(). It's usually not
526 * necessary to call this, just use unset() or let the variable holding
527 * the result object go out of scope.
529 * @param mixed $res A SQL result
531 public function freeResult( $res );
534 * A SELECT wrapper which returns a single field from a single result row.
536 * Usually throws a DBQueryError on failure. If errors are explicitly
537 * ignored, returns false on failure.
539 * If no result rows are returned from the query, false is returned.
541 * @param string|array $table Table name. See IDatabase::select() for details.
542 * @param string $var The field name to select. This must be a valid SQL
543 * fragment: do not use unvalidated user input.
544 * @param string|array $cond The condition array. See IDatabase::select() for details.
545 * @param string $fname The function name of the caller.
546 * @param string|array $options The query options. See IDatabase::select() for details.
547 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
549 * @return mixed The value from the field
552 public function selectField(
553 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
557 * A SELECT wrapper which returns a list of single field values from result rows.
559 * Usually throws a DBQueryError on failure. If errors are explicitly
560 * ignored, returns false on failure.
562 * If no result rows are returned from the query, false is returned.
564 * @param string|array $table Table name. See IDatabase::select() for details.
565 * @param string $var The field name to select. This must be a valid SQL
566 * fragment: do not use unvalidated user input.
567 * @param string|array $cond The condition array. See IDatabase::select() for details.
568 * @param string $fname The function name of the caller.
569 * @param string|array $options The query options. See IDatabase::select() for details.
570 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
572 * @return array The values from the field
576 public function selectFieldValues(
577 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
581 * Execute a SELECT query constructed using the various parameters provided.
582 * See below for full details of the parameters.
584 * @param string|array $table Table name
585 * @param string|array $vars Field names
586 * @param string|array $conds Conditions
587 * @param string $fname Caller function name
588 * @param array $options Query options
589 * @param array $join_conds Join conditions
592 * @param string|array $table
594 * May be either an array of table names, or a single string holding a table
595 * name. If an array is given, table aliases can be specified, for example:
599 * This includes the user table in the query, with the alias "a" available
600 * for use in field names (e.g. a.user_name).
602 * A derived table, defined by the result of selectSQLText(), requires an alias
603 * key and a Subquery instance value which wraps the SQL query, for example:
605 * [ 'c' => new Subquery( 'SELECT ...' ) ]
607 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
608 * constructed using nested arrays. For example,
610 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
612 * along with `$join_conds` like
614 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
616 * will produce SQL something like
618 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
620 * All of the table names given here are automatically run through
621 * Database::tableName(), which causes the table prefix (if any) to be
622 * added, and various other table name mappings to be performed.
624 * Do not use untrusted user input as a table name. Alias names should
625 * not have characters outside of the Basic multilingual plane.
627 * @param string|array $vars
629 * May be either a field name or an array of field names. The field names
630 * can be complete fragments of SQL, for direct inclusion into the SELECT
631 * query. If an array is given, field aliases can be specified, for example:
633 * [ 'maxrev' => 'MAX(rev_id)' ]
635 * This includes an expression with the alias "maxrev" in the query.
637 * If an expression is given, care must be taken to ensure that it is
640 * Untrusted user input must not be passed to this parameter.
642 * @param string|array $conds
644 * May be either a string containing a single condition, or an array of
645 * conditions. If an array is given, the conditions constructed from each
646 * element are combined with AND.
648 * Array elements may take one of two forms:
650 * - Elements with a numeric key are interpreted as raw SQL fragments.
651 * - Elements with a string key are interpreted as equality conditions,
652 * where the key is the field name.
653 * - If the value of such an array element is a scalar (such as a
654 * string), it will be treated as data and thus quoted appropriately.
655 * If it is null, an IS NULL clause will be added.
656 * - If the value is an array, an IN (...) clause will be constructed
657 * from its non-null elements, and an IS NULL clause will be added
658 * if null is present, such that the field may match any of the
659 * elements in the array. The non-null elements will be quoted.
661 * Note that expressions are often DBMS-dependent in their syntax.
662 * DBMS-independent wrappers are provided for constructing several types of
663 * expression commonly used in condition queries. See:
664 * - IDatabase::buildLike()
665 * - IDatabase::conditional()
667 * Untrusted user input is safe in the values of string keys, however untrusted
668 * input must not be used in the array key names or in the values of numeric keys.
