3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
16 * http://www.gnu.org/copyleft/gpl.html
20 namespace Wikimedia\Rdbms
;
22 use InvalidArgumentException
;
23 use Wikimedia\ScopedCallback
;
28 * @defgroup Database Database
29 * This group deals with database interface functions
30 * and query specifics/optimisations.
33 * Basic database interface for live and lazy-loaded relation database handles
35 * @note IDatabase and DBConnRef should be updated to reflect any changes
39 /** @var int Callback triggered immediately due to no active transaction */
40 const TRIGGER_IDLE
= 1;
41 /** @var int Callback triggered by COMMIT */
42 const TRIGGER_COMMIT
= 2;
43 /** @var int Callback triggered by ROLLBACK */
44 const TRIGGER_ROLLBACK
= 3;
45 /** @var int Callback triggered by atomic section cancel (ROLLBACK TO SAVEPOINT) */
46 const TRIGGER_CANCEL
= 4;
48 /** @var string Transaction is requested by regular caller outside of the DB layer */
49 const TRANSACTION_EXPLICIT
= '';
50 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
51 const TRANSACTION_INTERNAL
= 'implicit';
53 /** @var string Atomic section is not cancelable */
54 const ATOMIC_NOT_CANCELABLE
= '';
55 /** @var string Atomic section is cancelable */
56 const ATOMIC_CANCELABLE
= 'cancelable';
58 /** @var string Commit/rollback is from outside the IDatabase handle and connection manager */
59 const FLUSHING_ONE
= '';
60 /** @var string Commit/rollback is from the connection manager for the IDatabase handle */
61 const FLUSHING_ALL_PEERS
= 'flush';
62 /** @var string Commit/rollback is from the IDatabase handle internally */
63 const FLUSHING_INTERNAL
= 'flush-internal';
65 /** @var string Do not remember the prior flags */
66 const REMEMBER_NOTHING
= '';
67 /** @var string Remember the prior flags */
68 const REMEMBER_PRIOR
= 'remember';
69 /** @var string Restore to the prior flag state */
70 const RESTORE_PRIOR
= 'prior';
71 /** @var string Restore to the initial flag state */
72 const RESTORE_INITIAL
= 'initial';
74 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
75 const ESTIMATE_TOTAL
= 'total';
76 /** @var string Estimate time to apply (scanning, applying) */
77 const ESTIMATE_DB_APPLY
= 'apply';
79 /** @var int Combine list with comma delimeters */
81 /** @var int Combine list with AND clauses */
83 /** @var int Convert map into a SET clause */
85 /** @var int Treat as field name and do not apply value escaping */
87 /** @var int Combine list with OR clauses */
90 /** @var int Enable debug logging of all SQL queries */
92 /** @var int Disable query buffering (only one result set can be iterated at a time) */
93 const DBO_NOBUFFER
= 2;
94 /** @var int Ignore query errors (internal use only!) */
96 /** @var int Automatically start a transaction before running a query if none is active */
98 /** @var int Use DBO_TRX in non-CLI mode */
99 const DBO_DEFAULT
= 16;
100 /** @var int Use DB persistent connections if possible */
101 const DBO_PERSISTENT
= 32;
102 /** @var int DBA session mode; mostly for Oracle */
103 const DBO_SYSDBA
= 64;
104 /** @var int Schema file mode; mostly for Oracle */
105 const DBO_DDLMODE
= 128;
106 /** @var int Enable SSL/TLS in connection protocol */
108 /** @var int Enable compression in connection protocol */
109 const DBO_COMPRESS
= 512;
111 /** @var int Idiom for "no special flags" */
112 const QUERY_NORMAL
= 0;
113 /** @var int Ignore query errors and return false when they happen */
114 const QUERY_SILENCE_ERRORS
= 1; // b/c for 1.32 query() argument; note that (int)true = 1
116 * @var int Treat the TEMPORARY table from the given CREATE query as if it is
117 * permanent as far as write tracking is concerned. This is useful for testing.
119 const QUERY_PSEUDO_PERMANENT
= 2;
120 /** @var int Enforce that a query does not make effective writes */
121 const QUERY_REPLICA_ROLE
= 4;
122 /** @var int Ignore the current presence of any DBO_TRX flag */
123 const QUERY_IGNORE_DBO_TRX
= 8;
124 /** @var int Do not try to retry the query if the connection was lost */
125 const QUERY_NO_RETRY
= 16;
127 /** @var bool Parameter to unionQueries() for UNION ALL */
128 const UNION_ALL
= true;
129 /** @var bool Parameter to unionQueries() for UNION DISTINCT */
130 const UNION_DISTINCT
= false;
133 * A string describing the current software version, and possibly
134 * other details in a user-friendly way. Will be listed on Special:Version, etc.
135 * Use getServerVersion() to get machine-friendly information.
137 * @return string Version information from the database server
139 public function getServerInfo();
142 * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
144 * Unbuffered queries are very troublesome in MySQL:
146 * - If another query is executed while the first query is being read
147 * out, the first query is killed. This means you can't call normal
148 * Database functions while you are reading an unbuffered query result
149 * from a normal Database connection.
151 * - Unbuffered queries cause the MySQL server to use large amounts of
152 * memory and to hold broad locks which block other queries.
154 * If you want to limit client-side memory, it's almost always better to
155 * split up queries into batches using a LIMIT clause than to switch off
158 * @param null|bool $buffer
159 * @return null|bool The previous value of the flag
161 public function bufferResults( $buffer = null );
164 * Gets the current transaction level.
166 * Historically, transactions were allowed to be "nested". This is no
167 * longer supported, so this function really only returns a boolean.
169 * @return int The previous value
171 public function trxLevel();
174 * Get the UNIX timestamp of the time that the transaction was established
176 * This can be used to reason about the staleness of SELECT data in REPEATABLE-READ
177 * transaction isolation level. Callers can assume that if a view-snapshot isolation
178 * is used, then the data read by SQL queries is *at least* up to date to that point
179 * (possibly more up-to-date since the first SELECT defines the snapshot).
181 * @return float|null Returns null if there is not active transaction
184 public function trxTimestamp();
187 * @return bool Whether an explicit transaction or atomic sections are still open
190 public function explicitTrxActive();
193 * Assert that all explicit transactions or atomic sections have been closed.
194 * @throws DBTransactionError
197 public function assertNoOpenTransactions();
200 * Get/set the table prefix.
201 * @param string|null $prefix The table prefix to set, or omitted to leave it unchanged.
202 * @return string The previous table prefix
203 * @throws DBUnexpectedError
205 public function tablePrefix( $prefix = null );
208 * Get/set the db schema.
209 * @param string|null $schema The database schema to set, or omitted to leave it unchanged.
210 * @return string The previous db schema
212 public function dbSchema( $schema = null );
215 * Get properties passed down from the server info array of the load
218 * @param string|null $name The entry of the info array to get, or null to get the
221 * @return array|mixed|null
223 public function getLBInfo( $name = null );
226 * Set the entire array or a particular key of the managing load balancer info array
228 * @param array|string $nameOrArray The new array or the name of a key to set
229 * @param array|null $value If $nameOrArray is a string, the new key value (null to unset)
231 public function setLBInfo( $nameOrArray, $value = null );
234 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
236 * @param IDatabase $conn
239 public function setLazyMasterHandle( IDatabase
$conn );
242 * Returns true if this database does an implicit sort when doing GROUP BY
245 * @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
247 public function implicitGroupby();
250 * Returns true if this database does an implicit order by when the column has an index
251 * For example: SELECT page_title FROM page LIMIT 1
255 public function implicitOrderby();
258 * Return the last query that sent on account of IDatabase::query()
259 * @return string SQL text or empty string if there was no such query
261 public function lastQuery();
264 * Returns true if the connection may have been used for write queries.
