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;
109 /** @var int Ignore query errors and return false when they happen */
110 const QUERY_SILENCE_ERRORS
= 1; // b/c for 1.32 query() argument; note that (int)true = 1
112 * @var int Treat the TEMPORARY table from the given CREATE query as if it is
113 * permanent as far as write tracking is concerned. This is useful for testing.
115 const QUERY_PSEUDO_PERMANENT
= 2;
116 /** @var int Enforce that a query does not make effective writes */
117 const QUERY_REPLICA_ROLE
= 4;
119 /** @var bool Parameter to unionQueries() for UNION ALL */
120 const UNION_ALL
= true;
121 /** @var bool Parameter to unionQueries() for UNION DISTINCT */
122 const UNION_DISTINCT
= false;
125 * A string describing the current software version, and possibly
126 * other details in a user-friendly way. Will be listed on Special:Version, etc.
127 * Use getServerVersion() to get machine-friendly information.
129 * @return string Version information from the database server
131 public function getServerInfo();
134 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
136 * Unbuffered queries are very troublesome in MySQL:
138 * - If another query is executed while the first query is being read
139 * out, the first query is killed. This means you can't call normal
140 * Database functions while you are reading an unbuffered query result
141 * from a normal Database connection.
143 * - Unbuffered queries cause the MySQL server to use large amounts of
144 * memory and to hold broad locks which block other queries.
146 * If you want to limit client-side memory, it's almost always better to
147 * split up queries into batches using a LIMIT clause than to switch off
150 * @param null|bool $buffer
151 * @return null|bool The previous value of the flag
153 public function bufferResults( $buffer = null );
156 * Gets the current transaction level.
158 * Historically, transactions were allowed to be "nested". This is no
159 * longer supported, so this function really only returns a boolean.
161 * @return int The previous value
163 public function trxLevel();
166 * Get the UNIX timestamp of the time that the transaction was established
168 * This can be used to reason about the staleness of SELECT data
169 * in REPEATABLE-READ transaction isolation level.
171 * @return float|null Returns null if there is not active transaction
174 public function trxTimestamp();
177 * @return bool Whether an explicit transaction or atomic sections are still open
180 public function explicitTrxActive();
183 * Assert that all explicit transactions or atomic sections have been closed.
184 * @throws DBTransactionError
187 public function assertNoOpenTransactions();
190 * Get/set the table prefix.
191 * @param string|null $prefix The table prefix to set, or omitted to leave it unchanged.
192 * @return string The previous table prefix
193 * @throws DBUnexpectedError
195 public function tablePrefix( $prefix = null );
198 * Get/set the db schema.
199 * @param string|null $schema The database schema to set, or omitted to leave it unchanged.
200 * @return string The previous db schema
202 public function dbSchema( $schema = null );
205 * Get properties passed down from the server info array of the load
208 * @param string|null $name The entry of the info array to get, or null to get the
211 * @return array|mixed|null
213 public function getLBInfo( $name = null );
216 * Set the LB info array, or a member of it. If called with one parameter,
217 * the LB info array is set to that parameter. If it is called with two
218 * parameters, the member with the given name is set to the given value.
220 * @param string $name
221 * @param array|null $value
223 public function setLBInfo( $name, $value = null );
226 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
228 * @param IDatabase $conn
231 public function setLazyMasterHandle( IDatabase
$conn );
234 * Returns true if this database does an implicit sort when doing GROUP BY
237 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
239 public function implicitGroupby();
242 * Returns true if this database does an implicit order by when the column has an index
243 * For example: SELECT page_title FROM page LIMIT 1
247 public function implicitOrderby();
250 * Return the last query that went through IDatabase::query()
253 public function lastQuery();
256 * Returns true if the connection may have been used for write queries.
257 * Should return true if unsure.
260 * @deprecated Since 1.31; use lastDoneWrites()
262 public function doneWrites();
265 * Returns the last time the connection may have been used for write queries.
266 * Should return a timestamp if unsure.
268 * @return int|float UNIX timestamp or false
271 public function lastDoneWrites();
274 * @return bool Whether there is a transaction open with possible write queries
277 public function writesPending();
280 * @return bool Whether there is a transaction open with pre-commit callbacks pending
283 public function preCommitCallbacksPending();
286 * Whether there is a transaction open with either possible write queries
287 * or unresolved pre-commit/commit/resolution callbacks pending
289 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
293 public function writesOrCallbacksPending();
296 * Get the time spend running write queries for this transaction
298 * High times could be due to scanning, updates, locking, and such
300 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
301 * @return float|bool Returns false if not transaction is active
304 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
307 * Get the list of method names that did write queries for this transaction
312 public function pendingWriteCallers();
315 * Get the number of affected rows from pending write queries
320 public function pendingWriteRowsAffected();
323 * Is a connection to the database open?
326 public function isOpen();
329 * Set a flag for this connection
331 * @param int $flag DBO_* constants from Defines.php:
332 * - DBO_DEBUG: output some debug info (same as debug())
333 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
334 * - DBO_TRX: automatically start transactions
335 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
336 * and removes it in command line mode
337 * - DBO_PERSISTENT: use persistant database connection
338 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
340 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
343 * Clear a flag for this connection
345 * @param int $flag DBO_* constants from Defines.php:
346 * - DBO_DEBUG: output some debug info (same as debug())
347 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
348 * - DBO_TRX: automatically start transactions
349 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
350 * and removes it in command line mode
351 * - DBO_PERSISTENT: use persistant database connection
352 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
354 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
357 * Restore the flags to their prior state before the last setFlag/clearFlag call
359 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
362 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
365 * Returns a boolean whether the flag $flag is set for this connection
367 * @param int $flag DBO_* constants from Defines.php:
368 * - DBO_DEBUG: output some debug info (same as debug())
369 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
370 * - DBO_TRX: automatically start transactions
371 * - DBO_PERSISTENT: use persistant database connection
374 public function getFlag( $flag );
377 * Return the currently selected domain ID
379 * Null components (database/schema) might change once a connection is established
383 public function getDomainID();
386 * Alias for getDomainID()
391 public function getWikiID();
394 * Get the type of the DBMS, as it appears in $wgDBtype.
398 public function getType();
401 * Fetch the next row from the given result object, in object form.
402 * Fields can be retrieved with $row->fieldname, with fields acting like
404 * If no more rows are available, false is returned.
406 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
407 * @return stdClass|bool
408 * @throws DBUnexpectedError Thrown if the database returns an error
410 public function fetchObject( $res );
413 * Fetch the next row from the given result object, in associative array
414 * form. Fields are retrieved with $row['fieldname'].
415 * If no more rows are available, false is returned.
