3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
16 * http://www.gnu.org/copyleft/gpl.html
20 namespace Wikimedia\Rdbms
;
22 use InvalidArgumentException
;
23 use Wikimedia\ScopedCallback
;
28 * @defgroup Database Database
29 * This group deals with database interface functions
30 * and query specifics/optimisations.
33 * Basic database interface for live and lazy-loaded relation database handles
35 * @note IDatabase and DBConnRef should be updated to reflect any changes
39 /** @var int Callback triggered immediately due to no active transaction */
40 const TRIGGER_IDLE
= 1;
41 /** @var int Callback triggered by COMMIT */
42 const TRIGGER_COMMIT
= 2;
43 /** @var int Callback triggered by ROLLBACK */
44 const TRIGGER_ROLLBACK
= 3;
46 /** @var string Transaction is requested by regular caller outside of the DB layer */
47 const TRANSACTION_EXPLICIT
= '';
48 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
49 const TRANSACTION_INTERNAL
= 'implicit';
51 /** @var string Atomic section is not cancelable */
52 const ATOMIC_NOT_CANCELABLE
= '';
53 /** @var string Atomic section is cancelable */
54 const ATOMIC_CANCELABLE
= 'cancelable';
56 /** @var string Commit/rollback is from outside the IDatabase handle and connection manager */
57 const FLUSHING_ONE
= '';
58 /** @var string Commit/rollback is from the connection manager for the IDatabase handle */
59 const FLUSHING_ALL_PEERS
= 'flush';
60 /** @var string Commit/rollback is from the IDatabase handle internally */
61 const FLUSHING_INTERNAL
= 'flush-internal';
63 /** @var string Do not remember the prior flags */
64 const REMEMBER_NOTHING
= '';
65 /** @var string Remember the prior flags */
66 const REMEMBER_PRIOR
= 'remember';
67 /** @var string Restore to the prior flag state */
68 const RESTORE_PRIOR
= 'prior';
69 /** @var string Restore to the initial flag state */
70 const RESTORE_INITIAL
= 'initial';
72 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
73 const ESTIMATE_TOTAL
= 'total';
74 /** @var string Estimate time to apply (scanning, applying) */
75 const ESTIMATE_DB_APPLY
= 'apply';
77 /** @var int Combine list with comma delimeters */
79 /** @var int Combine list with AND clauses */
81 /** @var int Convert map into a SET clause */
83 /** @var int Treat as field name and do not apply value escaping */
85 /** @var int Combine list with OR clauses */
88 /** @var int Enable debug logging */
90 /** @var int Disable query buffering (only one result set can be iterated at a time) */
91 const DBO_NOBUFFER
= 2;
92 /** @var int Ignore query errors (internal use only!) */
94 /** @var int Automatically start a transaction before running a query if none is active */
96 /** @var int Use DBO_TRX in non-CLI mode */
97 const DBO_DEFAULT
= 16;
98 /** @var int Use DB persistent connections if possible */
99 const DBO_PERSISTENT
= 32;
100 /** @var int DBA session mode; mostly for Oracle */
101 const DBO_SYSDBA
= 64;
102 /** @var int Schema file mode; mostly for Oracle */
103 const DBO_DDLMODE
= 128;
104 /** @var int Enable SSL/TLS in connection protocol */
106 /** @var int Enable compression in connection protocol */
107 const DBO_COMPRESS
= 512;
110 * A string describing the current software version, and possibly
111 * other details in a user-friendly way. Will be listed on Special:Version, etc.
112 * Use getServerVersion() to get machine-friendly information.
114 * @return string Version information from the database server
116 public function getServerInfo();
119 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
121 * Unbuffered queries are very troublesome in MySQL:
123 * - If another query is executed while the first query is being read
124 * out, the first query is killed. This means you can't call normal
125 * Database functions while you are reading an unbuffered query result
126 * from a normal Database connection.
128 * - Unbuffered queries cause the MySQL server to use large amounts of
129 * memory and to hold broad locks which block other queries.
131 * If you want to limit client-side memory, it's almost always better to
132 * split up queries into batches using a LIMIT clause than to switch off
135 * @param null|bool $buffer
136 * @return null|bool The previous value of the flag
138 public function bufferResults( $buffer = null );
141 * Gets the current transaction level.
143 * Historically, transactions were allowed to be "nested". This is no
144 * longer supported, so this function really only returns a boolean.
146 * @return int The previous value
148 public function trxLevel();
151 * Get the UNIX timestamp of the time that the transaction was established
153 * This can be used to reason about the staleness of SELECT data
154 * in REPEATABLE-READ transaction isolation level.
156 * @return float|null Returns null if there is not active transaction
159 public function trxTimestamp();
162 * @return bool Whether an explicit transaction or atomic sections are still open
165 public function explicitTrxActive();
168 * Get/set the table prefix.
169 * @param string|null $prefix The table prefix to set, or omitted to leave it unchanged.
170 * @return string The previous table prefix.
172 public function tablePrefix( $prefix = null );
175 * Get/set the db schema.
176 * @param string|null $schema The database schema to set, or omitted to leave it unchanged.
177 * @return string The previous db schema.
179 public function dbSchema( $schema = null );
182 * Get properties passed down from the server info array of the load
185 * @param string|null $name The entry of the info array to get, or null to get the
188 * @return array|mixed|null
190 public function getLBInfo( $name = null );
193 * Set the LB info array, or a member of it. If called with one parameter,
194 * the LB info array is set to that parameter. If it is called with two
195 * parameters, the member with the given name is set to the given value.
197 * @param string $name
198 * @param array|null $value
200 public function setLBInfo( $name, $value = null );
203 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
205 * @param IDatabase $conn
208 public function setLazyMasterHandle( IDatabase
$conn );
211 * Returns true if this database does an implicit sort when doing GROUP BY
214 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
216 public function implicitGroupby();
219 * Returns true if this database does an implicit order by when the column has an index
220 * For example: SELECT page_title FROM page LIMIT 1
224 public function implicitOrderby();
227 * Return the last query that went through IDatabase::query()
230 public function lastQuery();
233 * Returns true if the connection may have been used for write queries.
234 * Should return true if unsure.
237 * @deprecated Since 1.31; use lastDoneWrites()
239 public function doneWrites();
242 * Returns the last time the connection may have been used for write queries.
243 * Should return a timestamp if unsure.
245 * @return int|float UNIX timestamp or false
248 public function lastDoneWrites();
251 * @return bool Whether there is a transaction open with possible write queries
254 public function writesPending();
257 * @return bool Whether there is a transaction open with pre-commit callbacks pending
260 public function preCommitCallbacksPending();
263 * Whether there is a transaction open with either possible write queries
264 * or unresolved pre-commit/commit/resolution callbacks pending
266 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
270 public function writesOrCallbacksPending();
273 * Get the time spend running write queries for this transaction
275 * High times could be due to scanning, updates, locking, and such
277 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
278 * @return float|bool Returns false if not transaction is active
281 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
284 * Get the list of method names that did write queries for this transaction
289 public function pendingWriteCallers();
292 * Get the number of affected rows from pending write queries
297 public function pendingWriteRowsAffected();
300 * Is a connection to the database open?
