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 internally 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 Do 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';
62 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
63 const ESTIMATE_TOTAL
= 'total';
64 /** @var string Estimate time to apply (scanning, applying) */
65 const ESTIMATE_DB_APPLY
= 'apply';
68 * A string describing the current software version, and possibly
69 * other details in a user-friendly way. Will be listed on Special:Version, etc.
70 * Use getServerVersion() to get machine-friendly information.
72 * @return string Version information from the database server
74 public function getServerInfo();
77 * Turns buffering of SQL result sets on (true) or off (false). Default is
80 * Unbuffered queries are very troublesome in MySQL:
82 * - If another query is executed while the first query is being read
83 * out, the first query is killed. This means you can't call normal
84 * MediaWiki functions while you are reading an unbuffered query result
85 * from a normal wfGetDB() connection.
87 * - Unbuffered queries cause the MySQL server to use large amounts of
88 * memory and to hold broad locks which block other queries.
90 * If you want to limit client-side memory, it's almost always better to
91 * split up queries into batches using a LIMIT clause than to switch off
94 * @param null|bool $buffer
95 * @return null|bool The previous value of the flag
97 public function bufferResults( $buffer = null );
100 * Gets the current transaction level.
102 * Historically, transactions were allowed to be "nested". This is no
103 * longer supported, so this function really only returns a boolean.
105 * @return int The previous value
107 public function trxLevel();
110 * Get the UNIX timestamp of the time that the transaction was established
112 * This can be used to reason about the staleness of SELECT data
113 * in REPEATABLE-READ transaction isolation level.
115 * @return float|null Returns null if there is not active transaction
118 public function trxTimestamp();
121 * @return bool Whether an explicit transaction or atomic sections are still open
124 public function explicitTrxActive();
127 * Get/set the table prefix.
128 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
129 * @return string The previous table prefix.
131 public function tablePrefix( $prefix = null );
134 * Get/set the db schema.
135 * @param string $schema The database schema to set, or omitted to leave it unchanged.
136 * @return string The previous db schema.
138 public function dbSchema( $schema = null );
141 * Get properties passed down from the server info array of the load
144 * @param string $name The entry of the info array to get, or null to get the
147 * @return array|mixed|null
149 public function getLBInfo( $name = null );
152 * Set the LB info array, or a member of it. If called with one parameter,
153 * the LB info array is set to that parameter. If it is called with two
154 * parameters, the member with the given name is set to the given value.
156 * @param string $name
157 * @param array $value
159 public function setLBInfo( $name, $value = null );
162 * Returns true if this database does an implicit sort when doing GROUP BY
166 public function implicitGroupby();
169 * Returns true if this database does an implicit order by when the column has an index
170 * For example: SELECT page_title FROM page LIMIT 1
174 public function implicitOrderby();
177 * Return the last query that went through IDatabase::query()
180 public function lastQuery();
183 * Returns true if the connection may have been used for write queries.
184 * Should return true if unsure.
188 public function doneWrites();
191 * Returns the last time the connection may have been used for write queries.
192 * Should return a timestamp if unsure.
194 * @return int|float UNIX timestamp or false
197 public function lastDoneWrites();
200 * @return bool Whether there is a transaction open with possible write queries
203 public function writesPending();
206 * Returns true if there is a transaction open with possible write
207 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
208 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
212 public function writesOrCallbacksPending();
215 * Get the time spend running write queries for this transaction
217 * High times could be due to scanning, updates, locking, and such
219 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
220 * @return float|bool Returns false if not transaction is active
223 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
226 * Get the list of method names that did write queries for this transaction
231 public function pendingWriteCallers();
234 * Is a connection to the database open?
237 public function isOpen();
240 * Set a flag for this connection
242 * @param int $flag DBO_* constants from Defines.php:
243 * - DBO_DEBUG: output some debug info (same as debug())
244 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
245 * - DBO_TRX: automatically start transactions
246 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
247 * and removes it in command line mode
248 * - DBO_PERSISTENT: use persistant database connection
249 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
251 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
254 * Clear a flag for this connection
256 * @param int $flag DBO_* constants from Defines.php:
257 * - DBO_DEBUG: output some debug info (same as debug())
258 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
259 * - DBO_TRX: automatically start transactions
260 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
261 * and removes it in command line mode
262 * - DBO_PERSISTENT: use persistant database connection
263 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
265 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
268 * Restore the flags to their prior state before the last setFlag/clearFlag call
270 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
273 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
276 * Returns a boolean whether the flag $flag is set for this connection
278 * @param int $flag DBO_* constants from Defines.php:
279 * - DBO_DEBUG: output some debug info (same as debug())
280 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
281 * - DBO_TRX: automatically start transactions
282 * - DBO_PERSISTENT: use persistant database connection
285 public function getFlag( $flag );
288 * General read-only accessor
290 * @param string $name
293 public function getProperty( $name );
298 public function getWikiID();
301 * Get the type of the DBMS, as it appears in $wgDBtype.