265 * Should return true if unsure.
268 * @deprecated Since 1.31; use lastDoneWrites()
270 public function doneWrites();
273 * Returns the last time the connection may have been used for write queries.
274 * Should return a timestamp if unsure.
276 * @return int|float UNIX timestamp or false
279 public function lastDoneWrites();
282 * @return bool Whether there is a transaction open with possible write queries
285 public function writesPending();
288 * @return bool Whether there is a transaction open with pre-commit callbacks pending
291 public function preCommitCallbacksPending();
294 * Whether there is a transaction open with either possible write queries
295 * or unresolved pre-commit/commit/resolution callbacks pending
297 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
301 public function writesOrCallbacksPending();
304 * Get the time spend running write queries for this transaction
306 * High times could be due to scanning, updates, locking, and such
308 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
309 * @return float|bool Returns false if not transaction is active
312 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
315 * Get the list of method names that did write queries for this transaction
320 public function pendingWriteCallers();
323 * Get the number of affected rows from pending write queries
328 public function pendingWriteRowsAffected();
331 * Is a connection to the database open?
334 public function isOpen();
337 * Set a flag for this connection
339 * @param int $flag IDatabase::DBO_DEBUG, IDatabase::DBO_NOBUFFER, or IDatabase::DBO_TRX
340 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
342 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
345 * Clear a flag for this connection
347 * @param int $flag IDatabase::DBO_DEBUG, IDatabase::DBO_NOBUFFER, or IDatabase::DBO_TRX
348 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
350 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
353 * Restore the flags to their prior state before the last setFlag/clearFlag call
355 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
358 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
361 * Returns a boolean whether the flag $flag is set for this connection
363 * @param int $flag One of the class IDatabase::DBO_* constants
366 public function getFlag( $flag );
369 * Return the currently selected domain ID
371 * Null components (database/schema) might change once a connection is established
375 public function getDomainID();
378 * Alias for getDomainID()
383 public function getWikiID();
386 * Get the type of the DBMS, as it appears in $wgDBtype.
390 public function getType();
393 * Fetch the next row from the given result object, in object form.
394 * Fields can be retrieved with $row->fieldname, with fields acting like
396 * If no more rows are available, false is returned.
398 * @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
399 * @return stdClass|bool
400 * @throws DBUnexpectedError Thrown if the database returns an error
402 public function fetchObject( $res );
405 * Fetch the next row from the given result object, in associative array
406 * form. Fields are retrieved with $row['fieldname'].
407 * If no more rows are available, false is returned.
409 * @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
411 * @throws DBUnexpectedError Thrown if the database returns an error
413 public function fetchRow( $res );
416 * Get the number of rows in a query result. If the query did not return
417 * any rows (for example, if it was a write query), this returns zero.
419 * @param mixed $res A SQL result
422 public function numRows( $res );
425 * Get the number of fields in a result object
426 * @see https://www.php.net/mysql_num_fields
428 * @param mixed $res A SQL result
431 public function numFields( $res );
434 * Get a field name in a result object
435 * @see https://www.php.net/mysql_field_name
437 * @param mixed $res A SQL result
441 public function fieldName( $res, $n );
444 * Get the inserted value of an auto-increment row
446 * This should only be called after an insert that used an auto-incremented
447 * value. If no such insert was previously done in the current database
448 * session, the return value is undefined.
452 public function insertId();
455 * Change the position of the cursor in a result object
456 * @see https://www.php.net/mysql_data_seek
458 * @param mixed $res A SQL result
461 public function dataSeek( $res, $row );
464 * Get the last error number
465 * @see https://www.php.net/mysql_errno
469 public function lastErrno();
472 * Get a description of the last error
473 * @see https://www.php.net/mysql_error
477 public function lastError();
480 * Get the number of rows affected by the last write query
481 * @see https://www.php.net/mysql_affected_rows
485 public function affectedRows();
488 * Returns a wikitext link to the DB's website, e.g.,
489 * return "[https://www.mysql.com/ MySQL]";
490 * Should at least contain plain text, if for some reason
491 * your database has no website.
493 * @return string Wikitext of a link to the server software's web site
495 public function getSoftwareLink();
498 * A string describing the current software version, like from
499 * mysql_get_server_info().
501 * @return string Version information from the database server.
503 public function getServerVersion();
506 * Close the database connection
508 * This should only be called after any transactions have been resolved,
509 * aside from read-only automatic transactions (assuming no callbacks are registered).
510 * If a transaction is still open anyway, it will be rolled back.
513 * @return bool Operation success. true if already closed.
515 public function close();
518 * Run an SQL query and return the result. Normally throws a DBQueryError
519 * on failure. If errors are ignored, returns false instead.
521 * If a connection loss is detected, then an attempt to reconnect will be made.
522 * For queries that involve no larger transactions or locks, they will be re-issued
523 * for convenience, provided the connection was re-established.
525 * In new code, the query wrappers select(), insert(), update(), delete(),
526 * etc. should be used where possible, since they give much better DBMS
527 * independence and automatically quote or validate user input in a variety
528 * of contexts. This function is generally only useful for queries which are
529 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
532 * However, the query wrappers themselves should call this function.
534 * @param string $sql SQL query
535 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
536 * comment (you can use __METHOD__ or add some extra info)
537 * @param int $flags Bitfield of IDatabase::QUERY_* constants. Note that suppression
538 * of errors is best handled by try/catch rather than using one of these flags.
539 * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
540 * for a successful read query, or false on failure if QUERY_SILENCE_ERRORS is set.
543 public function query( $sql, $fname = __METHOD__
, $flags = 0 );
546 * Free a result object returned by query() or select(). It's usually not
547 * necessary to call this, just use unset() or let the variable holding
548 * the result object go out of scope.
550 * @param mixed $res A SQL result
552 public function freeResult( $res );
555 * A SELECT wrapper which returns a single field from a single result row.
557 * Usually throws a DBQueryError on failure. If errors are explicitly
558 * ignored, returns false on failure.
560 * If no result rows are returned from the query, false is returned.
562 * @param string|array $table Table name. See IDatabase::select() for details.
563 * @param string $var The field name to select. This must be a valid SQL
564 * fragment: do not use unvalidated user input.
565 * @param string|array $cond The condition array. See IDatabase::select() for details.
566 * @param string $fname The function name of the caller.
567 * @param string|array $options The query options. See IDatabase::select() for details.
568 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
570 * @return mixed The value from the field
573 public function selectField(
574 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
578 * A SELECT wrapper which returns a list of single field values from result rows.
580 * Usually throws a DBQueryError on failure. If errors are explicitly
581 * ignored, returns false on failure.
583 * If no result rows are returned from the query, false is returned.
585 * @param string|array $table Table name. See IDatabase::select() for details.
586 * @param string $var The field name to select. This must be a valid SQL
587 * fragment: do not use unvalidated user input.
588 * @param string|array $cond The condition array. See IDatabase::select() for details.
589 * @param string $fname The function name of the caller.
590 * @param string|array $options The query options. See IDatabase::select() for details.
591 * @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
593 * @return array The values from the field in the order they were returned from the DB
597 public function selectFieldValues(
598 $table, $var, $cond = '', $fname = __METHOD__
, $options = [], $join_conds = []
602 * Execute a SELECT query constructed using the various parameters provided.
603 * See below for full details of the parameters.
