4 * @defgroup Database Database
6 * This file deals with database interface functions
7 * and query specifics/optimisations.
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write to the Free Software Foundation, Inc.,
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
22 * http://www.gnu.org/copyleft/gpl.html
29 * Basic database interface for live and lazy-loaded DB handles
31 * @todo: loosen up DB classes from MWException
32 * @note: IDatabase and DBConnRef should be updated to reflect any changes
36 /** @var int Callback triggered immediately due to no active transaction */
37 const TRIGGER_IDLE
= 1;
38 /** @var int Callback triggered by commit */
39 const TRIGGER_COMMIT
= 2;
40 /** @var int Callback triggered by rollback */
41 const TRIGGER_ROLLBACK
= 3;
43 /** @var string Transaction is requested by regular caller outside of the DB layer */
44 const TRANSACTION_EXPLICIT
= '';
45 /** @var string Transaction is requested interally via DBO_TRX/startAtomic() */
46 const TRANSACTION_INTERNAL
= 'implicit';
48 /** @var string Transaction operation comes from service managing all DBs */
49 const FLUSHING_ALL_PEERS
= 'flush';
50 /** @var string Transaction operation comes from the database class internally */
51 const FLUSHING_INTERNAL
= 'flush';
53 /** @var string No not remember the prior flags */
54 const REMEMBER_NOTHING
= '';
55 /** @var string Remember the prior flags */
56 const REMEMBER_PRIOR
= 'remember';
57 /** @var string Restore to the prior flag state */
58 const RESTORE_PRIOR
= 'prior';
59 /** @var string Restore to the initial flag state */
60 const RESTORE_INITIAL
= 'initial';
63 * A string describing the current software version, and possibly
64 * other details in a user-friendly way. Will be listed on Special:Version, etc.
65 * Use getServerVersion() to get machine-friendly information.
67 * @return string Version information from the database server
69 public function getServerInfo();
72 * Turns buffering of SQL result sets on (true) or off (false). Default is
75 * Unbuffered queries are very troublesome in MySQL:
77 * - If another query is executed while the first query is being read
78 * out, the first query is killed. This means you can't call normal
79 * MediaWiki functions while you are reading an unbuffered query result
80 * from a normal wfGetDB() connection.
82 * - Unbuffered queries cause the MySQL server to use large amounts of
83 * memory and to hold broad locks which block other queries.
85 * If you want to limit client-side memory, it's almost always better to
86 * split up queries into batches using a LIMIT clause than to switch off
89 * @param null|bool $buffer
90 * @return null|bool The previous value of the flag
92 public function bufferResults( $buffer = null );
95 * Gets the current transaction level.
97 * Historically, transactions were allowed to be "nested". This is no
98 * longer supported, so this function really only returns a boolean.
100 * @return int The previous value
102 public function trxLevel();
105 * Get the UNIX timestamp of the time that the transaction was established
107 * This can be used to reason about the staleness of SELECT data
108 * in REPEATABLE-READ transaction isolation level.
110 * @return float|null Returns null if there is not active transaction
113 public function trxTimestamp();
116 * @return bool Whether an explicit transaction or atomic sections are still open
119 public function explicitTrxActive();
122 * Get/set the table prefix.
123 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
124 * @return string The previous table prefix.
126 public function tablePrefix( $prefix = null );
129 * Get/set the db schema.
130 * @param string $schema The database schema to set, or omitted to leave it unchanged.
131 * @return string The previous db schema.
133 public function dbSchema( $schema = null );
136 * Get properties passed down from the server info array of the load
139 * @param string $name The entry of the info array to get, or null to get the
142 * @return array|mixed|null
144 public function getLBInfo( $name = null );
147 * Set the LB info array, or a member of it. If called with one parameter,
148 * the LB info array is set to that parameter. If it is called with two
149 * parameters, the member with the given name is set to the given value.
151 * @param string $name
152 * @param array $value
154 public function setLBInfo( $name, $value = null );
157 * Returns true if this database does an implicit sort when doing GROUP BY
161 public function implicitGroupby();
164 * Returns true if this database does an implicit order by when the column has an index
165 * For example: SELECT page_title FROM page LIMIT 1
169 public function implicitOrderby();
172 * Return the last query that went through IDatabase::query()
175 public function lastQuery();
178 * Returns true if the connection may have been used for write queries.
179 * Should return true if unsure.
183 public function doneWrites();
186 * Returns the last time the connection may have been used for write queries.
187 * Should return a timestamp if unsure.
189 * @return int|float UNIX timestamp or false
192 public function lastDoneWrites();
195 * @return bool Whether there is a transaction open with possible write queries
198 public function writesPending();
201 * Returns true if there is a transaction open with possible write
202 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
206 public function writesOrCallbacksPending();
209 * Get the time spend running write queries for this transaction
211 * High times could be due to scanning, updates, locking, and such
213 * @return float|bool Returns false if not transaction is active
216 public function pendingWriteQueryDuration();
219 * Get the list of method names that did write queries for this transaction
224 public function pendingWriteCallers();
227 * Is a connection to the database open?