305 public function getType();
308 * Open a connection to the database. Usually aborts on failure
310 * @param string $server Database server host
311 * @param string $user Database user name
312 * @param string $password Database user password
313 * @param string $dbName Database name
315 * @throws DBConnectionError
317 public function open( $server, $user, $password, $dbName );
320 * Fetch the next row from the given result object, in object form.
321 * Fields can be retrieved with $row->fieldname, with fields acting like
323 * If no more rows are available, false is returned.
325 * @param ResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
326 * @return stdClass|bool
327 * @throws DBUnexpectedError Thrown if the database returns an error
329 public function fetchObject( $res );
332 * Fetch the next row from the given result object, in associative array
333 * form. Fields are retrieved with $row['fieldname'].
334 * If no more rows are available, false is returned.
336 * @param ResultWrapper $res Result object as returned from IDatabase::query(), etc.
338 * @throws DBUnexpectedError Thrown if the database returns an error
340 public function fetchRow( $res );
343 * Get the number of rows in a result object
345 * @param mixed $res A SQL result
348 public function numRows( $res );
351 * Get the number of fields in a result object
352 * @see http://www.php.net/mysql_num_fields
354 * @param mixed $res A SQL result
357 public function numFields( $res );
360 * Get a field name in a result object
361 * @see http://www.php.net/mysql_field_name
363 * @param mixed $res A SQL result
367 public function fieldName( $res, $n );
370 * Get the inserted value of an auto-increment row
372 * The value inserted should be fetched from nextSequenceValue()
375 * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
376 * $dbw->insert( 'page', [ 'page_id' => $id ] );
377 * $id = $dbw->insertId();
381 public function insertId();
384 * Change the position of the cursor in a result object
385 * @see http://www.php.net/mysql_data_seek
387 * @param mixed $res A SQL result
390 public function dataSeek( $res, $row );
393 * Get the last error number
394 * @see http://www.php.net/mysql_errno
398 public function lastErrno();
401 * Get a description of the last error
402 * @see http://www.php.net/mysql_error
406 public function lastError();
409 * mysql_fetch_field() wrapper
410 * Returns false if the field doesn't exist
412 * @param string $table Table name
413 * @param string $field Field name
417 public function fieldInfo( $table, $field );
420 * Get the number of rows affected by the last write query
421 * @see http://www.php.net/mysql_affected_rows
425 public function affectedRows();
428 * Returns a wikitext link to the DB's website, e.g.,
429 * return "[http://www.mysql.com/ MySQL]";
430 * Should at least contain plain text, if for some reason
431 * your database has no website.
433 * @return string Wikitext of a link to the server software's web site
435 public function getSoftwareLink();
438 * A string describing the current software version, like from
439 * mysql_get_server_info().
441 * @return string Version information from the database server.
443 public function getServerVersion();
446 * Closes a database connection.
447 * if it is open : commits any open transactions
449 * @throws MWException
450 * @return bool Operation success. true if already closed.
452 public function close();
455 * @param string $error Fallback error message, used if none is given by DB
456 * @throws DBConnectionError
458 public function reportConnectionError( $error = 'Unknown error' );
461 * Run an SQL query and return the result. Normally throws a DBQueryError
462 * on failure. If errors are ignored, returns false instead.
464 * In new code, the query wrappers select(), insert(), update(), delete(),
465 * etc. should be used where possible, since they give much better DBMS
466 * independence and automatically quote or validate user input in a variety
467 * of contexts. This function is generally only useful for queries which are
468 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
471 * However, the query wrappers themselves should call this function.
473 * @param string $sql SQL query
474 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
475 * comment (you can use __METHOD__ or add some extra info)
476 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
477 * maybe best to catch the exception instead?
478 * @throws MWException
479 * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
480 * for a successful read query, or false on failure if $tempIgnore set
482 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
485 * Report a query error. Log the error, and if neither the object ignore
486 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
488 * @param string $error
491 * @param string $fname
492 * @param bool $tempIgnore
493 * @throws DBQueryError
495 public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
498 * Free a result object returned by query() or select(). It's usually not
499 * necessary to call this, just use unset() or let the variable holding
500 * the result object go out of scope.
502 * @param mixed $res A SQL result
504 public function freeResult( $res );
507 * A SELECT wrapper which returns a single field from a single result row.
509 * Usually throws a DBQueryError on failure. If errors are explicitly
510 * ignored, returns false on failure.
512 * If no result rows are returned from the query, false is returned.
514 * @param string|array $table Table name. See IDatabase::select() for details.
515 * @param string $var The field name to select. This must be a valid SQL
516 * fragment: do not use unvalidated user input.
517 * @param string|array $cond The condition array. See IDatabase::select() for details.
518 * @param string $fname The function name of the caller.
519 * @param string|array $options The query options. See IDatabase::select() for details.
521 * @return bool|mixed The value from the field, or false on failure.
523 public function selectField(
524 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
528 * A SELECT wrapper which returns a list of single field values from result rows.
530 * Usually throws a DBQueryError on failure. If errors are explicitly
531 * ignored, returns false on failure.
533 * If no result rows are returned from the query, false is returned.
535 * @param string|array $table Table name. See IDatabase::select() for details.