605 * @param string|array $table Table name(s)
607 * May be either an array of table names, or a single string holding a table
608 * name. If an array is given, table aliases can be specified, for example:
612 * This includes the user table in the query, with the alias "a" available
613 * for use in field names (e.g. a.user_name).
615 * A derived table, defined by the result of selectSQLText(), requires an alias
616 * key and a Subquery instance value which wraps the SQL query, for example:
618 * [ 'c' => new Subquery( 'SELECT ...' ) ]
620 * Joins using parentheses for grouping (since MediaWiki 1.31) may be
621 * constructed using nested arrays. For example,
623 * [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
625 * along with `$join_conds` like
627 * [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
629 * will produce SQL something like
631 * FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
633 * All of the table names given here are automatically run through
634 * Database::tableName(), which causes the table prefix (if any) to be
635 * added, and various other table name mappings to be performed.
637 * Do not use untrusted user input as a table name. Alias names should
638 * not have characters outside of the Basic multilingual plane.
640 * @param string|array $vars Field name(s)
642 * May be either a field name or an array of field names. The field names
643 * can be complete fragments of SQL, for direct inclusion into the SELECT
644 * query. If an array is given, field aliases can be specified, for example:
646 * [ 'maxrev' => 'MAX(rev_id)' ]
648 * This includes an expression with the alias "maxrev" in the query.
650 * If an expression is given, care must be taken to ensure that it is
653 * Untrusted user input must not be passed to this parameter.
655 * @param string|array $conds
657 * May be either a string containing a single condition, or an array of
658 * conditions. If an array is given, the conditions constructed from each
659 * element are combined with AND.
661 * Array elements may take one of two forms:
663 * - Elements with a numeric key are interpreted as raw SQL fragments.
664 * - Elements with a string key are interpreted as equality conditions,
665 * where the key is the field name.
666 * - If the value of such an array element is a scalar (such as a
667 * string), it will be treated as data and thus quoted appropriately.
668 * If it is null, an IS NULL clause will be added.
669 * - If the value is an array, an IN (...) clause will be constructed
670 * from its non-null elements, and an IS NULL clause will be added
671 * if null is present, such that the field may match any of the
672 * elements in the array. The non-null elements will be quoted.
674 * Note that expressions are often DBMS-dependent in their syntax.
675 * DBMS-independent wrappers are provided for constructing several types of
676 * expression commonly used in condition queries. See:
677 * - IDatabase::buildLike()
678 * - IDatabase::conditional()
680 * Untrusted user input is safe in the values of string keys, however untrusted
681 * input must not be used in the array key names or in the values of numeric keys.
682 * Escaping of untrusted input used in values of numeric keys should be done via
683 * IDatabase::addQuotes()
685 * Use an empty array, string, or '*' to update all rows.
687 * @param string $fname Caller function name
689 * @param string|array $options Query options
691 * Optional: Array of query options. Boolean options are specified by
692 * including them in the array as a string value with a numeric key, for
697 * The supported options are:
699 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
700 * with LIMIT can theoretically be used for paging through a result set,
701 * but this is discouraged for performance reasons.
703 * - LIMIT: Integer: return at most this many rows. The rows are sorted
704 * and then the first rows are taken until the limit is reached. LIMIT
705 * is applied to a result set after OFFSET.
707 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
708 * changed until the next COMMIT. Cannot be used with aggregate functions
709 * (COUNT, MAX, etc., but also DISTINCT).
711 * - DISTINCT: Boolean: return only unique result rows.
713 * - GROUP BY: May be either an SQL fragment string naming a field or
714 * expression to group by, or an array of such SQL fragments.
716 * - HAVING: May be either an string containing a HAVING clause or an array of
717 * conditions building the HAVING clause. If an array is given, the conditions
718 * constructed from each element are combined with AND.
720 * - ORDER BY: May be either an SQL fragment giving a field name or
721 * expression to order by, or an array of such SQL fragments.
723 * - USE INDEX: This may be either a string giving the index name to use
724 * for the query, or an array. If it is an associative array, each key
725 * gives the table name (or alias), each value gives the index name to
726 * use for that table. All strings are SQL fragments and so should be
727 * validated by the caller.
729 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
732 * And also the following boolean MySQL extensions, see the MySQL manual
735 * - LOCK IN SHARE MODE
739 * - SQL_BUFFER_RESULT
741 * - SQL_CALC_FOUND_ROWS
746 * @param string|array $join_conds Join conditions
748 * Optional associative array of table-specific join conditions. In the
749 * most common case, this is unnecessary, since the join condition can be
750 * in $conds. However, it is useful for doing a LEFT JOIN.
752 * The key of the array contains the table name or alias. The value is an
753 * array with two elements, numbered 0 and 1. The first gives the type of
754 * join, the second is the same as the $conds parameter. Thus it can be
755 * an SQL fragment, or an array where the string keys are equality and the
756 * numeric keys are SQL fragments all AND'd together. For example:
758 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
760 * @return IResultWrapper Resulting rows
763 public function select(
764 $table, $vars, $conds = '', $fname = __METHOD__
,
765 $options = [], $join_conds = []
769 * The equivalent of IDatabase::select() except that the constructed SQL
770 * is returned, instead of being immediately executed. This can be useful for
771 * doing UNION queries, where the SQL text of each query is needed. In general,
772 * however, callers outside of Database classes should just use select().
774 * @see IDatabase::select()
776 * @param string|array $table Table name
777 * @param string|array $vars Field names
778 * @param string|array $conds Conditions
779 * @param string $fname Caller function name
780 * @param string|array $options Query options
781 * @param string|array $join_conds Join conditions
782 * @return string SQL query string
784 public function selectSQLText(
785 $table, $vars, $conds = '', $fname = __METHOD__
,
786 $options = [], $join_conds = []
790 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
791 * that a single row object is returned. If the query returns no rows,
794 * @param string|array $table Table name
795 * @param string|array $vars Field names
796 * @param string|array $conds Conditions
797 * @param string $fname Caller function name
798 * @param string|array $options Query options
799 * @param array|string $join_conds Join conditions
801 * @return stdClass|bool
804 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
805 $options = [], $join_conds = []
809 * Estimate the number of rows in dataset
811 * MySQL allows you to estimate the number of rows that would be returned
812 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
813 * index cardinality statistics, and is notoriously inaccurate, especially
814 * when large numbers of rows have recently been added or deleted.
816 * For DBMSs that don't support fast result size estimation, this function
817 * will actually perform the SELECT COUNT(*).
819 * Takes the same arguments as IDatabase::select().
821 * @param string $table Table name
822 * @param string $var Column for which NULL values are not counted [default "*"]
823 * @param array|string $conds Filters on the table
824 * @param string $fname Function name for profiling
825 * @param array $options Options for select
826 * @param array|string $join_conds Join conditions
827 * @return int Row count
830 public function estimateRowCount(
831 $table, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
835 * Get the number of rows in dataset
837 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
839 * Takes the same arguments as IDatabase::select().
