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;
45 /** @var int Callback triggered by atomic section cancel (ROLLBACK TO SAVEPOINT) */
46 const TRIGGER_CANCEL
= 4;
48 /** @var string Transaction is requested by regular caller outside of the DB layer */
49 const TRANSACTION_EXPLICIT
= '';
50 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
51 const TRANSACTION_INTERNAL
= 'implicit';
53 /** @var string Atomic section is not cancelable */
54 const ATOMIC_NOT_CANCELABLE
= '';
55 /** @var string Atomic section is cancelable */
56 const ATOMIC_CANCELABLE
= 'cancelable';
58 /** @var string Commit/rollback is from outside the IDatabase handle and connection manager */
59 const FLUSHING_ONE
= '';
60 /** @var string Commit/rollback is from the connection manager for the IDatabase handle */
61 const FLUSHING_ALL_PEERS
= 'flush';
62 /** @var string Commit/rollback is from the IDatabase handle internally */
63 const FLUSHING_INTERNAL
= 'flush-internal';
65 /** @var string Do not remember the prior flags */
66 const REMEMBER_NOTHING
= '';
67 /** @var string Remember the prior flags */
68 const REMEMBER_PRIOR
= 'remember';
69 /** @var string Restore to the prior flag state */
70 const RESTORE_PRIOR
= 'prior';
71 /** @var string Restore to the initial flag state */
72 const RESTORE_INITIAL
= 'initial';
74 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
75 const ESTIMATE_TOTAL
= 'total';
76 /** @var string Estimate time to apply (scanning, applying) */
77 const ESTIMATE_DB_APPLY
= 'apply';
79 /** @var int Combine list with comma delimeters */
81 /** @var int Combine list with AND clauses */
83 /** @var int Convert map into a SET clause */
85 /** @var int Treat as field name and do not apply value escaping */
87 /** @var int Combine list with OR clauses */
90 /** @var int Enable debug logging */
92 /** @var int Disable query buffering (only one result set can be iterated at a time) */
93 const DBO_NOBUFFER
= 2;
94 /** @var int Ignore query errors (internal use only!) */
96 /** @var int Automatically start a transaction before running a query if none is active */
98 /** @var int Use DBO_TRX in non-CLI mode */
99 const DBO_DEFAULT
= 16;
100 /** @var int Use DB persistent connections if possible */
101 const DBO_PERSISTENT
= 32;
102 /** @var int DBA session mode; mostly for Oracle */
103 const DBO_SYSDBA
= 64;
104 /** @var int Schema file mode; mostly for Oracle */
105 const DBO_DDLMODE
= 128;
106 /** @var int Enable SSL/TLS in connection protocol */
108 /** @var int Enable compression in connection protocol */
109 const DBO_COMPRESS
= 512;
111 /** @var int Idiom for "no special flags" */
112 const QUERY_NORMAL
= 0;
113 /** @var int Ignore query errors and return false when they happen */
114 const QUERY_SILENCE_ERRORS
= 1; // b/c for 1.32 query() argument; note that (int)true = 1
116 * @var int Treat the TEMPORARY table from the given CREATE query as if it is
117 * permanent as far as write tracking is concerned. This is useful for testing.
119 const QUERY_PSEUDO_PERMANENT
= 2;
120 /** @var int Enforce that a query does not make effective writes */
121 const QUERY_REPLICA_ROLE
= 4;
122 /** @var int Ignore the current presence of any DBO_TRX flag */
123 const QUERY_IGNORE_DBO_TRX
= 8;
124 /** @var int Do not try to retry the query if the connection was lost */
125 const QUERY_NO_RETRY
= 16;
127 /** @var bool Parameter to unionQueries() for UNION ALL */
128 const UNION_ALL
= true;
129 /** @var bool Parameter to unionQueries() for UNION DISTINCT */
130 const UNION_DISTINCT
= false;
133 * A string describing the current software version, and possibly
134 * other details in a user-friendly way. Will be listed on Special:Version, etc.
135 * Use getServerVersion() to get machine-friendly information.
137 * @return string Version information from the database server
139 public function getServerInfo();
142 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
144 * Unbuffered queries are very troublesome in MySQL:
146 * - If another query is executed while the first query is being read
147 * out, the first query is killed. This means you can't call normal
148 * Database functions while you are reading an unbuffered query result
149 * from a normal Database connection.
151 * - Unbuffered queries cause the MySQL server to use large amounts of
152 * memory and to hold broad locks which block other queries.
154 * If you want to limit client-side memory, it's almost always better to
155 * split up queries into batches using a LIMIT clause than to switch off
158 * @param null|bool $buffer
159 * @return null|bool The previous value of the flag
161 public function bufferResults( $buffer = null );
164 * Gets the current transaction level.
166 * Historically, transactions were allowed to be "nested". This is no
167 * longer supported, so this function really only returns a boolean.
169 * @return int The previous value
171 public function trxLevel();
174 * Get the UNIX timestamp of the time that the transaction was established
176 * This can be used to reason about the staleness of SELECT data in REPEATABLE-READ
177 * transaction isolation level. Callers can assume that if a view-snapshot isolation
178 * is used, then the data read by SQL queries is *at least* up to date to that point
179 * (possibly more up-to-date since the first SELECT defines the snapshot).
181 * @return float|null Returns null if there is not active transaction
184 public function trxTimestamp();
187 * @return bool Whether an explicit transaction or atomic sections are still open
190 public function explicitTrxActive();
193 * Assert that all explicit transactions or atomic sections have been closed.
194 * @throws DBTransactionError
197 public function assertNoOpenTransactions();
200 * Get/set the table prefix.
201 * @param string|null $prefix The table prefix to set, or omitted to leave it unchanged.
202 * @return string The previous table prefix
203 * @throws DBUnexpectedError
205 public function tablePrefix( $prefix = null );
208 * Get/set the db schema.
209 * @param string|null $schema The database schema to set, or omitted to leave it unchanged.
210 * @return string The previous db schema
212 public function dbSchema( $schema = null );
215 * Get properties passed down from the server info array of the load
218 * @param string|null $name The entry of the info array to get, or null to get the
221 * @return array|mixed|null
223 public function getLBInfo( $name = null );
226 * Set the LB info array, or a member of it. If called with one parameter,
227 * the LB info array is set to that parameter. If it is called with two
228 * parameters, the member with the given name is set to the given value.
230 * @param array|string $name
231 * @param array|null $value
233 public function setLBInfo( $name, $value = null );
236 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
238 * @param IDatabase $conn
241 public function setLazyMasterHandle( IDatabase
$conn );
244 * Returns true if this database does an implicit sort when doing GROUP BY
247 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
249 public function implicitGroupby();
252 * Returns true if this database does an implicit order by when the column has an index
253 * For example: SELECT page_title FROM page LIMIT 1
257 public function implicitOrderby();
260 * Return the last query that sent on account of IDatabase::query()
261 * @return string SQL text or empty string if there was no such query
263 public function lastQuery();
266 * Returns true if the connection may have been used for write queries.
267 * Should return true if unsure.
270 * @deprecated Since 1.31; use lastDoneWrites()
272 public function doneWrites();
275 * Returns the last time the connection may have been used for write queries.
276 * Should return a timestamp if unsure.
