25e5912ac57c51ee700f4eaa20cd4d6c15a9ff40
4 * @defgroup Database Database
6 * This file deals with database interface functions
7 * and query specifics/optimisations.
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write to the Free Software Foundation, Inc.,
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
22 * http://www.gnu.org/copyleft/gpl.html
29 * Basic database interface for live and lazy-loaded DB handles
31 * @note: IDatabase and DBConnRef should be updated to reflect any changes
35 /** @var int Callback triggered immediately due to no active transaction */
36 const TRIGGER_IDLE
= 1;
37 /** @var int Callback triggered by COMMIT */
38 const TRIGGER_COMMIT
= 2;
39 /** @var int Callback triggered by ROLLBACK */
40 const TRIGGER_ROLLBACK
= 3;
42 /** @var string Transaction is requested by regular caller outside of the DB layer */
43 const TRANSACTION_EXPLICIT
= '';
44 /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
45 const TRANSACTION_INTERNAL
= 'implicit';
47 /** @var string Transaction operation comes from service managing all DBs */
48 const FLUSHING_ALL_PEERS
= 'flush';
49 /** @var string Transaction operation comes from the database class internally */
50 const FLUSHING_INTERNAL
= 'flush';
52 /** @var string Do not remember the prior flags */
53 const REMEMBER_NOTHING
= '';
54 /** @var string Remember the prior flags */
55 const REMEMBER_PRIOR
= 'remember';
56 /** @var string Restore to the prior flag state */
57 const RESTORE_PRIOR
= 'prior';
58 /** @var string Restore to the initial flag state */
59 const RESTORE_INITIAL
= 'initial';
61 /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
62 const ESTIMATE_TOTAL
= 'total';
63 /** @var string Estimate time to apply (scanning, applying) */
64 const ESTIMATE_DB_APPLY
= 'apply';
66 /** @var int Combine list with comma delimeters */
68 /** @var int Combine list with AND clauses */
70 /** @var int Convert map into a SET clause */
72 /** @var int Treat as field name and do not apply value escaping */
74 /** @var int Combine list with OR clauses */
78 * A string describing the current software version, and possibly
79 * other details in a user-friendly way. Will be listed on Special:Version, etc.
80 * Use getServerVersion() to get machine-friendly information.
82 * @return string Version information from the database server
84 public function getServerInfo();
87 * Turns buffering of SQL result sets on (true) or off (false). Default is
90 * Unbuffered queries are very troublesome in MySQL:
92 * - If another query is executed while the first query is being read
93 * out, the first query is killed. This means you can't call normal
94 * MediaWiki functions while you are reading an unbuffered query result
95 * from a normal wfGetDB() connection.
97 * - Unbuffered queries cause the MySQL server to use large amounts of
98 * memory and to hold broad locks which block other queries.
100 * If you want to limit client-side memory, it's almost always better to
101 * split up queries into batches using a LIMIT clause than to switch off
104 * @param null|bool $buffer
105 * @return null|bool The previous value of the flag
107 public function bufferResults( $buffer = null );
110 * Gets the current transaction level.
112 * Historically, transactions were allowed to be "nested". This is no
113 * longer supported, so this function really only returns a boolean.
115 * @return int The previous value
117 public function trxLevel();
120 * Get the UNIX timestamp of the time that the transaction was established
122 * This can be used to reason about the staleness of SELECT data
123 * in REPEATABLE-READ transaction isolation level.
125 * @return float|null Returns null if there is not active transaction
128 public function trxTimestamp();
131 * @return bool Whether an explicit transaction or atomic sections are still open
134 public function explicitTrxActive();
137 * Get/set the table prefix.
138 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
139 * @return string The previous table prefix.
141 public function tablePrefix( $prefix = null );
144 * Get/set the db schema.
145 * @param string $schema The database schema to set, or omitted to leave it unchanged.
146 * @return string The previous db schema.
148 public function dbSchema( $schema = null );
151 * Get properties passed down from the server info array of the load
154 * @param string $name The entry of the info array to get, or null to get the
157 * @return array|mixed|null
159 public function getLBInfo( $name = null );
162 * Set the LB info array, or a member of it. If called with one parameter,
163 * the LB info array is set to that parameter. If it is called with two
164 * parameters, the member with the given name is set to the given value.