230 public function isOpen();
233 * Set a flag for this connection
235 * @param int $flag DBO_* constants from Defines.php:
236 * - DBO_DEBUG: output some debug info (same as debug())
237 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
238 * - DBO_TRX: automatically start transactions
239 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
240 * and removes it in command line mode
241 * - DBO_PERSISTENT: use persistant database connection
242 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
244 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
247 * Clear a flag for this connection
249 * @param int $flag DBO_* constants from Defines.php:
250 * - DBO_DEBUG: output some debug info (same as debug())
251 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
252 * - DBO_TRX: automatically start transactions
253 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
254 * and removes it in command line mode
255 * - DBO_PERSISTENT: use persistant database connection
256 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
258 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
261 * Restore the flags to their prior state before the last setFlag/clearFlag call
263 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
266 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
269 * Returns a boolean whether the flag $flag is set for this connection
271 * @param int $flag DBO_* constants from Defines.php:
272 * - DBO_DEBUG: output some debug info (same as debug())
273 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
274 * - DBO_TRX: automatically start transactions
275 * - DBO_PERSISTENT: use persistant database connection
278 public function getFlag( $flag );
281 * General read-only accessor
283 * @param string $name
286 public function getProperty( $name );
291 public function getWikiID();
294 * Get the type of the DBMS, as it appears in $wgDBtype.
298 public function getType();
301 * Open a connection to the database. Usually aborts on failure
303 * @param string $server Database server host
304 * @param string $user Database user name
305 * @param string $password Database user password
306 * @param string $dbName Database name
308 * @throws DBConnectionError
310 public function open( $server, $user, $password, $dbName );
313 * Fetch the next row from the given result object, in object form.
314 * Fields can be retrieved with $row->fieldname, with fields acting like
316 * If no more rows are available, false is returned.
318 * @param ResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
319 * @return stdClass|bool
320 * @throws DBUnexpectedError Thrown if the database returns an error
322 public function fetchObject( $res );
325 * Fetch the next row from the given result object, in associative array
326 * form. Fields are retrieved with $row['fieldname'].
327 * If no more rows are available, false is returned.
329 * @param ResultWrapper $res Result object as returned from IDatabase::query(), etc.
331 * @throws DBUnexpectedError Thrown if the database returns an error
333 public function fetchRow( $res );
336 * Get the number of rows in a result object
338 * @param mixed $res A SQL result
341 public function numRows( $res );
344 * Get the number of fields in a result object
345 * @see http://www.php.net/mysql_num_fields
347 * @param mixed $res A SQL result
350 public function numFields( $res );
353 * Get a field name in a result object
354 * @see http://www.php.net/mysql_field_name
356 * @param mixed $res A SQL result
360 public function fieldName( $res, $n );
363 * Get the inserted value of an auto-increment row
365 * The value inserted should be fetched from nextSequenceValue()
368 * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
369 * $dbw->insert( 'page', [ 'page_id' => $id ] );
370 * $id = $dbw->insertId();
374 public function insertId();
377 * Change the position of the cursor in a result object
378 * @see http://www.php.net/mysql_data_seek
380 * @param mixed $res A SQL result
383 public function dataSeek( $res, $row );
386 * Get the last error number
387 * @see http://www.php.net/mysql_errno
391 public function lastErrno();
394 * Get a description of the last error
395 * @see http://www.php.net/mysql_error
399 public function lastError();
402 * mysql_fetch_field() wrapper
403 * Returns false if the field doesn't exist
405 * @param string $table Table name
406 * @param string $field Field name
410 public function fieldInfo( $table, $field );
413 * Get the number of rows affected by the last write query
414 * @see http://www.php.net/mysql_affected_rows
418 public function affectedRows();
421 * Returns a wikitext link to the DB's website, e.g.,
422 * return "[http://www.mysql.com/ MySQL]";
423 * Should at least contain plain text, if for some reason
424 * your database has no website.
426 * @return string Wikitext of a link to the server software's web site
428 public function getSoftwareLink();
431 * A string describing the current software version, like from
432 * mysql_get_server_info().
434 * @return string Version information from the database server.
436 public function getServerVersion();
439 * Closes a database connection.
440 * if it is open : commits any open transactions
442 * @throws MWException
443 * @return bool Operation success. true if already closed.
445 public function close();
448 * @param string $error Fallback error message, used if none is given by DB
449 * @throws DBConnectionError
451 public function reportConnectionError( $error = 'Unknown error' );
454 * Run an SQL query and return the result. Normally throws a DBQueryError
455 * on failure. If errors are ignored, returns false instead.
457 * In new code, the query wrappers select(), insert(), update(), delete(),
458 * etc. should be used where possible, since they give much better DBMS
459 * independence and automatically quote or validate user input in a variety
460 * of contexts. This function is generally only useful for queries which are
461 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
464 * However, the query wrappers themselves should call this function.
466 * @param string $sql SQL query
467 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
468 * comment (you can use __METHOD__ or add some extra info)
469 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
470 * maybe best to catch the exception instead?
471 * @throws MWException
472 * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
473 * for a successful read query, or false on failure if $tempIgnore set
475 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
478 * Report a query error. Log the error, and if neither the object ignore
479 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
481 * @param string $error
484 * @param string $fname
485 * @param bool $tempIgnore
486 * @throws DBQueryError
488 public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
491 * Free a result object returned by query() or select(). It's usually not
492 * necessary to call this, just use unset() or let the variable holding
493 * the result object go out of scope.
