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;
117 /** @var bool Parameter to unionQueries() for UNION ALL */
118 const UNION_ALL
= true;
119 /** @var bool Parameter to unionQueries() for UNION DISTINCT */
120 const UNION_DISTINCT
= false;
123 * A string describing the current software version, and possibly
124 * other details in a user-friendly way. Will be listed on Special:Version, etc.
125 * Use getServerVersion() to get machine-friendly information.
127 * @return string Version information from the database server
129 public function getServerInfo();
132 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
134 * Unbuffered queries are very troublesome in MySQL:
136 * - If another query is executed while the first query is being read
137 * out, the first query is killed. This means you can't call normal
138 * Database functions while you are reading an unbuffered query result
139 * from a normal Database connection.
141 * - Unbuffered queries cause the MySQL server to use large amounts of
142 * memory and to hold broad locks which block other queries.
144 * If you want to limit client-side memory, it's almost always better to
145 * split up queries into batches using a LIMIT clause than to switch off
148 * @param null|bool $buffer
149 * @return null|bool The previous value of the flag
151 public function bufferResults( $buffer = null );
154 * Gets the current transaction level.
156 * Historically, transactions were allowed to be "nested". This is no
157 * longer supported, so this function really only returns a boolean.
159 * @return int The previous value
161 public function trxLevel();
164 * Get the UNIX timestamp of the time that the transaction was established
166 * This can be used to reason about the staleness of SELECT data
167 * in REPEATABLE-READ transaction isolation level.
169 * @return float|null Returns null if there is not active transaction
172 public function trxTimestamp();
175 * @return bool Whether an explicit transaction or atomic sections are still open
178 public function explicitTrxActive();
181 * Assert that all explicit transactions or atomic sections have been closed.
182 * @throws DBTransactionError
185 public function assertNoOpenTransactions();
188 * Get/set the table prefix.
189 * @param string|null $prefix The table prefix to set, or omitted to leave it unchanged.
190 * @return string The previous table prefix
191 * @throws DBUnexpectedError
193 public function tablePrefix( $prefix = null );
196 * Get/set the db schema.
197 * @param string|null $schema The database schema to set, or omitted to leave it unchanged.
198 * @return string The previous db schema
200 public function dbSchema( $schema = null );
203 * Get properties passed down from the server info array of the load
206 * @param string|null $name The entry of the info array to get, or null to get the
209 * @return array|mixed|null
211 public function getLBInfo( $name = null );
214 * Set the LB info array, or a member of it. If called with one parameter,
215 * the LB info array is set to that parameter. If it is called with two
216 * parameters, the member with the given name is set to the given value.
218 * @param string $name
219 * @param array|null $value
221 public function setLBInfo( $name, $value = null );
224 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
226 * @param IDatabase $conn
229 public function setLazyMasterHandle( IDatabase
$conn );
232 * Returns true if this database does an implicit sort when doing GROUP BY
235 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
237 public function implicitGroupby();
240 * Returns true if this database does an implicit order by when the column has an index
241 * For example: SELECT page_title FROM page LIMIT 1
245 public function implicitOrderby();
248 * Return the last query that went through IDatabase::query()
251 public function lastQuery();
254 * Returns true if the connection may have been used for write queries.
255 * Should return true if unsure.
258 * @deprecated Since 1.31; use lastDoneWrites()
260 public function doneWrites();
263 * Returns the last time the connection may have been used for write queries.
264 * Should return a timestamp if unsure.
266 * @return int|float UNIX timestamp or false
269 public function lastDoneWrites();
272 * @return bool Whether there is a transaction open with possible write queries
275 public function writesPending();
278 * @return bool Whether there is a transaction open with pre-commit callbacks pending
281 public function preCommitCallbacksPending();
284 * Whether there is a transaction open with either possible write queries
285 * or unresolved pre-commit/commit/resolution callbacks pending
287 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
291 public function writesOrCallbacksPending();
294 * Get the time spend running write queries for this transaction
296 * High times could be due to scanning, updates, locking, and such
298 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
299 * @return float|bool Returns false if not transaction is active
302 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
305 * Get the list of method names that did write queries for this transaction
310 public function pendingWriteCallers();
313 * Get the number of affected rows from pending write queries
318 public function pendingWriteRowsAffected();
321 * Is a connection to the database open?
324 public function isOpen();
327 * Set a flag for this connection
329 * @param int $flag DBO_* constants from Defines.php:
330 * - DBO_DEBUG: output some debug info (same as debug())
331 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
332 * - DBO_TRX: automatically start transactions
333 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
334 * and removes it in command line mode
335 * - DBO_PERSISTENT: use persistant database connection
336 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
338 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
341 * Clear a flag for this connection
343 * @param int $flag DBO_* constants from Defines.php:
344 * - DBO_DEBUG: output some debug info (same as debug())
345 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
346 * - DBO_TRX: automatically start transactions
347 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
348 * and removes it in command line mode
349 * - DBO_PERSISTENT: use persistant database connection
350 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
352 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
355 * Restore the flags to their prior state before the last setFlag/clearFlag call
357 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
360 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
363 * Returns a boolean whether the flag $flag is set for this connection
365 * @param int $flag DBO_* constants from Defines.php:
366 * - DBO_DEBUG: output some debug info (same as debug())
367 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
368 * - DBO_TRX: automatically start transactions
369 * - DBO_PERSISTENT: use persistant database connection
372 public function getFlag( $flag );
375 * Return the currently selected domain ID
377 * Null components (database/schema) might change once a connection is established
381 public function getDomainID();
384 * Alias for getDomainID()
389 public function getWikiID();
392 * Get the type of the DBMS, as it appears in $wgDBtype.
396 public function getType();
399 * Fetch the next row from the given result object, in object form.
400 * Fields can be retrieved with $row->fieldname, with fields acting like
402 * If no more rows are available, false is returned.
404 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
405 * @return stdClass|bool
406 * @throws DBUnexpectedError Thrown if the database returns an error
408 public function fetchObject( $res );
411 * Fetch the next row from the given result object, in associative array
412 * form. Fields are retrieved with $row['fieldname'].
413 * If no more rows are available, false is returned.
415 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
417 * @throws DBUnexpectedError Thrown if the database returns an error
419 public function fetchRow( $res );
422 * Get the number of rows in a query result. If the query did not return
423 * any rows (for example, if it was a write query), this returns zero.