166 * @param string $name
167 * @param array $value
169 public function setLBInfo( $name, $value = null );
172 * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
174 * @param IDatabase $conn
177 public function setLazyMasterHandle( IDatabase
$conn );
180 * Returns true if this database does an implicit sort when doing GROUP BY
184 public function implicitGroupby();
187 * Returns true if this database does an implicit order by when the column has an index
188 * For example: SELECT page_title FROM page LIMIT 1
192 public function implicitOrderby();
195 * Return the last query that went through IDatabase::query()
198 public function lastQuery();
201 * Returns true if the connection may have been used for write queries.
202 * Should return true if unsure.
206 public function doneWrites();
209 * Returns the last time the connection may have been used for write queries.
210 * Should return a timestamp if unsure.
212 * @return int|float UNIX timestamp or false
215 public function lastDoneWrites();
218 * @return bool Whether there is a transaction open with possible write queries
221 public function writesPending();
224 * Returns true if there is a transaction open with possible write
225 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
226 * This does *not* count recurring callbacks, e.g. from setTransactionListener().
230 public function writesOrCallbacksPending();
233 * Get the time spend running write queries for this transaction
235 * High times could be due to scanning, updates, locking, and such
237 * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
238 * @return float|bool Returns false if not transaction is active
241 public function pendingWriteQueryDuration( $type = self
::ESTIMATE_TOTAL
);
244 * Get the list of method names that did write queries for this transaction
249 public function pendingWriteCallers();
252 * Is a connection to the database open?
255 public function isOpen();
258 * Set a flag for this connection
260 * @param int $flag DBO_* constants from Defines.php:
261 * - DBO_DEBUG: output some debug info (same as debug())
262 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
263 * - DBO_TRX: automatically start transactions
264 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
265 * and removes it in command line mode
266 * - DBO_PERSISTENT: use persistant database connection
267 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
269 public function setFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
272 * Clear a flag for this connection
274 * @param int $flag DBO_* constants from Defines.php:
275 * - DBO_DEBUG: output some debug info (same as debug())
276 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
277 * - DBO_TRX: automatically start transactions
278 * - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
279 * and removes it in command line mode
280 * - DBO_PERSISTENT: use persistant database connection
281 * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
283 public function clearFlag( $flag, $remember = self
::REMEMBER_NOTHING
);
286 * Restore the flags to their prior state before the last setFlag/clearFlag call
288 * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
291 public function restoreFlags( $state = self
::RESTORE_PRIOR
);
294 * Returns a boolean whether the flag $flag is set for this connection
296 * @param int $flag DBO_* constants from Defines.php:
297 * - DBO_DEBUG: output some debug info (same as debug())
298 * - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
299 * - DBO_TRX: automatically start transactions
300 * - DBO_PERSISTENT: use persistant database connection
303 public function getFlag( $flag );
306 * General read-only accessor
308 * @param string $name
311 public function getProperty( $name );
316 public function getDomainID();
319 * Alias for getDomainID()
323 public function getWikiID();
326 * Get the type of the DBMS, as it appears in $wgDBtype.
330 public function getType();
333 * Open a connection to the database. Usually aborts on failure
335 * @param string $server Database server host
336 * @param string $user Database user name
337 * @param string $password Database user password
338 * @param string $dbName Database name
340 * @throws DBConnectionError
342 public function open( $server, $user, $password, $dbName );
345 * Fetch the next row from the given result object, in object form.
346 * Fields can be retrieved with $row->fieldname, with fields acting like
348 * If no more rows are available, false is returned.
350 * @param ResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
351 * @return stdClass|bool
352 * @throws DBUnexpectedError Thrown if the database returns an error
354 public function fetchObject( $res );
357 * Fetch the next row from the given result object, in associative array
358 * form. Fields are retrieved with $row['fieldname'].
359 * If no more rows are available, false is returned.
361 * @param ResultWrapper $res Result object as returned from IDatabase::query(), etc.