417 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
419 * @throws DBUnexpectedError Thrown if the database returns an error
421 public function fetchRow( $res );
424 * Get the number of rows in a query result. If the query did not return
425 * any rows (for example, if it was a write query), this returns zero.
427 * @param mixed $res A SQL result
430 public function numRows( $res );
433 * Get the number of fields in a result object
434 * @see https://secure.php.net/mysql_num_fields
436 * @param mixed $res A SQL result
439 public function numFields( $res );
442 * Get a field name in a result object
443 * @see https://secure.php.net/mysql_field_name
445 * @param mixed $res A SQL result
449 public function fieldName( $res, $n );
452 * Get the inserted value of an auto-increment row
454 * This should only be called after an insert that used an auto-incremented
455 * value. If no such insert was previously done in the current database
456 * session, the return value is undefined.
460 public function insertId();
463 * Change the position of the cursor in a result object
464 * @see https://secure.php.net/mysql_data_seek
466 * @param mixed $res A SQL result
469 public function dataSeek( $res, $row );
472 * Get the last error number
473 * @see https://secure.php.net/mysql_errno
477 public function lastErrno();
480 * Get a description of the last error
481 * @see https://secure.php.net/mysql_error
485 public function lastError();
488 * Get the number of rows affected by the last write query
489 * @see https://secure.php.net/mysql_affected_rows
493 public function affectedRows();
496 * Returns a wikitext link to the DB's website, e.g.,
497 * return "[https://www.mysql.com/ MySQL]";
498 * Should at least contain plain text, if for some reason
499 * your database has no website.
501 * @return string Wikitext of a link to the server software's web site
503 public function getSoftwareLink();
506 * A string describing the current software version, like from
507 * mysql_get_server_info().
509 * @return string Version information from the database server.
511 public function getServerVersion();
514 * Close the database connection
516 * This should only be called after any transactions have been resolved,
517 * aside from read-only automatic transactions (assuming no callbacks are registered).
518 * If a transaction is still open anyway, it will be rolled back.
521 * @return bool Operation success. true if already closed.
523 public function close();
526 * Run an SQL query and return the result. Normally throws a DBQueryError
527 * on failure. If errors are ignored, returns false instead.
529 * If a connection loss is detected, then an attempt to reconnect will be made.
530 * For queries that involve no larger transactions or locks, they will be re-issued
531 * for convenience, provided the connection was re-established.
533 * In new code, the query wrappers select(), insert(), update(), delete(),
534 * etc. should be used where possible, since they give much better DBMS
535 * independence and automatically quote or validate user input in a variety
536 * of contexts. This function is generally only useful for queries which are
537 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
540 * However, the query wrappers themselves should call this function.
542 * @param string $sql SQL query
543 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
544 * comment (you can use __METHOD__ or add some extra info)
545 * @param int $flags Bitfield of IDatabase::QUERY_* constants. Note that suppression
546 * of errors is best handled by try/catch rather than using one of these flags.
547 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
548 * for a successful read query, or false on failure if QUERY_SILENCE_ERRORS is set.
551 public function query( $sql, $fname = __METHOD__
, $flags = 0 );
554 * Free a result object returned by query() or select(). It's usually not
555 * necessary to call this, just use unset() or let the variable holding
556 * the result object go out of scope.
558 * @param mixed $res A SQL result
560 public function freeResult( $res );
563 * A SELECT wrapper which returns a single field from a single result row.
565 * Usually throws a DBQueryError on failure. If errors are explicitly
566 * ignored, returns false on failure.
568 * If no result rows are returned from the query, false is returned.
570 * @param string|array $table Table name. See IDatabase::select() for details.
571 * @param string $var The field name to select. This must be a valid SQL
572 * fragment: do not use unvalidated user input.
573 * @param string|array $cond The condition array. See IDatabase::select() for details.
574 * @param string $fname The function name of the caller.
575 * @param string|array $options The query options. See IDatabase::select() for details.
576 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
578 * @return mixed The value from the field
581 public function selectField(
582 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
586 * A SELECT wrapper which returns a list of single field values from result rows.
588 * Usually throws a DBQueryError on failure. If errors are explicitly
589 * ignored, returns false on failure.
591 * If no result rows are returned from the query, false is returned.
593 * @param string|array $table Table name. See IDatabase::select() for details.
594 * @param string $var The field name to select. This must be a valid SQL
595 * fragment: do not use unvalidated user input.
596 * @param string|array $cond The condition array. See IDatabase::select() for details.
597 * @param string $fname The function name of the caller.
598 * @param string|array $options The query options. See IDatabase::select() for details.
599 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
601 * @return array The values from the field in the order they were returned from the DB
605 public function selectFieldValues(
606 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
610 * Execute a SELECT query constructed using the various parameters provided.
611 * See below for full details of the parameters.
613 * @param string|array $table Table name(s)
615 * May be either an array of table names, or a single string holding a table
616 * name. If an array is given, table aliases can be specified, for example:
620 * This includes the user table in the query, with the alias "a" available
621 * for use in field names (e.g. a.user_name).
623 * A derived table, defined by the result of selectSQLText(), requires an alias
624 * key and a Subquery instance value which wraps the SQL query, for example:
626 * [ 'c' => new Subquery( 'SELECT ...' ) ]
628 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
629 * constructed using nested arrays. For example,
631 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
633 * along with `$join_conds` like
635 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
637 * will produce SQL something like
639 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
641 * All of the table names given here are automatically run through
642 * Database::tableName(), which causes the table prefix (if any) to be
643 * added, and various other table name mappings to be performed.
645 * Do not use untrusted user input as a table name. Alias names should
646 * not have characters outside of the Basic multilingual plane.
648 * @param string|array $vars Field name(s)
650 * May be either a field name or an array of field names. The field names
651 * can be complete fragments of SQL, for direct inclusion into the SELECT
652 * query. If an array is given, field aliases can be specified, for example:
654 * [ 'maxrev' => 'MAX(rev_id)' ]
656 * This includes an expression with the alias "maxrev" in the query.
658 * If an expression is given, care must be taken to ensure that it is
661 * Untrusted user input must not be passed to this parameter.
663 * @param string|array $conds
665 * May be either a string containing a single condition, or an array of
666 * conditions. If an array is given, the conditions constructed from each
667 * element are combined with AND.
669 * Array elements may take one of two forms:
671 * - Elements with a numeric key are interpreted as raw SQL fragments.
672 * - Elements with a string key are interpreted as equality conditions,
673 * where the key is the field name.
674 * - If the value of such an array element is a scalar (such as a
675 * string), it will be treated as data and thus quoted appropriately.
676 * If it is null, an IS NULL clause will be added.
677 * - If the value is an array, an IN (...) clause will be constructed
678 * from its non-null elements, and an IS NULL clause will be added
679 * if null is present, such that the field may match any of the
680 * elements in the array. The non-null elements will be quoted.