425 * @param mixed $res A SQL result
428 public function numRows( $res );
431 * Get the number of fields in a result object
432 * @see https://secure.php.net/mysql_num_fields
434 * @param mixed $res A SQL result
437 public function numFields( $res );
440 * Get a field name in a result object
441 * @see https://secure.php.net/mysql_field_name
443 * @param mixed $res A SQL result
447 public function fieldName( $res, $n );
450 * Get the inserted value of an auto-increment row
452 * This should only be called after an insert that used an auto-incremented
453 * value. If no such insert was previously done in the current database
454 * session, the return value is undefined.
458 public function insertId();
461 * Change the position of the cursor in a result object
462 * @see https://secure.php.net/mysql_data_seek
464 * @param mixed $res A SQL result
467 public function dataSeek( $res, $row );
470 * Get the last error number
471 * @see https://secure.php.net/mysql_errno
475 public function lastErrno();
478 * Get a description of the last error
479 * @see https://secure.php.net/mysql_error
483 public function lastError();
486 * Get the number of rows affected by the last write query
487 * @see https://secure.php.net/mysql_affected_rows
491 public function affectedRows();
494 * Returns a wikitext link to the DB's website, e.g.,
495 * return "[https://www.mysql.com/ MySQL]";
496 * Should at least contain plain text, if for some reason
497 * your database has no website.
499 * @return string Wikitext of a link to the server software's web site
501 public function getSoftwareLink();
504 * A string describing the current software version, like from
505 * mysql_get_server_info().
507 * @return string Version information from the database server.
509 public function getServerVersion();
512 * Close the database connection
514 * This should only be called after any transactions have been resolved,
515 * aside from read-only automatic transactions (assuming no callbacks are registered).
516 * If a transaction is still open anyway, it will be rolled back.
519 * @return bool Operation success. true if already closed.
521 public function close();
524 * Run an SQL query and return the result. Normally throws a DBQueryError
525 * on failure. If errors are ignored, returns false instead.
527 * If a connection loss is detected, then an attempt to reconnect will be made.
528 * For queries that involve no larger transactions or locks, they will be re-issued
529 * for convenience, provided the connection was re-established.
531 * In new code, the query wrappers select(), insert(), update(), delete(),
532 * etc. should be used where possible, since they give much better DBMS
533 * independence and automatically quote or validate user input in a variety
534 * of contexts. This function is generally only useful for queries which are
535 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
538 * However, the query wrappers themselves should call this function.
540 * @param string $sql SQL query
541 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
542 * comment (you can use __METHOD__ or add some extra info)
543 * @param int $flags Bitfield of IDatabase::QUERY_* constants. Note that suppression
544 * of errors is best handled by try/catch rather than using one of these flags.
545 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
546 * for a successful read query, or false on failure if QUERY_SILENCE_ERRORS is set.
549 public function query( $sql, $fname = __METHOD__
, $flags = 0 );
552 * Free a result object returned by query() or select(). It's usually not
553 * necessary to call this, just use unset() or let the variable holding
554 * the result object go out of scope.
556 * @param mixed $res A SQL result
558 public function freeResult( $res );
561 * A SELECT wrapper which returns a single field from a single result row.
563 * Usually throws a DBQueryError on failure. If errors are explicitly
564 * ignored, returns false on failure.
566 * If no result rows are returned from the query, false is returned.
568 * @param string|array $table Table name. See IDatabase::select() for details.
569 * @param string $var The field name to select. This must be a valid SQL
570 * fragment: do not use unvalidated user input.
571 * @param string|array $cond The condition array. See IDatabase::select() for details.
572 * @param string $fname The function name of the caller.
573 * @param string|array $options The query options. See IDatabase::select() for details.
574 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
576 * @return mixed The value from the field
579 public function selectField(
580 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
584 * A SELECT wrapper which returns a list of single field values from result rows.
586 * Usually throws a DBQueryError on failure. If errors are explicitly
587 * ignored, returns false on failure.
589 * If no result rows are returned from the query, false is returned.
591 * @param string|array $table Table name. See IDatabase::select() for details.
592 * @param string $var The field name to select. This must be a valid SQL
593 * fragment: do not use unvalidated user input.
594 * @param string|array $cond The condition array. See IDatabase::select() for details.
595 * @param string $fname The function name of the caller.
596 * @param string|array $options The query options. See IDatabase::select() for details.
597 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
599 * @return array The values from the field in the order they were returned from the DB
603 public function selectFieldValues(
604 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
608 * Execute a SELECT query constructed using the various parameters provided.
609 * See below for full details of the parameters.
611 * @param string|array $table Table name(s)
613 * May be either an array of table names, or a single string holding a table
614 * name. If an array is given, table aliases can be specified, for example:
618 * This includes the user table in the query, with the alias "a" available
619 * for use in field names (e.g. a.user_name).
621 * A derived table, defined by the result of selectSQLText(), requires an alias
622 * key and a Subquery instance value which wraps the SQL query, for example:
624 * [ 'c' => new Subquery( 'SELECT ...' ) ]
626 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
627 * constructed using nested arrays. For example,
629 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
631 * along with `$join_conds` like
633 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
635 * will produce SQL something like
637 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
639 * All of the table names given here are automatically run through
640 * Database::tableName(), which causes the table prefix (if any) to be
641 * added, and various other table name mappings to be performed.
643 * Do not use untrusted user input as a table name. Alias names should
644 * not have characters outside of the Basic multilingual plane.
646 * @param string|array $vars Field name(s)
648 * May be either a field name or an array of field names. The field names
649 * can be complete fragments of SQL, for direct inclusion into the SELECT
650 * query. If an array is given, field aliases can be specified, for example:
652 * [ 'maxrev' => 'MAX(rev_id)' ]
654 * This includes an expression with the alias "maxrev" in the query.
656 * If an expression is given, care must be taken to ensure that it is
659 * Untrusted user input must not be passed to this parameter.
661 * @param string|array $conds
663 * May be either a string containing a single condition, or an array of
664 * conditions. If an array is given, the conditions constructed from each
665 * element are combined with AND.
667 * Array elements may take one of two forms:
669 * - Elements with a numeric key are interpreted as raw SQL fragments.
670 * - Elements with a string key are interpreted as equality conditions,
671 * where the key is the field name.
672 * - If the value of such an array element is a scalar (such as a
673 * string), it will be treated as data and thus quoted appropriately.
674 * If it is null, an IS NULL clause will be added.
675 * - If the value is an array, an IN (...) clause will be constructed
676 * from its non-null elements, and an IS NULL clause will be added
677 * if null is present, such that the field may match any of the
678 * elements in the array. The non-null elements will be quoted.