841 * @since 1.27 Added $join_conds parameter
843 * @param array|string $tables Table names
844 * @param string $var Column for which NULL values are not counted [default "*"]
845 * @param array|string $conds Filters on the table
846 * @param string $fname Function name for profiling
847 * @param array $options Options for select
848 * @param array $join_conds Join conditions (since 1.27)
849 * @return int Row count
852 public function selectRowCount(
853 $tables, $var = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
857 * Lock all rows meeting the given conditions/options FOR UPDATE
859 * @param array|string $table Table names
860 * @param array|string $conds Filters on the table
861 * @param string $fname Function name for profiling
862 * @param array $options Options for select ("FOR UPDATE" is added automatically)
863 * @param array $join_conds Join conditions
864 * @return int Number of matching rows found (and locked)
867 public function lockForUpdate(
868 $table, $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
872 * Determines whether a field exists in a table
874 * @param string $table Table name
875 * @param string $field Filed to check on that table
876 * @param string $fname Calling function name (optional)
877 * @return bool Whether $table has filed $field
880 public function fieldExists( $table, $field, $fname = __METHOD__
);
883 * Determines whether an index exists
884 * Usually throws a DBQueryError on failure
885 * If errors are explicitly ignored, returns NULL on failure
887 * @param string $table
888 * @param string $index
889 * @param string $fname
893 public function indexExists( $table, $index, $fname = __METHOD__
);
896 * Query whether a given table exists
898 * @param string $table
899 * @param string $fname
903 public function tableExists( $table, $fname = __METHOD__
);
906 * INSERT wrapper, inserts an array into a table.
910 * - A single associative array. The array keys are the field names, and
911 * the values are the values to insert. The values are treated as data
912 * and will be quoted appropriately. If NULL is inserted, this will be
913 * converted to a database NULL.
914 * - An array with numeric keys, holding a list of associative arrays.
915 * This causes a multi-row INSERT on DBMSs that support it. The keys in
916 * each subarray must be identical to each other, and in the same order.
918 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
921 * $options is an array of options, with boolean options encoded as values
922 * with numeric keys, in the same style as $options in
923 * IDatabase::select(). Supported options are:
925 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
926 * any rows which cause duplicate key errors are not inserted. It's
927 * possible to determine how many rows were successfully inserted using
928 * IDatabase::affectedRows().
930 * @param string $table Table name. This will be passed through
931 * Database::tableName().
932 * @param array $a Array of rows to insert
933 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
934 * @param array $options Array of options
935 * @return bool Return true if no exception was thrown (deprecated since 1.33)
938 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
941 * UPDATE wrapper. Takes a condition array and a SET array.
943 * @param string $table Name of the table to UPDATE. This will be passed through
944 * Database::tableName().
945 * @param array $values An array of values to SET. For each array element,
946 * the key gives the field name, and the value gives the data to set
947 * that field to. The data will be quoted by IDatabase::addQuotes().
948 * Values with integer keys form unquoted SET statements, which can be used for
949 * things like "field = field + 1" or similar computed values.
950 * @param array $conds An array of conditions (WHERE). See
951 * IDatabase::select() for the details of the format of condition
952 * arrays. Use '*' to update all rows.
953 * @param string $fname The function name of the caller (from __METHOD__),
954 * for logging and profiling.
955 * @param array $options An array of UPDATE options, can be:
956 * - IGNORE: Ignore unique key conflicts
957 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
958 * @return bool Return true if no exception was thrown (deprecated since 1.33)
961 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
964 * Makes an encoded list of strings from an array
966 * These can be used to make conjunctions or disjunctions on SQL condition strings
967 * derived from an array (see IDatabase::select() $conds documentation).
971 * $sql = $db->makeList( [
973 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
974 * ], $db::LIST_AND );
976 * This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
978 * @param array $a Containing the data
979 * @param int $mode IDatabase class constant:
980 * - IDatabase::LIST_COMMA: Comma separated, no field names
981 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
982 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
983 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
984 * - IDatabase::LIST_NAMES: Comma separated field names
988 public function makeList( $a, $mode = self
::LIST_COMMA
);
991 * Build a partial where clause from a 2-d array such as used for LinkBatch.
992 * The keys on each level may be either integers or strings.
994 * @param array $data Organized as 2-d
995 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
996 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
997 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
998 * @return string|bool SQL fragment, or false if no items in array
1000 public function makeWhereFrom2d( $data, $baseKey, $subKey );
1003 * Return aggregated value alias
1005 * @param array $valuedata
1006 * @param string $valuename
1009 * @deprecated Since 1.33
1011 public function aggregateValue( $valuedata, $valuename = 'value' );
1014 * @param string $field
1017 public function bitNot( $field );
1020 * @param string $fieldLeft
1021 * @param string $fieldRight
1024 public function bitAnd( $fieldLeft, $fieldRight );
1027 * @param string $fieldLeft
1028 * @param string $fieldRight
1031 public function bitOr( $fieldLeft, $fieldRight );
1034 * Build a concatenation list to feed into a SQL query
1035 * @param array $stringList List of raw SQL expressions; caller is
1036 * responsible for any quoting
1039 public function buildConcat( $stringList );
1042 * Build a GROUP_CONCAT or equivalent statement for a query.
1044 * This is useful for combining a field for several rows into a single string.
1045 * NULL values will not appear in the output, duplicated values will appear,
1046 * and the resulting delimiter-separated values have no defined sort order.
1047 * Code using the results may need to use the PHP unique() or sort() methods.
1049 * @param string $delim Glue to bind the results together
1050 * @param string|array $table Table name
1051 * @param string $field Field name
1052 * @param string|array $conds Conditions
1053 * @param string|array $join_conds Join conditions
1054 * @return string SQL text
1057 public function buildGroupConcatField(
1058 $delim, $table, $field, $conds = '', $join_conds = []
1062 * Build a SUBSTRING function.
1064 * Behavior for non-ASCII values is undefined.
1066 * @param string $input Field name
1067 * @param int $startPosition Positive integer
1068 * @param int|null $length Non-negative integer length or null for no limit
1069 * @throws InvalidArgumentException
1070 * @return string SQL text
1073 public function buildSubString( $input, $startPosition, $length = null );
1076 * @param string $field Field or column to cast
1080 public function buildStringCast( $field );
1083 * @param string $field Field or column to cast
1087 public function buildIntegerCast( $field );
1090 * Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
1092 * @see IDatabase::selectSQLText()
1094 * @param string|array $table Table name
1095 * @param string|array $vars Field names
1096 * @param string|array $conds Conditions
1097 * @param string $fname Caller function name
1098 * @param string|array $options Query options
1099 * @param string|array $join_conds Join conditions
1103 public function buildSelectSubquery(
1104 $table, $vars, $conds = '', $fname = __METHOD__
,
1105 $options = [], $join_conds = []
1109 * Construct a LIMIT query with optional offset. This is used for query
1110 * pages. The SQL should be adjusted so that only the first $limit rows
1111 * are returned. If $offset is provided as well, then the first $offset
1112 * rows should be discarded, and the next $limit rows should be returned.
1113 * If the result of the query is not ordered, then the rows to be returned
1114 * are theoretically arbitrary.
1116 * $sql is expected to be a SELECT, if that makes a difference.
1118 * @param string $sql SQL query we will append the limit too
1119 * @param int $limit The SQL limit
1120 * @param int|bool $offset The SQL offset (default false)
1121 * @throws DBUnexpectedError
1125 public function limitResult( $sql, $limit, $offset = false );
1128 * Returns true if DBs are assumed to be on potentially different servers
1130 * In systems like mysql/mariadb, different databases can easily be referenced on a single
1131 * connection merely by name, even in a single query via JOIN. On the other hand, Postgres
1132 * treats databases as fully separate, only allowing mechanisms like postgres_fdw to
1133 * effectively "mount" foreign DBs. This is true even among DBs on the same server.
1138 public function databasesAreIndependent();
1141 * Change the current database
1143 * This should only be called by a load balancer or if the handle is not attached to one
1146 * @return bool True unless an exception was thrown
1147 * @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
1149 * @deprecated Since 1.32 Use selectDomain() instead
1151 public function selectDB( $db );
1154 * Set the current domain (database, schema, and table prefix)
1156 * This will throw an error for some database types if the database is unspecified
1158 * This should only be called by a load balancer or if the handle is not attached to one
1160 * @param string|DatabaseDomain $domain
1162 * @throws DBConnectionError
1164 public function selectDomain( $domain );
1167 * Get the current DB name
1168 * @return string|null
1170 public function getDBname();
1173 * Get the server hostname or IP address
1176 public function getServer();
1179 * Adds quotes and backslashes.