536 * @param string $var The field name to select. This must be a valid SQL
537 * fragment: do not use unvalidated user input.
538 * @param string|array $cond The condition array. See IDatabase::select() for details.
539 * @param string $fname The function name of the caller.
540 * @param string|array $options The query options. See IDatabase::select() for details.
542 * @return bool|array The values from the field, or false on failure
545 public function selectFieldValues(
546 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
550 * Execute a SELECT query constructed using the various parameters provided.
551 * See below for full details of the parameters.
553 * @param string|array $table Table name
554 * @param string|array $vars Field names
555 * @param string|array $conds Conditions
556 * @param string $fname Caller function name
557 * @param array $options Query options
558 * @param array $join_conds Join conditions
561 * @param string|array $table
563 * May be either an array of table names, or a single string holding a table
564 * name. If an array is given, table aliases can be specified, for example:
568 * This includes the user table in the query, with the alias "a" available
569 * for use in field names (e.g. a.user_name).
571 * All of the table names given here are automatically run through
572 * DatabaseBase::tableName(), which causes the table prefix (if any) to be
573 * added, and various other table name mappings to be performed.
575 * Do not use untrusted user input as a table name. Alias names should
576 * not have characters outside of the Basic multilingual plane.
578 * @param string|array $vars
580 * May be either a field name or an array of field names. The field names
581 * can be complete fragments of SQL, for direct inclusion into the SELECT
582 * query. If an array is given, field aliases can be specified, for example:
584 * [ 'maxrev' => 'MAX(rev_id)' ]
586 * This includes an expression with the alias "maxrev" in the query.
588 * If an expression is given, care must be taken to ensure that it is
591 * Untrusted user input must not be passed to this parameter.
593 * @param string|array $conds
595 * May be either a string containing a single condition, or an array of
596 * conditions. If an array is given, the conditions constructed from each
597 * element are combined with AND.
599 * Array elements may take one of two forms:
601 * - Elements with a numeric key are interpreted as raw SQL fragments.
602 * - Elements with a string key are interpreted as equality conditions,
603 * where the key is the field name.
604 * - If the value of such an array element is a scalar (such as a
605 * string), it will be treated as data and thus quoted appropriately.
606 * If it is null, an IS NULL clause will be added.
607 * - If the value is an array, an IN (...) clause will be constructed
608 * from its non-null elements, and an IS NULL clause will be added
609 * if null is present, such that the field may match any of the
610 * elements in the array. The non-null elements will be quoted.
612 * Note that expressions are often DBMS-dependent in their syntax.
613 * DBMS-independent wrappers are provided for constructing several types of
614 * expression commonly used in condition queries. See:
615 * - IDatabase::buildLike()
616 * - IDatabase::conditional()
618 * Untrusted user input is safe in the values of string keys, however untrusted
619 * input must not be used in the array key names or in the values of numeric keys.
620 * Escaping of untrusted input used in values of numeric keys should be done via
621 * IDatabase::addQuotes()
623 * @param string|array $options
625 * Optional: Array of query options. Boolean options are specified by
626 * including them in the array as a string value with a numeric key, for
631 * The supported options are:
633 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
634 * with LIMIT can theoretically be used for paging through a result set,
635 * but this is discouraged in MediaWiki for performance reasons.
637 * - LIMIT: Integer: return at most this many rows. The rows are sorted
638 * and then the first rows are taken until the limit is reached. LIMIT
639 * is applied to a result set after OFFSET.
641 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
642 * changed until the next COMMIT.
644 * - DISTINCT: Boolean: return only unique result rows.
646 * - GROUP BY: May be either an SQL fragment string naming a field or
647 * expression to group by, or an array of such SQL fragments.
649 * - HAVING: May be either an string containing a HAVING clause or an array of
650 * conditions building the HAVING clause. If an array is given, the conditions
651 * constructed from each element are combined with AND.
653 * - ORDER BY: May be either an SQL fragment giving a field name or
654 * expression to order by, or an array of such SQL fragments.
656 * - USE INDEX: This may be either a string giving the index name to use
657 * for the query, or an array. If it is an associative array, each key
658 * gives the table name (or alias), each value gives the index name to
659 * use for that table. All strings are SQL fragments and so should be
660 * validated by the caller.
662 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
665 * And also the following boolean MySQL extensions, see the MySQL manual
668 * - LOCK IN SHARE MODE
672 * - SQL_BUFFER_RESULT
674 * - SQL_CALC_FOUND_ROWS
679 * @param string|array $join_conds
681 * Optional associative array of table-specific join conditions. In the
682 * most common case, this is unnecessary, since the join condition can be
683 * in $conds. However, it is useful for doing a LEFT JOIN.
685 * The key of the array contains the table name or alias. The value is an
686 * array with two elements, numbered 0 and 1. The first gives the type of
687 * join, the second is the same as the $conds parameter. Thus it can be
688 * an SQL fragment, or an array where the string keys are equality and the
689 * numeric keys are SQL fragments all AND'd together. For example:
691 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
693 * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
694 * with no rows in it will be returned. If there was a query error, a
695 * DBQueryError exception will be thrown, except if the "ignore errors"
696 * option was set, in which case false will be returned.