669 * Escaping of untrusted input used in values of numeric keys should be done via
670 * IDatabase::addQuotes()
672 * @param string|array $options
674 * Optional: Array of query options. Boolean options are specified by
675 * including them in the array as a string value with a numeric key, for
680 * The supported options are:
682 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
683 * with LIMIT can theoretically be used for paging through a result set,
684 * but this is discouraged for performance reasons.
686 * - LIMIT: Integer: return at most this many rows. The rows are sorted
687 * and then the first rows are taken until the limit is reached. LIMIT
688 * is applied to a result set after OFFSET.
690 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
691 * changed until the next COMMIT.
693 * - DISTINCT: Boolean: return only unique result rows.
695 * - GROUP BY: May be either an SQL fragment string naming a field or
696 * expression to group by, or an array of such SQL fragments.
698 * - HAVING: May be either an string containing a HAVING clause or an array of
699 * conditions building the HAVING clause. If an array is given, the conditions
700 * constructed from each element are combined with AND.
702 * - ORDER BY: May be either an SQL fragment giving a field name or
703 * expression to order by, or an array of such SQL fragments.
705 * - USE INDEX: This may be either a string giving the index name to use
706 * for the query, or an array. If it is an associative array, each key
707 * gives the table name (or alias), each value gives the index name to
708 * use for that table. All strings are SQL fragments and so should be
709 * validated by the caller.
711 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
714 * And also the following boolean MySQL extensions, see the MySQL manual
717 * - LOCK IN SHARE MODE
721 * - SQL_BUFFER_RESULT
723 * - SQL_CALC_FOUND_ROWS
728 * @param string|array $join_conds
730 * Optional associative array of table-specific join conditions. In the
731 * most common case, this is unnecessary, since the join condition can be
732 * in $conds. However, it is useful for doing a LEFT JOIN.
734 * The key of the array contains the table name or alias. The value is an
735 * array with two elements, numbered 0 and 1. The first gives the type of
736 * join, the second is the same as the $conds parameter. Thus it can be
737 * an SQL fragment, or an array where the string keys are equality and the
738 * numeric keys are SQL fragments all AND'd together. For example:
740 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
742 * @return IResultWrapper Resulting rows
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 * @see IDatabase::select()
758 * @param string|array $table Table name
759 * @param string|array $vars Field names
760 * @param string|array $conds Conditions
761 * @param string $fname Caller function name
762 * @param string|array $options Query options
763 * @param string|array $join_conds Join conditions
764 * @return string SQL query string
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
786 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
787 $options = [], $join_conds = []
791 * Estimate the number of rows in dataset
793 * MySQL allows you to estimate the number of rows that would be returned
794 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
795 * index cardinality statistics, and is notoriously inaccurate, especially
796 * when large numbers of rows have recently been added or deleted.
798 * For DBMSs that don't support fast result size estimation, this function
799 * will actually perform the SELECT COUNT(*).
801 * Takes the same arguments as IDatabase::select().
803 * @param string $table Table name
804 * @param string $var Column for which NULL values are not counted [default "*"]
805 * @param array|string $conds Filters on the table
806 * @param string $fname Function name for profiling
807 * @param array $options Options for select
808 * @param array|string $join_conds Join conditions
809 * @return int Row count
812 public function estimateRowCount(
813 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
817 * Get the number of rows in dataset
819 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
821 * Takes the same arguments as IDatabase::select().
823 * @since 1.27 Added $join_conds parameter
825 * @param array|string $tables Table names
826 * @param string $var Column for which NULL values are not counted [default "*"]
827 * @param array|string $conds Filters on the table
828 * @param string $fname Function name for profiling
829 * @param array $options Options for select
830 * @param array $join_conds Join conditions (since 1.27)
831 * @return int Row count
834 public function selectRowCount(
835 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
839 * Determines whether a field exists in a table
841 * @param string $table Table name
842 * @param string $field Filed to check on that table
843 * @param string $fname Calling function name (optional)
844 * @return bool Whether $table has filed $field
847 public function fieldExists( $table, $field, $fname = __METHOD__
);
850 * Determines whether an index exists
851 * Usually throws a DBQueryError on failure
852 * If errors are explicitly ignored, returns NULL on failure
854 * @param string $table
855 * @param string $index
856 * @param string $fname
860 public function indexExists( $table, $index, $fname = __METHOD__
);
863 * Query whether a given table exists
865 * @param string $table
866 * @param string $fname
870 public function tableExists( $table, $fname = __METHOD__
);
873 * INSERT wrapper, inserts an array into a table.
877 * - A single associative array. The array keys are the field names, and
878 * the values are the values to insert. The values are treated as data
879 * and will be quoted appropriately. If NULL is inserted, this will be
880 * converted to a database NULL.