1181 * @param string|int|null|bool|Blob $s
1182 * @return string|int
1184 public function addQuotes( $s );
1187 * Quotes an identifier, in order to make user controlled input safe
1189 * Depending on the database this will either be `backticks` or "double quotes"
1195 public function addIdentifierQuotes( $s );
1198 * LIKE statement wrapper, receives a variable-length argument list with
1199 * parts of pattern to match containing either string literals that will be
1200 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1201 * the function could be provided with an array of aforementioned
1204 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1205 * a LIKE clause that searches for subpages of 'My page title'.
1207 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1208 * $query .= $dbr->buildLike( $pattern );
1211 * @param array[]|string|LikeMatch $param
1212 * @return string Fully built LIKE statement
1213 * @phan-suppress-next-line PhanMismatchVariadicComment
1214 * @phan-param array|string|LikeMatch ...$param T226223
1216 public function buildLike( $param );
1219 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1223 public function anyChar();
1226 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1230 public function anyString();
1233 * Deprecated method, calls should be removed.
1235 * This was formerly used for PostgreSQL and Oracle to handle
1236 * self::insertId() auto-incrementing fields. It is no longer necessary
1237 * since DatabasePostgres::insertId() has been reimplemented using
1238 * `lastval()` and Oracle has been reimplemented using triggers.
1240 * Implementations should return null if inserting `NULL` into an
1241 * auto-incrementing field works, otherwise it should return an instance of
1242 * NextSequenceValue and filter it on calls to relevant methods.
1244 * @deprecated since 1.30, no longer needed
1245 * @param string $seqName
1246 * @return null|NextSequenceValue
1248 public function nextSequenceValue( $seqName );
1251 * REPLACE query wrapper.
1253 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1254 * except that when there is a duplicate key error, the old row is deleted
1255 * and the new row is inserted in its place.
1257 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1258 * perform the delete, we need to know what the unique indexes are so that
1259 * we know how to find the conflicting rows.
1261 * It may be more efficient to leave off unique indexes which are unlikely
1262 * to collide. However if you do this, you run the risk of encountering
1263 * errors which wouldn't have occurred in MySQL.
1265 * @param string $table The table to replace the row(s) in.
1266 * @param array[]|string[]|string $uniqueIndexes All unique indexes. One of the following:
1267 * a) the one unique field in the table (when no composite unique key exist)
1268 * b) a list of all unique fields in the table (when no composite unique key exist)
1269 * c) a list of all unique indexes in the table (each as a list of the indexed fields)
1270 * @param array $rows Can be either a single row to insert, or multiple rows,
1271 * in the same format as for IDatabase::insert()
1272 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1275 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1278 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1280 * This updates any conflicting rows (according to the unique indexes) using
1281 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1283 * $rows may be either:
1284 * - A single associative array. The array keys are the field names, and
1285 * the values are the values to insert. The values are treated as data
1286 * and will be quoted appropriately. If NULL is inserted, this will be
1287 * converted to a database NULL.
1288 * - An array with numeric keys, holding a list of associative arrays.
1289 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1290 * each subarray must be identical to each other, and in the same order.
1292 * It may be more efficient to leave off unique indexes which are unlikely
1293 * to collide. However if you do this, you run the risk of encountering
1294 * errors which wouldn't have occurred in MySQL.
1296 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1301 * @param string $table Table name. This will be passed through Database::tableName().
1302 * @param array $rows A single row or list of rows to insert
1303 * @param array[]|string[]|string $uniqueIndexes All unique indexes. One of the following:
1304 * a) the one unique field in the table (when no composite unique key exist)
1305 * b) a list of all unique fields in the table (when no composite unique key exist)
1306 * c) a list of all unique indexes in the table (each as a list of the indexed fields)
1307 * @param array $set An array of values to SET. For each array element, the
1308 * key gives the field name, and the value gives the data to set that
1309 * field to. The data will be quoted by IDatabase::addQuotes().
1310 * Values with integer keys form unquoted SET statements, which can be used for
1311 * things like "field = field + 1" or similar computed values.
1312 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1314 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1316 public function upsert(
1317 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1321 * DELETE where the condition is a join.
1323 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1324 * we use sub-selects
1326 * For safety, an empty $conds will not delete everything. If you want to
1327 * delete all rows where the join condition matches, set $conds='*'.
1329 * DO NOT put the join condition in $conds.
1331 * @param string $delTable The table to delete from.
1332 * @param string $joinTable The other table.
1333 * @param string $delVar The variable to join on, in the first table.
1334 * @param string $joinVar The variable to join on, in the second table.
1335 * @param array $conds Condition array of field names mapped to variables,
1336 * ANDed together in the WHERE clause
1337 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1340 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1345 * DELETE query wrapper.
1347 * @param string $table Table name
1348 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1349 * for the format. Use $conds == "*" to delete all rows
1350 * @param string $fname Name of the calling function
1351 * @throws DBUnexpectedError
1352 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1355 public function delete( $table, $conds, $fname = __METHOD__
);
1358 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1359 * into another table.
1361 * @warning If the insert will use an auto-increment or sequence to
1362 * determine the value of a column, this may break replication on
1363 * databases using statement-based replication if the SELECT is not
1364 * deterministically ordered.
1366 * @param string $destTable The table name to insert into
1367 * @param string|array $srcTable May be either a table name, or an array of table names
1368 * to include in a join.
1370 * @param array $varMap Must be an associative array of the form
1371 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1372 * rather than field names, but strings should be quoted with
1373 * IDatabase::addQuotes()
1375 * @param array $conds Condition array. See $conds in IDatabase::select() for
1376 * the details of the format of condition arrays. May be "*" to copy the
1379 * @param string $fname The function name of the caller, from __METHOD__
1381 * @param array $insertOptions Options for the INSERT part of the query, see
1382 * IDatabase::insert() for details. Also, one additional option is
1383 * available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
1384 * an auto-increment or sequence to determine any column values.
1385 * @param array $selectOptions Options for the SELECT part of the query, see
1386 * IDatabase::select() for details.
1387 * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
1388 * IDatabase::select() for details.
1390 * @return bool Return true if no exception was thrown (deprecated since 1.33)
1393 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1394 $fname = __METHOD__
,
1395 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
1399 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1400 * within the UNION construct.
1403 public function unionSupportsOrderAndLimit();
1406 * Construct a UNION query
1407 * This is used for providing overload point for other DB abstractions
1408 * not compatible with the MySQL syntax.
1409 * @param array $sqls SQL statements to combine
1410 * @param bool $all Either IDatabase::UNION_ALL or IDatabase::UNION_DISTINCT
1411 * @return string SQL fragment
1413 public function unionQueries( $sqls, $all );
1416 * Construct a UNION query for permutations of conditions
1418 * Databases sometimes have trouble with queries that have multiple values
1419 * for multiple condition parameters combined with limits and ordering.
1420 * This method constructs queries for the Cartesian product of the
1421 * conditions and unions them all together.