698 public function select(
699 $table, $vars, $conds = '', $fname = __METHOD__
,
700 $options = [], $join_conds = []
704 * The equivalent of IDatabase::select() except that the constructed SQL
705 * is returned, instead of being immediately executed. This can be useful for
706 * doing UNION queries, where the SQL text of each query is needed. In general,
707 * however, callers outside of Database classes should just use select().
709 * @param string|array $table Table name
710 * @param string|array $vars Field names
711 * @param string|array $conds Conditions
712 * @param string $fname Caller function name
713 * @param string|array $options Query options
714 * @param string|array $join_conds Join conditions
716 * @return string SQL query string.
717 * @see IDatabase::select()
719 public function selectSQLText(
720 $table, $vars, $conds = '', $fname = __METHOD__
,
721 $options = [], $join_conds = []
725 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
726 * that a single row object is returned. If the query returns no rows,
729 * @param string|array $table Table name
730 * @param string|array $vars Field names
731 * @param array $conds Conditions
732 * @param string $fname Caller function name
733 * @param string|array $options Query options
734 * @param array|string $join_conds Join conditions
736 * @return stdClass|bool
738 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
739 $options = [], $join_conds = []
743 * Estimate the number of rows in dataset
745 * MySQL allows you to estimate the number of rows that would be returned
746 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
747 * index cardinality statistics, and is notoriously inaccurate, especially
748 * when large numbers of rows have recently been added or deleted.
750 * For DBMSs that don't support fast result size estimation, this function
751 * will actually perform the SELECT COUNT(*).
753 * Takes the same arguments as IDatabase::select().
755 * @param string $table Table name
756 * @param string $vars Unused
757 * @param array|string $conds Filters on the table
758 * @param string $fname Function name for profiling
759 * @param array $options Options for select
760 * @return int Row count
762 public function estimateRowCount(
763 $table, $vars = '*', $conds = '', $fname = __METHOD__
, $options = []
767 * Get the number of rows in dataset
769 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
771 * Takes the same arguments as IDatabase::select().
773 * @since 1.27 Added $join_conds parameter
775 * @param array|string $tables Table names
776 * @param string $vars Unused
777 * @param array|string $conds Filters on the table
778 * @param string $fname Function name for profiling
779 * @param array $options Options for select
780 * @param array $join_conds Join conditions (since 1.27)
781 * @return int Row count
783 public function selectRowCount(
784 $tables, $vars = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
788 * Determines whether a field exists in a table
790 * @param string $table Table name
791 * @param string $field Filed to check on that table
792 * @param string $fname Calling function name (optional)
793 * @return bool Whether $table has filed $field
795 public function fieldExists( $table, $field, $fname = __METHOD__
);
798 * Determines whether an index exists
799 * Usually throws a DBQueryError on failure
800 * If errors are explicitly ignored, returns NULL on failure
802 * @param string $table
803 * @param string $index
804 * @param string $fname
807 public function indexExists( $table, $index, $fname = __METHOD__
);
810 * Query whether a given table exists
812 * @param string $table
813 * @param string $fname
816 public function tableExists( $table, $fname = __METHOD__
);
819 * Determines if a given index is unique
821 * @param string $table
822 * @param string $index
826 public function indexUnique( $table, $index );
829 * INSERT wrapper, inserts an array into a table.
833 * - A single associative array. The array keys are the field names, and
834 * the values are the values to insert. The values are treated as data
835 * and will be quoted appropriately. If NULL is inserted, this will be
836 * converted to a database NULL.
837 * - An array with numeric keys, holding a list of associative arrays.
838 * This causes a multi-row INSERT on DBMSs that support it. The keys in
839 * each subarray must be identical to each other, and in the same order.
841 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
844 * $options is an array of options, with boolean options encoded as values
845 * with numeric keys, in the same style as $options in
846 * IDatabase::select(). Supported options are:
848 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
849 * any rows which cause duplicate key errors are not inserted. It's
850 * possible to determine how many rows were successfully inserted using
851 * IDatabase::affectedRows().
853 * @param string $table Table name. This will be passed through
854 * DatabaseBase::tableName().
855 * @param array $a Array of rows to insert
856 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
857 * @param array $options Array of options
861 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
864 * UPDATE wrapper. Takes a condition array and a SET array.
866 * @param string $table Name of the table to UPDATE. This will be passed through
867 * DatabaseBase::tableName().
868 * @param array $values An array of values to SET. For each array element,
869 * the key gives the field name, and the value gives the data to set
870 * that field to. The data will be quoted by IDatabase::addQuotes().
871 * @param array $conds An array of conditions (WHERE). See
872 * IDatabase::select() for the details of the format of condition
873 * arrays. Use '*' to update all rows.
874 * @param string $fname The function name of the caller (from __METHOD__),
875 * for logging and profiling.