495 * @param mixed $res A SQL result
497 public function freeResult( $res );
500 * A SELECT wrapper which returns a single field from a single result row.
502 * Usually throws a DBQueryError on failure. If errors are explicitly
503 * ignored, returns false on failure.
505 * If no result rows are returned from the query, false is returned.
507 * @param string|array $table Table name. See IDatabase::select() for details.
508 * @param string $var The field name to select. This must be a valid SQL
509 * fragment: do not use unvalidated user input.
510 * @param string|array $cond The condition array. See IDatabase::select() for details.
511 * @param string $fname The function name of the caller.
512 * @param string|array $options The query options. See IDatabase::select() for details.
514 * @return bool|mixed The value from the field, or false on failure.
516 public function selectField(
517 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
521 * A SELECT wrapper which returns a list of single field values from result rows.
523 * Usually throws a DBQueryError on failure. If errors are explicitly
524 * ignored, returns false on failure.
526 * If no result rows are returned from the query, false is returned.
528 * @param string|array $table Table name. See IDatabase::select() for details.
529 * @param string $var The field name to select. This must be a valid SQL
530 * fragment: do not use unvalidated user input.
531 * @param string|array $cond The condition array. See IDatabase::select() for details.
532 * @param string $fname The function name of the caller.
533 * @param string|array $options The query options. See IDatabase::select() for details.
535 * @return bool|array The values from the field, or false on failure
538 public function selectFieldValues(
539 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
543 * Execute a SELECT query constructed using the various parameters provided.
544 * See below for full details of the parameters.
546 * @param string|array $table Table name
547 * @param string|array $vars Field names
548 * @param string|array $conds Conditions
549 * @param string $fname Caller function name
550 * @param array $options Query options
551 * @param array $join_conds Join conditions
554 * @param string|array $table
556 * May be either an array of table names, or a single string holding a table
557 * name. If an array is given, table aliases can be specified, for example:
561 * This includes the user table in the query, with the alias "a" available
562 * for use in field names (e.g. a.user_name).
564 * All of the table names given here are automatically run through
565 * DatabaseBase::tableName(), which causes the table prefix (if any) to be
566 * added, and various other table name mappings to be performed.
568 * Do not use untrusted user input as a table name. Alias names should
569 * not have characters outside of the Basic multilingual plane.
571 * @param string|array $vars
573 * May be either a field name or an array of field names. The field names
574 * can be complete fragments of SQL, for direct inclusion into the SELECT
575 * query. If an array is given, field aliases can be specified, for example:
577 * [ 'maxrev' => 'MAX(rev_id)' ]
579 * This includes an expression with the alias "maxrev" in the query.
581 * If an expression is given, care must be taken to ensure that it is
584 * Untrusted user input must not be passed to this parameter.
586 * @param string|array $conds
588 * May be either a string containing a single condition, or an array of
589 * conditions. If an array is given, the conditions constructed from each
590 * element are combined with AND.
592 * Array elements may take one of two forms:
594 * - Elements with a numeric key are interpreted as raw SQL fragments.
595 * - Elements with a string key are interpreted as equality conditions,
596 * where the key is the field name.
597 * - If the value of such an array element is a scalar (such as a
598 * string), it will be treated as data and thus quoted appropriately.
599 * If it is null, an IS NULL clause will be added.
600 * - If the value is an array, an IN (...) clause will be constructed
601 * from its non-null elements, and an IS NULL clause will be added
602 * if null is present, such that the field may match any of the
603 * elements in the array. The non-null elements will be quoted.
605 * Note that expressions are often DBMS-dependent in their syntax.
606 * DBMS-independent wrappers are provided for constructing several types of
607 * expression commonly used in condition queries. See:
608 * - IDatabase::buildLike()
609 * - IDatabase::conditional()
611 * Untrusted user input is safe in the values of string keys, however untrusted
612 * input must not be used in the array key names or in the values of numeric keys.
613 * Escaping of untrusted input used in values of numeric keys should be done via
614 * IDatabase::addQuotes()
616 * @param string|array $options
618 * Optional: Array of query options. Boolean options are specified by
619 * including them in the array as a string value with a numeric key, for
624 * The supported options are:
626 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
627 * with LIMIT can theoretically be used for paging through a result set,
628 * but this is discouraged in MediaWiki for performance reasons.
630 * - LIMIT: Integer: return at most this many rows. The rows are sorted
631 * and then the first rows are taken until the limit is reached. LIMIT
632 * is applied to a result set after OFFSET.
634 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
635 * changed until the next COMMIT.
637 * - DISTINCT: Boolean: return only unique result rows.
639 * - GROUP BY: May be either an SQL fragment string naming a field or
640 * expression to group by, or an array of such SQL fragments.
642 * - HAVING: May be either an string containing a HAVING clause or an array of
643 * conditions building the HAVING clause. If an array is given, the conditions
644 * constructed from each element are combined with AND.
646 * - ORDER BY: May be either an SQL fragment giving a field name or
647 * expression to order by, or an array of such SQL fragments.