680 * Note that expressions are often DBMS-dependent in their syntax.
681 * DBMS-independent wrappers are provided for constructing several types of
682 * expression commonly used in condition queries. See:
683 * - IDatabase::buildLike()
684 * - IDatabase::conditional()
686 * Untrusted user input is safe in the values of string keys, however untrusted
687 * input must not be used in the array key names or in the values of numeric keys.
688 * Escaping of untrusted input used in values of numeric keys should be done via
689 * IDatabase::addQuotes()
691 * Use an empty array, string, or '*' to update all rows.
693 * @param string $fname Caller function name
695 * @param string|array $options Query options
697 * Optional: Array of query options. Boolean options are specified by
698 * including them in the array as a string value with a numeric key, for
703 * The supported options are:
705 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
706 * with LIMIT can theoretically be used for paging through a result set,
707 * but this is discouraged for performance reasons.
709 * - LIMIT: Integer: return at most this many rows. The rows are sorted
710 * and then the first rows are taken until the limit is reached. LIMIT
711 * is applied to a result set after OFFSET.
713 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
714 * changed until the next COMMIT.
716 * - DISTINCT: Boolean: return only unique result rows.
718 * - GROUP BY: May be either an SQL fragment string naming a field or
719 * expression to group by, or an array of such SQL fragments.
721 * - HAVING: May be either an string containing a HAVING clause or an array of
722 * conditions building the HAVING clause. If an array is given, the conditions
723 * constructed from each element are combined with AND.
725 * - ORDER BY: May be either an SQL fragment giving a field name or
726 * expression to order by, or an array of such SQL fragments.
728 * - USE INDEX: This may be either a string giving the index name to use
729 * for the query, or an array. If it is an associative array, each key
730 * gives the table name (or alias), each value gives the index name to
731 * use for that table. All strings are SQL fragments and so should be
732 * validated by the caller.
734 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
737 * And also the following boolean MySQL extensions, see the MySQL manual
740 * - LOCK IN SHARE MODE
744 * - SQL_BUFFER_RESULT
746 * - SQL_CALC_FOUND_ROWS
751 * @param string|array $join_conds Join conditions
753 * Optional associative array of table-specific join conditions. In the
754 * most common case, this is unnecessary, since the join condition can be
755 * in $conds. However, it is useful for doing a LEFT JOIN.
757 * The key of the array contains the table name or alias. The value is an
758 * array with two elements, numbered 0 and 1. The first gives the type of
759 * join, the second is the same as the $conds parameter. Thus it can be
760 * an SQL fragment, or an array where the string keys are equality and the
761 * numeric keys are SQL fragments all AND'd together. For example:
763 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
765 * @return IResultWrapper Resulting rows
768 public function select(
769 $table, $vars, $conds = '', $fname = __METHOD__
,
770 $options = [], $join_conds = []
774 * The equivalent of IDatabase::select() except that the constructed SQL
775 * is returned, instead of being immediately executed. This can be useful for
776 * doing UNION queries, where the SQL text of each query is needed. In general,
777 * however, callers outside of Database classes should just use select().
779 * @see IDatabase::select()
781 * @param string|array $table Table name
782 * @param string|array $vars Field names
783 * @param string|array $conds Conditions
784 * @param string $fname Caller function name
785 * @param string|array $options Query options
786 * @param string|array $join_conds Join conditions
787 * @return string SQL query string
789 public function selectSQLText(
790 $table, $vars, $conds = '', $fname = __METHOD__
,
791 $options = [], $join_conds = []
795 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
796 * that a single row object is returned. If the query returns no rows,
799 * @param string|array $table Table name
800 * @param string|array $vars Field names
801 * @param array $conds Conditions
802 * @param string $fname Caller function name
803 * @param string|array $options Query options
804 * @param array|string $join_conds Join conditions
806 * @return stdClass|bool
809 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
810 $options = [], $join_conds = []
814 * Estimate the number of rows in dataset
816 * MySQL allows you to estimate the number of rows that would be returned
817 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
818 * index cardinality statistics, and is notoriously inaccurate, especially
819 * when large numbers of rows have recently been added or deleted.
821 * For DBMSs that don't support fast result size estimation, this function
822 * will actually perform the SELECT COUNT(*).
824 * Takes the same arguments as IDatabase::select().
826 * @param string $table Table name
827 * @param string $var Column for which NULL values are not counted [default "*"]
828 * @param array|string $conds Filters on the table
829 * @param string $fname Function name for profiling
830 * @param array $options Options for select
831 * @param array|string $join_conds Join conditions
832 * @return int Row count
835 public function estimateRowCount(
836 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
840 * Get the number of rows in dataset
842 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
844 * Takes the same arguments as IDatabase::select().
846 * @since 1.27 Added $join_conds parameter
848 * @param array|string $tables Table names
849 * @param string $var Column for which NULL values are not counted [default "*"]
850 * @param array|string $conds Filters on the table
851 * @param string $fname Function name for profiling
852 * @param array $options Options for select
853 * @param array $join_conds Join conditions (since 1.27)
854 * @return int Row count
857 public function selectRowCount(
858 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
862 * Lock all rows meeting the given conditions/options FOR UPDATE
864 * @param array|string $table Table names
865 * @param array|string $conds Filters on the table
866 * @param string $fname Function name for profiling
867 * @param array $options Options for select ("FOR UPDATE" is added automatically)
868 * @param array $join_conds Join conditions
869 * @return int Number of matching rows found (and locked)
872 public function lockForUpdate(
873 $table, $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
877 * Determines whether a field exists in a table
879 * @param string $table Table name
880 * @param string $field Filed to check on that table
881 * @param string $fname Calling function name (optional)
882 * @return bool Whether $table has filed $field
885 public function fieldExists( $table, $field, $fname = __METHOD__
);
888 * Determines whether an index exists
889 * Usually throws a DBQueryError on failure
890 * If errors are explicitly ignored, returns NULL on failure
892 * @param string $table
893 * @param string $index
894 * @param string $fname
898 public function indexExists( $table, $index, $fname = __METHOD__
);
901 * Query whether a given table exists
903 * @param string $table
904 * @param string $fname
908 public function tableExists( $table, $fname = __METHOD__
);
911 * INSERT wrapper, inserts an array into a table.
915 * - A single associative array. The array keys are the field names, and
916 * the values are the values to insert. The values are treated as data
917 * and will be quoted appropriately. If NULL is inserted, this will be
918 * converted to a database NULL.
