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 query result. If the query did not return
398 * any rows (for example, if it was a write query), this returns zero.
400 * @param mixed $res A SQL result
403 public function numRows( $res );
406 * Get the number of fields in a result object
407 * @see https://secure.php.net/mysql_num_fields
409 * @param mixed $res A SQL result
412 public function numFields( $res );
415 * Get a field name in a result object
416 * @see https://secure.php.net/mysql_field_name
418 * @param mixed $res A SQL result
422 public function fieldName( $res, $n );
425 * Get the inserted value of an auto-increment row
427 * This should only be called after an insert that used an auto-incremented
428 * value. If no such insert was previously done in the current database
429 * session, the return value is undefined.
433 public function insertId();
436 * Change the position of the cursor in a result object
437 * @see https://secure.php.net/mysql_data_seek
439 * @param mixed $res A SQL result
442 public function dataSeek( $res, $row );
445 * Get the last error number
446 * @see https://secure.php.net/mysql_errno
450 public function lastErrno();
453 * Get a description of the last error
454 * @see https://secure.php.net/mysql_error
458 public function lastError();
461 * Get the number of rows affected by the last write query
462 * @see https://secure.php.net/mysql_affected_rows
466 public function affectedRows();
469 * Returns a wikitext link to the DB's website, e.g.,
470 * return "[https://www.mysql.com/ MySQL]";
471 * Should at least contain plain text, if for some reason
472 * your database has no website.
474 * @return string Wikitext of a link to the server software's web site
476 public function getSoftwareLink();
479 * A string describing the current software version, like from
480 * mysql_get_server_info().
482 * @return string Version information from the database server.
484 public function getServerVersion();
487 * Close the database connection
489 * This should only be called after any transactions have been resolved,
490 * aside from read-only automatic transactions (assuming no callbacks are registered).
491 * If a transaction is still open anyway, it will be rolled back.
494 * @return bool Operation success. true if already closed.
496 public function close();
499 * Run an SQL query and return the result. Normally throws a DBQueryError
500 * on failure. If errors are ignored, returns false instead.
502 * If a connection loss is detected, then an attempt to reconnect will be made.
503 * For queries that involve no larger transactions or locks, they will be re-issued
504 * for convenience, provided the connection was re-established.
506 * In new code, the query wrappers select(), insert(), update(), delete(),
507 * etc. should be used where possible, since they give much better DBMS
508 * independence and automatically quote or validate user input in a variety
509 * of contexts. This function is generally only useful for queries which are
510 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
513 * However, the query wrappers themselves should call this function.
515 * @param string $sql SQL query
516 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
517 * comment (you can use __METHOD__ or add some extra info)
518 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
519 * maybe best to catch the exception instead?
520 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
521 * for a successful read query, or false on failure if $tempIgnore set
524 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
527 * Free a result object returned by query() or select(). It's usually not
528 * necessary to call this, just use unset() or let the variable holding
529 * the result object go out of scope.
531 * @param mixed $res A SQL result
533 public function freeResult( $res );
536 * A SELECT wrapper which returns a single field from a single result row.
538 * Usually throws a DBQueryError on failure. If errors are explicitly
539 * ignored, returns false on failure.
541 * If no result rows are returned from the query, false is returned.
543 * @param string|array $table Table name. See IDatabase::select() for details.
544 * @param string $var The field name to select. This must be a valid SQL
545 * fragment: do not use unvalidated user input.
546 * @param string|array $cond The condition array. See IDatabase::select() for details.
547 * @param string $fname The function name of the caller.
548 * @param string|array $options The query options. See IDatabase::select() for details.
549 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
551 * @return mixed The value from the field
554 public function selectField(
555 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
559 * A SELECT wrapper which returns a list of single field values from result rows.
561 * Usually throws a DBQueryError on failure. If errors are explicitly
562 * ignored, returns false on failure.
564 * If no result rows are returned from the query, false is returned.
566 * @param string|array $table Table name. See IDatabase::select() for details.
567 * @param string $var The field name to select. This must be a valid SQL
568 * fragment: do not use unvalidated user input.
569 * @param string|array $cond The condition array. See IDatabase::select() for details.
570 * @param string $fname The function name of the caller.
571 * @param string|array $options The query options. See IDatabase::select() for details.
572 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
574 * @return array The values from the field
578 public function selectFieldValues(
579 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
583 * Execute a SELECT query constructed using the various parameters provided.
584 * See below for full details of the parameters.
586 * @param string|array $table Table name
587 * @param string|array $vars Field names
588 * @param string|array $conds Conditions
589 * @param string $fname Caller function name
590 * @param array $options Query options
591 * @param array $join_conds Join conditions
594 * @param string|array $table
596 * May be either an array of table names, or a single string holding a table
597 * name. If an array is given, table aliases can be specified, for example:
601 * This includes the user table in the query, with the alias "a" available
602 * for use in field names (e.g. a.user_name).
604 * A derived table, defined by the result of selectSQLText(), requires an alias
605 * key and a Subquery instance value which wraps the SQL query, for example:
607 * [ 'c' => new Subquery( 'SELECT ...' ) ]
609 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
610 * constructed using nested arrays. For example,
612 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
614 * along with `$join_conds` like
616 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
618 * will produce SQL something like
620 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
622 * All of the table names given here are automatically run through
623 * Database::tableName(), which causes the table prefix (if any) to be
624 * added, and various other table name mappings to be performed.
626 * Do not use untrusted user input as a table name. Alias names should
627 * not have characters outside of the Basic multilingual plane.
629 * @param string|array $vars
631 * May be either a field name or an array of field names. The field names
632 * can be complete fragments of SQL, for direct inclusion into the SELECT
633 * query. If an array is given, field aliases can be specified, for example:
635 * [ 'maxrev' => 'MAX(rev_id)' ]
637 * This includes an expression with the alias "maxrev" in the query.