278 * @return int|float UNIX timestamp or false
281 public function lastDoneWrites();
284 * @return bool Whether there is a transaction open with possible write queries
287 public function writesPending();
290 * @return bool Whether there is a transaction open with pre-commit callbacks pending
293 public function preCommitCallbacksPending();
296 * Whether there is a transaction open with either possible write queries
297 * or unresolved pre-commit/commit/resolution callbacks pending
299 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
303 public function writesOrCallbacksPending();
306 * Get the time spend running write queries for this transaction
308 * High times could be due to scanning, updates, locking, and such
310 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
311 * @return float|bool Returns false if not transaction is active
314 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
317 * Get the list of method names that did write queries for this transaction
322 public function pendingWriteCallers();
325 * Get the number of affected rows from pending write queries
330 public function pendingWriteRowsAffected();
333 * Is a connection to the database open?
336 public function isOpen();
339 * Set a flag for this connection
341 * @param int $flag DBO_* constants from Defines.php:
342 * - DBO_DEBUG: output some debug info (same as debug())
343 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
344 * - DBO_TRX: automatically start transactions
345 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
346 * and removes it in command line mode
347 * - DBO_PERSISTENT: use persistant database connection
348 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
350 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
353 * Clear a flag for this connection
355 * @param int $flag DBO_* constants from Defines.php:
356 * - DBO_DEBUG: output some debug info (same as debug())
357 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
358 * - DBO_TRX: automatically start transactions
359 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
360 * and removes it in command line mode
361 * - DBO_PERSISTENT: use persistant database connection
362 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
364 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
367 * Restore the flags to their prior state before the last setFlag/clearFlag call
369 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
372 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
375 * Returns a boolean whether the flag $flag is set for this connection
377 * @param int $flag DBO_* constants from Defines.php:
378 * - DBO_DEBUG: output some debug info (same as debug())
379 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
380 * - DBO_TRX: automatically start transactions
381 * - DBO_PERSISTENT: use persistant database connection
384 public function getFlag( $flag );
387 * Return the currently selected domain ID
389 * Null components (database/schema) might change once a connection is established
393 public function getDomainID();
396 * Alias for getDomainID()
401 public function getWikiID();
404 * Get the type of the DBMS, as it appears in $wgDBtype.
408 public function getType();
411 * Fetch the next row from the given result object, in object form.
412 * Fields can be retrieved with $row->fieldname, with fields acting like
414 * If no more rows are available, false is returned.
416 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
417 * @return stdClass|bool
418 * @throws DBUnexpectedError Thrown if the database returns an error
420 public function fetchObject( $res );
423 * Fetch the next row from the given result object, in associative array
424 * form. Fields are retrieved with $row['fieldname'].
425 * If no more rows are available, false is returned.
427 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
429 * @throws DBUnexpectedError Thrown if the database returns an error
431 public function fetchRow( $res );
434 * Get the number of rows in a query result. If the query did not return
435 * any rows (for example, if it was a write query), this returns zero.
437 * @param mixed $res A SQL result
440 public function numRows( $res );
443 * Get the number of fields in a result object
444 * @see https://www.php.net/mysql_num_fields
446 * @param mixed $res A SQL result
449 public function numFields( $res );
452 * Get a field name in a result object
453 * @see https://www.php.net/mysql_field_name
455 * @param mixed $res A SQL result
459 public function fieldName( $res, $n );
462 * Get the inserted value of an auto-increment row
464 * This should only be called after an insert that used an auto-incremented
465 * value. If no such insert was previously done in the current database
466 * session, the return value is undefined.
470 public function insertId();
473 * Change the position of the cursor in a result object
474 * @see https://www.php.net/mysql_data_seek
476 * @param mixed $res A SQL result
479 public function dataSeek( $res, $row );
482 * Get the last error number
483 * @see https://www.php.net/mysql_errno
487 public function lastErrno();
490 * Get a description of the last error
491 * @see https://www.php.net/mysql_error
495 public function lastError();
498 * Get the number of rows affected by the last write query
499 * @see https://www.php.net/mysql_affected_rows
503 public function affectedRows();
506 * Returns a wikitext link to the DB's website, e.g.,
507 * return "[https://www.mysql.com/ MySQL]";
508 * Should at least contain plain text, if for some reason
509 * your database has no website.
511 * @return string Wikitext of a link to the server software's web site
513 public function getSoftwareLink();
516 * A string describing the current software version, like from
517 * mysql_get_server_info().
519 * @return string Version information from the database server.
521 public function getServerVersion();
524 * Close the database connection
526 * This should only be called after any transactions have been resolved,
527 * aside from read-only automatic transactions (assuming no callbacks are registered).
528 * If a transaction is still open anyway, it will be rolled back.
531 * @return bool Operation success. true if already closed.
533 public function close();
536 * Run an SQL query and return the result. Normally throws a DBQueryError
537 * on failure. If errors are ignored, returns false instead.
539 * If a connection loss is detected, then an attempt to reconnect will be made.
540 * For queries that involve no larger transactions or locks, they will be re-issued
541 * for convenience, provided the connection was re-established.
543 * In new code, the query wrappers select(), insert(), update(), delete(),
544 * etc. should be used where possible, since they give much better DBMS
545 * independence and automatically quote or validate user input in a variety
546 * of contexts. This function is generally only useful for queries which are
547 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
550 * However, the query wrappers themselves should call this function.
552 * @param string $sql SQL query
553 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
554 * comment (you can use __METHOD__ or add some extra info)
555 * @param int $flags Bitfield of IDatabase::QUERY_* constants. Note that suppression
556 * of errors is best handled by try/catch rather than using one of these flags.
557 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
558 * for a successful read query, or false on failure if QUERY_SILENCE_ERRORS is set.
561 public function query( $sql, $fname = __METHOD__
, $flags = 0 );
564 * Free a result object returned by query() or select(). It's usually not
565 * necessary to call this, just use unset() or let the variable holding
566 * the result object go out of scope.
568 * @param mixed $res A SQL result
570 public function freeResult( $res );
573 * A SELECT wrapper which returns a single field from a single result row.
575 * Usually throws a DBQueryError on failure. If errors are explicitly
576 * ignored, returns false on failure.
578 * If no result rows are returned from the query, false is returned.
580 * @param string|array $table Table name. See IDatabase::select() for details.
581 * @param string $var The field name to select. This must be a valid SQL
582 * fragment: do not use unvalidated user input.
583 * @param string|array $cond The condition array. See IDatabase::select() for details.
584 * @param string $fname The function name of the caller.
585 * @param string|array $options The query options. See IDatabase::select() for details.
586 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
588 * @return mixed The value from the field
591 public function selectField(
592 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
596 * A SELECT wrapper which returns a list of single field values from result rows.
598 * Usually throws a DBQueryError on failure. If errors are explicitly
599 * ignored, returns false on failure.
601 * If no result rows are returned from the query, false is returned.
603 * @param string|array $table Table name. See IDatabase::select() for details.
604 * @param string $var The field name to select. This must be a valid SQL
605 * fragment: do not use unvalidated user input.
606 * @param string|array $cond The condition array. See IDatabase::select() for details.
607 * @param string $fname The function name of the caller.
608 * @param string|array $options The query options. See IDatabase::select() for details.
609 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
611 * @return array The values from the field in the order they were returned from the DB
615 public function selectFieldValues(
616 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
620 * Execute a SELECT query constructed using the various parameters provided.
621 * See below for full details of the parameters.
623 * @param string|array $table Table name(s)
625 * May be either an array of table names, or a single string holding a table
626 * name. If an array is given, table aliases can be specified, for example:
630 * This includes the user table in the query, with the alias "a" available
631 * for use in field names (e.g. a.user_name).