1423 * @see IDatabase::select()
1425 * @param string|array $table Table name
1426 * @param string|array $vars Field names
1427 * @param array $permute_conds Conditions for the Cartesian product. Keys
1428 * are field names, values are arrays of the possible values for that
1430 * @param string|array $extra_conds Additional conditions to include in the
1432 * @param string $fname Caller function name
1433 * @param string|array $options Query options. In addition to the options
1434 * recognized by IDatabase::select(), the following may be used:
1435 * - NOTALL: Set to use UNION instead of UNION ALL.
1436 * - INNER ORDER BY: If specified and supported, subqueries will use this
1437 * instead of ORDER BY.
1438 * @param string|array $join_conds Join conditions
1439 * @return string SQL query string.
1441 public function unionConditionPermutations(
1442 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__
,
1443 $options = [], $join_conds = []
1447 * Returns an SQL expression for a simple conditional. This doesn't need
1448 * to be overridden unless CASE isn't supported in your DBMS.
1450 * @param string|array $cond SQL expression which will result in a boolean value
1451 * @param string $trueVal SQL expression to return if true
1452 * @param string $falseVal SQL expression to return if false
1453 * @return string SQL fragment
1455 public function conditional( $cond, $trueVal, $falseVal );
1458 * Returns a command for str_replace function in SQL query.
1459 * Uses REPLACE() in MySQL
1461 * @param string $orig Column to modify
1462 * @param string $old Column to seek
1463 * @param string $new Column to replace with
1467 public function strreplace( $orig, $old, $new );
1470 * Determines how long the server has been up
1475 public function getServerUptime();
1478 * Determines if the last failure was due to a deadlock
1480 * Note that during a deadlock, the prior transaction will have been lost
1484 public function wasDeadlock();
1487 * Determines if the last failure was due to a lock timeout
1489 * Note that during a lock wait timeout, the prior transaction will have been lost
1493 public function wasLockTimeout();
1496 * Determines if the last query error was due to a dropped connection
1498 * Note that during a connection loss, the prior transaction will have been lost
1503 public function wasConnectionLoss();
1506 * Determines if the last failure was due to the database being read-only.
1510 public function wasReadOnlyError();
1513 * Determines if the last query error was due to something outside of the query itself
1515 * Note that the transaction may have been lost, discarding prior writes and results
1519 public function wasErrorReissuable();
1522 * Wait for the replica DB to catch up to a given master position
1524 * Note that this does not start any new transactions. If any existing transaction
1525 * is flushed, and this is called, then queries will reflect the point the DB was synced
1526 * up to (on success) without interference from REPEATABLE-READ snapshots.
1528 * @param DBMasterPos $pos
1529 * @param int $timeout The maximum number of seconds to wait for synchronisation
1530 * @return int|null Zero if the replica DB was past that position already,
1531 * greater than zero if we waited for some period of time, less than
1532 * zero if it timed out, and null on error
1535 public function masterPosWait( DBMasterPos
$pos, $timeout );
1538 * Get the replication position of this replica DB
1540 * @return DBMasterPos|bool False if this is not a replica DB
1543 public function getReplicaPos();
1546 * Get the position of this master
1548 * @return DBMasterPos|bool False if this is not a master
1551 public function getMasterPos();
1554 * @return bool Whether the DB is marked as read-only server-side
1557 public function serverIsReadOnly();
1560 * Run a callback as soon as the current transaction commits or rolls back.
1561 * An error is thrown if no transaction is pending. Queries in the function will run in
1562 * AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1565 * This is useful for combining cooperative locks and DB transactions.
1567 * Note this is called when the whole transaction is resolved. To take action immediately
1568 * when an atomic section is cancelled, use onAtomicSectionCancel().
1570 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1572 * The callback takes the following arguments:
1573 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1574 * - This IDatabase instance (since 1.32)
1576 * @param callable $callback
1577 * @param string $fname Caller name
1580 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1583 * Run a callback as soon as there is no transaction pending.
1584 * If there is a transaction and it is rolled back, then the callback is cancelled.
1586 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1587 * of the round, just after all peer transactions COMMIT. If the transaction round
1588 * is rolled back, then the callback is cancelled.
1590 * Queries in the function will run in AUTOCOMMIT mode unless there are begin() calls.
1591 * Callbacks must commit any transactions that they begin.
1593 * This is useful for updates to different systems or when separate transactions are needed.
1594 * For example, one might want to enqueue jobs into a system outside the database, but only
1595 * after the database is updated so that the jobs will see the data when they actually run.
1596 * It can also be used for updates that easily suffer from lock timeouts and deadlocks,
1597 * but where atomicity is not essential.
1599 * Avoid using IDatabase instances aside from this one in the callback, unless such instances
1600 * never have IDatabase::DBO_TRX set. This keeps callbacks from interfering with one another.
1602 * Updates will execute in the order they were enqueued.
1604 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1606 * The callback takes the following arguments:
1607 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1608 * - This IDatabase instance (since 1.32)
1610 * @param callable $callback
1611 * @param string $fname Caller name
1614 public function onTransactionCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1617 * Alias for onTransactionCommitOrIdle() for backwards-compatibility
1619 * @param callable $callback
1620 * @param string $fname
1622 * @deprecated Since 1.32
1624 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1627 * Run a callback before the current transaction commits or now if there is none.
1628 * If there is a transaction and it is rolled back, then the callback is cancelled.
1630 * When transaction round mode (DBO_TRX) is set, the callback will run at the end
1631 * of the round, just before all peer transactions COMMIT. If the transaction round
1632 * is rolled back, then the callback is cancelled.
1634 * Callbacks must not start nor commit any transactions. If no transaction is active,
1635 * then a transaction will wrap the callback.
1637 * This is useful for updates that easily suffer from lock timeouts and deadlocks,
1638 * but where atomicity is strongly desired for these updates and some related updates.
1640 * Updates will execute in the order they were enqueued.
1642 * The callback takes the one argument:
1643 * - This IDatabase instance (since 1.32)
1645 * @param callable $callback
1646 * @param string $fname Caller name
1649 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1652 * Run a callback when the atomic section is cancelled.
1654 * The callback is run just after the current atomic section, any outer
1655 * atomic section, or the whole transaction is rolled back.
1657 * An error is thrown if no atomic section is pending. The atomic section
1658 * need not have been created with the ATOMIC_CANCELABLE flag.
1660 * Queries in the function may be running in the context of an outer
1661 * transaction or may be running in AUTOCOMMIT mode. The callback should
1662 * use atomic sections if necessary.
1664 * @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
1666 * The callback takes the following arguments:
1667 * - IDatabase::TRIGGER_CANCEL or IDatabase::TRIGGER_ROLLBACK
1668 * - This IDatabase instance
1670 * @param callable $callback
1671 * @param string $fname Caller name
1674 public function onAtomicSectionCancel( callable
$callback, $fname = __METHOD__
);
1677 * Run a callback after each time any transaction commits or rolls back
1679 * The callback takes two arguments:
1680 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1681 * - This IDatabase object
1682 * Callbacks must commit any transactions that they begin.
1684 * Registering a callback here will not affect writesOrCallbacks() pending.
1686 * Since callbacks from this or onTransactionCommitOrIdle() can start and end transactions,
1687 * a single call to IDatabase::commit might trigger multiple runs of the listener callbacks.
1689 * @param string $name Callback name
1690 * @param callable|null $callback Use null to unset a listener
1693 public function setTransactionListener( $name, callable
$callback = null );
1696 * Begin an atomic section of SQL statements
1698 * Start an implicit transaction if no transaction is already active, set a savepoint
1699 * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
1700 * that the transaction is not committed prematurely. The end of the section must be
1701 * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
1702 * have layers of inner sections (sub-sections), but all sections must be ended in order
1703 * of innermost to outermost. Transactions cannot be started or committed until all
1704 * atomic sections are closed.