682 * Note that expressions are often DBMS-dependent in their syntax.
683 * DBMS-independent wrappers are provided for constructing several types of
684 * expression commonly used in condition queries. See:
685 * - IDatabase::buildLike()
686 * - IDatabase::conditional()
688 * Untrusted user input is safe in the values of string keys, however untrusted
689 * input must not be used in the array key names or in the values of numeric keys.
690 * Escaping of untrusted input used in values of numeric keys should be done via
691 * IDatabase::addQuotes()
693 * Use an empty array, string, or '*' to update all rows.
695 * @param string $fname Caller function name
697 * @param string|array $options Query options
699 * Optional: Array of query options. Boolean options are specified by
700 * including them in the array as a string value with a numeric key, for
705 * The supported options are:
707 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
708 * with LIMIT can theoretically be used for paging through a result set,
709 * but this is discouraged for performance reasons.
711 * - LIMIT: Integer: return at most this many rows. The rows are sorted
712 * and then the first rows are taken until the limit is reached. LIMIT
713 * is applied to a result set after OFFSET.
715 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
716 * changed until the next COMMIT.
718 * - DISTINCT: Boolean: return only unique result rows.
720 * - GROUP BY: May be either an SQL fragment string naming a field or
721 * expression to group by, or an array of such SQL fragments.
723 * - HAVING: May be either an string containing a HAVING clause or an array of
724 * conditions building the HAVING clause. If an array is given, the conditions
725 * constructed from each element are combined with AND.
727 * - ORDER BY: May be either an SQL fragment giving a field name or
728 * expression to order by, or an array of such SQL fragments.
730 * - USE INDEX: This may be either a string giving the index name to use
731 * for the query, or an array. If it is an associative array, each key
732 * gives the table name (or alias), each value gives the index name to
733 * use for that table. All strings are SQL fragments and so should be
734 * validated by the caller.
736 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
739 * And also the following boolean MySQL extensions, see the MySQL manual
742 * - LOCK IN SHARE MODE
746 * - SQL_BUFFER_RESULT
748 * - SQL_CALC_FOUND_ROWS
753 * @param string|array $join_conds Join conditions
755 * Optional associative array of table-specific join conditions. In the
756 * most common case, this is unnecessary, since the join condition can be
757 * in $conds. However, it is useful for doing a LEFT JOIN.
759 * The key of the array contains the table name or alias. The value is an
760 * array with two elements, numbered 0 and 1. The first gives the type of
761 * join, the second is the same as the $conds parameter. Thus it can be
762 * an SQL fragment, or an array where the string keys are equality and the
763 * numeric keys are SQL fragments all AND'd together. For example:
765 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
767 * @return IResultWrapper Resulting rows
770 public function select(
771 $table, $vars, $conds = '', $fname = __METHOD__
,
772 $options = [], $join_conds = []
776 * The equivalent of IDatabase::select() except that the constructed SQL
777 * is returned, instead of being immediately executed. This can be useful for
778 * doing UNION queries, where the SQL text of each query is needed. In general,
779 * however, callers outside of Database classes should just use select().
781 * @see IDatabase::select()
783 * @param string|array $table Table name
784 * @param string|array $vars Field names
785 * @param string|array $conds Conditions
786 * @param string $fname Caller function name
787 * @param string|array $options Query options
788 * @param string|array $join_conds Join conditions
789 * @return string SQL query string
791 public function selectSQLText(
792 $table, $vars, $conds = '', $fname = __METHOD__
,
793 $options = [], $join_conds = []
797 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
798 * that a single row object is returned. If the query returns no rows,
801 * @param string|array $table Table name
802 * @param string|array $vars Field names
803 * @param array $conds Conditions
804 * @param string $fname Caller function name
805 * @param string|array $options Query options
806 * @param array|string $join_conds Join conditions
808 * @return stdClass|bool
811 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
812 $options = [], $join_conds = []
816 * Estimate the number of rows in dataset
818 * MySQL allows you to estimate the number of rows that would be returned
819 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
820 * index cardinality statistics, and is notoriously inaccurate, especially
821 * when large numbers of rows have recently been added or deleted.
823 * For DBMSs that don't support fast result size estimation, this function
824 * will actually perform the SELECT COUNT(*).
826 * Takes the same arguments as IDatabase::select().
828 * @param string $table Table name
829 * @param string $var Column for which NULL values are not counted [default "*"]
830 * @param array|string $conds Filters on the table
831 * @param string $fname Function name for profiling
832 * @param array $options Options for select
833 * @param array|string $join_conds Join conditions
834 * @return int Row count
837 public function estimateRowCount(
838 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
842 * Get the number of rows in dataset
844 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
846 * Takes the same arguments as IDatabase::select().
848 * @since 1.27 Added $join_conds parameter
850 * @param array|string $tables Table names
851 * @param string $var Column for which NULL values are not counted [default "*"]
852 * @param array|string $conds Filters on the table
853 * @param string $fname Function name for profiling
854 * @param array $options Options for select
855 * @param array $join_conds Join conditions (since 1.27)
856 * @return int Row count
859 public function selectRowCount(
860 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
864 * Lock all rows meeting the given conditions/options FOR UPDATE
866 * @param array|string $table Table names
867 * @param array|string $conds Filters on the table
868 * @param string $fname Function name for profiling
869 * @param array $options Options for select ("FOR UPDATE" is added automatically)
870 * @param array $join_conds Join conditions
871 * @return int Number of matching rows found (and locked)
874 public function lockForUpdate(
875 $table, $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
879 * Determines whether a field exists in a table
881 * @param string $table Table name
882 * @param string $field Filed to check on that table
883 * @param string $fname Calling function name (optional)
884 * @return bool Whether $table has filed $field
887 public function fieldExists( $table, $field, $fname = __METHOD__
);
890 * Determines whether an index exists
891 * Usually throws a DBQueryError on failure
892 * If errors are explicitly ignored, returns NULL on failure
894 * @param string $table
895 * @param string $index
896 * @param string $fname
900 public function indexExists( $table, $index, $fname = __METHOD__
);
903 * Query whether a given table exists
905 * @param string $table
906 * @param string $fname
910 public function tableExists( $table, $fname = __METHOD__
);
913 * INSERT wrapper, inserts an array into a table.
917 * - A single associative array. The array keys are the field names, and
918 * the values are the values to insert. The values are treated as data
919 * and will be quoted appropriately. If NULL is inserted, this will be
920 * converted to a database NULL.
921 * - An array with numeric keys, holding a list of associative arrays.
922 * This causes a multi-row INSERT on DBMSs that support it. The keys in
923 * each subarray must be identical to each other, and in the same order.