919 * - An array with numeric keys, holding a list of associative arrays.
920 * This causes a multi-row INSERT on DBMSs that support it. The keys in
921 * each subarray must be identical to each other, and in the same order.
923 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
926 * $options is an array of options, with boolean options encoded as values
927 * with numeric keys, in the same style as $options in
928 * IDatabase::select(). Supported options are:
930 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
931 * any rows which cause duplicate key errors are not inserted. It's
932 * possible to determine how many rows were successfully inserted using
933 * IDatabase::affectedRows().
935 * @param string $table Table name. This will be passed through
936 * Database::tableName().
937 * @param array $a Array of rows to insert
938 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
939 * @param array $options Array of options
940 * @return bool Return true if no exception was thrown (deprecated since 1.33)
943 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
946 * UPDATE wrapper. Takes a condition array and a SET array.
948 * @param string $table Name of the table to UPDATE. This will be passed through
949 * Database::tableName().
950 * @param array $values An array of values to SET. For each array element,
951 * the key gives the field name, and the value gives the data to set
952 * that field to. The data will be quoted by IDatabase::addQuotes().
953 * Values with integer keys form unquoted SET statements, which can be used for
954 * things like "field = field + 1" or similar computed values.
955 * @param array $conds An array of conditions (WHERE). See
956 * IDatabase::select() for the details of the format of condition
957 * arrays. Use '*' to update all rows.
958 * @param string $fname The function name of the caller (from __METHOD__),
959 * for logging and profiling.
960 * @param array $options An array of UPDATE options, can be:
961 * - IGNORE: Ignore unique key conflicts
962 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
963 * @return bool Return true if no exception was thrown (deprecated since 1.33)
966 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
969 * Makes an encoded list of strings from an array
971 * These can be used to make conjunctions or disjunctions on SQL condition strings
972 * derived from an array (see IDatabase::select() $conds documentation).
976 * $sql = $db->makeList( [
978 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
979 * ], $db::LIST_AND );
981 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
983 * @param array $a Containing the data
984 * @param int $mode IDatabase class constant:
985 * - IDatabase::LIST_COMMA: Comma separated, no field names
986 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
987 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
988 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
989 * - IDatabase::LIST_NAMES: Comma separated field names
993 public function makeList( $a, $mode = self
::LIST_COMMA
);
996 * Build a partial where clause from a 2-d array such as used for LinkBatch.
997 * The keys on each level may be either integers or strings.
999 * @param array $data Organized as 2-d
1000 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
1001 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
1002 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
1003 * @return string|bool SQL fragment, or false if no items in array
1005 public function makeWhereFrom2d( $data, $baseKey, $subKey );
1008 * Return aggregated value alias
1010 * @param array $valuedata
1011 * @param string $valuename
1014 * @deprecated Since 1.33
1016 public function aggregateValue( $valuedata, $valuename = 'value' );
1019 * @param string $field
1022 public function bitNot( $field );
1025 * @param string $fieldLeft
1026 * @param string $fieldRight
1029 public function bitAnd( $fieldLeft, $fieldRight );
1032 * @param string $fieldLeft
1033 * @param string $fieldRight
1036 public function bitOr( $fieldLeft, $fieldRight );
1039 * Build a concatenation list to feed into a SQL query
1040 * @param array $stringList List of raw SQL expressions; caller is
1041 * responsible for any quoting
1044 public function buildConcat( $stringList );
1047 * Build a GROUP_CONCAT or equivalent statement for a query.
1049 * This is useful for combining a field for several rows into a single string.
1050 * NULL values will not appear in the output, duplicated values will appear,
1051 * and the resulting delimiter-separated values have no defined sort order.
1052 * Code using the results may need to use the PHP unique() or sort() methods.
1054 * @param string $delim Glue to bind the results together
1055 * @param string|array $table Table name
1056 * @param string $field Field name
1057 * @param string|array $conds Conditions
1058 * @param string|array $join_conds Join conditions
1059 * @return string SQL text
1062 public function buildGroupConcatField(
1063 $delim, $table, $field, $conds = '', $join_conds = []
1067 * Build a SUBSTRING function.
1069 * Behavior for non-ASCII values is undefined.
1071 * @param string $input Field name
1072 * @param int $startPosition Positive integer
1073 * @param int|null $length Non-negative integer length or null for no limit
1074 * @throws InvalidArgumentException
1075 * @return string SQL text
1078 public function buildSubString( $input, $startPosition, $length = null );
1081 * @param string $field Field or column to cast
1085 public function buildStringCast( $field );
1088 * @param string $field Field or column to cast
1092 public function buildIntegerCast( $field );
1095 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1097 * @see IDatabase::selectSQLText()
1099 * @param string|array $table Table name
1100 * @param string|array $vars Field names
1101 * @param string|array $conds Conditions
1102 * @param string $fname Caller function name
1103 * @param string|array $options Query options
1104 * @param string|array $join_conds Join conditions
1108 public function buildSelectSubquery(
1109 $table, $vars, $conds = '', $fname = __METHOD__
,
1110 $options = [], $join_conds = []
1114 * Returns true if DBs are assumed to be on potentially different servers
1116 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1117 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1118 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1119 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1124 public function databasesAreIndependent();
1127 * Change the current database
1129 * This should not be called outside LoadBalancer for connections managed by a LoadBalancer
1132 * @return bool True unless an exception was thrown
1133 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1135 * @deprecated Since 1.32 Use selectDomain() instead
1137 public function selectDB( $db );
1140 * Set the current domain (database, schema, and table prefix)
1142 * This will throw an error for some database types if the database unspecified
1144 * This should not be called outside LoadBalancer for connections managed by a LoadBalancer
1146 * @param string|DatabaseDomain $domain
1148 * @throws DBConnectionError
1150 public function selectDomain( $domain );
1153 * Get the current DB name
1154 * @return string|null
1156 public function getDBname();
1159 * Get the server hostname or IP address
1162 public function getServer();
1165 * Adds quotes and backslashes.
1167 * @param string|int|null|bool|Blob $s
1168 * @return string|int
1170 public function addQuotes( $s );
1173 * Quotes an identifier, in order to make user controlled input safe
1175 * Depending on the database this will either be `backticks` or "double quotes"
1181 public function addIdentifierQuotes( $s );
1184 * LIKE statement wrapper, receives a variable-length argument list with
1185 * parts of pattern to match containing either string literals that will be
1186 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1187 * the function could be provided with an array of aforementioned
1190 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1191 * a LIKE clause that searches for subpages of 'My page title'.