1706 * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
1707 * by discarding the section's writes. This should not be used for failures when:
1708 * - upsert() could easily be used instead
1709 * - insert() with IGNORE could easily be used instead
1710 * - select() with FOR UPDATE could be checked before issuing writes instead
1711 * - The failure is from code that runs after the first write but doesn't need to
1712 * - The failures are from contention solvable via onTransactionPreCommitOrIdle()
1713 * - The failures are deadlocks; the RDBMs usually discard the whole transaction
1715 * @note callers must use additional measures for situations involving two or more
1716 * (peer) transactions (e.g. updating two database servers at once). The transaction
1717 * and savepoint logic of this method only applies to this specific IDatabase instance.
1721 * // Start a transaction if there isn't one already
1722 * $dbw->startAtomic( __METHOD__ );
1723 * // Serialize these thread table updates
1724 * $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
1725 * // Add a new comment for the thread
1726 * $dbw->insert( 'comment', $row, __METHOD__ );
1727 * $cid = $db->insertId();
1728 * // Update thread reference to last comment
1729 * $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
1730 * // Demark the end of this conceptual unit of updates
1731 * $dbw->endAtomic( __METHOD__ );
1734 * Example usage (atomic changes that might have to be discarded):
1736 * // Start a transaction if there isn't one already
1737 * $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
1738 * // Create new record metadata row
1739 * $dbw->insert( 'records', $row, __METHOD__ );
1740 * // Figure out where to store the data based on the new row's ID
1741 * $path = $recordDirectory . '/' . $dbw->insertId();
1742 * // Write the record data to the storage system
1743 * $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
1744 * if ( $status->isOK() ) {
1745 * // Try to cleanup files orphaned by transaction rollback
1746 * $dbw->onTransactionResolution(
1747 * function ( $type ) use ( $fileBackend, $path ) {
1748 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1749 * $fileBackend->delete( [ 'src' => $path ] );
1754 * // Demark the end of this conceptual unit of updates
1755 * $dbw->endAtomic( __METHOD__ );
1757 * // Discard these writes from the transaction (preserving prior writes)
1758 * $dbw->cancelAtomic( __METHOD__, $sectionId );
1763 * @param string $fname
1764 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1765 * savepoint and enable self::cancelAtomic() for this section.
1766 * @return AtomicSectionIdentifier section ID token
1769 public function startAtomic( $fname = __METHOD__
, $cancelable = self
::ATOMIC_NOT_CANCELABLE
);
1772 * Ends an atomic section of SQL statements
1774 * Ends the next section of atomic SQL statements and commits the transaction
1778 * @see IDatabase::startAtomic
1779 * @param string $fname
1782 public function endAtomic( $fname = __METHOD__
);
1785 * Cancel an atomic section of SQL statements
1787 * This will roll back only the statements executed since the start of the
1788 * most recent atomic section, and close that section. If a transaction was
1789 * open before the corresponding startAtomic() call, any statements before
1790 * that call are *not* rolled back and the transaction remains open. If the
1791 * corresponding startAtomic() implicitly started a transaction, that
1792 * transaction is rolled back.
1794 * @note callers must use additional measures for situations involving two or more
1795 * (peer) transactions (e.g. updating two database servers at once). The transaction
1796 * and savepoint logic of startAtomic() are bound to specific IDatabase instances.
1798 * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
1800 * @note As a micro-optimization to save a few DB calls, this method may only
1801 * be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
1803 * @see IDatabase::startAtomic
1804 * @param string $fname
1805 * @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
1806 * passing this enables cancellation of unclosed nested sections [optional]
1809 public function cancelAtomic( $fname = __METHOD__
, AtomicSectionIdentifier
$sectionId = null );
1812 * Perform an atomic section of reversable SQL statements from a callback
1814 * The $callback takes the following arguments:
1815 * - This database object
1816 * - The value of $fname
1818 * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
1819 * If any exception occurs during execution of the callback, it will be handled as follows:
1820 * - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
1821 * (and only) statements executed during the atomic section. If that succeeds, then the
1822 * exception will be re-thrown; if it fails, then a different exception will be thrown
1823 * and any further query attempts will fail until rollback() is called.
1824 * - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
1825 * end of the section and the error will be re-thrown. Any further query attempts will
1826 * fail until rollback() is called.
1828 * This method is convenient for letting calls to the caller of this method be wrapped
1829 * in a try/catch blocks for exception types that imply that the caller failed but was
1830 * able to properly discard the changes it made in the transaction. This method can be
1831 * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
1833 * Example usage, "RecordStore::save" method:
1835 * $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
1836 * // Create new record metadata row
1837 * $dbw->insert( 'records', $record->toArray(), __METHOD__ );
1838 * // Figure out where to store the data based on the new row's ID
1839 * $path = $this->recordDirectory . '/' . $dbw->insertId();
1840 * // Write the record data to the storage system;
1841 * // blob store throughs StoreFailureException on failure
1842 * $this->blobStore->create( $path, $record->getJSON() );
1843 * // Try to cleanup files orphaned by transaction rollback
1844 * $dbw->onTransactionResolution(
1845 * function ( $type ) use ( $path ) {
1846 * if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
1847 * $this->blobStore->delete( $path );
1852 * }, $dbw::ATOMIC_CANCELABLE );
1855 * Example usage, caller of the "RecordStore::save" method:
1857 * $dbw->startAtomic( __METHOD__ );
1858 * // ...various SQL writes happen...
1860 * $recordStore->save( $record );
1861 * } catch ( StoreFailureException $e ) {
1862 * // ...various SQL writes happen...
1864 * // ...various SQL writes happen...
1865 * $dbw->endAtomic( __METHOD__ );
1868 * @see Database::startAtomic
1869 * @see Database::endAtomic
1870 * @see Database::cancelAtomic
1872 * @param string $fname Caller name (usually __METHOD__)
1873 * @param callable $callback Callback that issues DB updates
1874 * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
1875 * savepoint and enable self::cancelAtomic() for this section.
1876 * @return mixed $res Result of the callback (since 1.28)
1878 * @throws RuntimeException
1879 * @since 1.27; prior to 1.31 this did a rollback() instead of
1880 * cancelAtomic(), and assumed no callers up the stack would ever try to
1881 * catch the exception.
1883 public function doAtomicSection(
1884 $fname, callable
$callback, $cancelable = self
::ATOMIC_NOT_CANCELABLE
1888 * Begin a transaction. If a transaction is already in progress,
1889 * that transaction will be committed before the new transaction is started.
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.
1895 * Note that when the DBO_TRX flag is set (which is usually the case for web
1896 * requests, but not for maintenance scripts), any previous database query
1897 * will have started a transaction automatically.
1899 * Nesting of transactions is not supported. Attempts to nest transactions
1900 * will cause a warning, unless the current transaction was started
1901 * automatically because of the DBO_TRX flag.
1903 * @param string $fname Calling function name
1904 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1907 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1910 * Commits a transaction previously started using begin().
1911 * If no transaction is in progress, a warning is issued.
1913 * Only call this from code with outer transcation scope.
1914 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1915 * Nesting of transactions is not supported.
1917 * @param string $fname
1918 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1919 * constant to disable warnings about explicitly committing implicit transactions,
1920 * or calling commit when no transaction is in progress.
1922 * This will trigger an exception if there is an ongoing explicit transaction.
1924 * Only set the flush flag if you are sure that these warnings are not applicable,
1925 * and no explicit transactions are open.
1929 public function commit( $fname = __METHOD__
, $flush = self
::FLUSHING_ONE
);
1932 * Rollback a transaction previously started using begin().