639 * If an expression is given, care must be taken to ensure that it is
642 * Untrusted user input must not be passed to this parameter.
644 * @param string|array $conds
646 * May be either a string containing a single condition, or an array of
647 * conditions. If an array is given, the conditions constructed from each
648 * element are combined with AND.
650 * Array elements may take one of two forms:
652 * - Elements with a numeric key are interpreted as raw SQL fragments.
653 * - Elements with a string key are interpreted as equality conditions,
654 * where the key is the field name.
655 * - If the value of such an array element is a scalar (such as a
656 * string), it will be treated as data and thus quoted appropriately.
657 * If it is null, an IS NULL clause will be added.
658 * - If the value is an array, an IN (...) clause will be constructed
659 * from its non-null elements, and an IS NULL clause will be added
660 * if null is present, such that the field may match any of the
661 * elements in the array. The non-null elements will be quoted.
663 * Note that expressions are often DBMS-dependent in their syntax.
664 * DBMS-independent wrappers are provided for constructing several types of
665 * expression commonly used in condition queries. See:
666 * - IDatabase::buildLike()
667 * - IDatabase::conditional()
669 * Untrusted user input is safe in the values of string keys, however untrusted
670 * input must not be used in the array key names or in the values of numeric keys.
671 * Escaping of untrusted input used in values of numeric keys should be done via
672 * IDatabase::addQuotes()
674 * Use an empty array, string, or '*' to update all rows.
676 * @param string|array $options
678 * Optional: Array of query options. Boolean options are specified by
679 * including them in the array as a string value with a numeric key, for
684 * The supported options are:
686 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
687 * with LIMIT can theoretically be used for paging through a result set,
688 * but this is discouraged for performance reasons.
690 * - LIMIT: Integer: return at most this many rows. The rows are sorted
691 * and then the first rows are taken until the limit is reached. LIMIT
692 * is applied to a result set after OFFSET.
694 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
695 * changed until the next COMMIT.
697 * - DISTINCT: Boolean: return only unique result rows.
699 * - GROUP BY: May be either an SQL fragment string naming a field or
700 * expression to group by, or an array of such SQL fragments.
702 * - HAVING: May be either an string containing a HAVING clause or an array of
703 * conditions building the HAVING clause. If an array is given, the conditions
704 * constructed from each element are combined with AND.
706 * - ORDER BY: May be either an SQL fragment giving a field name or
707 * expression to order by, or an array of such SQL fragments.
709 * - USE INDEX: This may be either a string giving the index name to use
710 * for the query, or an array. If it is an associative array, each key
711 * gives the table name (or alias), each value gives the index name to
712 * use for that table. All strings are SQL fragments and so should be
713 * validated by the caller.
715 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
718 * And also the following boolean MySQL extensions, see the MySQL manual
721 * - LOCK IN SHARE MODE
725 * - SQL_BUFFER_RESULT
727 * - SQL_CALC_FOUND_ROWS
732 * @param string|array $join_conds
734 * Optional associative array of table-specific join conditions. In the
735 * most common case, this is unnecessary, since the join condition can be
736 * in $conds. However, it is useful for doing a LEFT JOIN.
738 * The key of the array contains the table name or alias. The value is an
739 * array with two elements, numbered 0 and 1. The first gives the type of
740 * join, the second is the same as the $conds parameter. Thus it can be
741 * an SQL fragment, or an array where the string keys are equality and the
742 * numeric keys are SQL fragments all AND'd together. For example:
744 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
746 * @return IResultWrapper Resulting rows
749 public function select(
750 $table, $vars, $conds = '', $fname = __METHOD__
,
751 $options = [], $join_conds = []
755 * The equivalent of IDatabase::select() except that the constructed SQL
756 * is returned, instead of being immediately executed. This can be useful for
757 * doing UNION queries, where the SQL text of each query is needed. In general,
758 * however, callers outside of Database classes should just use select().
760 * @see IDatabase::select()
762 * @param string|array $table Table name
763 * @param string|array $vars Field names
764 * @param string|array $conds Conditions
765 * @param string $fname Caller function name
766 * @param string|array $options Query options
767 * @param string|array $join_conds Join conditions
768 * @return string SQL query string
770 public function selectSQLText(
771 $table, $vars, $conds = '', $fname = __METHOD__
,
772 $options = [], $join_conds = []
776 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
777 * that a single row object is returned. If the query returns no rows,
780 * @param string|array $table Table name
781 * @param string|array $vars Field names
782 * @param array $conds Conditions
783 * @param string $fname Caller function name
784 * @param string|array $options Query options
785 * @param array|string $join_conds Join conditions
787 * @return stdClass|bool
790 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
791 $options = [], $join_conds = []
795 * Estimate the number of rows in dataset
797 * MySQL allows you to estimate the number of rows that would be returned
798 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
799 * index cardinality statistics, and is notoriously inaccurate, especially
800 * when large numbers of rows have recently been added or deleted.
802 * For DBMSs that don't support fast result size estimation, this function
803 * will actually perform the SELECT COUNT(*).
805 * Takes the same arguments as IDatabase::select().
807 * @param string $table Table name
808 * @param string $var Column for which NULL values are not counted [default "*"]
809 * @param array|string $conds Filters on the table
810 * @param string $fname Function name for profiling
811 * @param array $options Options for select
812 * @param array|string $join_conds Join conditions
813 * @return int Row count
816 public function estimateRowCount(
817 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
821 * Get the number of rows in dataset
823 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
825 * Takes the same arguments as IDatabase::select().