876 * @param array $options An array of UPDATE options, can be:
877 * - IGNORE: Ignore unique key conflicts
878 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
881 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
884 * Makes an encoded list of strings from an array
886 * @param array $a Containing the data
887 * @param int $mode Constant
888 * - LIST_COMMA: Comma separated, no field names
889 * - LIST_AND: ANDed WHERE clause (without the WHERE). See the
890 * documentation for $conds in IDatabase::select().
891 * - LIST_OR: ORed WHERE clause (without the WHERE)
892 * - LIST_SET: Comma separated with field names, like a SET clause
893 * - LIST_NAMES: Comma separated field names
894 * @throws MWException|DBUnexpectedError
897 public function makeList( $a, $mode = LIST_COMMA
);
900 * Build a partial where clause from a 2-d array such as used for LinkBatch.
901 * The keys on each level may be either integers or strings.
903 * @param array $data Organized as 2-d
904 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
905 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
906 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
907 * @return string|bool SQL fragment, or false if no items in array
909 public function makeWhereFrom2d( $data, $baseKey, $subKey );
912 * @param string $field
915 public function bitNot( $field );
918 * @param string $fieldLeft
919 * @param string $fieldRight
922 public function bitAnd( $fieldLeft, $fieldRight );
925 * @param string $fieldLeft
926 * @param string $fieldRight
929 public function bitOr( $fieldLeft, $fieldRight );
932 * Build a concatenation list to feed into a SQL query
933 * @param array $stringList List of raw SQL expressions; caller is
934 * responsible for any quoting
937 public function buildConcat( $stringList );
940 * Build a GROUP_CONCAT or equivalent statement for a query.
942 * This is useful for combining a field for several rows into a single string.
943 * NULL values will not appear in the output, duplicated values will appear,
944 * and the resulting delimiter-separated values have no defined sort order.
945 * Code using the results may need to use the PHP unique() or sort() methods.
947 * @param string $delim Glue to bind the results together
948 * @param string|array $table Table name
949 * @param string $field Field name
950 * @param string|array $conds Conditions
951 * @param string|array $join_conds Join conditions
952 * @return string SQL text
955 public function buildGroupConcatField(
956 $delim, $table, $field, $conds = '', $join_conds = []
960 * Change the current database
963 * @return bool Success or failure
965 public function selectDB( $db );
968 * Get the current DB name
971 public function getDBname();
974 * Get the server hostname or IP address
977 public function getServer();
980 * Adds quotes and backslashes.
982 * @param string|Blob $s
985 public function addQuotes( $s );
988 * LIKE statement wrapper, receives a variable-length argument list with
989 * parts of pattern to match containing either string literals that will be
990 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
991 * the function could be provided with an array of aforementioned
994 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
995 * a LIKE clause that searches for subpages of 'My page title'.
997 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
998 * $query .= $dbr->buildLike( $pattern );
1001 * @return string Fully built LIKE statement
1003 public function buildLike();
1006 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1010 public function anyChar();
1013 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1017 public function anyString();
1020 * Returns an appropriately quoted sequence value for inserting a new row.
1021 * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1022 * subclass will return an integer, and save the value for insertId()
1024 * Any implementation of this function should *not* involve reusing
1025 * sequence numbers created for rolled-back transactions.
1026 * See http://bugs.mysql.com/bug.php?id=30767 for details.
1027 * @param string $seqName
1030 public function nextSequenceValue( $seqName );
1033 * REPLACE query wrapper.
1035 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1036 * except that when there is a duplicate key error, the old row is deleted
1037 * and the new row is inserted in its place.
1039 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1040 * perform the delete, we need to know what the unique indexes are so that
1041 * we know how to find the conflicting rows.
1043 * It may be more efficient to leave off unique indexes which are unlikely
1044 * to collide. However if you do this, you run the risk of encountering
1045 * errors which wouldn't have occurred in MySQL.
1047 * @param string $table The table to replace the row(s) in.
1048 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1049 * a field name or an array of field names
1050 * @param array $rows Can be either a single row to insert, or multiple rows,
1051 * in the same format as for IDatabase::insert()
1052 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1054 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1057 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1059 * This updates any conflicting rows (according to the unique indexes) using
1060 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1062 * $rows may be either:
1063 * - A single associative array. The array keys are the field names, and
1064 * the values are the values to insert. The values are treated as data
1065 * and will be quoted appropriately. If NULL is inserted, this will be
1066 * converted to a database NULL.
1067 * - An array with numeric keys, holding a list of associative arrays.
1068 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1069 * each subarray must be identical to each other, and in the same order.
1071 * It may be more efficient to leave off unique indexes which are unlikely
1072 * to collide. However if you do this, you run the risk of encountering
1073 * errors which wouldn't have occurred in MySQL.
1075 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1080 * @param string $table Table name. This will be passed through DatabaseBase::tableName().
1081 * @param array $rows A single row or list of rows to insert
1082 * @param array $uniqueIndexes List of single field names or field name tuples
1083 * @param array $set An array of values to SET. For each array element, the
1084 * key gives the field name, and the value gives the data to set that
1085 * field to. The data will be quoted by IDatabase::addQuotes().
1086 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1090 public function upsert(
1091 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1095 * DELETE where the condition is a join.