363 * @throws DBUnexpectedError Thrown if the database returns an error
365 public function fetchRow( $res );
368 * Get the number of rows in a result object
370 * @param mixed $res A SQL result
373 public function numRows( $res );
376 * Get the number of fields in a result object
377 * @see http://www.php.net/mysql_num_fields
379 * @param mixed $res A SQL result
382 public function numFields( $res );
385 * Get a field name in a result object
386 * @see http://www.php.net/mysql_field_name
388 * @param mixed $res A SQL result
392 public function fieldName( $res, $n );
395 * Get the inserted value of an auto-increment row
397 * The value inserted should be fetched from nextSequenceValue()
400 * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
401 * $dbw->insert( 'page', [ 'page_id' => $id ] );
402 * $id = $dbw->insertId();
406 public function insertId();
409 * Change the position of the cursor in a result object
410 * @see http://www.php.net/mysql_data_seek
412 * @param mixed $res A SQL result
415 public function dataSeek( $res, $row );
418 * Get the last error number
419 * @see http://www.php.net/mysql_errno
423 public function lastErrno();
426 * Get a description of the last error
427 * @see http://www.php.net/mysql_error
431 public function lastError();
434 * mysql_fetch_field() wrapper
435 * Returns false if the field doesn't exist
437 * @param string $table Table name
438 * @param string $field Field name
442 public function fieldInfo( $table, $field );
445 * Get the number of rows affected by the last write query
446 * @see http://www.php.net/mysql_affected_rows
450 public function affectedRows();
453 * Returns a wikitext link to the DB's website, e.g.,
454 * return "[http://www.mysql.com/ MySQL]";
455 * Should at least contain plain text, if for some reason
456 * your database has no website.
458 * @return string Wikitext of a link to the server software's web site
460 public function getSoftwareLink();
463 * A string describing the current software version, like from
464 * mysql_get_server_info().
466 * @return string Version information from the database server.
468 public function getServerVersion();
471 * Closes a database connection.
472 * if it is open : commits any open transactions
475 * @return bool Operation success. true if already closed.
477 public function close();
480 * @param string $error Fallback error message, used if none is given by DB
481 * @throws DBConnectionError
483 public function reportConnectionError( $error = 'Unknown error' );
486 * Run an SQL query and return the result. Normally throws a DBQueryError
487 * on failure. If errors are ignored, returns false instead.
489 * In new code, the query wrappers select(), insert(), update(), delete(),
490 * etc. should be used where possible, since they give much better DBMS
491 * independence and automatically quote or validate user input in a variety
492 * of contexts. This function is generally only useful for queries which are
493 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
496 * However, the query wrappers themselves should call this function.
498 * @param string $sql SQL query
499 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
500 * comment (you can use __METHOD__ or add some extra info)
501 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
502 * maybe best to catch the exception instead?
504 * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
505 * for a successful read query, or false on failure if $tempIgnore set
507 public function query( $sql, $fname = __METHOD__
, $tempIgnore = false );
510 * Report a query error. Log the error, and if neither the object ignore
511 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
513 * @param string $error
516 * @param string $fname
517 * @param bool $tempIgnore
518 * @throws DBQueryError
520 public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
523 * Free a result object returned by query() or select(). It's usually not
524 * necessary to call this, just use unset() or let the variable holding
525 * the result object go out of scope.
527 * @param mixed $res A SQL result
529 public function freeResult( $res );
532 * A SELECT wrapper which returns a single field from a single result row.
534 * Usually throws a DBQueryError on failure. If errors are explicitly
535 * ignored, returns false on failure.
537 * If no result rows are returned from the query, false is returned.
539 * @param string|array $table Table name. See IDatabase::select() for details.
540 * @param string $var The field name to select. This must be a valid SQL
541 * fragment: do not use unvalidated user input.
542 * @param string|array $cond The condition array. See IDatabase::select() for details.
543 * @param string $fname The function name of the caller.
544 * @param string|array $options The query options. See IDatabase::select() for details.
546 * @return bool|mixed The value from the field, or false on failure.
548 public function selectField(
549 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
553 * A SELECT wrapper which returns a list of single field values from result rows.
555 * Usually throws a DBQueryError on failure. If errors are explicitly
556 * ignored, returns false on failure.
558 * If no result rows are returned from the query, false is returned.
560 * @param string|array $table Table name. See IDatabase::select() for details.
561 * @param string $var The field name to select. This must be a valid SQL
562 * fragment: do not use unvalidated user input.
563 * @param string|array $cond The condition array. See IDatabase::select() for details.
564 * @param string $fname The function name of the caller.
565 * @param string|array $options The query options. See IDatabase::select() for details.
567 * @return bool|array The values from the field, or false on failure
570 public function selectFieldValues(
571 $table, $var, $cond = '', $fname = __METHOD__
, $options = []
575 * Execute a SELECT query constructed using the various parameters provided.
576 * See below for full details of the parameters.