633 * A derived table, defined by the result of selectSQLText(), requires an alias
634 * key and a Subquery instance value which wraps the SQL query, for example:
636 * [ 'c' => new Subquery( 'SELECT ...' ) ]
638 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
639 * constructed using nested arrays. For example,
641 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
643 * along with `$join_conds` like
645 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
647 * will produce SQL something like
649 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
651 * All of the table names given here are automatically run through
652 * Database::tableName(), which causes the table prefix (if any) to be
653 * added, and various other table name mappings to be performed.
655 * Do not use untrusted user input as a table name. Alias names should
656 * not have characters outside of the Basic multilingual plane.
658 * @param string|array $vars Field name(s)
660 * May be either a field name or an array of field names. The field names
661 * can be complete fragments of SQL, for direct inclusion into the SELECT
662 * query. If an array is given, field aliases can be specified, for example:
664 * [ 'maxrev' => 'MAX(rev_id)' ]
666 * This includes an expression with the alias "maxrev" in the query.
668 * If an expression is given, care must be taken to ensure that it is
671 * Untrusted user input must not be passed to this parameter.
673 * @param string|array $conds
675 * May be either a string containing a single condition, or an array of
676 * conditions. If an array is given, the conditions constructed from each
677 * element are combined with AND.
679 * Array elements may take one of two forms:
681 * - Elements with a numeric key are interpreted as raw SQL fragments.
682 * - Elements with a string key are interpreted as equality conditions,
683 * where the key is the field name.
684 * - If the value of such an array element is a scalar (such as a
685 * string), it will be treated as data and thus quoted appropriately.
686 * If it is null, an IS NULL clause will be added.
687 * - If the value is an array, an IN (...) clause will be constructed
688 * from its non-null elements, and an IS NULL clause will be added
689 * if null is present, such that the field may match any of the
690 * elements in the array. The non-null elements will be quoted.
692 * Note that expressions are often DBMS-dependent in their syntax.
693 * DBMS-independent wrappers are provided for constructing several types of
694 * expression commonly used in condition queries. See:
695 * - IDatabase::buildLike()
696 * - IDatabase::conditional()
698 * Untrusted user input is safe in the values of string keys, however untrusted
699 * input must not be used in the array key names or in the values of numeric keys.
700 * Escaping of untrusted input used in values of numeric keys should be done via
701 * IDatabase::addQuotes()
703 * Use an empty array, string, or '*' to update all rows.
705 * @param string $fname Caller function name
707 * @param string|array $options Query options
709 * Optional: Array of query options. Boolean options are specified by
710 * including them in the array as a string value with a numeric key, for
715 * The supported options are:
717 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
718 * with LIMIT can theoretically be used for paging through a result set,
719 * but this is discouraged for performance reasons.
721 * - LIMIT: Integer: return at most this many rows. The rows are sorted
722 * and then the first rows are taken until the limit is reached. LIMIT
723 * is applied to a result set after OFFSET.
725 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
726 * changed until the next COMMIT. Cannot be used with aggregate functions
727 * (COUNT, MAX, etc., but also DISTINCT).
729 * - DISTINCT: Boolean: return only unique result rows.
731 * - GROUP BY: May be either an SQL fragment string naming a field or
732 * expression to group by, or an array of such SQL fragments.
734 * - HAVING: May be either an string containing a HAVING clause or an array of
735 * conditions building the HAVING clause. If an array is given, the conditions
736 * constructed from each element are combined with AND.
738 * - ORDER BY: May be either an SQL fragment giving a field name or
739 * expression to order by, or an array of such SQL fragments.
741 * - USE INDEX: This may be either a string giving the index name to use
742 * for the query, or an array. If it is an associative array, each key
743 * gives the table name (or alias), each value gives the index name to
744 * use for that table. All strings are SQL fragments and so should be
745 * validated by the caller.
747 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
750 * And also the following boolean MySQL extensions, see the MySQL manual
753 * - LOCK IN SHARE MODE
757 * - SQL_BUFFER_RESULT
759 * - SQL_CALC_FOUND_ROWS
764 * @param string|array $join_conds Join conditions
766 * Optional associative array of table-specific join conditions. In the
767 * most common case, this is unnecessary, since the join condition can be
768 * in $conds. However, it is useful for doing a LEFT JOIN.
770 * The key of the array contains the table name or alias. The value is an
771 * array with two elements, numbered 0 and 1. The first gives the type of
772 * join, the second is the same as the $conds parameter. Thus it can be
773 * an SQL fragment, or an array where the string keys are equality and the
774 * numeric keys are SQL fragments all AND'd together. For example:
776 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
778 * @return IResultWrapper Resulting rows
781 public function select(
782 $table, $vars, $conds = '', $fname = __METHOD__
,
783 $options = [], $join_conds = []
787 * The equivalent of IDatabase::select() except that the constructed SQL
788 * is returned, instead of being immediately executed. This can be useful for
789 * doing UNION queries, where the SQL text of each query is needed. In general,
790 * however, callers outside of Database classes should just use select().
792 * @see IDatabase::select()
794 * @param string|array $table Table name
795 * @param string|array $vars Field names
796 * @param string|array $conds Conditions
797 * @param string $fname Caller function name
798 * @param string|array $options Query options
799 * @param string|array $join_conds Join conditions
800 * @return string SQL query string
802 public function selectSQLText(
803 $table, $vars, $conds = '', $fname = __METHOD__
,
804 $options = [], $join_conds = []
808 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
809 * that a single row object is returned. If the query returns no rows,
812 * @param string|array $table Table name
813 * @param string|array $vars Field names
814 * @param string|array $conds Conditions
815 * @param string $fname Caller function name
816 * @param string|array $options Query options
817 * @param array|string $join_conds Join conditions
819 * @return stdClass|bool
822 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
823 $options = [], $join_conds = []
827 * Estimate the number of rows in dataset
829 * MySQL allows you to estimate the number of rows that would be returned
830 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
831 * index cardinality statistics, and is notoriously inaccurate, especially
832 * when large numbers of rows have recently been added or deleted.
834 * For DBMSs that don't support fast result size estimation, this function
835 * will actually perform the SELECT COUNT(*).
837 * Takes the same arguments as IDatabase::select().
839 * @param string $table Table name
840 * @param string $var Column for which NULL values are not counted [default "*"]
841 * @param array|string $conds Filters on the table
842 * @param string $fname Function name for profiling
843 * @param array $options Options for select
844 * @param array|string $join_conds Join conditions
845 * @return int Row count
848 public function estimateRowCount(
849 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
853 * Get the number of rows in dataset
855 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
857 * Takes the same arguments as IDatabase::select().