303 public function isOpen();
306 * Set a flag for this connection
308 * @param int $flag DBO_* constants from Defines.php:
309 * - DBO_DEBUG: output some debug info (same as debug())
310 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
311 * - DBO_TRX: automatically start transactions
312 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
313 * and removes it in command line mode
314 * - DBO_PERSISTENT: use persistant database connection
315 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
317 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
320 * Clear a flag for this connection
322 * @param int $flag DBO_* constants from Defines.php:
323 * - DBO_DEBUG: output some debug info (same as debug())
324 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
325 * - DBO_TRX: automatically start transactions
326 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
327 * and removes it in command line mode
328 * - DBO_PERSISTENT: use persistant database connection
329 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
331 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
334 * Restore the flags to their prior state before the last setFlag/clearFlag call
336 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
339 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
342 * Returns a boolean whether the flag $flag is set for this connection
344 * @param int $flag DBO_* constants from Defines.php:
345 * - DBO_DEBUG: output some debug info (same as debug())
346 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
347 * - DBO_TRX: automatically start transactions
348 * - DBO_PERSISTENT: use persistant database connection
351 public function getFlag( $flag );
356 public function getDomainID();
359 * Alias for getDomainID()
364 public function getWikiID();
367 * Get the type of the DBMS, as it appears in $wgDBtype.
371 public function getType();
374 * Fetch the next row from the given result object, in object form.
375 * Fields can be retrieved with $row->fieldname, with fields acting like
377 * If no more rows are available, false is returned.
379 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
380 * @return stdClass|bool
381 * @throws DBUnexpectedError Thrown if the database returns an error
383 public function fetchObject( $res );
386 * Fetch the next row from the given result object, in associative array
387 * form. Fields are retrieved with $row['fieldname'].
388 * If no more rows are available, false is returned.
390 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
392 * @throws DBUnexpectedError Thrown if the database returns an error
394 public function fetchRow( $res );
397 * Get the number of rows in a result object
399 * @param mixed $res A SQL result
402 public function numRows( $res );
405 * Get the number of fields in a result object
406 * @see https://secure.php.net/mysql_num_fields
408 * @param mixed $res A SQL result
411 public function numFields( $res );
414 * Get a field name in a result object
415 * @see https://secure.php.net/mysql_field_name
417 * @param mixed $res A SQL result
421 public function fieldName( $res, $n );
424 * Get the inserted value of an auto-increment row
426 * This should only be called after an insert that used an auto-incremented
427 * value. If no such insert was previously done in the current database
428 * session, the return value is undefined.
432 public function insertId();
435 * Change the position of the cursor in a result object
436 * @see https://secure.php.net/mysql_data_seek
438 * @param mixed $res A SQL result
441 public function dataSeek( $res, $row );
444 * Get the last error number
445 * @see https://secure.php.net/mysql_errno
449 public function lastErrno();
452 * Get a description of the last error
453 * @see https://secure.php.net/mysql_error
457 public function lastError();
460 * Get the number of rows affected by the last write query
461 * @see https://secure.php.net/mysql_affected_rows
465 public function affectedRows();
468 * Returns a wikitext link to the DB's website, e.g.,
469 * return "[https://www.mysql.com/ MySQL]";
470 * Should at least contain plain text, if for some reason
471 * your database has no website.
473 * @return string Wikitext of a link to the server software's web site
475 public function getSoftwareLink();
478 * A string describing the current software version, like from
479 * mysql_get_server_info().
481 * @return string Version information from the database server.
483 public function getServerVersion();
486 * Close the database connection
488 * This should only be called after any transactions have been resolved,
489 * aside from read-only transactions (assuming no callbacks are registered).
490 * If a transaction is still open anyway, it will be committed if possible.
493 * @return bool Operation success. true if already closed.
495 public function close();
498 * Run an SQL query and return the result. Normally throws a DBQueryError
499 * on failure. If errors are ignored, returns false instead.
501 * If a connection loss is detected, then an attempt to reconnect will be made.
502 * For queries that involve no larger transactions or locks, they will be re-issued
503 * for convenience, provided the connection was re-established.
505 * In new code, the query wrappers select(), insert(), update(), delete(),
506 * etc. should be used where possible, since they give much better DBMS
507 * independence and automatically quote or validate user input in a variety
508 * of contexts. This function is generally only useful for queries which are
509 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
512 * However, the query wrappers themselves should call this function.
514 * @param string $sql SQL query
515 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
516 * comment (you can use __METHOD__ or add some extra info)
517 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
518 * maybe best to catch the exception instead?
519 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
520 * for a successful read query, or false on failure if $tempIgnore set
523 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
526 * Free a result object returned by query() or select(). It's usually not
527 * necessary to call this, just use unset() or let the variable holding
528 * the result object go out of scope.
530 * @param mixed $res A SQL result
532 public function freeResult( $res );
535 * A SELECT wrapper which returns a single field from a single result row.
537 * Usually throws a DBQueryError on failure. If errors are explicitly
538 * ignored, returns false on failure.
540 * If no result rows are returned from the query, false is returned.
542 * @param string|array $table Table name. See IDatabase::select() for details.
543 * @param string $var The field name to select. This must be a valid SQL
544 * fragment: do not use unvalidated user input.
545 * @param string|array $cond The condition array. See IDatabase::select() for details.
546 * @param string $fname The function name of the caller.
547 * @param string|array $options The query options. See IDatabase::select() for details.
548 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
550 * @return mixed The value from the field
553 public function selectField(
554 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
558 * A SELECT wrapper which returns a list of single field values from result rows.
560 * Usually throws a DBQueryError on failure. If errors are explicitly
561 * ignored, returns false on failure.
563 * If no result rows are returned from the query, false is returned.
565 * @param string|array $table Table name. See IDatabase::select() for details.
566 * @param string $var The field name to select. This must be a valid SQL
567 * fragment: do not use unvalidated user input.
568 * @param string|array $cond The condition array. See IDatabase::select() for details.
569 * @param string $fname The function name of the caller.
570 * @param string|array $options The query options. See IDatabase::select() for details.
571 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
573 * @return array The values from the field
577 public function selectFieldValues(
578 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
582 * Execute a SELECT query constructed using the various parameters provided.
583 * See below for full details of the parameters.