578 * @param string|array $table Table name
579 * @param string|array $vars Field names
580 * @param string|array $conds Conditions
581 * @param string $fname Caller function name
582 * @param array $options Query options
583 * @param array $join_conds Join conditions
586 * @param string|array $table
588 * May be either an array of table names, or a single string holding a table
589 * name. If an array is given, table aliases can be specified, for example:
593 * This includes the user table in the query, with the alias "a" available
594 * for use in field names (e.g. a.user_name).
596 * All of the table names given here are automatically run through
597 * DatabaseBase::tableName(), which causes the table prefix (if any) to be
598 * added, and various other table name mappings to be performed.
600 * Do not use untrusted user input as a table name. Alias names should
601 * not have characters outside of the Basic multilingual plane.
603 * @param string|array $vars
605 * May be either a field name or an array of field names. The field names
606 * can be complete fragments of SQL, for direct inclusion into the SELECT
607 * query. If an array is given, field aliases can be specified, for example:
609 * [ 'maxrev' => 'MAX(rev_id)' ]
611 * This includes an expression with the alias "maxrev" in the query.
613 * If an expression is given, care must be taken to ensure that it is
616 * Untrusted user input must not be passed to this parameter.
618 * @param string|array $conds
620 * May be either a string containing a single condition, or an array of
621 * conditions. If an array is given, the conditions constructed from each
622 * element are combined with AND.
624 * Array elements may take one of two forms:
626 * - Elements with a numeric key are interpreted as raw SQL fragments.
627 * - Elements with a string key are interpreted as equality conditions,
628 * where the key is the field name.
629 * - If the value of such an array element is a scalar (such as a
630 * string), it will be treated as data and thus quoted appropriately.
631 * If it is null, an IS NULL clause will be added.
632 * - If the value is an array, an IN (...) clause will be constructed
633 * from its non-null elements, and an IS NULL clause will be added
634 * if null is present, such that the field may match any of the
635 * elements in the array. The non-null elements will be quoted.
637 * Note that expressions are often DBMS-dependent in their syntax.
638 * DBMS-independent wrappers are provided for constructing several types of
639 * expression commonly used in condition queries. See:
640 * - IDatabase::buildLike()
641 * - IDatabase::conditional()
643 * Untrusted user input is safe in the values of string keys, however untrusted
644 * input must not be used in the array key names or in the values of numeric keys.
645 * Escaping of untrusted input used in values of numeric keys should be done via
646 * IDatabase::addQuotes()
648 * @param string|array $options
650 * Optional: Array of query options. Boolean options are specified by
651 * including them in the array as a string value with a numeric key, for
656 * The supported options are:
658 * - OFFSET: Skip this many rows at the start of the result set. OFFSET
659 * with LIMIT can theoretically be used for paging through a result set,
660 * but this is discouraged in MediaWiki for performance reasons.
662 * - LIMIT: Integer: return at most this many rows. The rows are sorted
663 * and then the first rows are taken until the limit is reached. LIMIT
664 * is applied to a result set after OFFSET.
666 * - FOR UPDATE: Boolean: lock the returned rows so that they can't be
667 * changed until the next COMMIT.
669 * - DISTINCT: Boolean: return only unique result rows.
671 * - GROUP BY: May be either an SQL fragment string naming a field or
672 * expression to group by, or an array of such SQL fragments.
674 * - HAVING: May be either an string containing a HAVING clause or an array of
675 * conditions building the HAVING clause. If an array is given, the conditions
676 * constructed from each element are combined with AND.
678 * - ORDER BY: May be either an SQL fragment giving a field name or
679 * expression to order by, or an array of such SQL fragments.
681 * - USE INDEX: This may be either a string giving the index name to use
682 * for the query, or an array. If it is an associative array, each key
683 * gives the table name (or alias), each value gives the index name to
684 * use for that table. All strings are SQL fragments and so should be
685 * validated by the caller.
687 * - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
690 * And also the following boolean MySQL extensions, see the MySQL manual
693 * - LOCK IN SHARE MODE
697 * - SQL_BUFFER_RESULT
699 * - SQL_CALC_FOUND_ROWS
704 * @param string|array $join_conds
706 * Optional associative array of table-specific join conditions. In the
707 * most common case, this is unnecessary, since the join condition can be
708 * in $conds. However, it is useful for doing a LEFT JOIN.