859 * @since 1.27 Added $join_conds parameter
861 * @param array|string $tables Table names
862 * @param string $var Column for which NULL values are not counted [default "*"]
863 * @param array|string $conds Filters on the table
864 * @param string $fname Function name for profiling
865 * @param array $options Options for select
866 * @param array $join_conds Join conditions (since 1.27)
867 * @return int Row count
870 public function selectRowCount(
871 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
875 * Lock all rows meeting the given conditions/options FOR UPDATE
877 * @param array|string $table Table names
878 * @param array|string $conds Filters on the table
879 * @param string $fname Function name for profiling
880 * @param array $options Options for select ("FOR UPDATE" is added automatically)
881 * @param array $join_conds Join conditions
882 * @return int Number of matching rows found (and locked)
885 public function lockForUpdate(
886 $table, $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
890 * Determines whether a field exists in a table
892 * @param string $table Table name
893 * @param string $field Filed to check on that table
894 * @param string $fname Calling function name (optional)
895 * @return bool Whether $table has filed $field
898 public function fieldExists( $table, $field, $fname = __METHOD__
);
901 * Determines whether an index exists
902 * Usually throws a DBQueryError on failure
903 * If errors are explicitly ignored, returns NULL on failure
905 * @param string $table
906 * @param string $index
907 * @param string $fname
911 public function indexExists( $table, $index, $fname = __METHOD__
);
914 * Query whether a given table exists
916 * @param string $table
917 * @param string $fname
921 public function tableExists( $table, $fname = __METHOD__
);
924 * INSERT wrapper, inserts an array into a table.
928 * - A single associative array. The array keys are the field names, and
929 * the values are the values to insert. The values are treated as data
930 * and will be quoted appropriately. If NULL is inserted, this will be
931 * converted to a database NULL.
932 * - An array with numeric keys, holding a list of associative arrays.
933 * This causes a multi-row INSERT on DBMSs that support it. The keys in
934 * each subarray must be identical to each other, and in the same order.
936 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
939 * $options is an array of options, with boolean options encoded as values
940 * with numeric keys, in the same style as $options in
941 * IDatabase::select(). Supported options are:
943 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
944 * any rows which cause duplicate key errors are not inserted. It's
945 * possible to determine how many rows were successfully inserted using
946 * IDatabase::affectedRows().
948 * @param string $table Table name. This will be passed through
949 * Database::tableName().
950 * @param array $a Array of rows to insert
951 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
952 * @param array $options Array of options
953 * @return bool Return true if no exception was thrown (deprecated since 1.33)
956 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
959 * UPDATE wrapper. Takes a condition array and a SET array.
961 * @param string $table Name of the table to UPDATE. This will be passed through
962 * Database::tableName().
963 * @param array $values An array of values to SET. For each array element,
964 * the key gives the field name, and the value gives the data to set
965 * that field to. The data will be quoted by IDatabase::addQuotes().
966 * Values with integer keys form unquoted SET statements, which can be used for
967 * things like "field = field + 1" or similar computed values.
968 * @param array $conds An array of conditions (WHERE). See
969 * IDatabase::select() for the details of the format of condition
970 * arrays. Use '*' to update all rows.
971 * @param string $fname The function name of the caller (from __METHOD__),
972 * for logging and profiling.
973 * @param array $options An array of UPDATE options, can be:
974 * - IGNORE: Ignore unique key conflicts
975 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
976 * @return bool Return true if no exception was thrown (deprecated since 1.33)
979 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
982 * Makes an encoded list of strings from an array
984 * These can be used to make conjunctions or disjunctions on SQL condition strings
985 * derived from an array (see IDatabase::select() $conds documentation).
989 * $sql = $db->makeList( [
991 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
992 * ], $db::LIST_AND );
994 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
996 * @param array $a Containing the data
997 * @param int $mode IDatabase class constant:
998 * - IDatabase::LIST_COMMA: Comma separated, no field names
999 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
1000 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
1001 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
1002 * - IDatabase::LIST_NAMES: Comma separated field names
1006 public function makeList( $a, $mode = self
::LIST_COMMA
);
1009 * Build a partial where clause from a 2-d array such as used for LinkBatch.
1010 * The keys on each level may be either integers or strings.
1012 * @param array $data Organized as 2-d
1013 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
1014 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
1015 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
1016 * @return string|bool SQL fragment, or false if no items in array
1018 public function makeWhereFrom2d( $data, $baseKey, $subKey );
1021 * Return aggregated value alias
1023 * @param array $valuedata
1024 * @param string $valuename
1027 * @deprecated Since 1.33
1029 public function aggregateValue( $valuedata, $valuename = 'value' );
1032 * @param string $field
1035 public function bitNot( $field );
1038 * @param string $fieldLeft
1039 * @param string $fieldRight
1042 public function bitAnd( $fieldLeft, $fieldRight );
1045 * @param string $fieldLeft
1046 * @param string $fieldRight
1049 public function bitOr( $fieldLeft, $fieldRight );
1052 * Build a concatenation list to feed into a SQL query
1053 * @param array $stringList List of raw SQL expressions; caller is
1054 * responsible for any quoting
1057 public function buildConcat( $stringList );
1060 * Build a GROUP_CONCAT or equivalent statement for a query.
1062 * This is useful for combining a field for several rows into a single string.
1063 * NULL values will not appear in the output, duplicated values will appear,
1064 * and the resulting delimiter-separated values have no defined sort order.
1065 * Code using the results may need to use the PHP unique() or sort() methods.
1067 * @param string $delim Glue to bind the results together
1068 * @param string|array $table Table name
1069 * @param string $field Field name
1070 * @param string|array $conds Conditions
1071 * @param string|array $join_conds Join conditions
1072 * @return string SQL text
1075 public function buildGroupConcatField(
1076 $delim, $table, $field, $conds = '', $join_conds = []
1080 * Build a SUBSTRING function.
1082 * Behavior for non-ASCII values is undefined.
1084 * @param string $input Field name
1085 * @param int $startPosition Positive integer
1086 * @param int|null $length Non-negative integer length or null for no limit
1087 * @throws InvalidArgumentException
1088 * @return string SQL text
1091 public function buildSubString( $input, $startPosition, $length = null );
1094 * @param string $field Field or column to cast
1098 public function buildStringCast( $field );
1101 * @param string $field Field or column to cast
1105 public function buildIntegerCast( $field );
1108 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1110 * @see IDatabase::selectSQLText()
1112 * @param string|array $table Table name
1113 * @param string|array $vars Field names
1114 * @param string|array $conds Conditions
1115 * @param string $fname Caller function name
1116 * @param string|array $options Query options
1117 * @param string|array $join_conds Join conditions
1121 public function buildSelectSubquery(
1122 $table, $vars, $conds = '', $fname = __METHOD__
,
1123 $options = [], $join_conds = []
1127 * Construct a LIMIT query with optional offset. This is used for query
1128 * pages. The SQL should be adjusted so that only the first $limit rows
1129 * are returned. If $offset is provided as well, then the first $offset
1130 * rows should be discarded, and the next $limit rows should be returned.
1131 * If the result of the query is not ordered, then the rows to be returned
1132 * are theoretically arbitrary.
1134 * $sql is expected to be a SELECT, if that makes a difference.
1136 * @param string $sql SQL query we will append the limit too
1137 * @param int $limit The SQL limit
1138 * @param int|bool $offset The SQL offset (default false)
1139 * @throws DBUnexpectedError
1143 public function limitResult( $sql, $limit, $offset = false );
1146 * Returns true if DBs are assumed to be on potentially different servers
1148 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1149 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1150 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1151 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1156 public function databasesAreIndependent();
1159 * Change the current database
1161 * This should not be called outside LoadBalancer for connections managed by a LoadBalancer
1164 * @return bool True unless an exception was thrown
1165 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1167 * @deprecated Since 1.32 Use selectDomain() instead
1169 public function selectDB( $db );
1172 * Set the current domain (database, schema, and table prefix)
1174 * This will throw an error for some database types if the database unspecified
1176 * This should not be called outside LoadBalancer for connections managed by a LoadBalancer
1178 * @param string|DatabaseDomain $domain
1180 * @throws DBConnectionError
1182 public function selectDomain( $domain );
1185 * Get the current DB name
1186 * @return string|null
1188 public function getDBname();
1191 * Get the server hostname or IP address
1194 public function getServer();
1197 * Adds quotes and backslashes.