585 * @param string|array $table Table name
586 * @param string|array $vars Field names
587 * @param string|array $conds Conditions
588 * @param string $fname Caller function name
589 * @param array $options Query options
590 * @param array $join_conds Join conditions
593 * @param string|array $table
595 * May be either an array of table names, or a single string holding a table
596 * name. If an array is given, table aliases can be specified, for example:
600 * This includes the user table in the query, with the alias "a" available
601 * for use in field names (e.g. a.user_name).
603 * A derived table, defined by the result of selectSQLText(), requires an alias
604 * key and a Subquery instance value which wraps the SQL query, for example:
606 * [ 'c' => new Subquery( 'SELECT ...' ) ]
608 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
609 * constructed using nested arrays. For example,
611 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
613 * along with `$join_conds` like
615 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
617 * will produce SQL something like
619 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
621 * All of the table names given here are automatically run through
622 * Database::tableName(), which causes the table prefix (if any) to be
623 * added, and various other table name mappings to be performed.
625 * Do not use untrusted user input as a table name. Alias names should
626 * not have characters outside of the Basic multilingual plane.
628 * @param string|array $vars
630 * May be either a field name or an array of field names. The field names
631 * can be complete fragments of SQL, for direct inclusion into the SELECT
632 * query. If an array is given, field aliases can be specified, for example:
634 * [ 'maxrev' => 'MAX(rev_id)' ]
636 * This includes an expression with the alias "maxrev" in the query.
638 * If an expression is given, care must be taken to ensure that it is
641 * Untrusted user input must not be passed to this parameter.
643 * @param string|array $conds
645 * May be either a string containing a single condition, or an array of
646 * conditions. If an array is given, the conditions constructed from each
647 * element are combined with AND.
649 * Array elements may take one of two forms:
651 * - Elements with a numeric key are interpreted as raw SQL fragments.
652 * - Elements with a string key are interpreted as equality conditions,
653 * where the key is the field name.
654 * - If the value of such an array element is a scalar (such as a
655 * string), it will be treated as data and thus quoted appropriately.
656 * If it is null, an IS NULL clause will be added.
657 * - If the value is an array, an IN (...) clause will be constructed
658 * from its non-null elements, and an IS NULL clause will be added
659 * if null is present, such that the field may match any of the
660 * elements in the array. The non-null elements will be quoted.
662 * Note that expressions are often DBMS-dependent in their syntax.
663 * DBMS-independent wrappers are provided for constructing several types of
664 * expression commonly used in condition queries. See:
665 * - IDatabase::buildLike()
666 * - IDatabase::conditional()
668 * Untrusted user input is safe in the values of string keys, however untrusted
669 * input must not be used in the array key names or in the values of numeric keys.
670 * Escaping of untrusted input used in values of numeric keys should be done via
671 * IDatabase::addQuotes()
673 * @param string|array $options
675 * Optional: Array of query options. Boolean options are specified by
676 * including them in the array as a string value with a numeric key, for
681 * The supported options are:
683 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
684 * with LIMIT can theoretically be used for paging through a result set,
685 * but this is discouraged for performance reasons.
687 * - LIMIT: Integer: return at most this many rows. The rows are sorted
688 * and then the first rows are taken until the limit is reached. LIMIT
689 * is applied to a result set after OFFSET.
691 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
692 * changed until the next COMMIT.
694 * - DISTINCT: Boolean: return only unique result rows.
696 * - GROUP BY: May be either an SQL fragment string naming a field or
697 * expression to group by, or an array of such SQL fragments.
699 * - HAVING: May be either an string containing a HAVING clause or an array of
700 * conditions building the HAVING clause. If an array is given, the conditions
701 * constructed from each element are combined with AND.
703 * - ORDER BY: May be either an SQL fragment giving a field name or
704 * expression to order by, or an array of such SQL fragments.
706 * - USE INDEX: This may be either a string giving the index name to use
707 * for the query, or an array. If it is an associative array, each key
708 * gives the table name (or alias), each value gives the index name to
709 * use for that table. All strings are SQL fragments and so should be
710 * validated by the caller.
712 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
715 * And also the following boolean MySQL extensions, see the MySQL manual
718 * - LOCK IN SHARE MODE
722 * - SQL_BUFFER_RESULT
724 * - SQL_CALC_FOUND_ROWS
729 * @param string|array $join_conds
731 * Optional associative array of table-specific join conditions. In the
732 * most common case, this is unnecessary, since the join condition can be
733 * in $conds. However, it is useful for doing a LEFT JOIN.
735 * The key of the array contains the table name or alias. The value is an
736 * array with two elements, numbered 0 and 1. The first gives the type of
737 * join, the second is the same as the $conds parameter. Thus it can be
738 * an SQL fragment, or an array where the string keys are equality and the
739 * numeric keys are SQL fragments all AND'd together. For example:
741 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
743 * @return IResultWrapper Resulting rows
746 public function select(
747 $table, $vars, $conds = '', $fname = __METHOD__
,
748 $options = [], $join_conds = []
752 * The equivalent of IDatabase::select() except that the constructed SQL
753 * is returned, instead of being immediately executed. This can be useful for
754 * doing UNION queries, where the SQL text of each query is needed. In general,
755 * however, callers outside of Database classes should just use select().
757 * @see IDatabase::select()
759 * @param string|array $table Table name
760 * @param string|array $vars Field names
761 * @param string|array $conds Conditions
762 * @param string $fname Caller function name
763 * @param string|array $options Query options
764 * @param string|array $join_conds Join conditions
765 * @return string SQL query string
767 public function selectSQLText(
768 $table, $vars, $conds = '', $fname = __METHOD__
,
769 $options = [], $join_conds = []
773 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
774 * that a single row object is returned. If the query returns no rows,
777 * @param string|array $table Table name
778 * @param string|array $vars Field names
779 * @param array $conds Conditions
780 * @param string $fname Caller function name
781 * @param string|array $options Query options
782 * @param array|string $join_conds Join conditions
784 * @return stdClass|bool
787 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
788 $options = [], $join_conds = []
792 * Estimate the number of rows in dataset
794 * MySQL allows you to estimate the number of rows that would be returned
795 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
796 * index cardinality statistics, and is notoriously inaccurate, especially
797 * when large numbers of rows have recently been added or deleted.
799 * For DBMSs that don't support fast result size estimation, this function
800 * will actually perform the SELECT COUNT(*).
802 * Takes the same arguments as IDatabase::select().
804 * @param string $table Table name
805 * @param string $var Column for which NULL values are not counted [default "*"]
806 * @param array|string $conds Filters on the table
807 * @param string $fname Function name for profiling
808 * @param array $options Options for select
809 * @param array|string $join_conds Join conditions
810 * @return int Row count
813 public function estimateRowCount(
814 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
818 * Get the number of rows in dataset
820 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
822 * Takes the same arguments as IDatabase::select().