1933 * If no transaction is in progress, a warning is issued.
1935 * Only call this from code with outer transcation scope.
1936 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1937 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1938 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1939 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1941 * Query, connection, and onTransaction* callback errors will be suppressed and logged.
1943 * @param string $fname Calling function name
1944 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1945 * constant to disable warnings about calling rollback when no transaction is in
1946 * progress. This will silently break any ongoing explicit transaction. Only set the
1947 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1949 * @since 1.23 Added $flush parameter
1951 public function rollback( $fname = __METHOD__
, $flush = self
::FLUSHING_ONE
);
1954 * Commit any transaction but error out if writes or callbacks are pending
1956 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1957 * see a new point-in-time of the database. This is useful when one of many transaction
1958 * rounds finished and significant time will pass in the script's lifetime. It is also
1959 * useful to call on a replica DB after waiting on replication to catch up to the master.
1961 * @param string $fname Calling function name
1962 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1963 * constant to disable warnings about explicitly committing implicit transactions,
1964 * or calling commit when no transaction is in progress.
1966 * This will trigger an exception if there is an ongoing explicit transaction.
1968 * Only set the flush flag if you are sure that these warnings are not applicable,
1969 * and no explicit transactions are open.
1973 * @since 1.34 Added $flush parameter
1975 public function flushSnapshot( $fname = __METHOD__
, $flush = self
::FLUSHING_ONE
);
1978 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1979 * to the format used for inserting into timestamp fields in this DBMS.
1981 * The result is unquoted, and needs to be passed through addQuotes()
1982 * before it can be included in raw SQL.
1984 * @param string|int $ts
1988 public function timestamp( $ts = 0 );
1991 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1992 * to the format used for inserting into timestamp fields in this DBMS. If
1993 * NULL is input, it is passed through, allowing NULL values to be inserted
1994 * into timestamp fields.
1996 * The result is unquoted, and needs to be passed through addQuotes()
1997 * before it can be included in raw SQL.
1999 * @param string|int|null $ts
2003 public function timestampOrNull( $ts = null );
2006 * Ping the server and try to reconnect if it there is no connection
2008 * @param float|null &$rtt Value to store the estimated RTT [optional]
2009 * @return bool Success or failure
2011 public function ping( &$rtt = null );
2014 * Get the amount of replication lag for this database server
2016 * Callers should avoid using this method while a transaction is active
2018 * @return int|bool Database replication lag in seconds or false on error
2021 public function getLag();
2024 * Get the replica DB lag when the current transaction started
2025 * or a general lag estimate if not transaction is active
2027 * This is useful when transactions might use snapshot isolation
2028 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2029 * is this lag plus transaction duration. If they don't, it is still
2030 * safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
2031 * indication of the staleness of subsequent reads.
2033 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2037 public function getSessionLagStatus();
2040 * Return the maximum number of items allowed in a list, or 0 for unlimited.
2044 public function maxListLen();
2047 * Some DBMSs have a special format for inserting into blob fields, they
2048 * don't allow simple quoted strings to be inserted. To insert into such
2049 * a field, pass the data through this function before passing it to
2050 * IDatabase::insert().
2053 * @return string|Blob
2055 public function encodeBlob( $b );
2058 * Some DBMSs return a special placeholder object representing blob fields
2059 * in result objects. Pass the object through this function to return the
2062 * @param string|Blob $b
2065 public function decodeBlob( $b );
2068 * Override database's default behavior. $options include:
2069 * 'connTimeout' : Set the connection timeout value in seconds.
2070 * May be useful for very long batch queries such as
2071 * full-wiki dumps, where a single query reads out over
2074 * @param array $options
2078 public function setSessionOptions( array $options );
2081 * Set variables to be used in sourceFile/sourceStream, in preference to the
2082 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
2083 * all. If it's set to false, $GLOBALS will be used.
2085 * @param bool|array $vars Mapping variable name to value.
2087 public function setSchemaVars( $vars );
2090 * Check to see if a named lock is not locked by any thread (non-blocking)
2092 * @param string $lockName Name of lock to poll
2093 * @param string $method Name of method calling us
2098 public function lockIsFree( $lockName, $method );
2101 * Acquire a named lock
2103 * Named locks are not related to transactions
2105 * @param string $lockName Name of lock to aquire
2106 * @param string $method Name of the calling method
2107 * @param int $timeout Acquisition timeout in seconds (0 means non-blocking)
2111 public function lock( $lockName, $method, $timeout = 5 );
2116 * Named locks are not related to transactions
2118 * @param string $lockName Name of lock to release
2119 * @param string $method Name of the calling method
2121 * @return int Returns 1 if the lock was released, 0 if the lock was not established
2122 * by this thread (in which case the lock is not released), and NULL if the named lock
2127 public function unlock( $lockName, $method );
2130 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
2132 * Only call this from outer transcation scope and when only one DB will be affected.
2133 * See https://www.mediawiki.org/wiki/Database_transactions for details.
2135 * This is suitiable for transactions that need to be serialized using cooperative locks,
2136 * where each transaction can see each others' changes. Any transaction is flushed to clear
2137 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
2138 * the lock will be released unless a transaction is active. If one is active, then the lock
2139 * will be released when it either commits or rolls back.
2141 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
2143 * @param string $lockKey Name of lock to release
2144 * @param string $fname Name of the calling method
2145 * @param int $timeout Acquisition timeout in seconds
2146 * @return ScopedCallback|null
2150 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
2153 * Check to see if a named lock used by lock() use blocking queues
2158 public function namedLocksEnqueue();
2161 * Find out when 'infinity' is. Most DBMSes support this. This is a special
2162 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
2163 * because "i" sorts after all numbers.
2167 public function getInfinity();
2170 * Encode an expiry time into the DBMS dependent format
2172 * @param string $expiry Timestamp for expiry, or the 'infinity' string
2175 public function encodeExpiry( $expiry );
2178 * Decode an expiry time into a DBMS independent format
2180 * @param string $expiry DB timestamp field value for expiry
2181 * @param int $format TS_* constant, defaults to TS_MW
2184 public function decodeExpiry( $expiry, $format = TS_MW
);
2187 * Allow or deny "big selects" for this session only. This is done by setting
2188 * the sql_big_selects session variable.
2190 * This is a MySQL-specific feature.
2192 * @param bool|string $value True for allow, false for deny, or "default" to
2193 * restore the initial value
2195 public function setBigSelects( $value = true );
2198 * @return bool Whether this DB is read-only
2201 public function isReadOnly();
2204 * Make certain table names use their own database, schema, and table prefix
2205 * when passed into SQL queries pre-escaped and without a qualified database name
2207 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
2208 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
2210 * Calling this twice will completely clear any old table aliases. Also, note that
2211 * callers are responsible for making sure the schemas and databases actually exist.
2213 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
2216 public function setTableAliases( array $aliases );
2219 * Convert certain index names to alternative names before querying the DB
2221 * Note that this applies to indexes regardless of the table they belong to.
2223 * This can be employed when an index was renamed X => Y in code, but the new Y-named
2224 * indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
2225 * the aliases can be removed, and then the old X-named indexes dropped.
2227 * @param string[] $aliases
2230 public function setIndexAliases( array $aliases );
2233 * Get a debugging string that mentions the database type, the ID of this instance,
2234 * and the ID of any underlying connection resource or driver object if one is present
2236 * @return string "<db type> object #<X>" or "<db type> object #<X> (resource/handle id #<Y>)"
2239 public function __toString();
2243 * @deprecated since 1.29
2245 class_alias( IDatabase
::class, 'IDatabase' );