881 * - An array with numeric keys, holding a list of associative arrays.
882 * This causes a multi-row INSERT on DBMSs that support it. The keys in
883 * each subarray must be identical to each other, and in the same order.
885 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
888 * $options is an array of options, with boolean options encoded as values
889 * with numeric keys, in the same style as $options in
890 * IDatabase::select(). Supported options are:
892 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
893 * any rows which cause duplicate key errors are not inserted. It's
894 * possible to determine how many rows were successfully inserted using
895 * IDatabase::affectedRows().
897 * @param string $table Table name. This will be passed through
898 * Database::tableName().
899 * @param array $a Array of rows to insert
900 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
901 * @param array $options Array of options
906 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
909 * UPDATE wrapper. Takes a condition array and a SET array.
911 * @param string $table Name of the table to UPDATE. This will be passed through
912 * Database::tableName().
913 * @param array $values An array of values to SET. For each array element,
914 * the key gives the field name, and the value gives the data to set
915 * that field to. The data will be quoted by IDatabase::addQuotes().
916 * Values with integer keys form unquoted SET statements, which can be used for
917 * things like "field = field + 1" or similar computed values.
918 * @param array $conds An array of conditions (WHERE). See
919 * IDatabase::select() for the details of the format of condition
920 * arrays. Use '*' to update all rows.
921 * @param string $fname The function name of the caller (from __METHOD__),
922 * for logging and profiling.
923 * @param array $options An array of UPDATE options, can be:
924 * - IGNORE: Ignore unique key conflicts
925 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
929 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
932 * Makes an encoded list of strings from an array
934 * These can be used to make conjunctions or disjunctions on SQL condition strings
935 * derived from an array (see IDatabase::select() $conds documentation).
939 * $sql = $db->makeList( [
941 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
942 * ], $db::LIST_AND );
944 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
946 * @param array $a Containing the data
947 * @param int $mode IDatabase class constant:
948 * - IDatabase::LIST_COMMA: Comma separated, no field names
949 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
950 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
951 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
952 * - IDatabase::LIST_NAMES: Comma separated field names
956 public function makeList( $a, $mode = self
::LIST_COMMA
);
959 * Build a partial where clause from a 2-d array such as used for LinkBatch.
960 * The keys on each level may be either integers or strings.
962 * @param array $data Organized as 2-d
963 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
964 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
965 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
966 * @return string|bool SQL fragment, or false if no items in array
968 public function makeWhereFrom2d( $data, $baseKey, $subKey );
971 * Return aggregated value alias
973 * @param array $valuedata
974 * @param string $valuename
978 public function aggregateValue( $valuedata, $valuename = 'value' );
981 * @param string $field
984 public function bitNot( $field );
987 * @param string $fieldLeft
988 * @param string $fieldRight
991 public function bitAnd( $fieldLeft, $fieldRight );
994 * @param string $fieldLeft
995 * @param string $fieldRight
998 public function bitOr( $fieldLeft, $fieldRight );
1001 * Build a concatenation list to feed into a SQL query
1002 * @param array $stringList List of raw SQL expressions; caller is
1003 * responsible for any quoting
1006 public function buildConcat( $stringList );
1009 * Build a GROUP_CONCAT or equivalent statement for a query.
1011 * This is useful for combining a field for several rows into a single string.
1012 * NULL values will not appear in the output, duplicated values will appear,
1013 * and the resulting delimiter-separated values have no defined sort order.
1014 * Code using the results may need to use the PHP unique() or sort() methods.
1016 * @param string $delim Glue to bind the results together
1017 * @param string|array $table Table name
1018 * @param string $field Field name
1019 * @param string|array $conds Conditions
1020 * @param string|array $join_conds Join conditions
1021 * @return string SQL text
1024 public function buildGroupConcatField(
1025 $delim, $table, $field, $conds = '', $join_conds = []
1029 * Build a SUBSTRING function.
1031 * Behavior for non-ASCII values is undefined.