1193 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1194 * $query .= $dbr->buildLike( $pattern );
1197 * @return string Fully built LIKE statement
1199 public function buildLike();
1202 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1206 public function anyChar();
1209 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1213 public function anyString();
1216 * Deprecated method, calls should be removed.
1218 * This was formerly used for PostgreSQL and Oracle to handle
1219 * self::insertId() auto-incrementing fields. It is no longer necessary
1220 * since DatabasePostgres::insertId() has been reimplemented using
1221 * `lastval()` and Oracle has been reimplemented using triggers.
1223 * Implementations should return null if inserting `NULL` into an
1224 * auto-incrementing field works, otherwise it should return an instance of
1225 * NextSequenceValue and filter it on calls to relevant methods.
1227 * @deprecated since 1.30, no longer needed
1228 * @param string $seqName
1229 * @return null|NextSequenceValue
1231 public function nextSequenceValue( $seqName );
1234 * REPLACE query wrapper.
1236 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1237 * except that when there is a duplicate key error, the old row is deleted
1238 * and the new row is inserted in its place.
1240 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1241 * perform the delete, we need to know what the unique indexes are so that
1242 * we know how to find the conflicting rows.
1244 * It may be more efficient to leave off unique indexes which are unlikely
1245 * to collide. However if you do this, you run the risk of encountering
1246 * errors which wouldn't have occurred in MySQL.
1248 * @param string $table The table to replace the row(s) in.
1249 * @param array[]|string[]|string $uniqueIndexes All unique indexes. One of the following:
1250 * a) the one unique field in the table (when no composite unique key exist)
1251 * b) a list of all unique fields in the table (when no composite unique key exist)
1252 * c) a list of all unique indexes in the table (each as a list of the indexed fields)
1253 * @param array $rows Can be either a single row to insert, or multiple rows,
1254 * in the same format as for IDatabase::insert()
1255 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1258 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1261 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1263 * This updates any conflicting rows (according to the unique indexes) using
1264 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1266 * $rows may be either:
1267 * - A single associative array. The array keys are the field names, and
1268 * the values are the values to insert. The values are treated as data
1269 * and will be quoted appropriately. If NULL is inserted, this will be
1270 * converted to a database NULL.
1271 * - An array with numeric keys, holding a list of associative arrays.
1272 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1273 * each subarray must be identical to each other, and in the same order.
1275 * It may be more efficient to leave off unique indexes which are unlikely
1276 * to collide. However if you do this, you run the risk of encountering
1277 * errors which wouldn't have occurred in MySQL.
1279 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1284 * @param string $table Table name. This will be passed through Database::tableName().
1285 * @param array $rows A single row or list of rows to insert
1286 * @param array[]|string[]|string $uniqueIndexes All unique indexes. One of the following:
1287 * a) the one unique field in the table (when no composite unique key exist)
1288 * b) a list of all unique fields in the table (when no composite unique key exist)
1289 * c) a list of all unique indexes in the table (each as a list of the indexed fields)
1290 * @param array $set An array of values to SET. For each array element, the
1291 * key gives the field name, and the value gives the data to set that
1292 * field to. The data will be quoted by IDatabase::addQuotes().
1293 * Values with integer keys form unquoted SET statements, which can be used for
1294 * things like "field = field + 1" or similar computed values.
1295 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1297 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1299 public function upsert(
1300 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1304 * DELETE where the condition is a join.
1306 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1307 * we use sub-selects
1309 * For safety, an empty $conds will not delete everything. If you want to
1310 * delete all rows where the join condition matches, set $conds='*'.
1312 * DO NOT put the join condition in $conds.
1314 * @param string $delTable The table to delete from.
1315 * @param string $joinTable The other table.
1316 * @param string $delVar The variable to join on, in the first table.
1317 * @param string $joinVar The variable to join on, in the second table.
1318 * @param array $conds Condition array of field names mapped to variables,
1319 * ANDed together in the WHERE clause
1320 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1323 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1328 * DELETE query wrapper.
1330 * @param string $table Table name
1331 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1332 * for the format. Use $conds == "*" to delete all rows
1333 * @param string $fname Name of the calling function
1334 * @throws DBUnexpectedError
1335 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1338 public function delete( $table, $conds, $fname = __METHOD__
);
1341 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1342 * into another table.
1344 * @warning If the insert will use an auto-increment or sequence to
1345 * determine the value of a column, this may break replication on
1346 * databases using statement-based replication if the SELECT is not
1347 * deterministically ordered.
1349 * @param string $destTable The table name to insert into
1350 * @param string|array $srcTable May be either a table name, or an array of table names
1351 * to include in a join.
1353 * @param array $varMap Must be an associative array of the form
1354 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1355 * rather than field names, but strings should be quoted with
1356 * IDatabase::addQuotes()
1358 * @param array $conds Condition array. See $conds in IDatabase::select() for
1359 * the details of the format of condition arrays. May be "*" to copy the
1362 * @param string $fname The function name of the caller, from __METHOD__
1364 * @param array $insertOptions Options for the INSERT part of the query, see
1365 * IDatabase::insert() for details. Also, one additional option is
1366 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1367 * an auto-increment or sequence to determine any column values.
1368 * @param array $selectOptions Options for the SELECT part of the query, see
1369 * IDatabase::select() for details.
1370 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1371 * IDatabase::select() for details.
1373 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1376 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1377 $fname = __METHOD__
,
1378 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1382 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1383 * within the UNION construct.
1386 public function unionSupportsOrderAndLimit();
1389 * Construct a UNION query
1390 * This is used for providing overload point for other DB abstractions
1391 * not compatible with the MySQL syntax.
1392 * @param array $sqls SQL statements to combine
1393 * @param bool $all Either IDatabase::UNION_ALL or IDatabase::UNION_DISTINCT
1394 * @return string SQL fragment
1396 public function unionQueries( $sqls, $all );
1399 * Construct a UNION query for permutations of conditions
1401 * Databases sometimes have trouble with queries that have multiple values
1402 * for multiple condition parameters combined with limits and ordering.
1403 * This method constructs queries for the Cartesian product of the
1404 * conditions and unions them all together.
1406 * @see IDatabase::select()
1408 * @param string|array $table Table name
1409 * @param string|array $vars Field names
1410 * @param array $permute_conds Conditions for the Cartesian product. Keys
1411 * are field names, values are arrays of the possible values for that
1413 * @param string|array $extra_conds Additional conditions to include in the
1415 * @param string $fname Caller function name
1416 * @param string|array $options Query options. In addition to the options
1417 * recognized by IDatabase::select(), the following may be used:
1418 * - NOTALL: Set to use UNION instead of UNION ALL.