1199 * @param string|int|null|bool|Blob $s
1200 * @return string|int
1202 public function addQuotes( $s );
1205 * Quotes an identifier, in order to make user controlled input safe
1207 * Depending on the database this will either be `backticks` or "double quotes"
1213 public function addIdentifierQuotes( $s );
1216 * LIKE statement wrapper, receives a variable-length argument list with
1217 * parts of pattern to match containing either string literals that will be
1218 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1219 * the function could be provided with an array of aforementioned
1222 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1223 * a LIKE clause that searches for subpages of 'My page title'.
1225 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1226 * $query .= $dbr->buildLike( $pattern );
1229 * @param array[]|string|LikeMatch $param
1230 * @return string Fully built LIKE statement
1231 * @phan-suppress-next-line PhanMismatchVariadicComment
1232 * @phan-param array|string|LikeMatch ...$param T226223
1234 public function buildLike( $param );
1237 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1241 public function anyChar();
1244 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1248 public function anyString();
1251 * Deprecated method, calls should be removed.
1253 * This was formerly used for PostgreSQL and Oracle to handle
1254 * self::insertId() auto-incrementing fields. It is no longer necessary
1255 * since DatabasePostgres::insertId() has been reimplemented using
1256 * `lastval()` and Oracle has been reimplemented using triggers.
1258 * Implementations should return null if inserting `NULL` into an
1259 * auto-incrementing field works, otherwise it should return an instance of
1260 * NextSequenceValue and filter it on calls to relevant methods.
1262 * @deprecated since 1.30, no longer needed
1263 * @param string $seqName
1264 * @return null|NextSequenceValue
1266 public function nextSequenceValue( $seqName );
1269 * REPLACE query wrapper.
1271 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1272 * except that when there is a duplicate key error, the old row is deleted
1273 * and the new row is inserted in its place.
1275 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1276 * perform the delete, we need to know what the unique indexes are so that
1277 * we know how to find the conflicting rows.
1279 * It may be more efficient to leave off unique indexes which are unlikely
1280 * to collide. However if you do this, you run the risk of encountering
1281 * errors which wouldn't have occurred in MySQL.
1283 * @param string $table The table to replace the row(s) in.
1284 * @param array[]|string[]|string $uniqueIndexes All unique indexes. One of the following:
1285 * a) the one unique field in the table (when no composite unique key exist)
1286 * b) a list of all unique fields in the table (when no composite unique key exist)
1287 * c) a list of all unique indexes in the table (each as a list of the indexed fields)
1288 * @param array $rows Can be either a single row to insert, or multiple rows,
1289 * in the same format as for IDatabase::insert()
1290 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1293 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1296 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1298 * This updates any conflicting rows (according to the unique indexes) using
1299 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1301 * $rows may be either:
1302 * - A single associative array. The array keys are the field names, and
1303 * the values are the values to insert. The values are treated as data
1304 * and will be quoted appropriately. If NULL is inserted, this will be
1305 * converted to a database NULL.
1306 * - An array with numeric keys, holding a list of associative arrays.
1307 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1308 * each subarray must be identical to each other, and in the same order.
1310 * It may be more efficient to leave off unique indexes which are unlikely
1311 * to collide. However if you do this, you run the risk of encountering
1312 * errors which wouldn't have occurred in MySQL.
1314 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1319 * @param string $table Table name. This will be passed through Database::tableName().
1320 * @param array $rows A single row or list of rows to insert
1321 * @param array[]|string[]|string $uniqueIndexes All unique indexes. One of the following:
1322 * a) the one unique field in the table (when no composite unique key exist)
1323 * b) a list of all unique fields in the table (when no composite unique key exist)
1324 * c) a list of all unique indexes in the table (each as a list of the indexed fields)
1325 * @param array $set An array of values to SET. For each array element, the
1326 * key gives the field name, and the value gives the data to set that
1327 * field to. The data will be quoted by IDatabase::addQuotes().
1328 * Values with integer keys form unquoted SET statements, which can be used for
1329 * things like "field = field + 1" or similar computed values.
1330 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1332 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1334 public function upsert(
1335 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1339 * DELETE where the condition is a join.
1341 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1342 * we use sub-selects
1344 * For safety, an empty $conds will not delete everything. If you want to
1345 * delete all rows where the join condition matches, set $conds='*'.
1347 * DO NOT put the join condition in $conds.
1349 * @param string $delTable The table to delete from.
1350 * @param string $joinTable The other table.
1351 * @param string $delVar The variable to join on, in the first table.
1352 * @param string $joinVar The variable to join on, in the second table.
1353 * @param array $conds Condition array of field names mapped to variables,
1354 * ANDed together in the WHERE clause
1355 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1358 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1363 * DELETE query wrapper.
1365 * @param string $table Table name
1366 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1367 * for the format. Use $conds == "*" to delete all rows
1368 * @param string $fname Name of the calling function
1369 * @throws DBUnexpectedError
1370 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1373 public function delete( $table, $conds, $fname = __METHOD__
);
1376 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1377 * into another table.
1379 * @warning If the insert will use an auto-increment or sequence to
1380 * determine the value of a column, this may break replication on
1381 * databases using statement-based replication if the SELECT is not
1382 * deterministically ordered.
1384 * @param string $destTable The table name to insert into
1385 * @param string|array $srcTable May be either a table name, or an array of table names
1386 * to include in a join.
1388 * @param array $varMap Must be an associative array of the form
1389 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1390 * rather than field names, but strings should be quoted with
1391 * IDatabase::addQuotes()
1393 * @param array $conds Condition array. See $conds in IDatabase::select() for
1394 * the details of the format of condition arrays. May be "*" to copy the
1397 * @param string $fname The function name of the caller, from __METHOD__
1399 * @param array $insertOptions Options for the INSERT part of the query, see
1400 * IDatabase::insert() for details. Also, one additional option is
1401 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1402 * an auto-increment or sequence to determine any column values.
1403 * @param array $selectOptions Options for the SELECT part of the query, see
1404 * IDatabase::select() for details.
1405 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1406 * IDatabase::select() for details.
1408 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1411 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1412 $fname = __METHOD__
,
1413 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1417 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1418 * within the UNION construct.
1421 public function unionSupportsOrderAndLimit();
1424 * Construct a UNION query
1425 * This is used for providing overload point for other DB abstractions
1426 * not compatible with the MySQL syntax.
1427 * @param array $sqls SQL statements to combine
1428 * @param bool $all Either IDatabase::UNION_ALL or IDatabase::UNION_DISTINCT
1429 * @return string SQL fragment
1431 public function unionQueries( $sqls, $all );
1434 * Construct a UNION query for permutations of conditions
1436 * Databases sometimes have trouble with queries that have multiple values
1437 * for multiple condition parameters combined with limits and ordering.
1438 * This method constructs queries for the Cartesian product of the
1439 * conditions and unions them all together.