1097 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1098 * we use sub-selects
1100 * For safety, an empty $conds will not delete everything. If you want to
1101 * delete all rows where the join condition matches, set $conds='*'.
1103 * DO NOT put the join condition in $conds.
1105 * @param string $delTable The table to delete from.
1106 * @param string $joinTable The other table.
1107 * @param string $delVar The variable to join on, in the first table.
1108 * @param string $joinVar The variable to join on, in the second table.
1109 * @param array $conds Condition array of field names mapped to variables,
1110 * ANDed together in the WHERE clause
1111 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1112 * @throws DBUnexpectedError
1114 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1119 * DELETE query wrapper.
1121 * @param array $table Table name
1122 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1123 * for the format. Use $conds == "*" to delete all rows
1124 * @param string $fname Name of the calling function
1125 * @throws DBUnexpectedError
1126 * @return bool|ResultWrapper
1128 public function delete( $table, $conds, $fname = __METHOD__
);
1131 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1132 * into another table.
1134 * @param string $destTable The table name to insert into
1135 * @param string|array $srcTable May be either a table name, or an array of table names
1136 * to include in a join.
1138 * @param array $varMap Must be an associative array of the form
1139 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1140 * rather than field names, but strings should be quoted with
1141 * IDatabase::addQuotes()
1143 * @param array $conds Condition array. See $conds in IDatabase::select() for
1144 * the details of the format of condition arrays. May be "*" to copy the
1147 * @param string $fname The function name of the caller, from __METHOD__
1149 * @param array $insertOptions Options for the INSERT part of the query, see
1150 * IDatabase::insert() for details.
1151 * @param array $selectOptions Options for the SELECT part of the query, see
1152 * IDatabase::select() for details.
1154 * @return ResultWrapper
1156 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1157 $fname = __METHOD__
,
1158 $insertOptions = [], $selectOptions = []
1162 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1163 * within the UNION construct.
1166 public function unionSupportsOrderAndLimit();
1169 * Construct a UNION query
1170 * This is used for providing overload point for other DB abstractions
1171 * not compatible with the MySQL syntax.
1172 * @param array $sqls SQL statements to combine
1173 * @param bool $all Use UNION ALL
1174 * @return string SQL fragment
1176 public function unionQueries( $sqls, $all );
1179 * Returns an SQL expression for a simple conditional. This doesn't need
1180 * to be overridden unless CASE isn't supported in your DBMS.
1182 * @param string|array $cond SQL expression which will result in a boolean value
1183 * @param string $trueVal SQL expression to return if true
1184 * @param string $falseVal SQL expression to return if false
1185 * @return string SQL fragment
1187 public function conditional( $cond, $trueVal, $falseVal );
1190 * Returns a comand for str_replace function in SQL query.
1191 * Uses REPLACE() in MySQL
1193 * @param string $orig Column to modify
1194 * @param string $old Column to seek
1195 * @param string $new Column to replace with
1199 public function strreplace( $orig, $old, $new );
1202 * Determines how long the server has been up
1206 public function getServerUptime();
1209 * Determines if the last failure was due to a deadlock
1213 public function wasDeadlock();
1216 * Determines if the last failure was due to a lock timeout
1220 public function wasLockTimeout();
1223 * Determines if the last query error was due to a dropped connection and should
1224 * be dealt with by pinging the connection and reissuing the query.
1228 public function wasErrorReissuable();
1231 * Determines if the last failure was due to the database being read-only.
1235 public function wasReadOnlyError();
1238 * Wait for the replica DB to catch up to a given master position
1240 * @param DBMasterPos $pos
1241 * @param int $timeout The maximum number of seconds to wait for synchronisation
1242 * @return int|null Zero if the replica DB was past that position already,
1243 * greater than zero if we waited for some period of time, less than
1244 * zero if it timed out, and null on error
1246 public function masterPosWait( DBMasterPos
$pos, $timeout );
1249 * Get the replication position of this replica DB
1251 * @return DBMasterPos|bool False if this is not a replica DB.
1253 public function getSlavePos();
1256 * Get the position of this master
1258 * @return DBMasterPos|bool False if this is not a master
1260 public function getMasterPos();
1263 * @return bool Whether the DB is marked as read-only server-side
1266 public function serverIsReadOnly();
1269 * Run a callback as soon as the current transaction commits or rolls back.
1270 * An error is thrown if no transaction is pending. Queries in the function will run in
1271 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1274 * This is useful for combining cooperative locks and DB transactions.
1276 * The callback takes one argument:
1277 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1279 * @param callable $callback
1283 public function onTransactionResolution( callable
$callback );
1286 * Run a callback as soon as there is no transaction pending.
1287 * If there is a transaction and it is rolled back, then the callback is cancelled.
1288 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1289 * Callbacks must commit any transactions that they begin.
1291 * This is useful for updates to different systems or when separate transactions are needed.
1292 * For example, one might want to enqueue jobs into a system outside the database, but only
1293 * after the database is updated so that the jobs will see the data when they actually run.