1033 * @param string $input Field name
1034 * @param int $startPosition Positive integer
1035 * @param int|null $length Non-negative integer length or null for no limit
1036 * @throws InvalidArgumentException
1037 * @return string SQL text
1040 public function buildSubString( $input, $startPosition, $length = null );
1043 * @param string $field Field or column to cast
1047 public function buildStringCast( $field );
1050 * @param string $field Field or column to cast
1054 public function buildIntegerCast( $field );
1057 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1059 * @see IDatabase::selectSQLText()
1061 * @param string|array $table Table name
1062 * @param string|array $vars Field names
1063 * @param string|array $conds Conditions
1064 * @param string $fname Caller function name
1065 * @param string|array $options Query options
1066 * @param string|array $join_conds Join conditions
1070 public function buildSelectSubquery(
1071 $table, $vars, $conds = '', $fname = __METHOD__
,
1072 $options = [], $join_conds = []
1076 * Returns true if DBs are assumed to be on potentially different servers
1078 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1079 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1080 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1081 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1086 public function databasesAreIndependent();
1089 * Change the current database
1092 * @return bool Success or failure
1093 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1095 public function selectDB( $db );
1098 * Get the current DB name
1101 public function getDBname();
1104 * Get the server hostname or IP address
1107 public function getServer();
1110 * Adds quotes and backslashes.
1112 * @param string|int|null|bool|Blob $s
1113 * @return string|int
1115 public function addQuotes( $s );
1118 * LIKE statement wrapper, receives a variable-length argument list with
1119 * parts of pattern to match containing either string literals that will be
1120 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1121 * the function could be provided with an array of aforementioned
1124 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1125 * a LIKE clause that searches for subpages of 'My page title'.
1127 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1128 * $query .= $dbr->buildLike( $pattern );
1131 * @return string Fully built LIKE statement
1133 public function buildLike();
1136 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1140 public function anyChar();
1143 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1147 public function anyString();
1150 * Deprecated method, calls should be removed.
1152 * This was formerly used for PostgreSQL and Oracle to handle
1153 * self::insertId() auto-incrementing fields. It is no longer necessary
1154 * since DatabasePostgres::insertId() has been reimplemented using
1155 * `lastval()` and Oracle has been reimplemented using triggers.
1157 * Implementations should return null if inserting `NULL` into an
1158 * auto-incrementing field works, otherwise it should return an instance of
1159 * NextSequenceValue and filter it on calls to relevant methods.
1161 * @deprecated since 1.30, no longer needed
1162 * @param string $seqName
1163 * @return null|NextSequenceValue
1165 public function nextSequenceValue( $seqName );
1168 * REPLACE query wrapper.
1170 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1171 * except that when there is a duplicate key error, the old row is deleted
1172 * and the new row is inserted in its place.
1174 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1175 * perform the delete, we need to know what the unique indexes are so that
1176 * we know how to find the conflicting rows.
1178 * It may be more efficient to leave off unique indexes which are unlikely
1179 * to collide. However if you do this, you run the risk of encountering
1180 * errors which wouldn't have occurred in MySQL.
1182 * @param string $table The table to replace the row(s) in.
1183 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1184 * a field name or an array of field names
1185 * @param array $rows Can be either a single row to insert, or multiple rows,
1186 * in the same format as for IDatabase::insert()
1187 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1190 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1193 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1195 * This updates any conflicting rows (according to the unique indexes) using
1196 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1198 * $rows may be either:
1199 * - A single associative array. The array keys are the field names, and
1200 * the values are the values to insert. The values are treated as data
1201 * and will be quoted appropriately. If NULL is inserted, this will be
1202 * converted to a database NULL.
1203 * - An array with numeric keys, holding a list of associative arrays.
1204 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1205 * each subarray must be identical to each other, and in the same order.
1207 * It may be more efficient to leave off unique indexes which are unlikely
1208 * to collide. However if you do this, you run the risk of encountering
1209 * errors which wouldn't have occurred in MySQL.
1211 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1216 * @param string $table Table name. This will be passed through Database::tableName().
1217 * @param array $rows A single row or list of rows to insert
1218 * @param array $uniqueIndexes List of single field names or field name tuples
1219 * @param array $set An array of values to SET. For each array element, the
1220 * key gives the field name, and the value gives the data to set that
1221 * field to. The data will be quoted by IDatabase::addQuotes().
1222 * Values with integer keys form unquoted SET statements, which can be used for
1223 * things like "field = field + 1" or similar computed values.
1224 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1228 public function upsert(
1229 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1233 * DELETE where the condition is a join.
1235 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1236 * we use sub-selects
1238 * For safety, an empty $conds will not delete everything. If you want to
1239 * delete all rows where the join condition matches, set $conds='*'.
1241 * DO NOT put the join condition in $conds.
1243 * @param string $delTable The table to delete from.
1244 * @param string $joinTable The other table.
1245 * @param string $delVar The variable to join on, in the first table.
1246 * @param string $joinVar The variable to join on, in the second table.