710 * The key of the array contains the table name or alias. The value is an
711 * array with two elements, numbered 0 and 1. The first gives the type of
712 * join, the second is the same as the $conds parameter. Thus it can be
713 * an SQL fragment, or an array where the string keys are equality and the
714 * numeric keys are SQL fragments all AND'd together. For example:
716 * [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
718 * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
719 * with no rows in it will be returned. If there was a query error, a
720 * DBQueryError exception will be thrown, except if the "ignore errors"
721 * option was set, in which case false will be returned.
723 public function select(
724 $table, $vars, $conds = '', $fname = __METHOD__
,
725 $options = [], $join_conds = []
729 * The equivalent of IDatabase::select() except that the constructed SQL
730 * is returned, instead of being immediately executed. This can be useful for
731 * doing UNION queries, where the SQL text of each query is needed. In general,
732 * however, callers outside of Database classes should just use select().
734 * @param string|array $table Table name
735 * @param string|array $vars Field names
736 * @param string|array $conds Conditions
737 * @param string $fname Caller function name
738 * @param string|array $options Query options
739 * @param string|array $join_conds Join conditions
741 * @return string SQL query string.
742 * @see IDatabase::select()
744 public function selectSQLText(
745 $table, $vars, $conds = '', $fname = __METHOD__
,
746 $options = [], $join_conds = []
750 * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
751 * that a single row object is returned. If the query returns no rows,
754 * @param string|array $table Table name
755 * @param string|array $vars Field names
756 * @param array $conds Conditions
757 * @param string $fname Caller function name
758 * @param string|array $options Query options
759 * @param array|string $join_conds Join conditions
761 * @return stdClass|bool
763 public function selectRow( $table, $vars, $conds, $fname = __METHOD__
,
764 $options = [], $join_conds = []
768 * Estimate the number of rows in dataset
770 * MySQL allows you to estimate the number of rows that would be returned
771 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
772 * index cardinality statistics, and is notoriously inaccurate, especially
773 * when large numbers of rows have recently been added or deleted.
775 * For DBMSs that don't support fast result size estimation, this function
776 * will actually perform the SELECT COUNT(*).
778 * Takes the same arguments as IDatabase::select().
780 * @param string $table Table name
781 * @param string $vars Unused
782 * @param array|string $conds Filters on the table
783 * @param string $fname Function name for profiling
784 * @param array $options Options for select
785 * @return int Row count
787 public function estimateRowCount(
788 $table, $vars = '*', $conds = '', $fname = __METHOD__
, $options = []
792 * Get the number of rows in dataset
794 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
796 * Takes the same arguments as IDatabase::select().
798 * @since 1.27 Added $join_conds parameter
800 * @param array|string $tables Table names
801 * @param string $vars Unused
802 * @param array|string $conds Filters on the table
803 * @param string $fname Function name for profiling
804 * @param array $options Options for select
805 * @param array $join_conds Join conditions (since 1.27)
806 * @return int Row count
808 public function selectRowCount(
809 $tables, $vars = '*', $conds = '', $fname = __METHOD__
, $options = [], $join_conds = []
813 * Determines whether a field exists in a table
815 * @param string $table Table name
816 * @param string $field Filed to check on that table
817 * @param string $fname Calling function name (optional)
818 * @return bool Whether $table has filed $field
820 public function fieldExists( $table, $field, $fname = __METHOD__
);
823 * Determines whether an index exists
824 * Usually throws a DBQueryError on failure
825 * If errors are explicitly ignored, returns NULL on failure
827 * @param string $table
828 * @param string $index
829 * @param string $fname
832 public function indexExists( $table, $index, $fname = __METHOD__
);
835 * Query whether a given table exists
837 * @param string $table
838 * @param string $fname
841 public function tableExists( $table, $fname = __METHOD__
);
844 * Determines if a given index is unique
846 * @param string $table
847 * @param string $index
851 public function indexUnique( $table, $index );
854 * INSERT wrapper, inserts an array into a table.
858 * - A single associative array. The array keys are the field names, and
859 * the values are the values to insert. The values are treated as data
860 * and will be quoted appropriately. If NULL is inserted, this will be
861 * converted to a database NULL.
862 * - An array with numeric keys, holding a list of associative arrays.
863 * This causes a multi-row INSERT on DBMSs that support it. The keys in
864 * each subarray must be identical to each other, and in the same order.