925 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
928 * $options is an array of options, with boolean options encoded as values
929 * with numeric keys, in the same style as $options in
930 * IDatabase::select(). Supported options are:
932 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
933 * any rows which cause duplicate key errors are not inserted. It's
934 * possible to determine how many rows were successfully inserted using
935 * IDatabase::affectedRows().
937 * @param string $table Table name. This will be passed through
938 * Database::tableName().
939 * @param array $a Array of rows to insert
940 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
941 * @param array $options Array of options
942 * @return bool Return true if no exception was thrown (deprecated since 1.33)
945 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
948 * UPDATE wrapper. Takes a condition array and a SET array.
950 * @param string $table Name of the table to UPDATE. This will be passed through
951 * Database::tableName().
952 * @param array $values An array of values to SET. For each array element,
953 * the key gives the field name, and the value gives the data to set
954 * that field to. The data will be quoted by IDatabase::addQuotes().
955 * Values with integer keys form unquoted SET statements, which can be used for
956 * things like "field = field + 1" or similar computed values.
957 * @param array $conds An array of conditions (WHERE). See
958 * IDatabase::select() for the details of the format of condition
959 * arrays. Use '*' to update all rows.
960 * @param string $fname The function name of the caller (from __METHOD__),
961 * for logging and profiling.
962 * @param array $options An array of UPDATE options, can be:
963 * - IGNORE: Ignore unique key conflicts
964 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
965 * @return bool Return true if no exception was thrown (deprecated since 1.33)
968 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
971 * Makes an encoded list of strings from an array
973 * These can be used to make conjunctions or disjunctions on SQL condition strings
974 * derived from an array (see IDatabase::select() $conds documentation).
978 * $sql = $db->makeList( [
980 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
981 * ], $db::LIST_AND );
983 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
985 * @param array $a Containing the data
986 * @param int $mode IDatabase class constant:
987 * - IDatabase::LIST_COMMA: Comma separated, no field names
988 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
989 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
990 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
991 * - IDatabase::LIST_NAMES: Comma separated field names
995 public function makeList( $a, $mode = self
::LIST_COMMA
);
998 * Build a partial where clause from a 2-d array such as used for LinkBatch.
999 * The keys on each level may be either integers or strings.
1001 * @param array $data Organized as 2-d
1002 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
1003 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
1004 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
1005 * @return string|bool SQL fragment, or false if no items in array
1007 public function makeWhereFrom2d( $data, $baseKey, $subKey );
1010 * Return aggregated value alias
1012 * @param array $valuedata
1013 * @param string $valuename
1017 public function aggregateValue( $valuedata, $valuename = 'value' );
1020 * @param string $field
1023 public function bitNot( $field );
1026 * @param string $fieldLeft
1027 * @param string $fieldRight
1030 public function bitAnd( $fieldLeft, $fieldRight );
1033 * @param string $fieldLeft
1034 * @param string $fieldRight
1037 public function bitOr( $fieldLeft, $fieldRight );
1040 * Build a concatenation list to feed into a SQL query
1041 * @param array $stringList List of raw SQL expressions; caller is
1042 * responsible for any quoting
1045 public function buildConcat( $stringList );
1048 * Build a GROUP_CONCAT or equivalent statement for a query.
1050 * This is useful for combining a field for several rows into a single string.
1051 * NULL values will not appear in the output, duplicated values will appear,
1052 * and the resulting delimiter-separated values have no defined sort order.
1053 * Code using the results may need to use the PHP unique() or sort() methods.
1055 * @param string $delim Glue to bind the results together
1056 * @param string|array $table Table name
1057 * @param string $field Field name
1058 * @param string|array $conds Conditions
1059 * @param string|array $join_conds Join conditions
1060 * @return string SQL text
1063 public function buildGroupConcatField(
1064 $delim, $table, $field, $conds = '', $join_conds = []
1068 * Build a SUBSTRING function.
1070 * Behavior for non-ASCII values is undefined.
1072 * @param string $input Field name
1073 * @param int $startPosition Positive integer
1074 * @param int|null $length Non-negative integer length or null for no limit
1075 * @throws InvalidArgumentException
1076 * @return string SQL text
1079 public function buildSubString( $input, $startPosition, $length = null );
1082 * @param string $field Field or column to cast
1086 public function buildStringCast( $field );
1089 * @param string $field Field or column to cast
1093 public function buildIntegerCast( $field );
1096 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1098 * @see IDatabase::selectSQLText()
1100 * @param string|array $table Table name
1101 * @param string|array $vars Field names
1102 * @param string|array $conds Conditions
1103 * @param string $fname Caller function name
1104 * @param string|array $options Query options
1105 * @param string|array $join_conds Join conditions
1109 public function buildSelectSubquery(
1110 $table, $vars, $conds = '', $fname = __METHOD__
,
1111 $options = [], $join_conds = []
1115 * Returns true if DBs are assumed to be on potentially different servers
1117 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1118 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1119 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1120 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1125 public function databasesAreIndependent();
1128 * Change the current database
1130 * This should not be called outside LoadBalancer for connections managed by a LoadBalancer
1133 * @return bool True unless an exception was thrown
1134 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1136 * @deprecated Since 1.32 Use selectDomain() instead
1138 public function selectDB( $db );
1141 * Set the current domain (database, schema, and table prefix)
1143 * This will throw an error for some database types if the database unspecified
1145 * This should not be called outside LoadBalancer for connections managed by a LoadBalancer
1147 * @param string|DatabaseDomain $domain
1149 * @throws DBConnectionError
1151 public function selectDomain( $domain );
1154 * Get the current DB name
1155 * @return string|null
1157 public function getDBname();
1160 * Get the server hostname or IP address
1163 public function getServer();
1166 * Adds quotes and backslashes.
1168 * @param string|int|null|bool|Blob $s
1169 * @return string|int
1171 public function addQuotes( $s );
1174 * Quotes an identifier, in order to make user controlled input safe
1176 * Depending on the database this will either be `backticks` or "double quotes"
1182 public function addIdentifierQuotes( $s );
1185 * LIKE statement wrapper, receives a variable-length argument list with
1186 * parts of pattern to match containing either string literals that will be
1187 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1188 * the function could be provided with an array of aforementioned
1191 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1192 * a LIKE clause that searches for subpages of 'My page title'.
1194 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1195 * $query .= $dbr->buildLike( $pattern );
1198 * @return string Fully built LIKE statement
1200 public function buildLike();
1203 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1207 public function anyChar();
1210 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1214 public function anyString();
1217 * Deprecated method, calls should be removed.