649 * - USE INDEX: This may be either a string giving the index name to use
650 * for the query, or an array. If it is an associative array, each key
651 * gives the table name (or alias), each value gives the index name to
652 * use for that table. All strings are SQL fragments and so should be
653 * validated by the caller.
655 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
658 * And also the following boolean MySQL extensions, see the MySQL manual
661 * - LOCK IN SHARE MODE
665 * - SQL_BUFFER_RESULT
667 * - SQL_CALC_FOUND_ROWS
672 * @param string|array $join_conds
674 * Optional associative array of table-specific join conditions. In the
675 * most common case, this is unnecessary, since the join condition can be
676 * in $conds. However, it is useful for doing a LEFT JOIN.
678 * The key of the array contains the table name or alias. The value is an
679 * array with two elements, numbered 0 and 1. The first gives the type of
680 * join, the second is the same as the $conds parameter. Thus it can be
681 * an SQL fragment, or an array where the string keys are equality and the
682 * numeric keys are SQL fragments all AND'd together. For example:
684 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
686 * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
687 * with no rows in it will be returned. If there was a query error, a
688 * DBQueryError exception will be thrown, except if the "ignore errors"
689 * option was set, in which case false will be returned.
691 public function select(
692 $table, $vars, $conds = '', $fname = __METHOD__
,
693 $options = [], $join_conds = []
697 * The equivalent of IDatabase::select() except that the constructed SQL
698 * is returned, instead of being immediately executed. This can be useful for
699 * doing UNION queries, where the SQL text of each query is needed. In general,
700 * however, callers outside of Database classes should just use select().
702 * @param string|array $table Table name
703 * @param string|array $vars Field names
704 * @param string|array $conds Conditions
705 * @param string $fname Caller function name
706 * @param string|array $options Query options
707 * @param string|array $join_conds Join conditions
709 * @return string SQL query string.
710 * @see IDatabase::select()
712 public function selectSQLText(
713 $table, $vars, $conds = '', $fname = __METHOD__
,
714 $options = [], $join_conds = []
718 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
719 * that a single row object is returned. If the query returns no rows,
722 * @param string|array $table Table name
723 * @param string|array $vars Field names
724 * @param array $conds Conditions
725 * @param string $fname Caller function name
726 * @param string|array $options Query options
727 * @param array|string $join_conds Join conditions
729 * @return stdClass|bool
731 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
732 $options = [], $join_conds = []
736 * Estimate the number of rows in dataset
738 * MySQL allows you to estimate the number of rows that would be returned
739 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
740 * index cardinality statistics, and is notoriously inaccurate, especially
741 * when large numbers of rows have recently been added or deleted.
743 * For DBMSs that don't support fast result size estimation, this function
744 * will actually perform the SELECT COUNT(*).
746 * Takes the same arguments as IDatabase::select().
748 * @param string $table Table name
749 * @param string $vars Unused
750 * @param array|string $conds Filters on the table
751 * @param string $fname Function name for profiling
752 * @param array $options Options for select
753 * @return int Row count
755 public function estimateRowCount(
756 $table, $vars = '*', $conds = '', $fname = __METHOD__
, $options = []
760 * Get the number of rows in dataset
762 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
764 * Takes the same arguments as IDatabase::select().
766 * @since 1.27 Added $join_conds parameter
768 * @param array|string $tables Table names
769 * @param string $vars Unused
770 * @param array|string $conds Filters on the table
771 * @param string $fname Function name for profiling
772 * @param array $options Options for select
773 * @param array $join_conds Join conditions (since 1.27)
774 * @return int Row count
776 public function selectRowCount(
777 $tables, $vars = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
781 * Determines whether a field exists in a table
783 * @param string $table Table name
784 * @param string $field Filed to check on that table
785 * @param string $fname Calling function name (optional)
786 * @return bool Whether $table has filed $field
788 public function fieldExists( $table, $field, $fname = __METHOD__
);
791 * Determines whether an index exists
792 * Usually throws a DBQueryError on failure
793 * If errors are explicitly ignored, returns NULL on failure
795 * @param string $table
796 * @param string $index
797 * @param string $fname
800 public function indexExists( $table, $index, $fname = __METHOD__
);
803 * Query whether a given table exists
805 * @param string $table
806 * @param string $fname
809 public function tableExists( $table, $fname = __METHOD__
);
812 * Determines if a given index is unique
814 * @param string $table
815 * @param string $index
819 public function indexUnique( $table, $index );
822 * INSERT wrapper, inserts an array into a table.
826 * - A single associative array. The array keys are the field names, and
827 * the values are the values to insert. The values are treated as data
828 * and will be quoted appropriately. If NULL is inserted, this will be
829 * converted to a database NULL.
830 * - An array with numeric keys, holding a list of associative arrays.
831 * This causes a multi-row INSERT on DBMSs that support it. The keys in
832 * each subarray must be identical to each other, and in the same order.
834 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
837 * $options is an array of options, with boolean options encoded as values
838 * with numeric keys, in the same style as $options in
839 * IDatabase::select(). Supported options are:
841 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
842 * any rows which cause duplicate key errors are not inserted. It's
843 * possible to determine how many rows were successfully inserted using
844 * IDatabase::affectedRows().