827 * @since 1.27 Added $join_conds parameter
829 * @param array|string $tables Table names
830 * @param string $var Column for which NULL values are not counted [default "*"]
831 * @param array|string $conds Filters on the table
832 * @param string $fname Function name for profiling
833 * @param array $options Options for select
834 * @param array $join_conds Join conditions (since 1.27)
835 * @return int Row count
838 public function selectRowCount(
839 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
843 * Lock all rows meeting the given conditions/options FOR UPDATE
845 * @param array|string $table Table names
846 * @param array|string $conds Filters on the table
847 * @param string $fname Function name for profiling
848 * @param array $options Options for select ("FOR UPDATE" is added automatically)
849 * @param array $join_conds Join conditions
850 * @return int Number of matching rows found (and locked)
853 public function lockForUpdate(
854 $table, $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
858 * Determines whether a field exists in a table
860 * @param string $table Table name
861 * @param string $field Filed to check on that table
862 * @param string $fname Calling function name (optional)
863 * @return bool Whether $table has filed $field
866 public function fieldExists( $table, $field, $fname = __METHOD__
);
869 * Determines whether an index exists
870 * Usually throws a DBQueryError on failure
871 * If errors are explicitly ignored, returns NULL on failure
873 * @param string $table
874 * @param string $index
875 * @param string $fname
879 public function indexExists( $table, $index, $fname = __METHOD__
);
882 * Query whether a given table exists
884 * @param string $table
885 * @param string $fname
889 public function tableExists( $table, $fname = __METHOD__
);
892 * INSERT wrapper, inserts an array into a table.
896 * - A single associative array. The array keys are the field names, and
897 * the values are the values to insert. The values are treated as data
898 * and will be quoted appropriately. If NULL is inserted, this will be
899 * converted to a database NULL.
900 * - An array with numeric keys, holding a list of associative arrays.
901 * This causes a multi-row INSERT on DBMSs that support it. The keys in
902 * each subarray must be identical to each other, and in the same order.
904 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
907 * $options is an array of options, with boolean options encoded as values
908 * with numeric keys, in the same style as $options in
909 * IDatabase::select(). Supported options are:
911 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
912 * any rows which cause duplicate key errors are not inserted. It's
913 * possible to determine how many rows were successfully inserted using
914 * IDatabase::affectedRows().
916 * @param string $table Table name. This will be passed through
917 * Database::tableName().
918 * @param array $a Array of rows to insert
919 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
920 * @param array $options Array of options
925 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
928 * UPDATE wrapper. Takes a condition array and a SET array.
930 * @param string $table Name of the table to UPDATE. This will be passed through
931 * Database::tableName().
932 * @param array $values An array of values to SET. For each array element,
933 * the key gives the field name, and the value gives the data to set
934 * that field to. The data will be quoted by IDatabase::addQuotes().
935 * Values with integer keys form unquoted SET statements, which can be used for
936 * things like "field = field + 1" or similar computed values.
937 * @param array $conds An array of conditions (WHERE). See
938 * IDatabase::select() for the details of the format of condition
939 * arrays. Use '*' to update all rows.
940 * @param string $fname The function name of the caller (from __METHOD__),
941 * for logging and profiling.
942 * @param array $options An array of UPDATE options, can be:
943 * - IGNORE: Ignore unique key conflicts
944 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
948 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
951 * Makes an encoded list of strings from an array
953 * These can be used to make conjunctions or disjunctions on SQL condition strings
954 * derived from an array (see IDatabase::select() $conds documentation).
958 * $sql = $db->makeList( [
960 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
961 * ], $db::LIST_AND );
963 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
965 * @param array $a Containing the data
966 * @param int $mode IDatabase class constant:
967 * - IDatabase::LIST_COMMA: Comma separated, no field names
968 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
969 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
970 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
971 * - IDatabase::LIST_NAMES: Comma separated field names
975 public function makeList( $a, $mode = self
::LIST_COMMA
);
978 * Build a partial where clause from a 2-d array such as used for LinkBatch.
979 * The keys on each level may be either integers or strings.
981 * @param array $data Organized as 2-d
982 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
983 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
984 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
985 * @return string|bool SQL fragment, or false if no items in array
987 public function makeWhereFrom2d( $data, $baseKey, $subKey );
990 * Return aggregated value alias
992 * @param array $valuedata
993 * @param string $valuename
997 public function aggregateValue( $valuedata, $valuename = 'value' );
1000 * @param string $field
1003 public function bitNot( $field );
1006 * @param string $fieldLeft
1007 * @param string $fieldRight
1010 public function bitAnd( $fieldLeft, $fieldRight );
1013 * @param string $fieldLeft
1014 * @param string $fieldRight
1017 public function bitOr( $fieldLeft, $fieldRight );
1020 * Build a concatenation list to feed into a SQL query
1021 * @param array $stringList List of raw SQL expressions; caller is
1022 * responsible for any quoting
1025 public function buildConcat( $stringList );
1028 * Build a GROUP_CONCAT or equivalent statement for a query.
1030 * This is useful for combining a field for several rows into a single string.
1031 * NULL values will not appear in the output, duplicated values will appear,
1032 * and the resulting delimiter-separated values have no defined sort order.
1033 * Code using the results may need to use the PHP unique() or sort() methods.
1035 * @param string $delim Glue to bind the results together
1036 * @param string|array $table Table name
1037 * @param string $field Field name
1038 * @param string|array $conds Conditions
1039 * @param string|array $join_conds Join conditions
1040 * @return string SQL text
1043 public function buildGroupConcatField(
1044 $delim, $table, $field, $conds = '', $join_conds = []
1048 * Build a SUBSTRING function.
1050 * Behavior for non-ASCII values is undefined.