1219 * This was formerly used for PostgreSQL and Oracle to handle
1220 * self::insertId() auto-incrementing fields. It is no longer necessary
1221 * since DatabasePostgres::insertId() has been reimplemented using
1222 * `lastval()` and Oracle has been reimplemented using triggers.
1224 * Implementations should return null if inserting `NULL` into an
1225 * auto-incrementing field works, otherwise it should return an instance of
1226 * NextSequenceValue and filter it on calls to relevant methods.
1228 * @deprecated since 1.30, no longer needed
1229 * @param string $seqName
1230 * @return null|NextSequenceValue
1232 public function nextSequenceValue( $seqName );
1235 * REPLACE query wrapper.
1237 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1238 * except that when there is a duplicate key error, the old row is deleted
1239 * and the new row is inserted in its place.
1241 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1242 * perform the delete, we need to know what the unique indexes are so that
1243 * we know how to find the conflicting rows.
1245 * It may be more efficient to leave off unique indexes which are unlikely
1246 * to collide. However if you do this, you run the risk of encountering
1247 * errors which wouldn't have occurred in MySQL.
1249 * @param string $table The table to replace the row(s) in.
1250 * @param array[]|string[]|string $uniqueIndexes All unique indexes. One of the following:
1251 * a) the one unique field in the table (when no composite unique key exist)
1252 * b) a list of all unique fields in the table (when no composite unique key exist)
1253 * c) a list of all unique indexes in the table (each as a list of the indexed fields)
1254 * @param array $rows Can be either a single row to insert, or multiple rows,
1255 * in the same format as for IDatabase::insert()
1256 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1259 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1262 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1264 * This updates any conflicting rows (according to the unique indexes) using
1265 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1267 * $rows may be either:
1268 * - A single associative array. The array keys are the field names, and
1269 * the values are the values to insert. The values are treated as data
1270 * and will be quoted appropriately. If NULL is inserted, this will be
1271 * converted to a database NULL.
1272 * - An array with numeric keys, holding a list of associative arrays.
1273 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1274 * each subarray must be identical to each other, and in the same order.
1276 * It may be more efficient to leave off unique indexes which are unlikely
1277 * to collide. However if you do this, you run the risk of encountering
1278 * errors which wouldn't have occurred in MySQL.
1280 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1285 * @param string $table Table name. This will be passed through Database::tableName().
1286 * @param array $rows A single row or list of rows to insert
1287 * @param array[]|string[]|string $uniqueIndexes All unique indexes. One of the following:
1288 * a) the one unique field in the table (when no composite unique key exist)
1289 * b) a list of all unique fields in the table (when no composite unique key exist)
1290 * c) a list of all unique indexes in the table (each as a list of the indexed fields)
1291 * @param array $set An array of values to SET. For each array element, the
1292 * key gives the field name, and the value gives the data to set that
1293 * field to. The data will be quoted by IDatabase::addQuotes().
1294 * Values with integer keys form unquoted SET statements, which can be used for
1295 * things like "field = field + 1" or similar computed values.
1296 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1298 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1300 public function upsert(
1301 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1305 * DELETE where the condition is a join.
1307 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1308 * we use sub-selects
1310 * For safety, an empty $conds will not delete everything. If you want to
1311 * delete all rows where the join condition matches, set $conds='*'.
1313 * DO NOT put the join condition in $conds.
1315 * @param string $delTable The table to delete from.
1316 * @param string $joinTable The other table.
1317 * @param string $delVar The variable to join on, in the first table.
1318 * @param string $joinVar The variable to join on, in the second table.
1319 * @param array $conds Condition array of field names mapped to variables,
1320 * ANDed together in the WHERE clause
1321 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1324 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1329 * DELETE query wrapper.
1331 * @param string $table Table name
1332 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1333 * for the format. Use $conds == "*" to delete all rows
1334 * @param string $fname Name of the calling function
1335 * @throws DBUnexpectedError
1336 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1339 public function delete( $table, $conds, $fname = __METHOD__
);
1342 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1343 * into another table.
1345 * @warning If the insert will use an auto-increment or sequence to
1346 * determine the value of a column, this may break replication on
1347 * databases using statement-based replication if the SELECT is not
1348 * deterministically ordered.
1350 * @param string $destTable The table name to insert into
1351 * @param string|array $srcTable May be either a table name, or an array of table names
1352 * to include in a join.
1354 * @param array $varMap Must be an associative array of the form
1355 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1356 * rather than field names, but strings should be quoted with
1357 * IDatabase::addQuotes()
1359 * @param array $conds Condition array. See $conds in IDatabase::select() for
1360 * the details of the format of condition arrays. May be "*" to copy the
1363 * @param string $fname The function name of the caller, from __METHOD__
1365 * @param array $insertOptions Options for the INSERT part of the query, see
1366 * IDatabase::insert() for details. Also, one additional option is
1367 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1368 * an auto-increment or sequence to determine any column values.
1369 * @param array $selectOptions Options for the SELECT part of the query, see
1370 * IDatabase::select() for details.
1371 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1372 * IDatabase::select() for details.
1374 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1377 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1378 $fname = __METHOD__
,
1379 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1383 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1384 * within the UNION construct.
1387 public function unionSupportsOrderAndLimit();
1390 * Construct a UNION query
1391 * This is used for providing overload point for other DB abstractions
1392 * not compatible with the MySQL syntax.
1393 * @param array $sqls SQL statements to combine
1394 * @param bool $all Either IDatabase::UNION_ALL or IDatabase::UNION_DISTINCT
1395 * @return string SQL fragment
1397 public function unionQueries( $sqls, $all );
1400 * Construct a UNION query for permutations of conditions
1402 * Databases sometimes have trouble with queries that have multiple values
1403 * for multiple condition parameters combined with limits and ordering.
1404 * This method constructs queries for the Cartesian product of the
1405 * conditions and unions them all together.
1407 * @see IDatabase::select()
1409 * @param string|array $table Table name
1410 * @param string|array $vars Field names
1411 * @param array $permute_conds Conditions for the Cartesian product. Keys
1412 * are field names, values are arrays of the possible values for that
1414 * @param string|array $extra_conds Additional conditions to include in the
1416 * @param string $fname Caller function name
1417 * @param string|array $options Query options. In addition to the options
1418 * recognized by IDatabase::select(), the following may be used:
1419 * - NOTALL: Set to use UNION instead of UNION ALL.
1420 * - INNER ORDER BY: If specified and supported, subqueries will use this
1421 * instead of ORDER BY.
1422 * @param string|array $join_conds Join conditions
1423 * @return string SQL query string.
1425 public function unionConditionPermutations(
1426 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1427 $options = [], $join_conds = []
1431 * Returns an SQL expression for a simple conditional. This doesn't need
1432 * to be overridden unless CASE isn't supported in your DBMS.