846 * @param string $table Table name. This will be passed through
847 * DatabaseBase::tableName().
848 * @param array $a Array of rows to insert
849 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
850 * @param array $options Array of options
854 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
857 * UPDATE wrapper. Takes a condition array and a SET array.
859 * @param string $table Name of the table to UPDATE. This will be passed through
860 * DatabaseBase::tableName().
861 * @param array $values An array of values to SET. For each array element,
862 * the key gives the field name, and the value gives the data to set
863 * that field to. The data will be quoted by IDatabase::addQuotes().
864 * @param array $conds An array of conditions (WHERE). See
865 * IDatabase::select() for the details of the format of condition
866 * arrays. Use '*' to update all rows.
867 * @param string $fname The function name of the caller (from __METHOD__),
868 * for logging and profiling.
869 * @param array $options An array of UPDATE options, can be:
870 * - IGNORE: Ignore unique key conflicts
871 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
874 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
877 * Makes an encoded list of strings from an array
879 * @param array $a Containing the data
880 * @param int $mode Constant
881 * - LIST_COMMA: Comma separated, no field names
882 * - LIST_AND: ANDed WHERE clause (without the WHERE). See the
883 * documentation for $conds in IDatabase::select().
884 * - LIST_OR: ORed WHERE clause (without the WHERE)
885 * - LIST_SET: Comma separated with field names, like a SET clause
886 * - LIST_NAMES: Comma separated field names
887 * @throws MWException|DBUnexpectedError
890 public function makeList( $a, $mode = LIST_COMMA
);
893 * Build a partial where clause from a 2-d array such as used for LinkBatch.
894 * The keys on each level may be either integers or strings.
896 * @param array $data Organized as 2-d
897 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
898 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
899 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
900 * @return string|bool SQL fragment, or false if no items in array
902 public function makeWhereFrom2d( $data, $baseKey, $subKey );
905 * @param string $field
908 public function bitNot( $field );
911 * @param string $fieldLeft
912 * @param string $fieldRight
915 public function bitAnd( $fieldLeft, $fieldRight );
918 * @param string $fieldLeft
919 * @param string $fieldRight
922 public function bitOr( $fieldLeft, $fieldRight );
925 * Build a concatenation list to feed into a SQL query
926 * @param array $stringList List of raw SQL expressions; caller is
927 * responsible for any quoting
930 public function buildConcat( $stringList );
933 * Build a GROUP_CONCAT or equivalent statement for a query.
935 * This is useful for combining a field for several rows into a single string.
936 * NULL values will not appear in the output, duplicated values will appear,
937 * and the resulting delimiter-separated values have no defined sort order.
938 * Code using the results may need to use the PHP unique() or sort() methods.
940 * @param string $delim Glue to bind the results together
941 * @param string|array $table Table name
942 * @param string $field Field name
943 * @param string|array $conds Conditions
944 * @param string|array $join_conds Join conditions
945 * @return string SQL text
948 public function buildGroupConcatField(
949 $delim, $table, $field, $conds = '', $join_conds = []
953 * Change the current database
956 * @return bool Success or failure
958 public function selectDB( $db );
961 * Get the current DB name
964 public function getDBname();
967 * Get the server hostname or IP address
970 public function getServer();
973 * Adds quotes and backslashes.
975 * @param string|Blob $s
978 public function addQuotes( $s );
981 * LIKE statement wrapper, receives a variable-length argument list with
982 * parts of pattern to match containing either string literals that will be
983 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
984 * the function could be provided with an array of aforementioned
987 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
988 * a LIKE clause that searches for subpages of 'My page title'.
990 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
991 * $query .= $dbr->buildLike( $pattern );
994 * @return string Fully built LIKE statement
996 public function buildLike();
999 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1003 public function anyChar();
1006 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1010 public function anyString();
1013 * Returns an appropriately quoted sequence value for inserting a new row.
1014 * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1015 * subclass will return an integer, and save the value for insertId()
1017 * Any implementation of this function should *not* involve reusing
1018 * sequence numbers created for rolled-back transactions.
1019 * See http://bugs.mysql.com/bug.php?id=30767 for details.
1020 * @param string $seqName
1023 public function nextSequenceValue( $seqName );
1026 * REPLACE query wrapper.
1028 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1029 * except that when there is a duplicate key error, the old row is deleted
1030 * and the new row is inserted in its place.
1032 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1033 * perform the delete, we need to know what the unique indexes are so that
1034 * we know how to find the conflicting rows.
1036 * It may be more efficient to leave off unique indexes which are unlikely
1037 * to collide. However if you do this, you run the risk of encountering
1038 * errors which wouldn't have occurred in MySQL.
1040 * @param string $table The table to replace the row(s) in.
1041 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1042 * a field name or an array of field names
1043 * @param array $rows Can be either a single row to insert, or multiple rows,
1044 * in the same format as for IDatabase::insert()
1045 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1047 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1050 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1052 * This updates any conflicting rows (according to the unique indexes) using
1053 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1055 * $rows may be either:
1056 * - A single associative array. The array keys are the field names, and
1057 * the values are the values to insert. The values are treated as data
1058 * and will be quoted appropriately. If NULL is inserted, this will be
1059 * converted to a database NULL.