824 * @since 1.27 Added $join_conds parameter
826 * @param array|string $tables Table names
827 * @param string $var Column for which NULL values are not counted [default "*"]
828 * @param array|string $conds Filters on the table
829 * @param string $fname Function name for profiling
830 * @param array $options Options for select
831 * @param array $join_conds Join conditions (since 1.27)
832 * @return int Row count
835 public function selectRowCount(
836 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
840 * Lock all rows meeting the given conditions/options FOR UPDATE
842 * @param array|string $table Table names
843 * @param array|string $conds Filters on the table
844 * @param string $fname Function name for profiling
845 * @param array $options Options for select ("FOR UPDATE" is added automatically)
846 * @param array $join_conds Join conditions
847 * @return int Number of matching rows found (and locked)
850 public function lockForUpdate(
851 $table, $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
855 * Determines whether a field exists in a table
857 * @param string $table Table name
858 * @param string $field Filed to check on that table
859 * @param string $fname Calling function name (optional)
860 * @return bool Whether $table has filed $field
863 public function fieldExists( $table, $field, $fname = __METHOD__
);
866 * Determines whether an index exists
867 * Usually throws a DBQueryError on failure
868 * If errors are explicitly ignored, returns NULL on failure
870 * @param string $table
871 * @param string $index
872 * @param string $fname
876 public function indexExists( $table, $index, $fname = __METHOD__
);
879 * Query whether a given table exists
881 * @param string $table
882 * @param string $fname
886 public function tableExists( $table, $fname = __METHOD__
);
889 * INSERT wrapper, inserts an array into a table.
893 * - A single associative array. The array keys are the field names, and
894 * the values are the values to insert. The values are treated as data
895 * and will be quoted appropriately. If NULL is inserted, this will be
896 * converted to a database NULL.
897 * - An array with numeric keys, holding a list of associative arrays.
898 * This causes a multi-row INSERT on DBMSs that support it. The keys in
899 * each subarray must be identical to each other, and in the same order.
901 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
904 * $options is an array of options, with boolean options encoded as values
905 * with numeric keys, in the same style as $options in
906 * IDatabase::select(). Supported options are:
908 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
909 * any rows which cause duplicate key errors are not inserted. It's
910 * possible to determine how many rows were successfully inserted using
911 * IDatabase::affectedRows().
913 * @param string $table Table name. This will be passed through
914 * Database::tableName().
915 * @param array $a Array of rows to insert
916 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
917 * @param array $options Array of options
922 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
925 * UPDATE wrapper. Takes a condition array and a SET array.
927 * @param string $table Name of the table to UPDATE. This will be passed through
928 * Database::tableName().
929 * @param array $values An array of values to SET. For each array element,
930 * the key gives the field name, and the value gives the data to set
931 * that field to. The data will be quoted by IDatabase::addQuotes().
932 * Values with integer keys form unquoted SET statements, which can be used for
933 * things like "field = field + 1" or similar computed values.
934 * @param array $conds An array of conditions (WHERE). See
935 * IDatabase::select() for the details of the format of condition
936 * arrays. Use '*' to update all rows.
937 * @param string $fname The function name of the caller (from __METHOD__),
938 * for logging and profiling.
939 * @param array $options An array of UPDATE options, can be:
940 * - IGNORE: Ignore unique key conflicts
941 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
945 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
948 * Makes an encoded list of strings from an array
950 * These can be used to make conjunctions or disjunctions on SQL condition strings
951 * derived from an array (see IDatabase::select() $conds documentation).
955 * $sql = $db->makeList( [
957 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
958 * ], $db::LIST_AND );
960 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
962 * @param array $a Containing the data
963 * @param int $mode IDatabase class constant:
964 * - IDatabase::LIST_COMMA: Comma separated, no field names
965 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
966 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
967 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
968 * - IDatabase::LIST_NAMES: Comma separated field names
972 public function makeList( $a, $mode = self
::LIST_COMMA
);
975 * Build a partial where clause from a 2-d array such as used for LinkBatch.
976 * The keys on each level may be either integers or strings.
978 * @param array $data Organized as 2-d
979 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
980 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
981 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
982 * @return string|bool SQL fragment, or false if no items in array
984 public function makeWhereFrom2d( $data, $baseKey, $subKey );
987 * Return aggregated value alias
989 * @param array $valuedata
990 * @param string $valuename
994 public function aggregateValue( $valuedata, $valuename = 'value' );
997 * @param string $field
1000 public function bitNot( $field );
1003 * @param string $fieldLeft
1004 * @param string $fieldRight
1007 public function bitAnd( $fieldLeft, $fieldRight );
1010 * @param string $fieldLeft
1011 * @param string $fieldRight
1014 public function bitOr( $fieldLeft, $fieldRight );
1017 * Build a concatenation list to feed into a SQL query
1018 * @param array $stringList List of raw SQL expressions; caller is
1019 * responsible for any quoting
1022 public function buildConcat( $stringList );
1025 * Build a GROUP_CONCAT or equivalent statement for a query.
1027 * This is useful for combining a field for several rows into a single string.
1028 * NULL values will not appear in the output, duplicated values will appear,
1029 * and the resulting delimiter-separated values have no defined sort order.
1030 * Code using the results may need to use the PHP unique() or sort() methods.
1032 * @param string $delim Glue to bind the results together
1033 * @param string|array $table Table name
1034 * @param string $field Field name
1035 * @param string|array $conds Conditions
1036 * @param string|array $join_conds Join conditions
1037 * @return string SQL text
1040 public function buildGroupConcatField(
1041 $delim, $table, $field, $conds = '', $join_conds = []
1045 * Build a SUBSTRING function.
1047 * Behavior for non-ASCII values is undefined.
1049 * @param string $input Field name
1050 * @param int $startPosition Positive integer
1051 * @param int|null $length Non-negative integer length or null for no limit
1052 * @throws InvalidArgumentException
1053 * @return string SQL text
1056 public function buildSubString( $input, $startPosition, $length = null );
1059 * @param string $field Field or column to cast
1063 public function buildStringCast( $field );
1066 * @param string $field Field or column to cast
1070 public function buildIntegerCast( $field );
1073 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1075 * @see IDatabase::selectSQLText()
1077 * @param string|array $table Table name
1078 * @param string|array $vars Field names
1079 * @param string|array $conds Conditions
1080 * @param string $fname Caller function name
1081 * @param string|array $options Query options
1082 * @param string|array $join_conds Join conditions
1086 public function buildSelectSubquery(
1087 $table, $vars, $conds = '', $fname = __METHOD__
,
1088 $options = [], $join_conds = []
1092 * Returns true if DBs are assumed to be on potentially different servers
1094 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1095 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1096 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1097 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1102 public function databasesAreIndependent();
1105 * Change the current database
1108 * @return bool Success or failure
1109 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1111 public function selectDB( $db );
1114 * Get the current DB name
1117 public function getDBname();
1120 * Get the server hostname or IP address
1123 public function getServer();
1126 * Adds quotes and backslashes.