1434 * @param string|array $cond SQL expression which will result in a boolean value
1435 * @param string $trueVal SQL expression to return if true
1436 * @param string $falseVal SQL expression to return if false
1437 * @return string SQL fragment
1439 public function conditional( $cond, $trueVal, $falseVal );
1442 * Returns a command for str_replace function in SQL query.
1443 * Uses REPLACE() in MySQL
1445 * @param string $orig Column to modify
1446 * @param string $old Column to seek
1447 * @param string $new Column to replace with
1451 public function strreplace( $orig, $old, $new );
1454 * Determines how long the server has been up
1459 public function getServerUptime();
1462 * Determines if the last failure was due to a deadlock
1464 * Note that during a deadlock, the prior transaction will have been lost
1468 public function wasDeadlock();
1471 * Determines if the last failure was due to a lock timeout
1473 * Note that during a lock wait timeout, the prior transaction will have been lost
1477 public function wasLockTimeout();
1480 * Determines if the last query error was due to a dropped connection
1482 * Note that during a connection loss, the prior transaction will have been lost
1487 public function wasConnectionLoss();
1490 * Determines if the last failure was due to the database being read-only.
1494 public function wasReadOnlyError();
1497 * Determines if the last query error was due to something outside of the query itself
1499 * Note that the transaction may have been lost, discarding prior writes and results
1503 public function wasErrorReissuable();
1506 * Wait for the replica DB to catch up to a given master position
1508 * Note that this does not start any new transactions. If any existing transaction
1509 * is flushed, and this is called, then queries will reflect the point the DB was synced
1510 * up to (on success) without interference from REPEATABLE-READ snapshots.
1512 * @param DBMasterPos $pos
1513 * @param int $timeout The maximum number of seconds to wait for synchronisation
1514 * @return int|null Zero if the replica DB was past that position already,
1515 * greater than zero if we waited for some period of time, less than
1516 * zero if it timed out, and null on error
1519 public function masterPosWait( DBMasterPos
$pos, $timeout );
1522 * Get the replication position of this replica DB
1524 * @return DBMasterPos|bool False if this is not a replica DB
1527 public function getReplicaPos();
1530 * Get the position of this master
1532 * @return DBMasterPos|bool False if this is not a master
1535 public function getMasterPos();
1538 * @return bool Whether the DB is marked as read-only server-side
1541 public function serverIsReadOnly();
1544 * Run a callback as soon as the current transaction commits or rolls back.
1545 * An error is thrown if no transaction is pending. Queries in the function will run in
1546 * AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1549 * This is useful for combining cooperative locks and DB transactions.
1551 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1553 * The callback takes the following arguments:
1554 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1555 * - This IDatabase instance (since 1.32)
1557 * @param callable $callback
1558 * @param string $fname Caller name
1561 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1564 * Run a callback as soon as there is no transaction pending.
1565 * If there is a transaction and it is rolled back, then the callback is cancelled.
1567 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1568 * of the round, just after all peer transactions COMMIT. If the transaction round
1569 * is rolled back, then the callback is cancelled.
1571 * Queries in the function will run in AUTOCOMMIT mode unless there are begin() calls.
1572 * Callbacks must commit any transactions that they begin.
1574 * This is useful for updates to different systems or when separate transactions are needed.
1575 * For example, one might want to enqueue jobs into a system outside the database, but only
1576 * after the database is updated so that the jobs will see the data when they actually run.
1577 * It can also be used for updates that easily suffer from lock timeouts and deadlocks,
1578 * but where atomicity is not essential.
1580 * Avoid using IDatabase instances aside from this one in the callback, unless such instances
1581 * never have IDatabase::DBO_TRX set. This keeps callbacks from interfering with one another.
1583 * Updates will execute in the order they were enqueued.
1585 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1587 * The callback takes the following arguments:
1588 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1589 * - This IDatabase instance (since 1.32)
1591 * @param callable $callback
1592 * @param string $fname Caller name
1595 public function onTransactionCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1598 * Alias for onTransactionCommitOrIdle() for backwards-compatibility
1600 * @param callable $callback
1601 * @param string $fname
1603 * @deprecated Since 1.32
1605 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1608 * Run a callback before the current transaction commits or now if there is none.
1609 * If there is a transaction and it is rolled back, then the callback is cancelled.
1611 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1612 * of the round, just before all peer transactions COMMIT. If the transaction round
1613 * is rolled back, then the callback is cancelled.
1615 * Callbacks must not start nor commit any transactions. If no transaction is active,
1616 * then a transaction will wrap the callback.
1618 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1619 * but where atomicity is strongly desired for these updates and some related updates.
1621 * Updates will execute in the order they were enqueued.
1623 * The callback takes the one argument:
1624 * - This IDatabase instance (since 1.32)
1626 * @param callable $callback
1627 * @param string $fname Caller name
1630 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1633 * Run a callback after each time any transaction commits or rolls back
1635 * The callback takes two arguments:
1636 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1637 * - This IDatabase object
1638 * Callbacks must commit any transactions that they begin.
1640 * Registering a callback here will not affect writesOrCallbacks() pending.
1642 * Since callbacks from this or onTransactionCommitOrIdle() can start and end transactions,
1643 * a single call to IDatabase::commit might trigger multiple runs of the listener callbacks.
1645 * @param string $name Callback name
1646 * @param callable|null $callback Use null to unset a listener
1649 public function setTransactionListener( $name, callable
$callback = null );
1652 * Begin an atomic section of SQL statements
1654 * Start an implicit transaction if no transaction is already active, set a savepoint
1655 * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
1656 * that the transaction is not committed prematurely. The end of the section must be
1657 * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
1658 * have layers of inner sections (sub-sections), but all sections must be ended in order
1659 * of innermost to outermost. Transactions cannot be started or committed until all
1660 * atomic sections are closed.
1662 * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
1663 * by discarding the section's writes. This should not be used for failures when:
1664 * - upsert() could easily be used instead
1665 * - insert() with IGNORE could easily be used instead
1666 * - select() with FOR UPDATE could be checked before issuing writes instead
1667 * - The failure is from code that runs after the first write but doesn't need to
1668 * - The failures are from contention solvable via onTransactionPreCommitOrIdle()
1669 * - The failures are deadlocks; the RDBMs usually discard the whole transaction
1671 * @note callers must use additional measures for situations involving two or more
1672 * (peer) transactions (e.g. updating two database servers at once). The transaction
1673 * and savepoint logic of this method only applies to this specific IDatabase instance.