1060 * - An array with numeric keys, holding a list of associative arrays.
1061 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1062 * each subarray must be identical to each other, and in the same order.
1064 * It may be more efficient to leave off unique indexes which are unlikely
1065 * to collide. However if you do this, you run the risk of encountering
1066 * errors which wouldn't have occurred in MySQL.
1068 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1073 * @param string $table Table name. This will be passed through DatabaseBase::tableName().
1074 * @param array $rows A single row or list of rows to insert
1075 * @param array $uniqueIndexes List of single field names or field name tuples
1076 * @param array $set An array of values to SET. For each array element, the
1077 * key gives the field name, and the value gives the data to set that
1078 * field to. The data will be quoted by IDatabase::addQuotes().
1079 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1083 public function upsert(
1084 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1088 * DELETE where the condition is a join.
1090 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1091 * we use sub-selects
1093 * For safety, an empty $conds will not delete everything. If you want to
1094 * delete all rows where the join condition matches, set $conds='*'.
1096 * DO NOT put the join condition in $conds.
1098 * @param string $delTable The table to delete from.
1099 * @param string $joinTable The other table.
1100 * @param string $delVar The variable to join on, in the first table.
1101 * @param string $joinVar The variable to join on, in the second table.
1102 * @param array $conds Condition array of field names mapped to variables,
1103 * ANDed together in the WHERE clause
1104 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1105 * @throws DBUnexpectedError
1107 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1112 * DELETE query wrapper.
1114 * @param array $table Table name
1115 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1116 * for the format. Use $conds == "*" to delete all rows
1117 * @param string $fname Name of the calling function
1118 * @throws DBUnexpectedError
1119 * @return bool|ResultWrapper
1121 public function delete( $table, $conds, $fname = __METHOD__
);
1124 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1125 * into another table.
1127 * @param string $destTable The table name to insert into
1128 * @param string|array $srcTable May be either a table name, or an array of table names
1129 * to include in a join.
1131 * @param array $varMap Must be an associative array of the form
1132 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1133 * rather than field names, but strings should be quoted with
1134 * IDatabase::addQuotes()
1136 * @param array $conds Condition array. See $conds in IDatabase::select() for
1137 * the details of the format of condition arrays. May be "*" to copy the
1140 * @param string $fname The function name of the caller, from __METHOD__
1142 * @param array $insertOptions Options for the INSERT part of the query, see
1143 * IDatabase::insert() for details.
1144 * @param array $selectOptions Options for the SELECT part of the query, see
1145 * IDatabase::select() for details.
1147 * @return ResultWrapper
1149 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1150 $fname = __METHOD__
,
1151 $insertOptions = [], $selectOptions = []
1155 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1156 * within the UNION construct.
1159 public function unionSupportsOrderAndLimit();
1162 * Construct a UNION query
1163 * This is used for providing overload point for other DB abstractions
1164 * not compatible with the MySQL syntax.
1165 * @param array $sqls SQL statements to combine
1166 * @param bool $all Use UNION ALL
1167 * @return string SQL fragment
1169 public function unionQueries( $sqls, $all );
1172 * Returns an SQL expression for a simple conditional. This doesn't need
1173 * to be overridden unless CASE isn't supported in your DBMS.
1175 * @param string|array $cond SQL expression which will result in a boolean value
1176 * @param string $trueVal SQL expression to return if true
1177 * @param string $falseVal SQL expression to return if false
1178 * @return string SQL fragment
1180 public function conditional( $cond, $trueVal, $falseVal );
1183 * Returns a comand for str_replace function in SQL query.
1184 * Uses REPLACE() in MySQL
1186 * @param string $orig Column to modify
1187 * @param string $old Column to seek
1188 * @param string $new Column to replace with
1192 public function strreplace( $orig, $old, $new );
1195 * Determines how long the server has been up
1199 public function getServerUptime();
1202 * Determines if the last failure was due to a deadlock
1206 public function wasDeadlock();
1209 * Determines if the last failure was due to a lock timeout
1213 public function wasLockTimeout();
1216 * Determines if the last query error was due to a dropped connection and should
1217 * be dealt with by pinging the connection and reissuing the query.
1221 public function wasErrorReissuable();
1224 * Determines if the last failure was due to the database being read-only.
1228 public function wasReadOnlyError();
1231 * Wait for the slave to catch up to a given master position
1233 * @param DBMasterPos $pos
1234 * @param int $timeout The maximum number of seconds to wait for synchronisation
1235 * @return int|null Zero if the slave was past that position already,
1236 * greater than zero if we waited for some period of time, less than
1237 * zero if it timed out, and null on error
1239 public function masterPosWait( DBMasterPos
$pos, $timeout );
1242 * Get the replication position of this slave
1244 * @return DBMasterPos|bool False if this is not a slave.
1246 public function getSlavePos();
1249 * Get the position of this master
1251 * @return DBMasterPos|bool False if this is not a master
1253 public function getMasterPos();
1256 * @return bool Whether the DB is marked as read-only server-side
1259 public function serverIsReadOnly();
1262 * Run a callback as soon as the current transaction commits or rolls back.