1128 * @param string|int|null|bool|Blob $s
1129 * @return string|int
1131 public function addQuotes( $s );
1134 * LIKE statement wrapper, receives a variable-length argument list with
1135 * parts of pattern to match containing either string literals that will be
1136 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1137 * the function could be provided with an array of aforementioned
1140 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1141 * a LIKE clause that searches for subpages of 'My page title'.
1143 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1144 * $query .= $dbr->buildLike( $pattern );
1147 * @return string Fully built LIKE statement
1149 public function buildLike();
1152 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1156 public function anyChar();
1159 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1163 public function anyString();
1166 * Deprecated method, calls should be removed.
1168 * This was formerly used for PostgreSQL and Oracle to handle
1169 * self::insertId() auto-incrementing fields. It is no longer necessary
1170 * since DatabasePostgres::insertId() has been reimplemented using
1171 * `lastval()` and Oracle has been reimplemented using triggers.
1173 * Implementations should return null if inserting `NULL` into an
1174 * auto-incrementing field works, otherwise it should return an instance of
1175 * NextSequenceValue and filter it on calls to relevant methods.
1177 * @deprecated since 1.30, no longer needed
1178 * @param string $seqName
1179 * @return null|NextSequenceValue
1181 public function nextSequenceValue( $seqName );
1184 * REPLACE query wrapper.
1186 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1187 * except that when there is a duplicate key error, the old row is deleted
1188 * and the new row is inserted in its place.
1190 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1191 * perform the delete, we need to know what the unique indexes are so that
1192 * we know how to find the conflicting rows.
1194 * It may be more efficient to leave off unique indexes which are unlikely
1195 * to collide. However if you do this, you run the risk of encountering
1196 * errors which wouldn't have occurred in MySQL.
1198 * @param string $table The table to replace the row(s) in.
1199 * @param array $uniqueIndexes Either a list of fields that define a unique index or
1200 * an array of such lists if there are multiple unique indexes defined in the schema
1201 * @param array $rows Can be either a single row to insert, or multiple rows,
1202 * in the same format as for IDatabase::insert()
1203 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1206 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1209 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1211 * This updates any conflicting rows (according to the unique indexes) using
1212 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1214 * $rows may be either:
1215 * - A single associative array. The array keys are the field names, and
1216 * the values are the values to insert. The values are treated as data
1217 * and will be quoted appropriately. If NULL is inserted, this will be
1218 * converted to a database NULL.
1219 * - An array with numeric keys, holding a list of associative arrays.
1220 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1221 * each subarray must be identical to each other, and in the same order.
1223 * It may be more efficient to leave off unique indexes which are unlikely
1224 * to collide. However if you do this, you run the risk of encountering
1225 * errors which wouldn't have occurred in MySQL.
1227 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1232 * @param string $table Table name. This will be passed through Database::tableName().
1233 * @param array $rows A single row or list of rows to insert
1234 * @param array $uniqueIndexes Either a list of fields that define a unique index or
1235 * an array of such lists if there are multiple unique indexes defined in the schema
1236 * @param array $set An array of values to SET. For each array element, the
1237 * key gives the field name, and the value gives the data to set that
1238 * field to. The data will be quoted by IDatabase::addQuotes().
1239 * Values with integer keys form unquoted SET statements, which can be used for
1240 * things like "field = field + 1" or similar computed values.
1241 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1245 public function upsert(
1246 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1250 * DELETE where the condition is a join.
1252 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1253 * we use sub-selects
1255 * For safety, an empty $conds will not delete everything. If you want to
1256 * delete all rows where the join condition matches, set $conds='*'.
1258 * DO NOT put the join condition in $conds.
1260 * @param string $delTable The table to delete from.
1261 * @param string $joinTable The other table.
1262 * @param string $delVar The variable to join on, in the first table.
1263 * @param string $joinVar The variable to join on, in the second table.
1264 * @param array $conds Condition array of field names mapped to variables,
1265 * ANDed together in the WHERE clause
1266 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1269 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1274 * DELETE query wrapper.
1276 * @param string $table Table name
1277 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1278 * for the format. Use $conds == "*" to delete all rows
1279 * @param string $fname Name of the calling function
1280 * @throws DBUnexpectedError
1281 * @return bool|IResultWrapper
1284 public function delete( $table, $conds, $fname = __METHOD__
);
1287 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1288 * into another table.
1290 * @warning If the insert will use an auto-increment or sequence to
1291 * determine the value of a column, this may break replication on
1292 * databases using statement-based replication if the SELECT is not
1293 * deterministically ordered.
1295 * @param string $destTable The table name to insert into
1296 * @param string|array $srcTable May be either a table name, or an array of table names
1297 * to include in a join.
1299 * @param array $varMap Must be an associative array of the form
1300 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1301 * rather than field names, but strings should be quoted with
1302 * IDatabase::addQuotes()
1304 * @param array $conds Condition array. See $conds in IDatabase::select() for
1305 * the details of the format of condition arrays. May be "*" to copy the
1308 * @param string $fname The function name of the caller, from __METHOD__
1310 * @param array $insertOptions Options for the INSERT part of the query, see
1311 * IDatabase::insert() for details. Also, one additional option is
1312 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1313 * an auto-increment or sequence to determine any column values.
1314 * @param array $selectOptions Options for the SELECT part of the query, see
1315 * IDatabase::select() for details.
1316 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1317 * IDatabase::select() for details.
1322 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1323 $fname = __METHOD__
,
1324 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1328 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1329 * within the UNION construct.
1332 public function unionSupportsOrderAndLimit();
1335 * Construct a UNION query
1336 * This is used for providing overload point for other DB abstractions
1337 * not compatible with the MySQL syntax.
1338 * @param array $sqls SQL statements to combine
1339 * @param bool $all Use UNION ALL
1340 * @return string SQL fragment
1342 public function unionQueries( $sqls, $all );
1345 * Construct a UNION query for permutations of conditions
1347 * Databases sometimes have trouble with queries that have multiple values
1348 * for multiple condition parameters combined with limits and ordering.
1349 * This method constructs queries for the Cartesian product of the
1350 * conditions and unions them all together.
1352 * @see IDatabase::select()
1354 * @param string|array $table Table name
1355 * @param string|array $vars Field names
1356 * @param array $permute_conds Conditions for the Cartesian product. Keys
1357 * are field names, values are arrays of the possible values for that
1359 * @param string|array $extra_conds Additional conditions to include in the
1361 * @param string $fname Caller function name
1362 * @param string|array $options Query options. In addition to the options
1363 * recognized by IDatabase::select(), the following may be used:
1364 * - NOTALL: Set to use UNION instead of UNION ALL.