1677 * // Start a transaction if there isn't one already
1678 * $dbw->startAtomic( __METHOD__ );
1679 * // Serialize these thread table updates
1680 * $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
1681 * // Add a new comment for the thread
1682 * $dbw->insert( 'comment', $row, __METHOD__ );
1683 * $cid = $db->insertId();
1684 * // Update thread reference to last comment
1685 * $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
1686 * // Demark the end of this conceptual unit of updates
1687 * $dbw->endAtomic( __METHOD__ );
1690 * Example usage (atomic changes that might have to be discarded):
1692 * // Start a transaction if there isn't one already
1693 * $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
1694 * // Create new record metadata row
1695 * $dbw->insert( 'records', $row, __METHOD__ );
1696 * // Figure out where to store the data based on the new row's ID
1697 * $path = $recordDirectory . '/' . $dbw->insertId();
1698 * // Write the record data to the storage system
1699 * $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
1700 * if ( $status->isOK() ) {
1701 * // Try to cleanup files orphaned by transaction rollback
1702 * $dbw->onTransactionResolution(
1703 * function ( $type ) use ( $fileBackend, $path ) {
1704 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1705 * $fileBackend->delete( [ 'src' => $path ] );
1710 * // Demark the end of this conceptual unit of updates
1711 * $dbw->endAtomic( __METHOD__ );
1713 * // Discard these writes from the transaction (preserving prior writes)
1714 * $dbw->cancelAtomic( __METHOD__, $sectionId );
1719 * @param string $fname
1720 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1721 * savepoint and enable self::cancelAtomic() for this section.
1722 * @return AtomicSectionIdentifier section ID token
1725 public function startAtomic( $fname = __METHOD__
, $cancelable = self
::ATOMIC_NOT_CANCELABLE
);
1728 * Ends an atomic section of SQL statements
1730 * Ends the next section of atomic SQL statements and commits the transaction
1734 * @see IDatabase::startAtomic
1735 * @param string $fname
1738 public function endAtomic( $fname = __METHOD__
);
1741 * Cancel an atomic section of SQL statements
1743 * This will roll back only the statements executed since the start of the
1744 * most recent atomic section, and close that section. If a transaction was
1745 * open before the corresponding startAtomic() call, any statements before
1746 * that call are *not* rolled back and the transaction remains open. If the
1747 * corresponding startAtomic() implicitly started a transaction, that
1748 * transaction is rolled back.
1750 * @note callers must use additional measures for situations involving two or more
1751 * (peer) transactions (e.g. updating two database servers at once). The transaction
1752 * and savepoint logic of startAtomic() are bound to specific IDatabase instances.
1754 * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
1756 * @note As a micro-optimization to save a few DB calls, this method may only
1757 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1759 * @see IDatabase::startAtomic
1760 * @param string $fname
1761 * @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
1762 * passing this enables cancellation of unclosed nested sections [optional]
1765 public function cancelAtomic( $fname = __METHOD__
, AtomicSectionIdentifier
$sectionId = null );
1768 * Perform an atomic section of reversable SQL statements from a callback
1770 * The $callback takes the following arguments:
1771 * - This database object
1772 * - The value of $fname
1774 * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
1775 * If any exception occurs during execution of the callback, it will be handled as follows:
1776 * - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
1777 * (and only) statements executed during the atomic section. If that succeeds, then the
1778 * exception will be re-thrown; if it fails, then a different exception will be thrown
1779 * and any further query attempts will fail until rollback() is called.
1780 * - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
1781 * end of the section and the error will be re-thrown. Any further query attempts will
1782 * fail until rollback() is called.
1784 * This method is convenient for letting calls to the caller of this method be wrapped
1785 * in a try/catch blocks for exception types that imply that the caller failed but was
1786 * able to properly discard the changes it made in the transaction. This method can be
1787 * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
1789 * Example usage, "RecordStore::save" method:
1791 * $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
1792 * // Create new record metadata row
1793 * $dbw->insert( 'records', $record->toArray(), __METHOD__ );
1794 * // Figure out where to store the data based on the new row's ID
1795 * $path = $this->recordDirectory . '/' . $dbw->insertId();
1796 * // Write the record data to the storage system;
1797 * // blob store throughs StoreFailureException on failure
1798 * $this->blobStore->create( $path, $record->getJSON() );
1799 * // Try to cleanup files orphaned by transaction rollback
1800 * $dbw->onTransactionResolution(
1801 * function ( $type ) use ( $path ) {
1802 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1803 * $this->blobStore->delete( $path );
1808 * }, $dbw::ATOMIC_CANCELABLE );
1811 * Example usage, caller of the "RecordStore::save" method:
1813 * $dbw->startAtomic( __METHOD__ );
1814 * // ...various SQL writes happen...
1816 * $recordStore->save( $record );
1817 * } catch ( StoreFailureException $e ) {
1818 * // ...various SQL writes happen...
1820 * // ...various SQL writes happen...
1821 * $dbw->endAtomic( __METHOD__ );
1824 * @see Database::startAtomic
1825 * @see Database::endAtomic
1826 * @see Database::cancelAtomic
1828 * @param string $fname Caller name (usually __METHOD__)
1829 * @param callable $callback Callback that issues DB updates
1830 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1831 * savepoint and enable self::cancelAtomic() for this section.
1832 * @return mixed $res Result of the callback (since 1.28)
1834 * @throws RuntimeException
1835 * @since 1.27; prior to 1.31 this did a rollback() instead of
1836 * cancelAtomic(), and assumed no callers up the stack would ever try to
1837 * catch the exception.
1839 public function doAtomicSection(
1840 $fname, callable
$callback, $cancelable = self
::ATOMIC_NOT_CANCELABLE
1844 * Begin a transaction. If a transaction is already in progress,
1845 * that transaction will be committed before the new transaction is started.
1847 * Only call this from code with outer transcation scope.
1848 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1849 * Nesting of transactions is not supported.
1851 * Note that when the DBO_TRX flag is set (which is usually the case for web
1852 * requests, but not for maintenance scripts), any previous database query
1853 * will have started a transaction automatically.
1855 * Nesting of transactions is not supported. Attempts to nest transactions
1856 * will cause a warning, unless the current transaction was started
1857 * automatically because of the DBO_TRX flag.
1859 * @param string $fname Calling function name
1860 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1863 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1866 * Commits a transaction previously started using begin().
1867 * If no transaction is in progress, a warning is issued.
1869 * Only call this from code with outer transcation scope.
1870 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1871 * Nesting of transactions is not supported.
1873 * @param string $fname
1874 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1875 * constant to disable warnings about explicitly committing implicit transactions,
1876 * or calling commit when no transaction is in progress.
1878 * This will trigger an exception if there is an ongoing explicit transaction.
1880 * Only set the flush flag if you are sure that these warnings are not applicable,
1881 * and no explicit transactions are open.
1885 public function commit( $fname = __METHOD__
, $flush = '' );
1888 * Rollback a transaction previously started using begin().