1263 * An error is thrown if no transaction is pending. Queries in the function will run in
1264 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1267 * This is useful for combining cooperative locks and DB transactions.
1269 * The callback takes one argument:
1270 * How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1272 * @param callable $callback
1276 public function onTransactionResolution( callable
$callback );
1279 * Run a callback as soon as there is no transaction pending.
1280 * If there is a transaction and it is rolled back, then the callback is cancelled.
1281 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1282 * Callbacks must commit any transactions that they begin.
1284 * This is useful for updates to different systems or when separate transactions are needed.
1285 * For example, one might want to enqueue jobs into a system outside the database, but only
1286 * after the database is updated so that the jobs will see the data when they actually run.
1287 * It can also be used for updates that easily cause deadlocks if locks are held too long.
1289 * Updates will execute in the order they were enqueued.
1291 * The callback takes one argument:
1292 * How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1294 * @param callable $callback
1297 public function onTransactionIdle( callable
$callback );
1300 * Run a callback before the current transaction commits or now if there is none.
1301 * If there is a transaction and it is rolled back, then the callback is cancelled.
1302 * Callbacks must not start nor commit any transactions. If no transaction is active,
1303 * then a transaction will wrap the callback.
1305 * This is useful for updates that easily cause deadlocks if locks are held too long
1306 * but where atomicity is strongly desired for these updates and some related updates.
1308 * Updates will execute in the order they were enqueued.
1310 * @param callable $callback
1313 public function onTransactionPreCommitOrIdle( callable
$callback );
1316 * Begin an atomic section of statements
1318 * If a transaction has been started already, just keep track of the given
1319 * section name to make sure the transaction is not committed pre-maturely.
1320 * This function can be used in layers (with sub-sections), so use a stack
1321 * to keep track of the different atomic sections. If there is no transaction,
1322 * start one implicitly.
1324 * The goal of this function is to create an atomic section of SQL queries
1325 * without having to start a new transaction if it already exists.
1327 * Atomic sections are more strict than transactions. With transactions,
1328 * attempting to begin a new transaction when one is already running results
1329 * in MediaWiki issuing a brief warning and doing an implicit commit. All
1330 * atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1331 * and any database transactions cannot be began or committed until all atomic
1332 * levels are closed. There is no such thing as implicitly opening or closing
1333 * an atomic section.
1336 * @param string $fname
1339 public function startAtomic( $fname = __METHOD__
);
1342 * Ends an atomic section of SQL statements
1344 * Ends the next section of atomic SQL statements and commits the transaction
1348 * @see IDatabase::startAtomic
1349 * @param string $fname
1352 public function endAtomic( $fname = __METHOD__
);
1355 * Run a callback to do an atomic set of updates for this database
1357 * The $callback takes the following arguments:
1358 * - This database object
1359 * - The value of $fname
1361 * If any exception occurs in the callback, then rollback() will be called and the error will
1362 * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1363 * In any case, such errors are expected to terminate the request, without any outside caller
1364 * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1365 * atomic section and uncommitted updates, which trashes the current request, requiring an
1366 * error to be displayed.
1368 * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1370 * @see DatabaseBase::startAtomic
1371 * @see DatabaseBase::endAtomic
1373 * @param string $fname Caller name (usually __METHOD__)
1374 * @param callable $callback Callback that issues DB updates
1375 * @return mixed $res Result of the callback (since 1.28)
1377 * @throws RuntimeException
1378 * @throws UnexpectedValueException
1381 public function doAtomicSection( $fname, callable
$callback );
1384 * Begin a transaction. If a transaction is already in progress,
1385 * that transaction will be committed before the new transaction is started.
1387 * Only call this from code with outer transcation scope.
1388 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1389 * Nesting of transactions is not supported.
1391 * Note that when the DBO_TRX flag is set (which is usually the case for web
1392 * requests, but not for maintenance scripts), any previous database query
1393 * will have started a transaction automatically.
1395 * Nesting of transactions is not supported. Attempts to nest transactions
1396 * will cause a warning, unless the current transaction was started
1397 * automatically because of the DBO_TRX flag.
1399 * @param string $fname
1400 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1403 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1406 * Commits a transaction previously started using begin().
1407 * If no transaction is in progress, a warning is issued.
1409 * Only call this from code with outer transcation scope.
1410 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1411 * Nesting of transactions is not supported.
1413 * @param string $fname
1414 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1415 * constant to disable warnings about explicitly committing implicit transactions,
1416 * or calling commit when no transaction is in progress.
1418 * This will trigger an exception if there is an ongoing explicit transaction.
1420 * Only set the flush flag if you are sure that these warnings are not applicable,
1421 * and no explicit transactions are open.
1423 * @throws DBUnexpectedError
1425 public function commit( $fname = __METHOD__
, $flush = '' );
1428 * Rollback a transaction previously started using begin().
1429 * If no transaction is in progress, a warning is issued.
1431 * Only call this from code with outer transcation scope.