1247 * @param array $conds Condition array of field names mapped to variables,
1248 * ANDed together in the WHERE clause
1249 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1252 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1257 * DELETE query wrapper.
1259 * @param string $table Table name
1260 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1261 * for the format. Use $conds == "*" to delete all rows
1262 * @param string $fname Name of the calling function
1263 * @throws DBUnexpectedError
1264 * @return bool|IResultWrapper
1267 public function delete( $table, $conds, $fname = __METHOD__
);
1270 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1271 * into another table.
1273 * @warning If the insert will use an auto-increment or sequence to
1274 * determine the value of a column, this may break replication on
1275 * databases using statement-based replication if the SELECT is not
1276 * deterministically ordered.
1278 * @param string $destTable The table name to insert into
1279 * @param string|array $srcTable May be either a table name, or an array of table names
1280 * to include in a join.
1282 * @param array $varMap Must be an associative array of the form
1283 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1284 * rather than field names, but strings should be quoted with
1285 * IDatabase::addQuotes()
1287 * @param array $conds Condition array. See $conds in IDatabase::select() for
1288 * the details of the format of condition arrays. May be "*" to copy the
1291 * @param string $fname The function name of the caller, from __METHOD__
1293 * @param array $insertOptions Options for the INSERT part of the query, see
1294 * IDatabase::insert() for details. Also, one additional option is
1295 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1296 * an auto-increment or sequence to determine any column values.
1297 * @param array $selectOptions Options for the SELECT part of the query, see
1298 * IDatabase::select() for details.
1299 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1300 * IDatabase::select() for details.
1305 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1306 $fname = __METHOD__
,
1307 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1311 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1312 * within the UNION construct.
1315 public function unionSupportsOrderAndLimit();
1318 * Construct a UNION query
1319 * This is used for providing overload point for other DB abstractions
1320 * not compatible with the MySQL syntax.
1321 * @param array $sqls SQL statements to combine
1322 * @param bool $all Use UNION ALL
1323 * @return string SQL fragment
1325 public function unionQueries( $sqls, $all );
1328 * Construct a UNION query for permutations of conditions
1330 * Databases sometimes have trouble with queries that have multiple values
1331 * for multiple condition parameters combined with limits and ordering.
1332 * This method constructs queries for the Cartesian product of the
1333 * conditions and unions them all together.
1335 * @see IDatabase::select()
1337 * @param string|array $table Table name
1338 * @param string|array $vars Field names
1339 * @param array $permute_conds Conditions for the Cartesian product. Keys
1340 * are field names, values are arrays of the possible values for that
1342 * @param string|array $extra_conds Additional conditions to include in the
1344 * @param string $fname Caller function name
1345 * @param string|array $options Query options. In addition to the options
1346 * recognized by IDatabase::select(), the following may be used:
1347 * - NOTALL: Set to use UNION instead of UNION ALL.
1348 * - INNER ORDER BY: If specified and supported, subqueries will use this
1349 * instead of ORDER BY.
1350 * @param string|array $join_conds Join conditions
1351 * @return string SQL query string.
1353 public function unionConditionPermutations(
1354 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1355 $options = [], $join_conds = []
1359 * Returns an SQL expression for a simple conditional. This doesn't need
1360 * to be overridden unless CASE isn't supported in your DBMS.
1362 * @param string|array $cond SQL expression which will result in a boolean value
1363 * @param string $trueVal SQL expression to return if true
1364 * @param string $falseVal SQL expression to return if false
1365 * @return string SQL fragment
1367 public function conditional( $cond, $trueVal, $falseVal );
1370 * Returns a command for str_replace function in SQL query.
1371 * Uses REPLACE() in MySQL
1373 * @param string $orig Column to modify
1374 * @param string $old Column to seek
1375 * @param string $new Column to replace with
1379 public function strreplace( $orig, $old, $new );
1382 * Determines how long the server has been up
1387 public function getServerUptime();
1390 * Determines if the last failure was due to a deadlock
1392 * Note that during a deadlock, the prior transaction will have been lost
1396 public function wasDeadlock();
1399 * Determines if the last failure was due to a lock timeout
1401 * Note that during a lock wait timeout, the prior transaction will have been lost
1405 public function wasLockTimeout();
1408 * Determines if the last query error was due to a dropped connection
1410 * Note that during a connection loss, the prior transaction will have been lost
1415 public function wasConnectionLoss();
1418 * Determines if the last failure was due to the database being read-only.