1294 * It can also be used for updates that easily cause deadlocks if locks are held too long.
1296 * Updates will execute in the order they were enqueued.
1298 * The callback takes one argument:
1299 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1301 * @param callable $callback
1304 public function onTransactionIdle( callable
$callback );
1307 * Run a callback before the current transaction commits or now if there is none.
1308 * If there is a transaction and it is rolled back, then the callback is cancelled.
1309 * Callbacks must not start nor commit any transactions. If no transaction is active,
1310 * then a transaction will wrap the callback.
1312 * This is useful for updates that easily cause deadlocks if locks are held too long
1313 * but where atomicity is strongly desired for these updates and some related updates.
1315 * Updates will execute in the order they were enqueued.
1317 * @param callable $callback
1320 public function onTransactionPreCommitOrIdle( callable
$callback );
1323 * Run a callback each time any transaction commits or rolls back
1325 * The callback takes two arguments:
1326 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1327 * - This IDatabase object
1328 * Callbacks must commit any transactions that they begin.
1330 * Registering a callback here will not affect writesOrCallbacks() pending
1332 * @param string $name Callback name
1333 * @param callable|null $callback Use null to unset a listener
1337 public function setTransactionListener( $name, callable
$callback = null );
1340 * Begin an atomic section of statements
1342 * If a transaction has been started already, just keep track of the given
1343 * section name to make sure the transaction is not committed pre-maturely.
1344 * This function can be used in layers (with sub-sections), so use a stack
1345 * to keep track of the different atomic sections. If there is no transaction,
1346 * start one implicitly.
1348 * The goal of this function is to create an atomic section of SQL queries
1349 * without having to start a new transaction if it already exists.
1351 * Atomic sections are more strict than transactions. With transactions,
1352 * attempting to begin a new transaction when one is already running results
1353 * in MediaWiki issuing a brief warning and doing an implicit commit. All
1354 * atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1355 * and any database transactions cannot be began or committed until all atomic
1356 * levels are closed. There is no such thing as implicitly opening or closing
1357 * an atomic section.
1360 * @param string $fname
1363 public function startAtomic( $fname = __METHOD__
);
1366 * Ends an atomic section of SQL statements
1368 * Ends the next section of atomic SQL statements and commits the transaction
1372 * @see IDatabase::startAtomic
1373 * @param string $fname
1376 public function endAtomic( $fname = __METHOD__
);
1379 * Run a callback to do an atomic set of updates for this database
1381 * The $callback takes the following arguments:
1382 * - This database object
1383 * - The value of $fname
1385 * If any exception occurs in the callback, then rollback() will be called and the error will
1386 * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1387 * In any case, such errors are expected to terminate the request, without any outside caller
1388 * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1389 * atomic section and uncommitted updates, which trashes the current request, requiring an
1390 * error to be displayed.
1392 * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1394 * @see DatabaseBase::startAtomic
1395 * @see DatabaseBase::endAtomic
1397 * @param string $fname Caller name (usually __METHOD__)
1398 * @param callable $callback Callback that issues DB updates
1399 * @return mixed $res Result of the callback (since 1.28)
1401 * @throws RuntimeException
1402 * @throws UnexpectedValueException
1405 public function doAtomicSection( $fname, callable
$callback );
1408 * Begin a transaction. If a transaction is already in progress,
1409 * that transaction will be committed before the new transaction is started.
1411 * Only call this from code with outer transcation scope.
1412 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1413 * Nesting of transactions is not supported.
1415 * Note that when the DBO_TRX flag is set (which is usually the case for web
1416 * requests, but not for maintenance scripts), any previous database query
1417 * will have started a transaction automatically.
1419 * Nesting of transactions is not supported. Attempts to nest transactions
1420 * will cause a warning, unless the current transaction was started
1421 * automatically because of the DBO_TRX flag.
1423 * @param string $fname
1424 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1427 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1430 * Commits a transaction previously started using begin().
1431 * If no transaction is in progress, a warning is issued.
1433 * Only call this from code with outer transcation scope.
1434 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1435 * Nesting of transactions is not supported.
1437 * @param string $fname
1438 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1439 * constant to disable warnings about explicitly committing implicit transactions,
1440 * or calling commit when no transaction is in progress.
1442 * This will trigger an exception if there is an ongoing explicit transaction.
1444 * Only set the flush flag if you are sure that these warnings are not applicable,
1445 * and no explicit transactions are open.
1447 * @throws DBUnexpectedError
1449 public function commit( $fname = __METHOD__
, $flush = '' );
1452 * Rollback a transaction previously started using begin().
1453 * If no transaction is in progress, a warning is issued.
1455 * Only call this from code with outer transcation scope.
1456 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1457 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1458 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1459 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1461 * @param string $fname
1462 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1463 * constant to disable warnings about calling rollback when no transaction is in
1464 * progress. This will silently break any ongoing explicit transaction. Only set the
1465 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1466 * @throws DBUnexpectedError
1467 * @since 1.23 Added $flush parameter
1469 public function rollback( $fname = __METHOD__
, $flush = '' );
1472 * List all tables on the database
1474 * @param string $prefix Only show tables with this prefix, e.g. mw_
1475 * @param string $fname Calling function name
1476 * @throws MWException
1479 public function listTables( $prefix = null, $fname = __METHOD__
);
1482 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1483 * to the format used for inserting into timestamp fields in this DBMS.