1441 * @see IDatabase::select()
1443 * @param string|array $table Table name
1444 * @param string|array $vars Field names
1445 * @param array $permute_conds Conditions for the Cartesian product. Keys
1446 * are field names, values are arrays of the possible values for that
1448 * @param string|array $extra_conds Additional conditions to include in the
1450 * @param string $fname Caller function name
1451 * @param string|array $options Query options. In addition to the options
1452 * recognized by IDatabase::select(), the following may be used:
1453 * - NOTALL: Set to use UNION instead of UNION ALL.
1454 * - INNER ORDER BY: If specified and supported, subqueries will use this
1455 * instead of ORDER BY.
1456 * @param string|array $join_conds Join conditions
1457 * @return string SQL query string.
1459 public function unionConditionPermutations(
1460 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1461 $options = [], $join_conds = []
1465 * Returns an SQL expression for a simple conditional. This doesn't need
1466 * to be overridden unless CASE isn't supported in your DBMS.
1468 * @param string|array $cond SQL expression which will result in a boolean value
1469 * @param string $trueVal SQL expression to return if true
1470 * @param string $falseVal SQL expression to return if false
1471 * @return string SQL fragment
1473 public function conditional( $cond, $trueVal, $falseVal );
1476 * Returns a command for str_replace function in SQL query.
1477 * Uses REPLACE() in MySQL
1479 * @param string $orig Column to modify
1480 * @param string $old Column to seek
1481 * @param string $new Column to replace with
1485 public function strreplace( $orig, $old, $new );
1488 * Determines how long the server has been up
1493 public function getServerUptime();
1496 * Determines if the last failure was due to a deadlock
1498 * Note that during a deadlock, the prior transaction will have been lost
1502 public function wasDeadlock();
1505 * Determines if the last failure was due to a lock timeout
1507 * Note that during a lock wait timeout, the prior transaction will have been lost
1511 public function wasLockTimeout();
1514 * Determines if the last query error was due to a dropped connection
1516 * Note that during a connection loss, the prior transaction will have been lost
1521 public function wasConnectionLoss();
1524 * Determines if the last failure was due to the database being read-only.
1528 public function wasReadOnlyError();
1531 * Determines if the last query error was due to something outside of the query itself
1533 * Note that the transaction may have been lost, discarding prior writes and results
1537 public function wasErrorReissuable();
1540 * Wait for the replica DB to catch up to a given master position
1542 * Note that this does not start any new transactions. If any existing transaction
1543 * is flushed, and this is called, then queries will reflect the point the DB was synced
1544 * up to (on success) without interference from REPEATABLE-READ snapshots.
1546 * @param DBMasterPos $pos
1547 * @param int $timeout The maximum number of seconds to wait for synchronisation
1548 * @return int|null Zero if the replica DB was past that position already,
1549 * greater than zero if we waited for some period of time, less than
1550 * zero if it timed out, and null on error
1553 public function masterPosWait( DBMasterPos
$pos, $timeout );
1556 * Get the replication position of this replica DB
1558 * @return DBMasterPos|bool False if this is not a replica DB
1561 public function getReplicaPos();
1564 * Get the position of this master
1566 * @return DBMasterPos|bool False if this is not a master
1569 public function getMasterPos();
1572 * @return bool Whether the DB is marked as read-only server-side
1575 public function serverIsReadOnly();
1578 * Run a callback as soon as the current transaction commits or rolls back.
1579 * An error is thrown if no transaction is pending. Queries in the function will run in
1580 * AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1583 * This is useful for combining cooperative locks and DB transactions.
1585 * Note this is called when the whole transaction is resolved. To take action immediately
1586 * when an atomic section is cancelled, use onAtomicSectionCancel().
1588 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1590 * The callback takes the following arguments:
1591 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1592 * - This IDatabase instance (since 1.32)
1594 * @param callable $callback
1595 * @param string $fname Caller name
1598 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1601 * Run a callback as soon as there is no transaction pending.
1602 * If there is a transaction and it is rolled back, then the callback is cancelled.
1604 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1605 * of the round, just after all peer transactions COMMIT. If the transaction round
1606 * is rolled back, then the callback is cancelled.
1608 * Queries in the function will run in AUTOCOMMIT mode unless there are begin() calls.
1609 * Callbacks must commit any transactions that they begin.
1611 * This is useful for updates to different systems or when separate transactions are needed.
1612 * For example, one might want to enqueue jobs into a system outside the database, but only
1613 * after the database is updated so that the jobs will see the data when they actually run.
1614 * It can also be used for updates that easily suffer from lock timeouts and deadlocks,
1615 * but where atomicity is not essential.
1617 * Avoid using IDatabase instances aside from this one in the callback, unless such instances
1618 * never have IDatabase::DBO_TRX set. This keeps callbacks from interfering with one another.
1620 * Updates will execute in the order they were enqueued.
1622 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1624 * The callback takes the following arguments:
1625 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1626 * - This IDatabase instance (since 1.32)
1628 * @param callable $callback
1629 * @param string $fname Caller name
1632 public function onTransactionCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1635 * Alias for onTransactionCommitOrIdle() for backwards-compatibility
1637 * @param callable $callback
1638 * @param string $fname
1640 * @deprecated Since 1.32
1642 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1645 * Run a callback before the current transaction commits or now if there is none.
1646 * If there is a transaction and it is rolled back, then the callback is cancelled.
1648 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1649 * of the round, just before all peer transactions COMMIT. If the transaction round
1650 * is rolled back, then the callback is cancelled.
1652 * Callbacks must not start nor commit any transactions. If no transaction is active,
1653 * then a transaction will wrap the callback.
1655 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1656 * but where atomicity is strongly desired for these updates and some related updates.
1658 * Updates will execute in the order they were enqueued.
1660 * The callback takes the one argument:
1661 * - This IDatabase instance (since 1.32)
1663 * @param callable $callback
1664 * @param string $fname Caller name
1667 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1670 * Run a callback when the atomic section is cancelled.
1672 * The callback is run just after the current atomic section, any outer
1673 * atomic section, or the whole transaction is rolled back.
1675 * An error is thrown if no atomic section is pending. The atomic section
1676 * need not have been created with the ATOMIC_CANCELABLE flag.
1678 * Queries in the function may be running in the context of an outer
1679 * transaction or may be running in AUTOCOMMIT mode. The callback should
1680 * use atomic sections if necessary.
1682 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1684 * The callback takes the following arguments:
1685 * - IDatabase::TRIGGER_CANCEL or IDatabase::TRIGGER_ROLLBACK
1686 * - This IDatabase instance
1688 * @param callable $callback
1689 * @param string $fname Caller name
1692 public function onAtomicSectionCancel( callable
$callback, $fname = __METHOD__
);
1695 * Run a callback after each time any transaction commits or rolls back
1697 * The callback takes two arguments:
1698 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1699 * - This IDatabase object
1700 * Callbacks must commit any transactions that they begin.
1702 * Registering a callback here will not affect writesOrCallbacks() pending.
1704 * Since callbacks from this or onTransactionCommitOrIdle() can start and end transactions,
1705 * a single call to IDatabase::commit might trigger multiple runs of the listener callbacks.
1707 * @param string $name Callback name
1708 * @param callable|null $callback Use null to unset a listener
1711 public function setTransactionListener( $name, callable
$callback = null );
1714 * Begin an atomic section of SQL statements
1716 * Start an implicit transaction if no transaction is already active, set a savepoint
1717 * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
1718 * that the transaction is not committed prematurely. The end of the section must be
1719 * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
1720 * have layers of inner sections (sub-sections), but all sections must be ended in order
1721 * of innermost to outermost. Transactions cannot be started or committed until all
1722 * atomic sections are closed.