1365 * - INNER ORDER BY: If specified and supported, subqueries will use this
1366 * instead of ORDER BY.
1367 * @param string|array $join_conds Join conditions
1368 * @return string SQL query string.
1370 public function unionConditionPermutations(
1371 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1372 $options = [], $join_conds = []
1376 * Returns an SQL expression for a simple conditional. This doesn't need
1377 * to be overridden unless CASE isn't supported in your DBMS.
1379 * @param string|array $cond SQL expression which will result in a boolean value
1380 * @param string $trueVal SQL expression to return if true
1381 * @param string $falseVal SQL expression to return if false
1382 * @return string SQL fragment
1384 public function conditional( $cond, $trueVal, $falseVal );
1387 * Returns a command for str_replace function in SQL query.
1388 * Uses REPLACE() in MySQL
1390 * @param string $orig Column to modify
1391 * @param string $old Column to seek
1392 * @param string $new Column to replace with
1396 public function strreplace( $orig, $old, $new );
1399 * Determines how long the server has been up
1404 public function getServerUptime();
1407 * Determines if the last failure was due to a deadlock
1409 * Note that during a deadlock, the prior transaction will have been lost
1413 public function wasDeadlock();
1416 * Determines if the last failure was due to a lock timeout
1418 * Note that during a lock wait timeout, the prior transaction will have been lost
1422 public function wasLockTimeout();
1425 * Determines if the last query error was due to a dropped connection
1427 * Note that during a connection loss, the prior transaction will have been lost
1432 public function wasConnectionLoss();
1435 * Determines if the last failure was due to the database being read-only.
1439 public function wasReadOnlyError();
1442 * Determines if the last query error was due to something outside of the query itself
1444 * Note that the transaction may have been lost, discarding prior writes and results
1448 public function wasErrorReissuable();
1451 * Wait for the replica DB to catch up to a given master position
1453 * @param DBMasterPos $pos
1454 * @param int $timeout The maximum number of seconds to wait for synchronisation
1455 * @return int|null Zero if the replica DB was past that position already,
1456 * greater than zero if we waited for some period of time, less than
1457 * zero if it timed out, and null on error
1460 public function masterPosWait( DBMasterPos
$pos, $timeout );
1463 * Get the replication position of this replica DB
1465 * @return DBMasterPos|bool False if this is not a replica DB
1468 public function getReplicaPos();
1471 * Get the position of this master
1473 * @return DBMasterPos|bool False if this is not a master
1476 public function getMasterPos();
1479 * @return bool Whether the DB is marked as read-only server-side
1482 public function serverIsReadOnly();
1485 * Run a callback as soon as the current transaction commits or rolls back.
1486 * An error is thrown if no transaction is pending. Queries in the function will run in
1487 * AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1490 * This is useful for combining cooperative locks and DB transactions.
1492 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1494 * The callback takes the following arguments:
1495 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1496 * - This IDatabase instance (since 1.32)
1498 * @param callable $callback
1499 * @param string $fname Caller name
1503 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1506 * Run a callback as soon as there is no transaction pending.
1507 * If there is a transaction and it is rolled back, then the callback is cancelled.
1509 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1510 * of the round, just after all peer transactions COMMIT. If the transaction round
1511 * is rolled back, then the callback is cancelled.
1513 * Queries in the function will run in AUTOCOMMIT mode unless there are begin() calls.
1514 * Callbacks must commit any transactions that they begin.
1516 * This is useful for updates to different systems or when separate transactions are needed.
1517 * For example, one might want to enqueue jobs into a system outside the database, but only
1518 * after the database is updated so that the jobs will see the data when they actually run.
1519 * It can also be used for updates that easily suffer from lock timeouts and deadlocks,
1520 * but where atomicity is not essential.
1522 * Avoid using IDatabase instances aside from this one in the callback, unless such instances
1523 * never have IDatabase::DBO_TRX set. This keeps callbacks from interfering with one another.
1525 * Updates will execute in the order they were enqueued.
1527 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1529 * The callback takes the following arguments:
1530 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1531 * - This IDatabase instance (since 1.32)
1533 * @param callable $callback
1534 * @param string $fname Caller name
1537 public function onTransactionCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1540 * Alias for onTransactionCommitOrIdle() for backwards-compatibility
1542 * @param callable $callback
1543 * @param string $fname
1546 * @deprecated Since 1.32
1548 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1551 * Run a callback before the current transaction commits or now if there is none.
1552 * If there is a transaction and it is rolled back, then the callback is cancelled.
1554 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1555 * of the round, just before all peer transactions COMMIT. If the transaction round
1556 * is rolled back, then the callback is cancelled.
1558 * Callbacks must not start nor commit any transactions. If no transaction is active,
1559 * then a transaction will wrap the callback.
1561 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1562 * but where atomicity is strongly desired for these updates and some related updates.
1564 * Updates will execute in the order they were enqueued.
1566 * The callback takes the one argument:
1567 * - This IDatabase instance (since 1.32)
1569 * @param callable $callback
1570 * @param string $fname Caller name
1573 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1576 * Run a callback each time any transaction commits or rolls back
1578 * The callback takes two arguments:
1579 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1580 * - This IDatabase object
1581 * Callbacks must commit any transactions that they begin.
1583 * Registering a callback here will not affect writesOrCallbacks() pending.
1585 * Since callbacks from this or onTransactionCommitOrIdle() can start and end transactions,
1586 * a single call to IDatabase::commit might trigger multiple runs of the listener callbacks.
1588 * @param string $name Callback name
1589 * @param callable|null $callback Use null to unset a listener
1593 public function setTransactionListener( $name, callable
$callback = null );
1596 * Begin an atomic section of SQL statements
1598 * Start an implicit transaction if no transaction is already active, set a savepoint
1599 * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
1600 * that the transaction is not committed prematurely. The end of the section must be
1601 * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
1602 * have layers of inner sections (sub-sections), but all sections must be ended in order
1603 * of innermost to outermost. Transactions cannot be started or committed until all
1604 * atomic sections are closed.
1606 * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
1607 * by discarding the section's writes. This should not be used for failures when:
1608 * - upsert() could easily be used instead
1609 * - insert() with IGNORE could easily be used instead
1610 * - select() with FOR UPDATE could be checked before issuing writes instead
1611 * - The failure is from code that runs after the first write but doesn't need to
1612 * - The failures are from contention solvable via onTransactionPreCommitOrIdle()
1613 * - The failures are deadlocks; the RDBMs usually discard the whole transaction
1615 * @note callers must use additional measures for situations involving two or more
1616 * (peer) transactions (e.g. updating two database servers at once). The transaction
1617 * and savepoint logic of this method only applies to this specific IDatabase instance.