1052 * @param string $input Field name
1053 * @param int $startPosition Positive integer
1054 * @param int|null $length Non-negative integer length or null for no limit
1055 * @throws InvalidArgumentException
1056 * @return string SQL text
1059 public function buildSubString( $input, $startPosition, $length = null );
1062 * @param string $field Field or column to cast
1066 public function buildStringCast( $field );
1069 * @param string $field Field or column to cast
1073 public function buildIntegerCast( $field );
1076 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1078 * @see IDatabase::selectSQLText()
1080 * @param string|array $table Table name
1081 * @param string|array $vars Field names
1082 * @param string|array $conds Conditions
1083 * @param string $fname Caller function name
1084 * @param string|array $options Query options
1085 * @param string|array $join_conds Join conditions
1089 public function buildSelectSubquery(
1090 $table, $vars, $conds = '', $fname = __METHOD__
,
1091 $options = [], $join_conds = []
1095 * Returns true if DBs are assumed to be on potentially different servers
1097 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1098 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1099 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1100 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1105 public function databasesAreIndependent();
1108 * Change the current database
1111 * @return bool Success or failure
1112 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1114 public function selectDB( $db );
1117 * Get the current DB name
1120 public function getDBname();
1123 * Get the server hostname or IP address
1126 public function getServer();
1129 * Adds quotes and backslashes.
1131 * @param string|int|null|bool|Blob $s
1132 * @return string|int
1134 public function addQuotes( $s );
1137 * LIKE statement wrapper, receives a variable-length argument list with
1138 * parts of pattern to match containing either string literals that will be
1139 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1140 * the function could be provided with an array of aforementioned
1143 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1144 * a LIKE clause that searches for subpages of 'My page title'.
1146 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1147 * $query .= $dbr->buildLike( $pattern );
1150 * @return string Fully built LIKE statement
1152 public function buildLike();
1155 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1159 public function anyChar();
1162 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1166 public function anyString();
1169 * Deprecated method, calls should be removed.
1171 * This was formerly used for PostgreSQL and Oracle to handle
1172 * self::insertId() auto-incrementing fields. It is no longer necessary
1173 * since DatabasePostgres::insertId() has been reimplemented using
1174 * `lastval()` and Oracle has been reimplemented using triggers.
1176 * Implementations should return null if inserting `NULL` into an
1177 * auto-incrementing field works, otherwise it should return an instance of
1178 * NextSequenceValue and filter it on calls to relevant methods.
1180 * @deprecated since 1.30, no longer needed
1181 * @param string $seqName
1182 * @return null|NextSequenceValue
1184 public function nextSequenceValue( $seqName );
1187 * REPLACE query wrapper.
1189 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1190 * except that when there is a duplicate key error, the old row is deleted
1191 * and the new row is inserted in its place.
1193 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1194 * perform the delete, we need to know what the unique indexes are so that
1195 * we know how to find the conflicting rows.
1197 * It may be more efficient to leave off unique indexes which are unlikely
1198 * to collide. However if you do this, you run the risk of encountering
1199 * errors which wouldn't have occurred in MySQL.
1201 * @param string $table The table to replace the row(s) in.
1202 * @param array $uniqueIndexes Either a list of fields that define a unique index or
1203 * an array of such lists if there are multiple unique indexes defined in the schema
1204 * @param array $rows Can be either a single row to insert, or multiple rows,
1205 * in the same format as for IDatabase::insert()
1206 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1209 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1212 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1214 * This updates any conflicting rows (according to the unique indexes) using
1215 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1217 * $rows may be either:
1218 * - A single associative array. The array keys are the field names, and
1219 * the values are the values to insert. The values are treated as data
1220 * and will be quoted appropriately. If NULL is inserted, this will be
1221 * converted to a database NULL.
1222 * - An array with numeric keys, holding a list of associative arrays.
1223 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1224 * each subarray must be identical to each other, and in the same order.
1226 * It may be more efficient to leave off unique indexes which are unlikely
1227 * to collide. However if you do this, you run the risk of encountering
1228 * errors which wouldn't have occurred in MySQL.
1230 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1235 * @param string $table Table name. This will be passed through Database::tableName().
1236 * @param array $rows A single row or list of rows to insert
1237 * @param array $uniqueIndexes Either a list of fields that define a unique index or
1238 * an array of such lists if there are multiple unique indexes defined in the schema
1239 * @param array $set An array of values to SET. For each array element, the
1240 * key gives the field name, and the value gives the data to set that
1241 * field to. The data will be quoted by IDatabase::addQuotes().
1242 * Values with integer keys form unquoted SET statements, which can be used for
1243 * things like "field = field + 1" or similar computed values.
1244 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1248 public function upsert(
1249 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1253 * DELETE where the condition is a join.
1255 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1256 * we use sub-selects
1258 * For safety, an empty $conds will not delete everything. If you want to
1259 * delete all rows where the join condition matches, set $conds='*'.
1261 * DO NOT put the join condition in $conds.
1263 * @param string $delTable The table to delete from.
1264 * @param string $joinTable The other table.
1265 * @param string $delVar The variable to join on, in the first table.
1266 * @param string $joinVar The variable to join on, in the second table.
1267 * @param array $conds Condition array of field names mapped to variables,
1268 * ANDed together in the WHERE clause
1269 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1272 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1277 * DELETE query wrapper.
1279 * @param string $table Table name
1280 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1281 * for the format. Use $conds == "*" to delete all rows
1282 * @param string $fname Name of the calling function
1283 * @throws DBUnexpectedError
1284 * @return bool|IResultWrapper
1287 public function delete( $table, $conds, $fname = __METHOD__
);
1290 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1291 * into another table.