1724 * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
1725 * by discarding the section's writes. This should not be used for failures when:
1726 * - upsert() could easily be used instead
1727 * - insert() with IGNORE could easily be used instead
1728 * - select() with FOR UPDATE could be checked before issuing writes instead
1729 * - The failure is from code that runs after the first write but doesn't need to
1730 * - The failures are from contention solvable via onTransactionPreCommitOrIdle()
1731 * - The failures are deadlocks; the RDBMs usually discard the whole transaction
1733 * @note callers must use additional measures for situations involving two or more
1734 * (peer) transactions (e.g. updating two database servers at once). The transaction
1735 * and savepoint logic of this method only applies to this specific IDatabase instance.
1739 * // Start a transaction if there isn't one already
1740 * $dbw->startAtomic( __METHOD__ );
1741 * // Serialize these thread table updates
1742 * $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
1743 * // Add a new comment for the thread
1744 * $dbw->insert( 'comment', $row, __METHOD__ );
1745 * $cid = $db->insertId();
1746 * // Update thread reference to last comment
1747 * $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
1748 * // Demark the end of this conceptual unit of updates
1749 * $dbw->endAtomic( __METHOD__ );
1752 * Example usage (atomic changes that might have to be discarded):
1754 * // Start a transaction if there isn't one already
1755 * $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
1756 * // Create new record metadata row
1757 * $dbw->insert( 'records', $row, __METHOD__ );
1758 * // Figure out where to store the data based on the new row's ID
1759 * $path = $recordDirectory . '/' . $dbw->insertId();
1760 * // Write the record data to the storage system
1761 * $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
1762 * if ( $status->isOK() ) {
1763 * // Try to cleanup files orphaned by transaction rollback
1764 * $dbw->onTransactionResolution(
1765 * function ( $type ) use ( $fileBackend, $path ) {
1766 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1767 * $fileBackend->delete( [ 'src' => $path ] );
1772 * // Demark the end of this conceptual unit of updates
1773 * $dbw->endAtomic( __METHOD__ );
1775 * // Discard these writes from the transaction (preserving prior writes)
1776 * $dbw->cancelAtomic( __METHOD__, $sectionId );
1781 * @param string $fname
1782 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1783 * savepoint and enable self::cancelAtomic() for this section.
1784 * @return AtomicSectionIdentifier section ID token
1787 public function startAtomic( $fname = __METHOD__
, $cancelable = self
::ATOMIC_NOT_CANCELABLE
);
1790 * Ends an atomic section of SQL statements
1792 * Ends the next section of atomic SQL statements and commits the transaction
1796 * @see IDatabase::startAtomic
1797 * @param string $fname
1800 public function endAtomic( $fname = __METHOD__
);
1803 * Cancel an atomic section of SQL statements
1805 * This will roll back only the statements executed since the start of the
1806 * most recent atomic section, and close that section. If a transaction was
1807 * open before the corresponding startAtomic() call, any statements before
1808 * that call are *not* rolled back and the transaction remains open. If the
1809 * corresponding startAtomic() implicitly started a transaction, that
1810 * transaction is rolled back.
1812 * @note callers must use additional measures for situations involving two or more
1813 * (peer) transactions (e.g. updating two database servers at once). The transaction
1814 * and savepoint logic of startAtomic() are bound to specific IDatabase instances.
1816 * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
1818 * @note As a micro-optimization to save a few DB calls, this method may only
1819 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1821 * @see IDatabase::startAtomic
1822 * @param string $fname
1823 * @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
1824 * passing this enables cancellation of unclosed nested sections [optional]
1827 public function cancelAtomic( $fname = __METHOD__
, AtomicSectionIdentifier
$sectionId = null );
1830 * Perform an atomic section of reversable SQL statements from a callback
1832 * The $callback takes the following arguments:
1833 * - This database object
1834 * - The value of $fname
1836 * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
1837 * If any exception occurs during execution of the callback, it will be handled as follows:
1838 * - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
1839 * (and only) statements executed during the atomic section. If that succeeds, then the
1840 * exception will be re-thrown; if it fails, then a different exception will be thrown
1841 * and any further query attempts will fail until rollback() is called.
1842 * - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
1843 * end of the section and the error will be re-thrown. Any further query attempts will
1844 * fail until rollback() is called.
1846 * This method is convenient for letting calls to the caller of this method be wrapped
1847 * in a try/catch blocks for exception types that imply that the caller failed but was
1848 * able to properly discard the changes it made in the transaction. This method can be
1849 * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
1851 * Example usage, "RecordStore::save" method:
1853 * $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
1854 * // Create new record metadata row
1855 * $dbw->insert( 'records', $record->toArray(), __METHOD__ );
1856 * // Figure out where to store the data based on the new row's ID
1857 * $path = $this->recordDirectory . '/' . $dbw->insertId();
1858 * // Write the record data to the storage system;
1859 * // blob store throughs StoreFailureException on failure
1860 * $this->blobStore->create( $path, $record->getJSON() );
1861 * // Try to cleanup files orphaned by transaction rollback
1862 * $dbw->onTransactionResolution(
1863 * function ( $type ) use ( $path ) {
1864 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1865 * $this->blobStore->delete( $path );
1870 * }, $dbw::ATOMIC_CANCELABLE );
1873 * Example usage, caller of the "RecordStore::save" method:
1875 * $dbw->startAtomic( __METHOD__ );
1876 * // ...various SQL writes happen...
1878 * $recordStore->save( $record );
1879 * } catch ( StoreFailureException $e ) {
1880 * // ...various SQL writes happen...
1882 * // ...various SQL writes happen...
1883 * $dbw->endAtomic( __METHOD__ );
1886 * @see Database::startAtomic
1887 * @see Database::endAtomic
1888 * @see Database::cancelAtomic
1890 * @param string $fname Caller name (usually __METHOD__)
1891 * @param callable $callback Callback that issues DB updates
1892 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1893 * savepoint and enable self::cancelAtomic() for this section.
1894 * @return mixed $res Result of the callback (since 1.28)
1896 * @throws RuntimeException
1897 * @since 1.27; prior to 1.31 this did a rollback() instead of
1898 * cancelAtomic(), and assumed no callers up the stack would ever try to
1899 * catch the exception.
1901 public function doAtomicSection(
1902 $fname, callable
$callback, $cancelable = self
::ATOMIC_NOT_CANCELABLE
1906 * Begin a transaction. If a transaction is already in progress,
1907 * that transaction will be committed before the new transaction is started.
1909 * Only call this from code with outer transcation scope.
1910 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1911 * Nesting of transactions is not supported.
1913 * Note that when the DBO_TRX flag is set (which is usually the case for web
1914 * requests, but not for maintenance scripts), any previous database query
1915 * will have started a transaction automatically.
1917 * Nesting of transactions is not supported. Attempts to nest transactions
1918 * will cause a warning, unless the current transaction was started
1919 * automatically because of the DBO_TRX flag.
1921 * @param string $fname Calling function name
1922 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1925 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1928 * Commits a transaction previously started using begin().
1929 * If no transaction is in progress, a warning is issued.
1931 * Only call this from code with outer transcation scope.
1932 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1933 * Nesting of transactions is not supported.
1935 * @param string $fname
1936 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1937 * constant to disable warnings about explicitly committing implicit transactions,
1938 * or calling commit when no transaction is in progress.