1621 * // Start a transaction if there isn't one already
1622 * $dbw->startAtomic( __METHOD__ );
1623 * // Serialize these thread table updates
1624 * $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
1625 * // Add a new comment for the thread
1626 * $dbw->insert( 'comment', $row, __METHOD__ );
1627 * $cid = $db->insertId();
1628 * // Update thread reference to last comment
1629 * $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
1630 * // Demark the end of this conceptual unit of updates
1631 * $dbw->endAtomic( __METHOD__ );
1634 * Example usage (atomic changes that might have to be discarded):
1636 * // Start a transaction if there isn't one already
1637 * $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
1638 * // Create new record metadata row
1639 * $dbw->insert( 'records', $row, __METHOD__ );
1640 * // Figure out where to store the data based on the new row's ID
1641 * $path = $recordDirectory . '/' . $dbw->insertId();
1642 * // Write the record data to the storage system
1643 * $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
1644 * if ( $status->isOK() ) {
1645 * // Try to cleanup files orphaned by transaction rollback
1646 * $dbw->onTransactionResolution(
1647 * function ( $type ) use ( $fileBackend, $path ) {
1648 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1649 * $fileBackend->delete( [ 'src' => $path ] );
1654 * // Demark the end of this conceptual unit of updates
1655 * $dbw->endAtomic( __METHOD__ );
1657 * // Discard these writes from the transaction (preserving prior writes)
1658 * $dbw->cancelAtomic( __METHOD__, $sectionId );
1663 * @param string $fname
1664 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1665 * savepoint and enable self::cancelAtomic() for this section.
1666 * @return AtomicSectionIdentifier section ID token
1669 public function startAtomic( $fname = __METHOD__
, $cancelable = self
::ATOMIC_NOT_CANCELABLE
);
1672 * Ends an atomic section of SQL statements
1674 * Ends the next section of atomic SQL statements and commits the transaction
1678 * @see IDatabase::startAtomic
1679 * @param string $fname
1682 public function endAtomic( $fname = __METHOD__
);
1685 * Cancel an atomic section of SQL statements
1687 * This will roll back only the statements executed since the start of the
1688 * most recent atomic section, and close that section. If a transaction was
1689 * open before the corresponding startAtomic() call, any statements before
1690 * that call are *not* rolled back and the transaction remains open. If the
1691 * corresponding startAtomic() implicitly started a transaction, that
1692 * transaction is rolled back.
1694 * @note callers must use additional measures for situations involving two or more
1695 * (peer) transactions (e.g. updating two database servers at once). The transaction
1696 * and savepoint logic of startAtomic() are bound to specific IDatabase instances.
1698 * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
1700 * @note As a micro-optimization to save a few DB calls, this method may only
1701 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1703 * @see IDatabase::startAtomic
1704 * @param string $fname
1705 * @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
1706 * passing this enables cancellation of unclosed nested sections [optional]
1709 public function cancelAtomic( $fname = __METHOD__
, AtomicSectionIdentifier
$sectionId = null );
1712 * Perform an atomic section of reversable SQL statements from a callback
1714 * The $callback takes the following arguments:
1715 * - This database object
1716 * - The value of $fname
1718 * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
1719 * If any exception occurs during execution of the callback, it will be handled as follows:
1720 * - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
1721 * (and only) statements executed during the atomic section. If that succeeds, then the
1722 * exception will be re-thrown; if it fails, then a different exception will be thrown
1723 * and any further query attempts will fail until rollback() is called.
1724 * - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
1725 * end of the section and the error will be re-thrown. Any further query attempts will
1726 * fail until rollback() is called.
1728 * This method is convenient for letting calls to the caller of this method be wrapped
1729 * in a try/catch blocks for exception types that imply that the caller failed but was
1730 * able to properly discard the changes it made in the transaction. This method can be
1731 * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
1733 * Example usage, "RecordStore::save" method:
1735 * $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
1736 * // Create new record metadata row
1737 * $dbw->insert( 'records', $record->toArray(), __METHOD__ );
1738 * // Figure out where to store the data based on the new row's ID
1739 * $path = $this->recordDirectory . '/' . $dbw->insertId();
1740 * // Write the record data to the storage system;
1741 * // blob store throughs StoreFailureException on failure
1742 * $this->blobStore->create( $path, $record->getJSON() );
1743 * // Try to cleanup files orphaned by transaction rollback
1744 * $dbw->onTransactionResolution(
1745 * function ( $type ) use ( $path ) {
1746 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1747 * $this->blobStore->delete( $path );
1752 * }, $dbw::ATOMIC_CANCELABLE );
1755 * Example usage, caller of the "RecordStore::save" method:
1757 * $dbw->startAtomic( __METHOD__ );
1758 * // ...various SQL writes happen...
1760 * $recordStore->save( $record );
1761 * } catch ( StoreFailureException $e ) {
1762 * // ...various SQL writes happen...
1764 * // ...various SQL writes happen...
1765 * $dbw->endAtomic( __METHOD__ );
1768 * @see Database::startAtomic
1769 * @see Database::endAtomic
1770 * @see Database::cancelAtomic
1772 * @param string $fname Caller name (usually __METHOD__)
1773 * @param callable $callback Callback that issues DB updates
1774 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1775 * savepoint and enable self::cancelAtomic() for this section.
1776 * @return mixed $res Result of the callback (since 1.28)
1778 * @throws RuntimeException
1779 * @since 1.27; prior to 1.31 this did a rollback() instead of
1780 * cancelAtomic(), and assumed no callers up the stack would ever try to
1781 * catch the exception.
1783 public function doAtomicSection(
1784 $fname, callable
$callback, $cancelable = self
::ATOMIC_NOT_CANCELABLE
1788 * Begin a transaction. If a transaction is already in progress,
1789 * that transaction will be committed before the new transaction is started.
1791 * Only call this from code with outer transcation scope.
1792 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1793 * Nesting of transactions is not supported.
1795 * Note that when the DBO_TRX flag is set (which is usually the case for web
1796 * requests, but not for maintenance scripts), any previous database query
1797 * will have started a transaction automatically.
1799 * Nesting of transactions is not supported. Attempts to nest transactions
1800 * will cause a warning, unless the current transaction was started
1801 * automatically because of the DBO_TRX flag.
1803 * @param string $fname Calling function name
1804 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1807 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1810 * Commits a transaction previously started using begin().
1811 * If no transaction is in progress, a warning is issued.
1813 * Only call this from code with outer transcation scope.
1814 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1815 * Nesting of transactions is not supported.
1817 * @param string $fname
1818 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1819 * constant to disable warnings about explicitly committing implicit transactions,
1820 * or calling commit when no transaction is in progress.
1822 * This will trigger an exception if there is an ongoing explicit transaction.
1824 * Only set the flush flag if you are sure that these warnings are not applicable,
1825 * and no explicit transactions are open.