1422 public function wasReadOnlyError();
1425 * Determines if the last query error was due to something outside of the query itself
1427 * Note that the transaction may have been lost, discarding prior writes and results
1431 public function wasErrorReissuable();
1434 * Wait for the replica DB to catch up to a given master position
1436 * @param DBMasterPos $pos
1437 * @param int $timeout The maximum number of seconds to wait for synchronisation
1438 * @return int|null Zero if the replica DB was past that position already,
1439 * greater than zero if we waited for some period of time, less than
1440 * zero if it timed out, and null on error
1443 public function masterPosWait( DBMasterPos
$pos, $timeout );
1446 * Get the replication position of this replica DB
1448 * @return DBMasterPos|bool False if this is not a replica DB
1451 public function getReplicaPos();
1454 * Get the position of this master
1456 * @return DBMasterPos|bool False if this is not a master
1459 public function getMasterPos();
1462 * @return bool Whether the DB is marked as read-only server-side
1465 public function serverIsReadOnly();
1468 * Run a callback as soon as the current transaction commits or rolls back.
1469 * An error is thrown if no transaction is pending. Queries in the function will run in
1470 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1473 * This is useful for combining cooperative locks and DB transactions.
1475 * The callback takes one argument:
1476 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1478 * @param callable $callback
1479 * @param string $fname Caller name
1483 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1486 * Run a callback as soon as there is no transaction pending.
1487 * If there is a transaction and it is rolled back, then the callback is cancelled.
1488 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1489 * Callbacks must commit any transactions that they begin.
1491 * This is useful for updates to different systems or when separate transactions are needed.
1492 * For example, one might want to enqueue jobs into a system outside the database, but only
1493 * after the database is updated so that the jobs will see the data when they actually run.
1494 * It can also be used for updates that easily cause deadlocks if locks are held too long.
1496 * Updates will execute in the order they were enqueued.
1498 * The callback takes one argument:
1499 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1501 * @param callable $callback
1502 * @param string $fname Caller name
1505 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1508 * Run a callback before the current transaction commits or now if there is none.
1509 * If there is a transaction and it is rolled back, then the callback is cancelled.
1510 * Callbacks must not start nor commit any transactions. If no transaction is active,
1511 * then a transaction will wrap the callback.
1513 * This is useful for updates that easily cause deadlocks if locks are held too long
1514 * but where atomicity is strongly desired for these updates and some related updates.
1516 * Updates will execute in the order they were enqueued.
1518 * @param callable $callback
1519 * @param string $fname Caller name
1522 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1525 * Run a callback each time any transaction commits or rolls back
1527 * The callback takes two arguments:
1528 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1529 * - This IDatabase object
1530 * Callbacks must commit any transactions that they begin.
1532 * Registering a callback here will not affect writesOrCallbacks() pending
1534 * @param string $name Callback name
1535 * @param callable|null $callback Use null to unset a listener
1539 public function setTransactionListener( $name, callable
$callback = null );
1542 * Begin an atomic section of statements
1544 * If a transaction has been started already, sets a savepoint and tracks
1545 * the given section name to make sure the transaction is not committed
1546 * pre-maturely. This function can be used in layers (with sub-sections),
1547 * so use a stack to keep track of the different atomic sections. If there
1548 * is no transaction, one is started implicitly.
1550 * The goal of this function is to create an atomic section of SQL queries
1551 * without having to start a new transaction if it already exists.
1553 * All atomic levels *must* be explicitly closed using IDatabase::endAtomic()
1554 * or IDatabase::cancelAtomic(), and any database transactions cannot be
1555 * began or committed until all atomic levels are closed. There is no such
1556 * thing as implicitly opening or closing an atomic section.
1559 * @param string $fname
1562 public function startAtomic( $fname = __METHOD__
);
1565 * Ends an atomic section of SQL statements
1567 * Ends the next section of atomic SQL statements and commits the transaction
1571 * @see IDatabase::startAtomic
1572 * @param string $fname
1575 public function endAtomic( $fname = __METHOD__
);
1578 * Cancel an atomic section of SQL statements
1580 * This will roll back only the statements executed since the start of the
1581 * most recent atomic section, and close that section. If a transaction was
1582 * open before the corresponding startAtomic() call, any statements before
1583 * that call are *not* rolled back and the transaction remains open. If the
1584 * corresponding startAtomic() implicitly started a transaction, that
1585 * transaction is rolled back.