1419 * - INNER ORDER BY: If specified and supported, subqueries will use this
1420 * instead of ORDER BY.
1421 * @param string|array $join_conds Join conditions
1422 * @return string SQL query string.
1424 public function unionConditionPermutations(
1425 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1426 $options = [], $join_conds = []
1430 * Returns an SQL expression for a simple conditional. This doesn't need
1431 * to be overridden unless CASE isn't supported in your DBMS.
1433 * @param string|array $cond SQL expression which will result in a boolean value
1434 * @param string $trueVal SQL expression to return if true
1435 * @param string $falseVal SQL expression to return if false
1436 * @return string SQL fragment
1438 public function conditional( $cond, $trueVal, $falseVal );
1441 * Returns a command for str_replace function in SQL query.
1442 * Uses REPLACE() in MySQL
1444 * @param string $orig Column to modify
1445 * @param string $old Column to seek
1446 * @param string $new Column to replace with
1450 public function strreplace( $orig, $old, $new );
1453 * Determines how long the server has been up
1458 public function getServerUptime();
1461 * Determines if the last failure was due to a deadlock
1463 * Note that during a deadlock, the prior transaction will have been lost
1467 public function wasDeadlock();
1470 * Determines if the last failure was due to a lock timeout
1472 * Note that during a lock wait timeout, the prior transaction will have been lost
1476 public function wasLockTimeout();
1479 * Determines if the last query error was due to a dropped connection
1481 * Note that during a connection loss, the prior transaction will have been lost
1486 public function wasConnectionLoss();
1489 * Determines if the last failure was due to the database being read-only.
1493 public function wasReadOnlyError();
1496 * Determines if the last query error was due to something outside of the query itself
1498 * Note that the transaction may have been lost, discarding prior writes and results
1502 public function wasErrorReissuable();
1505 * Wait for the replica DB to catch up to a given master position
1507 * Note that this does not start any new transactions. If any existing transaction
1508 * is flushed, and this is called, then queries will reflect the point the DB was synced
1509 * up to (on success) without interference from REPEATABLE-READ snapshots.
1511 * @param DBMasterPos $pos
1512 * @param int $timeout The maximum number of seconds to wait for synchronisation
1513 * @return int|null Zero if the replica DB was past that position already,
1514 * greater than zero if we waited for some period of time, less than
1515 * zero if it timed out, and null on error
1518 public function masterPosWait( DBMasterPos
$pos, $timeout );
1521 * Get the replication position of this replica DB
1523 * @return DBMasterPos|bool False if this is not a replica DB
1526 public function getReplicaPos();
1529 * Get the position of this master
1531 * @return DBMasterPos|bool False if this is not a master
1534 public function getMasterPos();
1537 * @return bool Whether the DB is marked as read-only server-side
1540 public function serverIsReadOnly();
1543 * Run a callback as soon as the current transaction commits or rolls back.
1544 * An error is thrown if no transaction is pending. Queries in the function will run in
1545 * AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1548 * This is useful for combining cooperative locks and DB transactions.
1550 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1552 * The callback takes the following arguments:
1553 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1554 * - This IDatabase instance (since 1.32)
1556 * @param callable $callback
1557 * @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
1604 * @deprecated Since 1.32
1606 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1609 * Run a callback before the current transaction commits or now if there is none.
1610 * If there is a transaction and it is rolled back, then the callback is cancelled.
1612 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1613 * of the round, just before all peer transactions COMMIT. If the transaction round
1614 * is rolled back, then the callback is cancelled.
1616 * Callbacks must not start nor commit any transactions. If no transaction is active,
1617 * then a transaction will wrap the callback.
1619 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1620 * but where atomicity is strongly desired for these updates and some related updates.
1622 * Updates will execute in the order they were enqueued.
1624 * The callback takes the one argument:
1625 * - This IDatabase instance (since 1.32)
1627 * @param callable $callback
1628 * @param string $fname Caller name
1631 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1634 * Run a callback after each time any transaction commits or rolls back
1636 * The callback takes two arguments:
1637 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1638 * - This IDatabase object
1639 * Callbacks must commit any transactions that they begin.
1641 * Registering a callback here will not affect writesOrCallbacks() pending.
1643 * Since callbacks from this or onTransactionCommitOrIdle() can start and end transactions,
1644 * a single call to IDatabase::commit might trigger multiple runs of the listener callbacks.
1646 * @param string $name Callback name
1647 * @param callable|null $callback Use null to unset a listener
1651 public function setTransactionListener( $name, callable
$callback = null );
1654 * Begin an atomic section of SQL statements
1656 * Start an implicit transaction if no transaction is already active, set a savepoint
1657 * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
1658 * that the transaction is not committed prematurely. The end of the section must be
1659 * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
1660 * have layers of inner sections (sub-sections), but all sections must be ended in order
1661 * of innermost to outermost. Transactions cannot be started or committed until all
1662 * atomic sections are closed.
1664 * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
1665 * by discarding the section's writes. This should not be used for failures when:
1666 * - upsert() could easily be used instead
1667 * - insert() with IGNORE could easily be used instead
1668 * - select() with FOR UPDATE could be checked before issuing writes instead
1669 * - The failure is from code that runs after the first write but doesn't need to
1670 * - The failures are from contention solvable via onTransactionPreCommitOrIdle()
1671 * - The failures are deadlocks; the RDBMs usually discard the whole transaction
1673 * @note callers must use additional measures for situations involving two or more
1674 * (peer) transactions (e.g. updating two database servers at once). The transaction
1675 * and savepoint logic of this method only applies to this specific IDatabase instance.