1293 * @warning If the insert will use an auto-increment or sequence to
1294 * determine the value of a column, this may break replication on
1295 * databases using statement-based replication if the SELECT is not
1296 * deterministically ordered.
1298 * @param string $destTable The table name to insert into
1299 * @param string|array $srcTable May be either a table name, or an array of table names
1300 * to include in a join.
1302 * @param array $varMap Must be an associative array of the form
1303 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1304 * rather than field names, but strings should be quoted with
1305 * IDatabase::addQuotes()
1307 * @param array $conds Condition array. See $conds in IDatabase::select() for
1308 * the details of the format of condition arrays. May be "*" to copy the
1311 * @param string $fname The function name of the caller, from __METHOD__
1313 * @param array $insertOptions Options for the INSERT part of the query, see
1314 * IDatabase::insert() for details. Also, one additional option is
1315 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1316 * an auto-increment or sequence to determine any column values.
1317 * @param array $selectOptions Options for the SELECT part of the query, see
1318 * IDatabase::select() for details.
1319 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1320 * IDatabase::select() for details.
1325 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1326 $fname = __METHOD__
,
1327 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1331 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1332 * within the UNION construct.
1335 public function unionSupportsOrderAndLimit();
1338 * Construct a UNION query
1339 * This is used for providing overload point for other DB abstractions
1340 * not compatible with the MySQL syntax.
1341 * @param array $sqls SQL statements to combine
1342 * @param bool $all Use UNION ALL
1343 * @return string SQL fragment
1345 public function unionQueries( $sqls, $all );
1348 * Construct a UNION query for permutations of conditions
1350 * Databases sometimes have trouble with queries that have multiple values
1351 * for multiple condition parameters combined with limits and ordering.
1352 * This method constructs queries for the Cartesian product of the
1353 * conditions and unions them all together.
1355 * @see IDatabase::select()
1357 * @param string|array $table Table name
1358 * @param string|array $vars Field names
1359 * @param array $permute_conds Conditions for the Cartesian product. Keys
1360 * are field names, values are arrays of the possible values for that
1362 * @param string|array $extra_conds Additional conditions to include in the
1364 * @param string $fname Caller function name
1365 * @param string|array $options Query options. In addition to the options
1366 * recognized by IDatabase::select(), the following may be used:
1367 * - NOTALL: Set to use UNION instead of UNION ALL.
1368 * - INNER ORDER BY: If specified and supported, subqueries will use this
1369 * instead of ORDER BY.
1370 * @param string|array $join_conds Join conditions
1371 * @return string SQL query string.
1373 public function unionConditionPermutations(
1374 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1375 $options = [], $join_conds = []
1379 * Returns an SQL expression for a simple conditional. This doesn't need
1380 * to be overridden unless CASE isn't supported in your DBMS.
1382 * @param string|array $cond SQL expression which will result in a boolean value
1383 * @param string $trueVal SQL expression to return if true
1384 * @param string $falseVal SQL expression to return if false
1385 * @return string SQL fragment
1387 public function conditional( $cond, $trueVal, $falseVal );
1390 * Returns a command for str_replace function in SQL query.
1391 * Uses REPLACE() in MySQL
1393 * @param string $orig Column to modify
1394 * @param string $old Column to seek
1395 * @param string $new Column to replace with
1399 public function strreplace( $orig, $old, $new );
1402 * Determines how long the server has been up
1407 public function getServerUptime();
1410 * Determines if the last failure was due to a deadlock
1412 * Note that during a deadlock, the prior transaction will have been lost
1416 public function wasDeadlock();
1419 * Determines if the last failure was due to a lock timeout
1421 * Note that during a lock wait timeout, the prior transaction will have been lost
1425 public function wasLockTimeout();
1428 * Determines if the last query error was due to a dropped connection
1430 * Note that during a connection loss, the prior transaction will have been lost
1435 public function wasConnectionLoss();
1438 * Determines if the last failure was due to the database being read-only.
1442 public function wasReadOnlyError();
1445 * Determines if the last query error was due to something outside of the query itself
1447 * Note that the transaction may have been lost, discarding prior writes and results
1451 public function wasErrorReissuable();
1454 * Wait for the replica DB to catch up to a given master position
1456 * @param DBMasterPos $pos
1457 * @param int $timeout The maximum number of seconds to wait for synchronisation
1458 * @return int|null Zero if the replica DB was past that position already,
1459 * greater than zero if we waited for some period of time, less than
1460 * zero if it timed out, and null on error
1463 public function masterPosWait( DBMasterPos
$pos, $timeout );
1466 * Get the replication position of this replica DB
1468 * @return DBMasterPos|bool False if this is not a replica DB
1471 public function getReplicaPos();
1474 * Get the position of this master
1476 * @return DBMasterPos|bool False if this is not a master
1479 public function getMasterPos();
1482 * @return bool Whether the DB is marked as read-only server-side
1485 public function serverIsReadOnly();
1488 * Run a callback as soon as the current transaction commits or rolls back.
1489 * An error is thrown if no transaction is pending. Queries in the function will run in
1490 * AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1493 * This is useful for combining cooperative locks and DB transactions.
1495 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1497 * The callback takes the following arguments:
1498 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1499 * - This IDatabase instance (since 1.32)
1501 * @param callable $callback
1502 * @param string $fname Caller name
1506 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1509 * Run a callback as soon as there is no transaction pending.
1510 * If there is a transaction and it is rolled back, then the callback is cancelled.
1512 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1513 * of the round, just after all peer transactions COMMIT. If the transaction round
1514 * is rolled back, then the callback is cancelled.
1516 * Queries in the function will run in AUTOCOMMIT mode unless there are begin() calls.
1517 * Callbacks must commit any transactions that they begin.