1889 * If no transaction is in progress, a warning is issued.
1891 * Only call this from code with outer transcation scope.
1892 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1893 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1894 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1895 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1897 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1899 * @param string $fname Calling function name
1900 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1901 * constant to disable warnings about calling rollback when no transaction is in
1902 * progress. This will silently break any ongoing explicit transaction. Only set the
1903 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1905 * @since 1.23 Added $flush parameter
1907 public function rollback( $fname = __METHOD__
, $flush = '' );
1910 * Commit any transaction but error out if writes or callbacks are pending
1912 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1913 * see a new point-in-time of the database. This is useful when one of many transaction
1914 * rounds finished and significant time will pass in the script's lifetime. It is also
1915 * useful to call on a replica DB after waiting on replication to catch up to the master.
1917 * @param string $fname Calling function name
1921 public function flushSnapshot( $fname = __METHOD__
);
1924 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1925 * to the format used for inserting into timestamp fields in this DBMS.
1927 * The result is unquoted, and needs to be passed through addQuotes()
1928 * before it can be included in raw SQL.
1930 * @param string|int $ts
1934 public function timestamp( $ts = 0 );
1937 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1938 * to the format used for inserting into timestamp fields in this DBMS. If
1939 * NULL is input, it is passed through, allowing NULL values to be inserted
1940 * into timestamp fields.
1942 * The result is unquoted, and needs to be passed through addQuotes()
1943 * before it can be included in raw SQL.
1945 * @param string|int|null $ts
1949 public function timestampOrNull( $ts = null );
1952 * Ping the server and try to reconnect if it there is no connection
1954 * @param float|null &$rtt Value to store the estimated RTT [optional]
1955 * @return bool Success or failure
1957 public function ping( &$rtt = null );
1960 * Get the amount of replication lag for this database server
1962 * Callers should avoid using this method while a transaction is active
1964 * @return int|bool Database replication lag in seconds or false on error
1967 public function getLag();
1970 * Get the replica DB lag when the current transaction started
1971 * or a general lag estimate if not transaction is active
1973 * This is useful when transactions might use snapshot isolation
1974 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1975 * is this lag plus transaction duration. If they don't, it is still
1976 * safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
1977 * indication of the staleness of subsequent reads.
1979 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1983 public function getSessionLagStatus();
1986 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1990 public function maxListLen();
1993 * Some DBMSs have a special format for inserting into blob fields, they
1994 * don't allow simple quoted strings to be inserted. To insert into such
1995 * a field, pass the data through this function before passing it to
1996 * IDatabase::insert().
1999 * @return string|Blob
2001 public function encodeBlob( $b );
2004 * Some DBMSs return a special placeholder object representing blob fields
2005 * in result objects. Pass the object through this function to return the
2008 * @param string|Blob $b
2011 public function decodeBlob( $b );
2014 * Override database's default behavior. $options include:
2015 * 'connTimeout' : Set the connection timeout value in seconds.
2016 * May be useful for very long batch queries such as
2017 * full-wiki dumps, where a single query reads out over
2020 * @param array $options
2024 public function setSessionOptions( array $options );
2027 * Set variables to be used in sourceFile/sourceStream, in preference to the
2028 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
2029 * all. If it's set to false, $GLOBALS will be used.
2031 * @param bool|array $vars Mapping variable name to value.
2033 public function setSchemaVars( $vars );
2036 * Check to see if a named lock is not locked by any thread (non-blocking)
2038 * @param string $lockName Name of lock to poll
2039 * @param string $method Name of method calling us
2044 public function lockIsFree( $lockName, $method );
2047 * Acquire a named lock
2049 * Named locks are not related to transactions
2051 * @param string $lockName Name of lock to aquire
2052 * @param string $method Name of the calling method
2053 * @param int $timeout Acquisition timeout in seconds
2057 public function lock( $lockName, $method, $timeout = 5 );
2062 * Named locks are not related to transactions
2064 * @param string $lockName Name of lock to release
2065 * @param string $method Name of the calling method
2067 * @return int Returns 1 if the lock was released, 0 if the lock was not established
2068 * by this thread (in which case the lock is not released), and NULL if the named lock
2073 public function unlock( $lockName, $method );
2076 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
2078 * Only call this from outer transcation scope and when only one DB will be affected.
2079 * See https://www.mediawiki.org/wiki/Database_transactions for details.
2081 * This is suitiable for transactions that need to be serialized using cooperative locks,
2082 * where each transaction can see each others' changes. Any transaction is flushed to clear
2083 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
2084 * the lock will be released unless a transaction is active. If one is active, then the lock
2085 * will be released when it either commits or rolls back.
2087 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
2089 * @param string $lockKey Name of lock to release
2090 * @param string $fname Name of the calling method
2091 * @param int $timeout Acquisition timeout in seconds
2092 * @return ScopedCallback|null
2096 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
2099 * Check to see if a named lock used by lock() use blocking queues
2104 public function namedLocksEnqueue();
2107 * Find out when 'infinity' is. Most DBMSes support this. This is a special
2108 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
2109 * because "i" sorts after all numbers.
2113 public function getInfinity();
2116 * Encode an expiry time into the DBMS dependent format
2118 * @param string $expiry Timestamp for expiry, or the 'infinity' string
2121 public function encodeExpiry( $expiry );
2124 * Decode an expiry time into a DBMS independent format
2126 * @param string $expiry DB timestamp field value for expiry
2127 * @param int $format TS_* constant, defaults to TS_MW
2130 public function decodeExpiry( $expiry, $format = TS_MW
);
2133 * Allow or deny "big selects" for this session only. This is done by setting
2134 * the sql_big_selects session variable.
2136 * This is a MySQL-specific feature.
2138 * @param bool|string $value True for allow, false for deny, or "default" to
2139 * restore the initial value
2141 public function setBigSelects( $value = true );
2144 * @return bool Whether this DB is read-only
2147 public function isReadOnly();
2150 * Make certain table names use their own database, schema, and table prefix
2151 * when passed into SQL queries pre-escaped and without a qualified database name
2153 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
2154 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
2156 * Calling this twice will completely clear any old table aliases. Also, note that
2157 * callers are responsible for making sure the schemas and databases actually exist.
2159 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
2162 public function setTableAliases( array $aliases );
2165 * Convert certain index names to alternative names before querying the DB
2167 * Note that this applies to indexes regardless of the table they belong to.
2169 * This can be employed when an index was renamed X => Y in code, but the new Y-named
2170 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
2171 * the aliases can be removed, and then the old X-named indexes dropped.
2173 * @param string[] $aliases
2176 public function setIndexAliases( array $aliases );
2180 * @deprecated since 1.29
2182 class_alias( IDatabase
::class, 'IDatabase' );