1587 * Note that a call to IDatabase::rollback() will also roll back any open
1591 * @see IDatabase::startAtomic
1592 * @param string $fname
1595 public function cancelAtomic( $fname = __METHOD__
);
1598 * Run a callback to do an atomic set of updates for this database
1600 * The $callback takes the following arguments:
1601 * - This database object
1602 * - The value of $fname
1604 * If any exception occurs in the callback, then cancelAtomic() will be
1605 * called to back out any statements executed by the callback and the error
1606 * will be re-thrown. It may also be that the cancel itself fails with an
1607 * exception before then. In any case, such errors are expected to
1608 * terminate the request, without any outside caller attempting to catch
1609 * errors and commit anyway.
1611 * This can be an alternative to explicit startAtomic()/endAtomic()/cancelAtomic() calls.
1613 * @see Database::startAtomic
1614 * @see Database::endAtomic
1615 * @see Database::cancelAtomic
1617 * @param string $fname Caller name (usually __METHOD__)
1618 * @param callable $callback Callback that issues DB updates
1619 * @return mixed $res Result of the callback (since 1.28)
1621 * @throws RuntimeException
1622 * @throws UnexpectedValueException
1623 * @since 1.27; prior to 1.31 this did a rollback() instead of
1624 * cancelAtomic(), and assumed no callers up the stack would ever try to
1625 * catch the exception.
1627 public function doAtomicSection( $fname, callable
$callback );
1630 * Begin a transaction. If a transaction is already in progress,
1631 * that transaction will be committed before the new transaction is started.
1633 * Only call this from code with outer transcation scope.
1634 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1635 * Nesting of transactions is not supported.
1637 * Note that when the DBO_TRX flag is set (which is usually the case for web
1638 * requests, but not for maintenance scripts), any previous database query
1639 * will have started a transaction automatically.
1641 * Nesting of transactions is not supported. Attempts to nest transactions
1642 * will cause a warning, unless the current transaction was started
1643 * automatically because of the DBO_TRX flag.
1645 * @param string $fname Calling function name
1646 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1649 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1652 * Commits a transaction previously started using begin().
1653 * If no transaction is in progress, a warning is issued.
1655 * Only call this from code with outer transcation scope.
1656 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1657 * Nesting of transactions is not supported.
1659 * @param string $fname
1660 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1661 * constant to disable warnings about explicitly committing implicit transactions,
1662 * or calling commit when no transaction is in progress.
1664 * This will trigger an exception if there is an ongoing explicit transaction.
1666 * Only set the flush flag if you are sure that these warnings are not applicable,
1667 * and no explicit transactions are open.
1671 public function commit( $fname = __METHOD__
, $flush = '' );
1674 * Rollback a transaction previously started using begin().
1675 * If no transaction is in progress, a warning is issued.
1677 * Only call this from code with outer transcation scope.
1678 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1679 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1680 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1681 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1683 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1685 * @param string $fname Calling function name
1686 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1687 * constant to disable warnings about calling rollback when no transaction is in
1688 * progress. This will silently break any ongoing explicit transaction. Only set the
1689 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1691 * @since 1.23 Added $flush parameter
1693 public function rollback( $fname = __METHOD__
, $flush = '' );
1696 * Commit any transaction but error out if writes or callbacks are pending
1698 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1699 * see a new point-in-time of the database. This is useful when one of many transaction
1700 * rounds finished and significant time will pass in the script's lifetime. It is also
1701 * useful to call on a replica DB after waiting on replication to catch up to the master.
1703 * @param string $fname Calling function name
1707 public function flushSnapshot( $fname = __METHOD__
);
1710 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1711 * to the format used for inserting into timestamp fields in this DBMS.
1713 * The result is unquoted, and needs to be passed through addQuotes()
1714 * before it can be included in raw SQL.
1716 * @param string|int $ts
1720 public function timestamp( $ts = 0 );
1723 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1724 * to the format used for inserting into timestamp fields in this DBMS. If
1725 * NULL is input, it is passed through, allowing NULL values to be inserted
1726 * into timestamp fields.
1728 * The result is unquoted, and needs to be passed through addQuotes()
1729 * before it can be included in raw SQL.
1731 * @param string|int $ts
1735 public function timestampOrNull( $ts = null );
1738 * Ping the server and try to reconnect if it there is no connection
1740 * @param float|null &$rtt Value to store the estimated RTT [optional]
1741 * @return bool Success or failure
1743 public function ping( &$rtt = null );
1746 * Get replica DB lag. Currently supported only by MySQL.