1519 * This is useful for updates to different systems or when separate transactions are needed.
1520 * For example, one might want to enqueue jobs into a system outside the database, but only
1521 * after the database is updated so that the jobs will see the data when they actually run.
1522 * It can also be used for updates that easily suffer from lock timeouts and deadlocks,
1523 * but where atomicity is not essential.
1525 * Avoid using IDatabase instances aside from this one in the callback, unless such instances
1526 * never have IDatabase::DBO_TRX set. This keeps callbacks from interfering with one another.
1528 * Updates will execute in the order they were enqueued.
1530 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1532 * The callback takes the following arguments:
1533 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1534 * - This IDatabase instance (since 1.32)
1536 * @param callable $callback
1537 * @param string $fname Caller name
1540 public function onTransactionCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1543 * Alias for onTransactionCommitOrIdle() for backwards-compatibility
1545 * @param callable $callback
1546 * @param string $fname
1549 * @deprecated Since 1.32
1551 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1554 * Run a callback before the current transaction commits or now if there is none.
1555 * If there is a transaction and it is rolled back, then the callback is cancelled.
1557 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1558 * of the round, just before all peer transactions COMMIT. If the transaction round
1559 * is rolled back, then the callback is cancelled.
1561 * Callbacks must not start nor commit any transactions. If no transaction is active,
1562 * then a transaction will wrap the callback.
1564 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1565 * but where atomicity is strongly desired for these updates and some related updates.
1567 * Updates will execute in the order they were enqueued.
1569 * The callback takes the one argument:
1570 * - This IDatabase instance (since 1.32)
1572 * @param callable $callback
1573 * @param string $fname Caller name
1576 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1579 * Run a callback after each time any transaction commits or rolls back
1581 * The callback takes two arguments:
1582 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1583 * - This IDatabase object
1584 * Callbacks must commit any transactions that they begin.
1586 * Registering a callback here will not affect writesOrCallbacks() pending.
1588 * Since callbacks from this or onTransactionCommitOrIdle() can start and end transactions,
1589 * a single call to IDatabase::commit might trigger multiple runs of the listener callbacks.
1591 * @param string $name Callback name
1592 * @param callable|null $callback Use null to unset a listener
1596 public function setTransactionListener( $name, callable
$callback = null );
1599 * Begin an atomic section of SQL statements
1601 * Start an implicit transaction if no transaction is already active, set a savepoint
1602 * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
1603 * that the transaction is not committed prematurely. The end of the section must be
1604 * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
1605 * have layers of inner sections (sub-sections), but all sections must be ended in order
1606 * of innermost to outermost. Transactions cannot be started or committed until all
1607 * atomic sections are closed.
1609 * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
1610 * by discarding the section's writes. This should not be used for failures when:
1611 * - upsert() could easily be used instead
1612 * - insert() with IGNORE could easily be used instead
1613 * - select() with FOR UPDATE could be checked before issuing writes instead
1614 * - The failure is from code that runs after the first write but doesn't need to
1615 * - The failures are from contention solvable via onTransactionPreCommitOrIdle()
1616 * - The failures are deadlocks; the RDBMs usually discard the whole transaction
1618 * @note callers must use additional measures for situations involving two or more
1619 * (peer) transactions (e.g. updating two database servers at once). The transaction
1620 * and savepoint logic of this method only applies to this specific IDatabase instance.
1624 * // Start a transaction if there isn't one already
1625 * $dbw->startAtomic( __METHOD__ );
1626 * // Serialize these thread table updates
1627 * $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
1628 * // Add a new comment for the thread
1629 * $dbw->insert( 'comment', $row, __METHOD__ );
1630 * $cid = $db->insertId();
1631 * // Update thread reference to last comment
1632 * $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
1633 * // Demark the end of this conceptual unit of updates
1634 * $dbw->endAtomic( __METHOD__ );
1637 * Example usage (atomic changes that might have to be discarded):
1639 * // Start a transaction if there isn't one already
1640 * $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
1641 * // Create new record metadata row
1642 * $dbw->insert( 'records', $row, __METHOD__ );
1643 * // Figure out where to store the data based on the new row's ID
1644 * $path = $recordDirectory . '/' . $dbw->insertId();
1645 * // Write the record data to the storage system
1646 * $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
1647 * if ( $status->isOK() ) {
1648 * // Try to cleanup files orphaned by transaction rollback
1649 * $dbw->onTransactionResolution(
1650 * function ( $type ) use ( $fileBackend, $path ) {
1651 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1652 * $fileBackend->delete( [ 'src' => $path ] );
1657 * // Demark the end of this conceptual unit of updates
1658 * $dbw->endAtomic( __METHOD__ );
1660 * // Discard these writes from the transaction (preserving prior writes)
1661 * $dbw->cancelAtomic( __METHOD__, $sectionId );
1666 * @param string $fname
1667 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1668 * savepoint and enable self::cancelAtomic() for this section.
1669 * @return AtomicSectionIdentifier section ID token
1672 public function startAtomic( $fname = __METHOD__
, $cancelable = self
::ATOMIC_NOT_CANCELABLE
);
1675 * Ends an atomic section of SQL statements
1677 * Ends the next section of atomic SQL statements and commits the transaction
1681 * @see IDatabase::startAtomic
1682 * @param string $fname
1685 public function endAtomic( $fname = __METHOD__
);
1688 * Cancel an atomic section of SQL statements
1690 * This will roll back only the statements executed since the start of the
1691 * most recent atomic section, and close that section. If a transaction was
1692 * open before the corresponding startAtomic() call, any statements before
1693 * that call are *not* rolled back and the transaction remains open. If the
1694 * corresponding startAtomic() implicitly started a transaction, that
1695 * transaction is rolled back.