1679 * // Start a transaction if there isn't one already
1680 * $dbw->startAtomic( __METHOD__ );
1681 * // Serialize these thread table updates
1682 * $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
1683 * // Add a new comment for the thread
1684 * $dbw->insert( 'comment', $row, __METHOD__ );
1685 * $cid = $db->insertId();
1686 * // Update thread reference to last comment
1687 * $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
1688 * // Demark the end of this conceptual unit of updates
1689 * $dbw->endAtomic( __METHOD__ );
1692 * Example usage (atomic changes that might have to be discarded):
1694 * // Start a transaction if there isn't one already
1695 * $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
1696 * // Create new record metadata row
1697 * $dbw->insert( 'records', $row, __METHOD__ );
1698 * // Figure out where to store the data based on the new row's ID
1699 * $path = $recordDirectory . '/' . $dbw->insertId();
1700 * // Write the record data to the storage system
1701 * $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
1702 * if ( $status->isOK() ) {
1703 * // Try to cleanup files orphaned by transaction rollback
1704 * $dbw->onTransactionResolution(
1705 * function ( $type ) use ( $fileBackend, $path ) {
1706 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1707 * $fileBackend->delete( [ 'src' => $path ] );
1712 * // Demark the end of this conceptual unit of updates
1713 * $dbw->endAtomic( __METHOD__ );
1715 * // Discard these writes from the transaction (preserving prior writes)
1716 * $dbw->cancelAtomic( __METHOD__, $sectionId );
1721 * @param string $fname
1722 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1723 * savepoint and enable self::cancelAtomic() for this section.
1724 * @return AtomicSectionIdentifier section ID token
1727 public function startAtomic( $fname = __METHOD__
, $cancelable = self
::ATOMIC_NOT_CANCELABLE
);
1730 * Ends an atomic section of SQL statements
1732 * Ends the next section of atomic SQL statements and commits the transaction
1736 * @see IDatabase::startAtomic
1737 * @param string $fname
1740 public function endAtomic( $fname = __METHOD__
);
1743 * Cancel an atomic section of SQL statements
1745 * This will roll back only the statements executed since the start of the
1746 * most recent atomic section, and close that section. If a transaction was
1747 * open before the corresponding startAtomic() call, any statements before
1748 * that call are *not* rolled back and the transaction remains open. If the
1749 * corresponding startAtomic() implicitly started a transaction, that
1750 * transaction is rolled back.
1752 * @note callers must use additional measures for situations involving two or more
1753 * (peer) transactions (e.g. updating two database servers at once). The transaction
1754 * and savepoint logic of startAtomic() are bound to specific IDatabase instances.
1756 * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
1758 * @note As a micro-optimization to save a few DB calls, this method may only
1759 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1761 * @see IDatabase::startAtomic
1762 * @param string $fname
1763 * @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
1764 * passing this enables cancellation of unclosed nested sections [optional]
1767 public function cancelAtomic( $fname = __METHOD__
, AtomicSectionIdentifier
$sectionId = null );
1770 * Perform an atomic section of reversable SQL statements from a callback
1772 * The $callback takes the following arguments:
1773 * - This database object
1774 * - The value of $fname
1776 * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
1777 * If any exception occurs during execution of the callback, it will be handled as follows:
1778 * - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
1779 * (and only) statements executed during the atomic section. If that succeeds, then the
1780 * exception will be re-thrown; if it fails, then a different exception will be thrown
1781 * and any further query attempts will fail until rollback() is called.
1782 * - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
1783 * end of the section and the error will be re-thrown. Any further query attempts will
1784 * fail until rollback() is called.
1786 * This method is convenient for letting calls to the caller of this method be wrapped
1787 * in a try/catch blocks for exception types that imply that the caller failed but was
1788 * able to properly discard the changes it made in the transaction. This method can be
1789 * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
1791 * Example usage, "RecordStore::save" method:
1793 * $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
1794 * // Create new record metadata row
1795 * $dbw->insert( 'records', $record->toArray(), __METHOD__ );
1796 * // Figure out where to store the data based on the new row's ID
1797 * $path = $this->recordDirectory . '/' . $dbw->insertId();
1798 * // Write the record data to the storage system;
1799 * // blob store throughs StoreFailureException on failure
1800 * $this->blobStore->create( $path, $record->getJSON() );
1801 * // Try to cleanup files orphaned by transaction rollback
1802 * $dbw->onTransactionResolution(
1803 * function ( $type ) use ( $path ) {
1804 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1805 * $this->blobStore->delete( $path );
1810 * }, $dbw::ATOMIC_CANCELABLE );
1813 * Example usage, caller of the "RecordStore::save" method:
1815 * $dbw->startAtomic( __METHOD__ );
1816 * // ...various SQL writes happen...
1818 * $recordStore->save( $record );
1819 * } catch ( StoreFailureException $e ) {
1820 * // ...various SQL writes happen...
1822 * // ...various SQL writes happen...
1823 * $dbw->endAtomic( __METHOD__ );
1826 * @see Database::startAtomic
1827 * @see Database::endAtomic
1828 * @see Database::cancelAtomic
1830 * @param string $fname Caller name (usually __METHOD__)
1831 * @param callable $callback Callback that issues DB updates
1832 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1833 * savepoint and enable self::cancelAtomic() for this section.
1834 * @return mixed $res Result of the callback (since 1.28)
1836 * @throws RuntimeException
1837 * @since 1.27; prior to 1.31 this did a rollback() instead of
1838 * cancelAtomic(), and assumed no callers up the stack would ever try to
1839 * catch the exception.
1841 public function doAtomicSection(
1842 $fname, callable
$callback, $cancelable = self
::ATOMIC_NOT_CANCELABLE
1846 * Begin a transaction. If a transaction is already in progress,
1847 * that transaction will be committed before the new transaction is started.
1849 * Only call this from code with outer transcation scope.
1850 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1851 * Nesting of transactions is not supported.
1853 * Note that when the DBO_TRX flag is set (which is usually the case for web
1854 * requests, but not for maintenance scripts), any previous database query
1855 * will have started a transaction automatically.
1857 * Nesting of transactions is not supported. Attempts to nest transactions
1858 * will cause a warning, unless the current transaction was started
1859 * automatically because of the DBO_TRX flag.
1861 * @param string $fname Calling function name
1862 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1865 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1868 * Commits a transaction previously started using begin().
1869 * If no transaction is in progress, a warning is issued.
1871 * Only call this from code with outer transcation scope.
1872 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1873 * Nesting of transactions is not supported.
1875 * @param string $fname
1876 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1877 * constant to disable warnings about explicitly committing implicit transactions,
1878 * or calling commit when no transaction is in progress.
1880 * This will trigger an exception if there is an ongoing explicit transaction.
1882 * Only set the flush flag if you are sure that these warnings are not applicable,
1883 * and no explicit transactions are open.
1887 public function commit( $fname = __METHOD__
, $flush = '' );
1890 * Rollback a transaction previously started using begin().
1891 * If no transaction is in progress, a warning is issued.
1893 * Only call this from code with outer transcation scope.