1485 * The result is unquoted, and needs to be passed through addQuotes()
1486 * before it can be included in raw SQL.
1488 * @param string|int $ts
1492 public function timestamp( $ts = 0 );
1495 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1496 * to the format used for inserting into timestamp fields in this DBMS. If
1497 * NULL is input, it is passed through, allowing NULL values to be inserted
1498 * into timestamp fields.
1500 * The result is unquoted, and needs to be passed through addQuotes()
1501 * before it can be included in raw SQL.
1503 * @param string|int $ts
1507 public function timestampOrNull( $ts = null );
1510 * Ping the server and try to reconnect if it there is no connection
1512 * @param float|null &$rtt Value to store the estimated RTT [optional]
1513 * @return bool Success or failure
1515 public function ping( &$rtt = null );
1518 * Get replica DB lag. Currently supported only by MySQL.
1520 * Note that this function will generate a fatal error on many
1521 * installations. Most callers should use LoadBalancer::safeGetLag()
1524 * @return int|bool Database replication lag in seconds or false on error
1526 public function getLag();
1529 * Get the replica DB lag when the current transaction started
1530 * or a general lag estimate if not transaction is active
1532 * This is useful when transactions might use snapshot isolation
1533 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1534 * is this lag plus transaction duration. If they don't, it is still
1535 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1536 * indication of the staleness of subsequent reads.
1538 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1541 public function getSessionLagStatus();
1544 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1548 public function maxListLen();
1551 * Some DBMSs have a special format for inserting into blob fields, they
1552 * don't allow simple quoted strings to be inserted. To insert into such
1553 * a field, pass the data through this function before passing it to
1554 * IDatabase::insert().
1559 public function encodeBlob( $b );
1562 * Some DBMSs return a special placeholder object representing blob fields
1563 * in result objects. Pass the object through this function to return the
1566 * @param string|Blob $b
1569 public function decodeBlob( $b );
1572 * Override database's default behavior. $options include:
1573 * 'connTimeout' : Set the connection timeout value in seconds.
1574 * May be useful for very long batch queries such as
1575 * full-wiki dumps, where a single query reads out over
1578 * @param array $options
1581 public function setSessionOptions( array $options );
1584 * Set variables to be used in sourceFile/sourceStream, in preference to the
1585 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1586 * all. If it's set to false, $GLOBALS will be used.
1588 * @param bool|array $vars Mapping variable name to value.
1590 public function setSchemaVars( $vars );
1593 * Check to see if a named lock is available (non-blocking)
1595 * @param string $lockName Name of lock to poll
1596 * @param string $method Name of method calling us
1600 public function lockIsFree( $lockName, $method );
1603 * Acquire a named lock
1605 * Named locks are not related to transactions
1607 * @param string $lockName Name of lock to aquire
1608 * @param string $method Name of the calling method
1609 * @param int $timeout Acquisition timeout in seconds
1612 public function lock( $lockName, $method, $timeout = 5 );
1617 * Named locks are not related to transactions
1619 * @param string $lockName Name of lock to release
1620 * @param string $method Name of the calling method
1622 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1623 * by this thread (in which case the lock is not released), and NULL if the named
1624 * lock did not exist
1626 public function unlock( $lockName, $method );
1629 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1631 * Only call this from outer transcation scope and when only one DB will be affected.
1632 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1634 * This is suitiable for transactions that need to be serialized using cooperative locks,
1635 * where each transaction can see each others' changes. Any transaction is flushed to clear
1636 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1637 * the lock will be released unless a transaction is active. If one is active, then the lock
1638 * will be released when it either commits or rolls back.
1640 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1642 * @param string $lockKey Name of lock to release
1643 * @param string $fname Name of the calling method
1644 * @param int $timeout Acquisition timeout in seconds
1645 * @return ScopedCallback|null
1646 * @throws DBUnexpectedError
1649 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1652 * Check to see if a named lock used by lock() use blocking queues
1657 public function namedLocksEnqueue();
1660 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1661 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1662 * because "i" sorts after all numbers.
1666 public function getInfinity();
1669 * Encode an expiry time into the DBMS dependent format
1671 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1674 public function encodeExpiry( $expiry );
1677 * Decode an expiry time into a DBMS independent format
1679 * @param string $expiry DB timestamp field value for expiry
1680 * @param int $format TS_* constant, defaults to TS_MW
1683 public function decodeExpiry( $expiry, $format = TS_MW
);
1686 * Allow or deny "big selects" for this session only. This is done by setting
1687 * the sql_big_selects session variable.
1689 * This is a MySQL-specific feature.
1691 * @param bool|string $value True for allow, false for deny, or "default" to
1692 * restore the initial value
1694 public function setBigSelects( $value = true );
1697 * @return bool Whether this DB is read-only
1700 public function isReadOnly();