1697 * @note callers must use additional measures for situations involving two or more
1698 * (peer) transactions (e.g. updating two database servers at once). The transaction
1699 * and savepoint logic of startAtomic() are bound to specific IDatabase instances.
1701 * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
1703 * @note As a micro-optimization to save a few DB calls, this method may only
1704 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1706 * @see IDatabase::startAtomic
1707 * @param string $fname
1708 * @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
1709 * passing this enables cancellation of unclosed nested sections [optional]
1712 public function cancelAtomic( $fname = __METHOD__
, AtomicSectionIdentifier
$sectionId = null );
1715 * Perform an atomic section of reversable SQL statements from a callback
1717 * The $callback takes the following arguments:
1718 * - This database object
1719 * - The value of $fname
1721 * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
1722 * If any exception occurs during execution of the callback, it will be handled as follows:
1723 * - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
1724 * (and only) statements executed during the atomic section. If that succeeds, then the
1725 * exception will be re-thrown; if it fails, then a different exception will be thrown
1726 * and any further query attempts will fail until rollback() is called.
1727 * - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
1728 * end of the section and the error will be re-thrown. Any further query attempts will
1729 * fail until rollback() is called.
1731 * This method is convenient for letting calls to the caller of this method be wrapped
1732 * in a try/catch blocks for exception types that imply that the caller failed but was
1733 * able to properly discard the changes it made in the transaction. This method can be
1734 * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
1736 * Example usage, "RecordStore::save" method:
1738 * $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
1739 * // Create new record metadata row
1740 * $dbw->insert( 'records', $record->toArray(), __METHOD__ );
1741 * // Figure out where to store the data based on the new row's ID
1742 * $path = $this->recordDirectory . '/' . $dbw->insertId();
1743 * // Write the record data to the storage system;
1744 * // blob store throughs StoreFailureException on failure
1745 * $this->blobStore->create( $path, $record->getJSON() );
1746 * // Try to cleanup files orphaned by transaction rollback
1747 * $dbw->onTransactionResolution(
1748 * function ( $type ) use ( $path ) {
1749 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1750 * $this->blobStore->delete( $path );
1755 * }, $dbw::ATOMIC_CANCELABLE );
1758 * Example usage, caller of the "RecordStore::save" method:
1760 * $dbw->startAtomic( __METHOD__ );
1761 * // ...various SQL writes happen...
1763 * $recordStore->save( $record );
1764 * } catch ( StoreFailureException $e ) {
1765 * // ...various SQL writes happen...
1767 * // ...various SQL writes happen...
1768 * $dbw->endAtomic( __METHOD__ );
1771 * @see Database::startAtomic
1772 * @see Database::endAtomic
1773 * @see Database::cancelAtomic
1775 * @param string $fname Caller name (usually __METHOD__)
1776 * @param callable $callback Callback that issues DB updates
1777 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1778 * savepoint and enable self::cancelAtomic() for this section.
1779 * @return mixed $res Result of the callback (since 1.28)
1781 * @throws RuntimeException
1782 * @since 1.27; prior to 1.31 this did a rollback() instead of
1783 * cancelAtomic(), and assumed no callers up the stack would ever try to
1784 * catch the exception.
1786 public function doAtomicSection(
1787 $fname, callable
$callback, $cancelable = self
::ATOMIC_NOT_CANCELABLE
1791 * Begin a transaction. If a transaction is already in progress,
1792 * that transaction will be committed before the new transaction is started.
1794 * Only call this from code with outer transcation scope.
1795 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1796 * Nesting of transactions is not supported.
1798 * Note that when the DBO_TRX flag is set (which is usually the case for web
1799 * requests, but not for maintenance scripts), any previous database query
1800 * will have started a transaction automatically.
1802 * Nesting of transactions is not supported. Attempts to nest transactions
1803 * will cause a warning, unless the current transaction was started
1804 * automatically because of the DBO_TRX flag.
1806 * @param string $fname Calling function name
1807 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1810 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1813 * Commits a transaction previously started using begin().
1814 * If no transaction is in progress, a warning is issued.
1816 * Only call this from code with outer transcation scope.
1817 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1818 * Nesting of transactions is not supported.
1820 * @param string $fname
1821 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1822 * constant to disable warnings about explicitly committing implicit transactions,
1823 * or calling commit when no transaction is in progress.
1825 * This will trigger an exception if there is an ongoing explicit transaction.
1827 * Only set the flush flag if you are sure that these warnings are not applicable,
1828 * and no explicit transactions are open.
1832 public function commit( $fname = __METHOD__
, $flush = '' );
1835 * Rollback a transaction previously started using begin().
1836 * If no transaction is in progress, a warning is issued.
1838 * Only call this from code with outer transcation scope.
1839 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1840 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1841 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1842 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1844 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1846 * @param string $fname Calling function name
1847 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1848 * constant to disable warnings about calling rollback when no transaction is in
1849 * progress. This will silently break any ongoing explicit transaction. Only set the
1850 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1852 * @since 1.23 Added $flush parameter
1854 public function rollback( $fname = __METHOD__
, $flush = '' );
1857 * Commit any transaction but error out if writes or callbacks are pending
1859 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1860 * see a new point-in-time of the database. This is useful when one of many transaction
1861 * rounds finished and significant time will pass in the script's lifetime. It is also
1862 * useful to call on a replica DB after waiting on replication to catch up to the master.
1864 * @param string $fname Calling function name
1868 public function flushSnapshot( $fname = __METHOD__
);
1871 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1872 * to the format used for inserting into timestamp fields in this DBMS.
1874 * The result is unquoted, and needs to be passed through addQuotes()
1875 * before it can be included in raw SQL.