1940 * This will trigger an exception if there is an ongoing explicit transaction.
1942 * Only set the flush flag if you are sure that these warnings are not applicable,
1943 * and no explicit transactions are open.
1947 public function commit( $fname = __METHOD__
, $flush = '' );
1950 * Rollback a transaction previously started using begin().
1951 * If no transaction is in progress, a warning is issued.
1953 * Only call this from code with outer transcation scope.
1954 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1955 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1956 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1957 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1959 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1961 * @param string $fname Calling function name
1962 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1963 * constant to disable warnings about calling rollback when no transaction is in
1964 * progress. This will silently break any ongoing explicit transaction. Only set the
1965 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1967 * @since 1.23 Added $flush parameter
1969 public function rollback( $fname = __METHOD__
, $flush = '' );
1972 * Commit any transaction but error out if writes or callbacks are pending
1974 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1975 * see a new point-in-time of the database. This is useful when one of many transaction
1976 * rounds finished and significant time will pass in the script's lifetime. It is also
1977 * useful to call on a replica DB after waiting on replication to catch up to the master.
1979 * @param string $fname Calling function name
1983 public function flushSnapshot( $fname = __METHOD__
);
1986 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1987 * to the format used for inserting into timestamp fields in this DBMS.
1989 * The result is unquoted, and needs to be passed through addQuotes()
1990 * before it can be included in raw SQL.
1992 * @param string|int $ts
1996 public function timestamp( $ts = 0 );
1999 * Convert a timestamp in one of the formats accepted by wfTimestamp()
2000 * to the format used for inserting into timestamp fields in this DBMS. If
2001 * NULL is input, it is passed through, allowing NULL values to be inserted
2002 * into timestamp fields.
2004 * The result is unquoted, and needs to be passed through addQuotes()
2005 * before it can be included in raw SQL.
2007 * @param string|int|null $ts
2011 public function timestampOrNull( $ts = null );
2014 * Ping the server and try to reconnect if it there is no connection
2016 * @param float|null &$rtt Value to store the estimated RTT [optional]
2017 * @return bool Success or failure
2019 public function ping( &$rtt = null );
2022 * Get the amount of replication lag for this database server
2024 * Callers should avoid using this method while a transaction is active
2026 * @return int|bool Database replication lag in seconds or false on error
2029 public function getLag();
2032 * Get the replica DB lag when the current transaction started
2033 * or a general lag estimate if not transaction is active
2035 * This is useful when transactions might use snapshot isolation
2036 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2037 * is this lag plus transaction duration. If they don't, it is still
2038 * safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
2039 * indication of the staleness of subsequent reads.
2041 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2045 public function getSessionLagStatus();
2048 * Return the maximum number of items allowed in a list, or 0 for unlimited.
2052 public function maxListLen();
2055 * Some DBMSs have a special format for inserting into blob fields, they
2056 * don't allow simple quoted strings to be inserted. To insert into such
2057 * a field, pass the data through this function before passing it to
2058 * IDatabase::insert().
2061 * @return string|Blob
2063 public function encodeBlob( $b );
2066 * Some DBMSs return a special placeholder object representing blob fields
2067 * in result objects. Pass the object through this function to return the
2070 * @param string|Blob $b
2073 public function decodeBlob( $b );
2076 * Override database's default behavior. $options include:
2077 * 'connTimeout' : Set the connection timeout value in seconds.
2078 * May be useful for very long batch queries such as
2079 * full-wiki dumps, where a single query reads out over
2082 * @param array $options
2086 public function setSessionOptions( array $options );
2089 * Set variables to be used in sourceFile/sourceStream, in preference to the
2090 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
2091 * all. If it's set to false, $GLOBALS will be used.
2093 * @param bool|array $vars Mapping variable name to value.
2095 public function setSchemaVars( $vars );
2098 * Check to see if a named lock is not locked by any thread (non-blocking)
2100 * @param string $lockName Name of lock to poll
2101 * @param string $method Name of method calling us
2106 public function lockIsFree( $lockName, $method );
2109 * Acquire a named lock
2111 * Named locks are not related to transactions
2113 * @param string $lockName Name of lock to aquire
2114 * @param string $method Name of the calling method
2115 * @param int $timeout Acquisition timeout in seconds
2119 public function lock( $lockName, $method, $timeout = 5 );
2124 * Named locks are not related to transactions
2126 * @param string $lockName Name of lock to release
2127 * @param string $method Name of the calling method
2129 * @return int Returns 1 if the lock was released, 0 if the lock was not established
2130 * by this thread (in which case the lock is not released), and NULL if the named lock
2135 public function unlock( $lockName, $method );
2138 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
2140 * Only call this from outer transcation scope and when only one DB will be affected.
2141 * See https://www.mediawiki.org/wiki/Database_transactions for details.
2143 * This is suitiable for transactions that need to be serialized using cooperative locks,
2144 * where each transaction can see each others' changes. Any transaction is flushed to clear
2145 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
2146 * the lock will be released unless a transaction is active. If one is active, then the lock
2147 * will be released when it either commits or rolls back.
2149 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
2151 * @param string $lockKey Name of lock to release
2152 * @param string $fname Name of the calling method
2153 * @param int $timeout Acquisition timeout in seconds
2154 * @return ScopedCallback|null
2158 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
2161 * Check to see if a named lock used by lock() use blocking queues
2166 public function namedLocksEnqueue();
2169 * Find out when 'infinity' is. Most DBMSes support this. This is a special
2170 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
2171 * because "i" sorts after all numbers.
2175 public function getInfinity();
2178 * Encode an expiry time into the DBMS dependent format
2180 * @param string $expiry Timestamp for expiry, or the 'infinity' string
2183 public function encodeExpiry( $expiry );
2186 * Decode an expiry time into a DBMS independent format
2188 * @param string $expiry DB timestamp field value for expiry
2189 * @param int $format TS_* constant, defaults to TS_MW
2192 public function decodeExpiry( $expiry, $format = TS_MW
);
2195 * Allow or deny "big selects" for this session only. This is done by setting
2196 * the sql_big_selects session variable.
2198 * This is a MySQL-specific feature.
2200 * @param bool|string $value True for allow, false for deny, or "default" to
2201 * restore the initial value
2203 public function setBigSelects( $value = true );
2206 * @return bool Whether this DB is read-only
2209 public function isReadOnly();
2212 * Make certain table names use their own database, schema, and table prefix
2213 * when passed into SQL queries pre-escaped and without a qualified database name
2215 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
2216 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
2218 * Calling this twice will completely clear any old table aliases. Also, note that
2219 * callers are responsible for making sure the schemas and databases actually exist.
2221 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
2224 public function setTableAliases( array $aliases );
2227 * Convert certain index names to alternative names before querying the DB
2229 * Note that this applies to indexes regardless of the table they belong to.
2231 * This can be employed when an index was renamed X => Y in code, but the new Y-named
2232 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
2233 * the aliases can be removed, and then the old X-named indexes dropped.
2235 * @param string[] $aliases
2238 public function setIndexAliases( array $aliases );
2241 * Get a debugging string that mentions the database type, the ID of this instance,
2242 * and the ID of any underlying connection resource or driver object if one is present
2244 * @return string "<db type> object #<X>" or "<db type> object #<X> (resource/handle id #<Y>)"
2247 public function __toString();
2251 * @deprecated since 1.29
2253 class_alias( IDatabase
::class, 'IDatabase' );