866 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
869 * $options is an array of options, with boolean options encoded as values
870 * with numeric keys, in the same style as $options in
871 * IDatabase::select(). Supported options are:
873 * - IGNORE: Boolean: if present, duplicate key errors are ignored, and
874 * any rows which cause duplicate key errors are not inserted. It's
875 * possible to determine how many rows were successfully inserted using
876 * IDatabase::affectedRows().
878 * @param string $table Table name. This will be passed through
879 * DatabaseBase::tableName().
880 * @param array $a Array of rows to insert
881 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
882 * @param array $options Array of options
886 public function insert( $table, $a, $fname = __METHOD__
, $options = [] );
889 * UPDATE wrapper. Takes a condition array and a SET array.
891 * @param string $table Name of the table to UPDATE. This will be passed through
892 * DatabaseBase::tableName().
893 * @param array $values An array of values to SET. For each array element,
894 * the key gives the field name, and the value gives the data to set
895 * that field to. The data will be quoted by IDatabase::addQuotes().
896 * @param array $conds An array of conditions (WHERE). See
897 * IDatabase::select() for the details of the format of condition
898 * arrays. Use '*' to update all rows.
899 * @param string $fname The function name of the caller (from __METHOD__),
900 * for logging and profiling.
901 * @param array $options An array of UPDATE options, can be:
902 * - IGNORE: Ignore unique key conflicts
903 * - LOW_PRIORITY: MySQL-specific, see MySQL manual.
906 public function update( $table, $values, $conds, $fname = __METHOD__
, $options = [] );
909 * Makes an encoded list of strings from an array
911 * These can be used to make conjunctions or disjunctions on SQL condition strings
912 * derived from an array (see IDatabase::select() $conds documentation).
916 * $sql = $db->makeList( [
918 * $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
919 * ], $db::LIST_AND );
921 * This would set $sql to "rev_user = '$id' AND (rev_minor = '1' OR rev_len < '500')"
923 * @param array $a Containing the data
924 * @param int $mode IDatabase class constant:
925 * - IDatabase::LIST_COMMA: Comma separated, no field names
926 * - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
927 * - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
928 * - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
929 * - IDatabase::LIST_NAMES: Comma separated field names
933 public function makeList( $a, $mode = self
::LIST_COMMA
);
936 * Build a partial where clause from a 2-d array such as used for LinkBatch.
937 * The keys on each level may be either integers or strings.
939 * @param array $data Organized as 2-d
940 * [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
941 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
942 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
943 * @return string|bool SQL fragment, or false if no items in array
945 public function makeWhereFrom2d( $data, $baseKey, $subKey );
948 * @param string $field
951 public function bitNot( $field );
954 * @param string $fieldLeft
955 * @param string $fieldRight
958 public function bitAnd( $fieldLeft, $fieldRight );
961 * @param string $fieldLeft
962 * @param string $fieldRight
965 public function bitOr( $fieldLeft, $fieldRight );
968 * Build a concatenation list to feed into a SQL query
969 * @param array $stringList List of raw SQL expressions; caller is
970 * responsible for any quoting
973 public function buildConcat( $stringList );
976 * Build a GROUP_CONCAT or equivalent statement for a query.
978 * This is useful for combining a field for several rows into a single string.
979 * NULL values will not appear in the output, duplicated values will appear,
980 * and the resulting delimiter-separated values have no defined sort order.
981 * Code using the results may need to use the PHP unique() or sort() methods.
983 * @param string $delim Glue to bind the results together
984 * @param string|array $table Table name
985 * @param string $field Field name
986 * @param string|array $conds Conditions
987 * @param string|array $join_conds Join conditions
988 * @return string SQL text
991 public function buildGroupConcatField(
992 $delim, $table, $field, $conds = '', $join_conds = []
996 * Change the current database
999 * @return bool Success or failure
1001 public function selectDB( $db );
1004 * Get the current DB name
1007 public function getDBname();
1010 * Get the server hostname or IP address
1013 public function getServer();
1016 * Adds quotes and backslashes.
1018 * @param string|Blob $s
1021 public function addQuotes( $s );
1024 * LIKE statement wrapper, receives a variable-length argument list with
1025 * parts of pattern to match containing either string literals that will be
1026 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1027 * the function could be provided with an array of aforementioned
1030 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1031 * a LIKE clause that searches for subpages of 'My page title'.