1748 * Note that this function will generate a fatal error on many
1749 * installations. Most callers should use LoadBalancer::safeGetLag()
1752 * @return int|bool Database replication lag in seconds or false on error
1755 public function getLag();
1758 * Get the replica DB lag when the current transaction started
1759 * or a general lag estimate if not transaction is active
1761 * This is useful when transactions might use snapshot isolation
1762 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1763 * is this lag plus transaction duration. If they don't, it is still
1764 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1765 * indication of the staleness of subsequent reads.
1767 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1771 public function getSessionLagStatus();
1774 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1778 public function maxListLen();
1781 * Some DBMSs have a special format for inserting into blob fields, they
1782 * don't allow simple quoted strings to be inserted. To insert into such
1783 * a field, pass the data through this function before passing it to
1784 * IDatabase::insert().
1787 * @return string|Blob
1789 public function encodeBlob( $b );
1792 * Some DBMSs return a special placeholder object representing blob fields
1793 * in result objects. Pass the object through this function to return the
1796 * @param string|Blob $b
1799 public function decodeBlob( $b );
1802 * Override database's default behavior. $options include:
1803 * 'connTimeout' : Set the connection timeout value in seconds.
1804 * May be useful for very long batch queries such as
1805 * full-wiki dumps, where a single query reads out over
1808 * @param array $options
1812 public function setSessionOptions( array $options );
1815 * Set variables to be used in sourceFile/sourceStream, in preference to the
1816 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1817 * all. If it's set to false, $GLOBALS will be used.
1819 * @param bool|array $vars Mapping variable name to value.
1821 public function setSchemaVars( $vars );
1824 * Check to see if a named lock is not locked by any thread (non-blocking)
1826 * @param string $lockName Name of lock to poll
1827 * @param string $method Name of method calling us
1832 public function lockIsFree( $lockName, $method );
1835 * Acquire a named lock
1837 * Named locks are not related to transactions
1839 * @param string $lockName Name of lock to aquire
1840 * @param string $method Name of the calling method
1841 * @param int $timeout Acquisition timeout in seconds
1845 public function lock( $lockName, $method, $timeout = 5 );
1850 * Named locks are not related to transactions
1852 * @param string $lockName Name of lock to release
1853 * @param string $method Name of the calling method
1855 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1856 * by this thread (in which case the lock is not released), and NULL if the named lock
1861 public function unlock( $lockName, $method );
1864 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1866 * Only call this from outer transcation scope and when only one DB will be affected.
1867 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1869 * This is suitiable for transactions that need to be serialized using cooperative locks,
1870 * where each transaction can see each others' changes. Any transaction is flushed to clear
1871 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1872 * the lock will be released unless a transaction is active. If one is active, then the lock
1873 * will be released when it either commits or rolls back.
1875 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1877 * @param string $lockKey Name of lock to release
1878 * @param string $fname Name of the calling method
1879 * @param int $timeout Acquisition timeout in seconds
1880 * @return ScopedCallback|null
1884 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1887 * Check to see if a named lock used by lock() use blocking queues
1892 public function namedLocksEnqueue();
1895 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1896 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1897 * because "i" sorts after all numbers.
1901 public function getInfinity();
1904 * Encode an expiry time into the DBMS dependent format
1906 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1909 public function encodeExpiry( $expiry );
1912 * Decode an expiry time into a DBMS independent format
1914 * @param string $expiry DB timestamp field value for expiry
1915 * @param int $format TS_* constant, defaults to TS_MW
1918 public function decodeExpiry( $expiry, $format = TS_MW
);
1921 * Allow or deny "big selects" for this session only. This is done by setting
1922 * the sql_big_selects session variable.
1924 * This is a MySQL-specific feature.
1926 * @param bool|string $value True for allow, false for deny, or "default" to
1927 * restore the initial value
1929 public function setBigSelects( $value = true );
1932 * @return bool Whether this DB is read-only
1935 public function isReadOnly();
1938 * Make certain table names use their own database, schema, and table prefix
1939 * when passed into SQL queries pre-escaped and without a qualified database name
1941 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1942 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1944 * Calling this twice will completely clear any old table aliases. Also, note that
1945 * callers are responsible for making sure the schemas and databases actually exist.
1947 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1950 public function setTableAliases( array $aliases );
1953 * Convert certain index names to alternative names before querying the DB
1955 * Note that this applies to indexes regardless of the table they belong to.
1957 * This can be employed when an index was renamed X => Y in code, but the new Y-named
1958 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
1959 * the aliases can be removed, and then the old X-named indexes dropped.
1961 * @param string[] $aliases
1965 public function setIndexAliases( array $aliases );
1968 class_alias( IDatabase
::class, 'IDatabase' );