1432 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1433 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1434 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1435 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1437 * @param string $fname
1438 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1439 * constant to disable warnings about calling rollback when no transaction is in
1440 * progress. This will silently break any ongoing explicit transaction. Only set the
1441 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1442 * @throws DBUnexpectedError
1443 * @since 1.23 Added $flush parameter
1445 public function rollback( $fname = __METHOD__
, $flush = '' );
1448 * List all tables on the database
1450 * @param string $prefix Only show tables with this prefix, e.g. mw_
1451 * @param string $fname Calling function name
1452 * @throws MWException
1455 public function listTables( $prefix = null, $fname = __METHOD__
);
1458 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1459 * to the format used for inserting into timestamp fields in this DBMS.
1461 * The result is unquoted, and needs to be passed through addQuotes()
1462 * before it can be included in raw SQL.
1464 * @param string|int $ts
1468 public function timestamp( $ts = 0 );
1471 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1472 * to the format used for inserting into timestamp fields in this DBMS. If
1473 * NULL is input, it is passed through, allowing NULL values to be inserted
1474 * into timestamp fields.
1476 * The result is unquoted, and needs to be passed through addQuotes()
1477 * before it can be included in raw SQL.
1479 * @param string|int $ts
1483 public function timestampOrNull( $ts = null );
1486 * Ping the server and try to reconnect if it there is no connection
1488 * @return bool Success or failure
1490 public function ping();
1493 * Get slave lag. Currently supported only by MySQL.
1495 * Note that this function will generate a fatal error on many
1496 * installations. Most callers should use LoadBalancer::safeGetLag()
1499 * @return int|bool Database replication lag in seconds or false on error
1501 public function getLag();
1504 * Get the slave lag when the current transaction started
1505 * or a general lag estimate if not transaction is active
1507 * This is useful when transactions might use snapshot isolation
1508 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1509 * is this lag plus transaction duration. If they don't, it is still
1510 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1511 * indication of the staleness of subsequent reads.
1513 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1516 public function getSessionLagStatus();
1519 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1523 public function maxListLen();
1526 * Some DBMSs have a special format for inserting into blob fields, they
1527 * don't allow simple quoted strings to be inserted. To insert into such
1528 * a field, pass the data through this function before passing it to
1529 * IDatabase::insert().
1534 public function encodeBlob( $b );
1537 * Some DBMSs return a special placeholder object representing blob fields
1538 * in result objects. Pass the object through this function to return the
1541 * @param string|Blob $b
1544 public function decodeBlob( $b );
1547 * Override database's default behavior. $options include:
1548 * 'connTimeout' : Set the connection timeout value in seconds.
1549 * May be useful for very long batch queries such as
1550 * full-wiki dumps, where a single query reads out over
1553 * @param array $options
1556 public function setSessionOptions( array $options );
1559 * Set variables to be used in sourceFile/sourceStream, in preference to the
1560 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1561 * all. If it's set to false, $GLOBALS will be used.
1563 * @param bool|array $vars Mapping variable name to value.
1565 public function setSchemaVars( $vars );
1568 * Check to see if a named lock is available (non-blocking)
1570 * @param string $lockName Name of lock to poll
1571 * @param string $method Name of method calling us
1575 public function lockIsFree( $lockName, $method );
1578 * Acquire a named lock
1580 * Named locks are not related to transactions
1582 * @param string $lockName Name of lock to aquire
1583 * @param string $method Name of the calling method
1584 * @param int $timeout Acquisition timeout in seconds
1587 public function lock( $lockName, $method, $timeout = 5 );
1592 * Named locks are not related to transactions
1594 * @param string $lockName Name of lock to release
1595 * @param string $method Name of the calling method
1597 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1598 * by this thread (in which case the lock is not released), and NULL if the named
1599 * lock did not exist
1601 public function unlock( $lockName, $method );
1604 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1606 * Only call this from outer transcation scope and when only one DB will be affected.
1607 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1609 * This is suitiable for transactions that need to be serialized using cooperative locks,
1610 * where each transaction can see each others' changes. Any transaction is flushed to clear
1611 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1612 * the lock will be released unless a transaction is active. If one is active, then the lock
1613 * will be released when it either commits or rolls back.
1615 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1617 * @param string $lockKey Name of lock to release
1618 * @param string $fname Name of the calling method
1619 * @param int $timeout Acquisition timeout in seconds
1620 * @return ScopedCallback|null
1621 * @throws DBUnexpectedError
1624 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1627 * Check to see if a named lock used by lock() use blocking queues
1632 public function namedLocksEnqueue();
1635 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1636 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1637 * because "i" sorts after all numbers.
1641 public function getInfinity();
1644 * Encode an expiry time into the DBMS dependent format
1646 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1649 public function encodeExpiry( $expiry );
1652 * Decode an expiry time into a DBMS independent format
1654 * @param string $expiry DB timestamp field value for expiry
1655 * @param int $format TS_* constant, defaults to TS_MW
1658 public function decodeExpiry( $expiry, $format = TS_MW
);
1661 * Allow or deny "big selects" for this session only. This is done by setting
1662 * the sql_big_selects session variable.
1664 * This is a MySQL-specific feature.
1666 * @param bool|string $value True for allow, false for deny, or "default" to
1667 * restore the initial value
1669 public function setBigSelects( $value = true );
1672 * @return bool Whether this DB is read-only
1675 public function isReadOnly();