1894 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1895 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1896 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1897 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1899 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1901 * @param string $fname Calling function name
1902 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1903 * constant to disable warnings about calling rollback when no transaction is in
1904 * progress. This will silently break any ongoing explicit transaction. Only set the
1905 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1907 * @since 1.23 Added $flush parameter
1909 public function rollback( $fname = __METHOD__
, $flush = '' );
1912 * Commit any transaction but error out if writes or callbacks are pending
1914 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1915 * see a new point-in-time of the database. This is useful when one of many transaction
1916 * rounds finished and significant time will pass in the script's lifetime. It is also
1917 * useful to call on a replica DB after waiting on replication to catch up to the master.
1919 * @param string $fname Calling function name
1923 public function flushSnapshot( $fname = __METHOD__
);
1926 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1927 * to the format used for inserting into timestamp fields in this DBMS.
1929 * The result is unquoted, and needs to be passed through addQuotes()
1930 * before it can be included in raw SQL.
1932 * @param string|int $ts
1936 public function timestamp( $ts = 0 );
1939 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1940 * to the format used for inserting into timestamp fields in this DBMS. If
1941 * NULL is input, it is passed through, allowing NULL values to be inserted
1942 * into timestamp fields.
1944 * The result is unquoted, and needs to be passed through addQuotes()
1945 * before it can be included in raw SQL.
1947 * @param string|int|null $ts
1951 public function timestampOrNull( $ts = null );
1954 * Ping the server and try to reconnect if it there is no connection
1956 * @param float|null &$rtt Value to store the estimated RTT [optional]
1957 * @return bool Success or failure
1959 public function ping( &$rtt = null );
1962 * Get the amount of replication lag for this database server
1964 * Callers should avoid using this method while a transaction is active
1966 * @return int|bool Database replication lag in seconds or false on error
1969 public function getLag();
1972 * Get the replica DB lag when the current transaction started
1973 * or a general lag estimate if not transaction is active
1975 * This is useful when transactions might use snapshot isolation
1976 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1977 * is this lag plus transaction duration. If they don't, it is still
1978 * safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
1979 * indication of the staleness of subsequent reads.
1981 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1985 public function getSessionLagStatus();
1988 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1992 public function maxListLen();
1995 * Some DBMSs have a special format for inserting into blob fields, they
1996 * don't allow simple quoted strings to be inserted. To insert into such
1997 * a field, pass the data through this function before passing it to
1998 * IDatabase::insert().
2001 * @return string|Blob
2003 public function encodeBlob( $b );
2006 * Some DBMSs return a special placeholder object representing blob fields
2007 * in result objects. Pass the object through this function to return the
2010 * @param string|Blob $b
2013 public function decodeBlob( $b );
2016 * Override database's default behavior. $options include:
2017 * 'connTimeout' : Set the connection timeout value in seconds.
2018 * May be useful for very long batch queries such as
2019 * full-wiki dumps, where a single query reads out over
2022 * @param array $options
2026 public function setSessionOptions( array $options );
2029 * Set variables to be used in sourceFile/sourceStream, in preference to the
2030 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
2031 * all. If it's set to false, $GLOBALS will be used.
2033 * @param bool|array $vars Mapping variable name to value.
2035 public function setSchemaVars( $vars );
2038 * Check to see if a named lock is not locked by any thread (non-blocking)
2040 * @param string $lockName Name of lock to poll
2041 * @param string $method Name of method calling us
2046 public function lockIsFree( $lockName, $method );
2049 * Acquire a named lock
2051 * Named locks are not related to transactions
2053 * @param string $lockName Name of lock to aquire
2054 * @param string $method Name of the calling method
2055 * @param int $timeout Acquisition timeout in seconds
2059 public function lock( $lockName, $method, $timeout = 5 );
2064 * Named locks are not related to transactions
2066 * @param string $lockName Name of lock to release
2067 * @param string $method Name of the calling method
2069 * @return int Returns 1 if the lock was released, 0 if the lock was not established
2070 * by this thread (in which case the lock is not released), and NULL if the named lock
2075 public function unlock( $lockName, $method );
2078 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
2080 * Only call this from outer transcation scope and when only one DB will be affected.
2081 * See https://www.mediawiki.org/wiki/Database_transactions for details.
2083 * This is suitiable for transactions that need to be serialized using cooperative locks,
2084 * where each transaction can see each others' changes. Any transaction is flushed to clear
2085 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
2086 * the lock will be released unless a transaction is active. If one is active, then the lock
2087 * will be released when it either commits or rolls back.
2089 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
2091 * @param string $lockKey Name of lock to release
2092 * @param string $fname Name of the calling method
2093 * @param int $timeout Acquisition timeout in seconds
2094 * @return ScopedCallback|null
2098 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
2101 * Check to see if a named lock used by lock() use blocking queues
2106 public function namedLocksEnqueue();
2109 * Find out when 'infinity' is. Most DBMSes support this. This is a special
2110 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
2111 * because "i" sorts after all numbers.
2115 public function getInfinity();
2118 * Encode an expiry time into the DBMS dependent format
2120 * @param string $expiry Timestamp for expiry, or the 'infinity' string
2123 public function encodeExpiry( $expiry );
2126 * Decode an expiry time into a DBMS independent format
2128 * @param string $expiry DB timestamp field value for expiry
2129 * @param int $format TS_* constant, defaults to TS_MW
2132 public function decodeExpiry( $expiry, $format = TS_MW
);
2135 * Allow or deny "big selects" for this session only. This is done by setting
2136 * the sql_big_selects session variable.
2138 * This is a MySQL-specific feature.
2140 * @param bool|string $value True for allow, false for deny, or "default" to
2141 * restore the initial value
2143 public function setBigSelects( $value = true );
2146 * @return bool Whether this DB is read-only
2149 public function isReadOnly();
2152 * Make certain table names use their own database, schema, and table prefix
2153 * when passed into SQL queries pre-escaped and without a qualified database name
2155 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
2156 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
2158 * Calling this twice will completely clear any old table aliases. Also, note that
2159 * callers are responsible for making sure the schemas and databases actually exist.
2161 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
2164 public function setTableAliases( array $aliases );
2167 * Convert certain index names to alternative names before querying the DB
2169 * Note that this applies to indexes regardless of the table they belong to.
2171 * This can be employed when an index was renamed X => Y in code, but the new Y-named
2172 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
2173 * the aliases can be removed, and then the old X-named indexes dropped.
2175 * @param string[] $aliases
2179 public function setIndexAliases( array $aliases );
2183 * @deprecated since 1.29
2185 class_alias( IDatabase
::class, 'IDatabase' );