1829 public function commit( $fname = __METHOD__
, $flush = '' );
1832 * Rollback a transaction previously started using begin().
1833 * If no transaction is in progress, a warning is issued.
1835 * Only call this from code with outer transcation scope.
1836 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1837 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1838 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1839 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1841 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1843 * @param string $fname Calling function name
1844 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1845 * constant to disable warnings about calling rollback when no transaction is in
1846 * progress. This will silently break any ongoing explicit transaction. Only set the
1847 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1849 * @since 1.23 Added $flush parameter
1851 public function rollback( $fname = __METHOD__
, $flush = '' );
1854 * Commit any transaction but error out if writes or callbacks are pending
1856 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1857 * see a new point-in-time of the database. This is useful when one of many transaction
1858 * rounds finished and significant time will pass in the script's lifetime. It is also
1859 * useful to call on a replica DB after waiting on replication to catch up to the master.
1861 * @param string $fname Calling function name
1865 public function flushSnapshot( $fname = __METHOD__
);
1868 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1869 * to the format used for inserting into timestamp fields in this DBMS.
1871 * The result is unquoted, and needs to be passed through addQuotes()
1872 * before it can be included in raw SQL.
1874 * @param string|int $ts
1878 public function timestamp( $ts = 0 );
1881 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1882 * to the format used for inserting into timestamp fields in this DBMS. If
1883 * NULL is input, it is passed through, allowing NULL values to be inserted
1884 * into timestamp fields.
1886 * The result is unquoted, and needs to be passed through addQuotes()
1887 * before it can be included in raw SQL.
1889 * @param string|int|null $ts
1893 public function timestampOrNull( $ts = null );
1896 * Ping the server and try to reconnect if it there is no connection
1898 * @param float|null &$rtt Value to store the estimated RTT [optional]
1899 * @return bool Success or failure
1901 public function ping( &$rtt = null );
1904 * Get the amount of replication lag for this database server
1906 * Callers should avoid using this method while a transaction is active
1908 * @return int|bool Database replication lag in seconds or false on error
1911 public function getLag();
1914 * Get the replica DB lag when the current transaction started
1915 * or a general lag estimate if not transaction is active
1917 * This is useful when transactions might use snapshot isolation
1918 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1919 * is this lag plus transaction duration. If they don't, it is still
1920 * safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
1921 * indication of the staleness of subsequent reads.
1923 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1927 public function getSessionLagStatus();
1930 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1934 public function maxListLen();
1937 * Some DBMSs have a special format for inserting into blob fields, they
1938 * don't allow simple quoted strings to be inserted. To insert into such
1939 * a field, pass the data through this function before passing it to
1940 * IDatabase::insert().
1943 * @return string|Blob
1945 public function encodeBlob( $b );
1948 * Some DBMSs return a special placeholder object representing blob fields
1949 * in result objects. Pass the object through this function to return the
1952 * @param string|Blob $b
1955 public function decodeBlob( $b );
1958 * Override database's default behavior. $options include:
1959 * 'connTimeout' : Set the connection timeout value in seconds.
1960 * May be useful for very long batch queries such as
1961 * full-wiki dumps, where a single query reads out over
1964 * @param array $options
1968 public function setSessionOptions( array $options );
1971 * Set variables to be used in sourceFile/sourceStream, in preference to the
1972 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1973 * all. If it's set to false, $GLOBALS will be used.
1975 * @param bool|array $vars Mapping variable name to value.
1977 public function setSchemaVars( $vars );
1980 * Check to see if a named lock is not locked by any thread (non-blocking)
1982 * @param string $lockName Name of lock to poll
1983 * @param string $method Name of method calling us
1988 public function lockIsFree( $lockName, $method );
1991 * Acquire a named lock
1993 * Named locks are not related to transactions
1995 * @param string $lockName Name of lock to aquire
1996 * @param string $method Name of the calling method
1997 * @param int $timeout Acquisition timeout in seconds
2001 public function lock( $lockName, $method, $timeout = 5 );
2006 * Named locks are not related to transactions
2008 * @param string $lockName Name of lock to release
2009 * @param string $method Name of the calling method
2011 * @return int Returns 1 if the lock was released, 0 if the lock was not established
2012 * by this thread (in which case the lock is not released), and NULL if the named lock
2017 public function unlock( $lockName, $method );
2020 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
2022 * Only call this from outer transcation scope and when only one DB will be affected.
2023 * See https://www.mediawiki.org/wiki/Database_transactions for details.
2025 * This is suitiable for transactions that need to be serialized using cooperative locks,
2026 * where each transaction can see each others' changes. Any transaction is flushed to clear
2027 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
2028 * the lock will be released unless a transaction is active. If one is active, then the lock
2029 * will be released when it either commits or rolls back.
2031 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
2033 * @param string $lockKey Name of lock to release
2034 * @param string $fname Name of the calling method
2035 * @param int $timeout Acquisition timeout in seconds
2036 * @return ScopedCallback|null
2040 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
2043 * Check to see if a named lock used by lock() use blocking queues
2048 public function namedLocksEnqueue();
2051 * Find out when 'infinity' is. Most DBMSes support this. This is a special
2052 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
2053 * because "i" sorts after all numbers.
2057 public function getInfinity();
2060 * Encode an expiry time into the DBMS dependent format
2062 * @param string $expiry Timestamp for expiry, or the 'infinity' string
2065 public function encodeExpiry( $expiry );
2068 * Decode an expiry time into a DBMS independent format
2070 * @param string $expiry DB timestamp field value for expiry
2071 * @param int $format TS_* constant, defaults to TS_MW
2074 public function decodeExpiry( $expiry, $format = TS_MW
);
2077 * Allow or deny "big selects" for this session only. This is done by setting
2078 * the sql_big_selects session variable.
2080 * This is a MySQL-specific feature.
2082 * @param bool|string $value True for allow, false for deny, or "default" to
2083 * restore the initial value
2085 public function setBigSelects( $value = true );
2088 * @return bool Whether this DB is read-only
2091 public function isReadOnly();
2094 * Make certain table names use their own database, schema, and table prefix
2095 * when passed into SQL queries pre-escaped and without a qualified database name
2097 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
2098 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
2100 * Calling this twice will completely clear any old table aliases. Also, note that
2101 * callers are responsible for making sure the schemas and databases actually exist.
2103 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
2106 public function setTableAliases( array $aliases );
2109 * Convert certain index names to alternative names before querying the DB
2111 * Note that this applies to indexes regardless of the table they belong to.
2113 * This can be employed when an index was renamed X => Y in code, but the new Y-named
2114 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
2115 * the aliases can be removed, and then the old X-named indexes dropped.
2117 * @param string[] $aliases
2121 public function setIndexAliases( array $aliases );
2125 * @deprecated since 1.29
2127 class_alias( IDatabase
::class, 'IDatabase' );