1877 * @param string|int $ts
1881 public function timestamp( $ts = 0 );
1884 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1885 * to the format used for inserting into timestamp fields in this DBMS. If
1886 * NULL is input, it is passed through, allowing NULL values to be inserted
1887 * into timestamp fields.
1889 * The result is unquoted, and needs to be passed through addQuotes()
1890 * before it can be included in raw SQL.
1892 * @param string|int|null $ts
1896 public function timestampOrNull( $ts = null );
1899 * Ping the server and try to reconnect if it there is no connection
1901 * @param float|null &$rtt Value to store the estimated RTT [optional]
1902 * @return bool Success or failure
1904 public function ping( &$rtt = null );
1907 * Get the amount of replication lag for this database server
1909 * Callers should avoid using this method while a transaction is active
1911 * @return int|bool Database replication lag in seconds or false on error
1914 public function getLag();
1917 * Get the replica DB lag when the current transaction started
1918 * or a general lag estimate if not transaction is active
1920 * This is useful when transactions might use snapshot isolation
1921 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1922 * is this lag plus transaction duration. If they don't, it is still
1923 * safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
1924 * indication of the staleness of subsequent reads.
1926 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1930 public function getSessionLagStatus();
1933 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1937 public function maxListLen();
1940 * Some DBMSs have a special format for inserting into blob fields, they
1941 * don't allow simple quoted strings to be inserted. To insert into such
1942 * a field, pass the data through this function before passing it to
1943 * IDatabase::insert().
1946 * @return string|Blob
1948 public function encodeBlob( $b );
1951 * Some DBMSs return a special placeholder object representing blob fields
1952 * in result objects. Pass the object through this function to return the
1955 * @param string|Blob $b
1958 public function decodeBlob( $b );
1961 * Override database's default behavior. $options include:
1962 * 'connTimeout' : Set the connection timeout value in seconds.
1963 * May be useful for very long batch queries such as
1964 * full-wiki dumps, where a single query reads out over
1967 * @param array $options
1971 public function setSessionOptions( array $options );
1974 * Set variables to be used in sourceFile/sourceStream, in preference to the
1975 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1976 * all. If it's set to false, $GLOBALS will be used.
1978 * @param bool|array $vars Mapping variable name to value.
1980 public function setSchemaVars( $vars );
1983 * Check to see if a named lock is not locked by any thread (non-blocking)
1985 * @param string $lockName Name of lock to poll
1986 * @param string $method Name of method calling us
1991 public function lockIsFree( $lockName, $method );
1994 * Acquire a named lock
1996 * Named locks are not related to transactions
1998 * @param string $lockName Name of lock to aquire
1999 * @param string $method Name of the calling method
2000 * @param int $timeout Acquisition timeout in seconds
2004 public function lock( $lockName, $method, $timeout = 5 );
2009 * Named locks are not related to transactions
2011 * @param string $lockName Name of lock to release
2012 * @param string $method Name of the calling method
2014 * @return int Returns 1 if the lock was released, 0 if the lock was not established
2015 * by this thread (in which case the lock is not released), and NULL if the named lock
2020 public function unlock( $lockName, $method );
2023 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
2025 * Only call this from outer transcation scope and when only one DB will be affected.
2026 * See https://www.mediawiki.org/wiki/Database_transactions for details.
2028 * This is suitiable for transactions that need to be serialized using cooperative locks,
2029 * where each transaction can see each others' changes. Any transaction is flushed to clear
2030 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
2031 * the lock will be released unless a transaction is active. If one is active, then the lock
2032 * will be released when it either commits or rolls back.
2034 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
2036 * @param string $lockKey Name of lock to release
2037 * @param string $fname Name of the calling method
2038 * @param int $timeout Acquisition timeout in seconds
2039 * @return ScopedCallback|null
2043 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
2046 * Check to see if a named lock used by lock() use blocking queues
2051 public function namedLocksEnqueue();
2054 * Find out when 'infinity' is. Most DBMSes support this. This is a special
2055 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
2056 * because "i" sorts after all numbers.
2060 public function getInfinity();
2063 * Encode an expiry time into the DBMS dependent format
2065 * @param string $expiry Timestamp for expiry, or the 'infinity' string
2068 public function encodeExpiry( $expiry );
2071 * Decode an expiry time into a DBMS independent format
2073 * @param string $expiry DB timestamp field value for expiry
2074 * @param int $format TS_* constant, defaults to TS_MW
2077 public function decodeExpiry( $expiry, $format = TS_MW
);
2080 * Allow or deny "big selects" for this session only. This is done by setting
2081 * the sql_big_selects session variable.
2083 * This is a MySQL-specific feature.
2085 * @param bool|string $value True for allow, false for deny, or "default" to
2086 * restore the initial value
2088 public function setBigSelects( $value = true );
2091 * @return bool Whether this DB is read-only
2094 public function isReadOnly();
2097 * Make certain table names use their own database, schema, and table prefix
2098 * when passed into SQL queries pre-escaped and without a qualified database name
2100 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
2101 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
2103 * Calling this twice will completely clear any old table aliases. Also, note that
2104 * callers are responsible for making sure the schemas and databases actually exist.
2106 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
2109 public function setTableAliases( array $aliases );
2112 * Convert certain index names to alternative names before querying the DB
2114 * Note that this applies to indexes regardless of the table they belong to.
2116 * This can be employed when an index was renamed X => Y in code, but the new Y-named
2117 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
2118 * the aliases can be removed, and then the old X-named indexes dropped.
2120 * @param string[] $aliases
2124 public function setIndexAliases( array $aliases );
2128 * @deprecated since 1.29
2130 class_alias( IDatabase
::class, 'IDatabase' );