1033 * $pattern = [ 'My_page_title/', $dbr->anyString() ];
1034 * $query .= $dbr->buildLike( $pattern );
1037 * @return string Fully built LIKE statement
1039 public function buildLike();
1042 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1046 public function anyChar();
1049 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1053 public function anyString();
1056 * Returns an appropriately quoted sequence value for inserting a new row.
1057 * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1058 * subclass will return an integer, and save the value for insertId()
1060 * Any implementation of this function should *not* involve reusing
1061 * sequence numbers created for rolled-back transactions.
1062 * See http://bugs.mysql.com/bug.php?id=30767 for details.
1063 * @param string $seqName
1066 public function nextSequenceValue( $seqName );
1069 * REPLACE query wrapper.
1071 * REPLACE is a very handy MySQL extension, which functions like an INSERT
1072 * except that when there is a duplicate key error, the old row is deleted
1073 * and the new row is inserted in its place.
1075 * We simulate this with standard SQL with a DELETE followed by INSERT. To
1076 * perform the delete, we need to know what the unique indexes are so that
1077 * we know how to find the conflicting rows.
1079 * It may be more efficient to leave off unique indexes which are unlikely
1080 * to collide. However if you do this, you run the risk of encountering
1081 * errors which wouldn't have occurred in MySQL.
1083 * @param string $table The table to replace the row(s) in.
1084 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1085 * a field name or an array of field names
1086 * @param array $rows Can be either a single row to insert, or multiple rows,
1087 * in the same format as for IDatabase::insert()
1088 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1090 public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__
);
1093 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1095 * This updates any conflicting rows (according to the unique indexes) using
1096 * the provided SET clause and inserts any remaining (non-conflicted) rows.
1098 * $rows may be either:
1099 * - A single associative array. The array keys are the field names, and
1100 * the values are the values to insert. The values are treated as data
1101 * and will be quoted appropriately. If NULL is inserted, this will be
1102 * converted to a database NULL.
1103 * - An array with numeric keys, holding a list of associative arrays.
1104 * This causes a multi-row INSERT on DBMSs that support it. The keys in
1105 * each subarray must be identical to each other, and in the same order.
1107 * It may be more efficient to leave off unique indexes which are unlikely
1108 * to collide. However if you do this, you run the risk of encountering
1109 * errors which wouldn't have occurred in MySQL.
1111 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1116 * @param string $table Table name. This will be passed through DatabaseBase::tableName().
1117 * @param array $rows A single row or list of rows to insert
1118 * @param array $uniqueIndexes List of single field names or field name tuples
1119 * @param array $set An array of values to SET. For each array element, the
1120 * key gives the field name, and the value gives the data to set that
1121 * field to. The data will be quoted by IDatabase::addQuotes().
1122 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1126 public function upsert(
1127 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1131 * DELETE where the condition is a join.
1133 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1134 * we use sub-selects
1136 * For safety, an empty $conds will not delete everything. If you want to
1137 * delete all rows where the join condition matches, set $conds='*'.
1139 * DO NOT put the join condition in $conds.
1141 * @param string $delTable The table to delete from.
1142 * @param string $joinTable The other table.
1143 * @param string $delVar The variable to join on, in the first table.
1144 * @param string $joinVar The variable to join on, in the second table.
1145 * @param array $conds Condition array of field names mapped to variables,
1146 * ANDed together in the WHERE clause
1147 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1148 * @throws DBUnexpectedError
1150 public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1155 * DELETE query wrapper.
1157 * @param array $table Table name
1158 * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1159 * for the format. Use $conds == "*" to delete all rows
1160 * @param string $fname Name of the calling function
1161 * @throws DBUnexpectedError
1162 * @return bool|ResultWrapper
1164 public function delete( $table, $conds, $fname = __METHOD__
);
1167 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1168 * into another table.
1170 * @param string $destTable The table name to insert into
1171 * @param string|array $srcTable May be either a table name, or an array of table names
1172 * to include in a join.
1174 * @param array $varMap Must be an associative array of the form
1175 * [ 'dest1' => 'source1', ... ]. Source items may be literals
1176 * rather than field names, but strings should be quoted with
1177 * IDatabase::addQuotes()
1179 * @param array $conds Condition array. See $conds in IDatabase::select() for
1180 * the details of the format of condition arrays. May be "*" to copy the
1183 * @param string $fname The function name of the caller, from __METHOD__
1185 * @param array $insertOptions Options for the INSERT part of the query, see
1186 * IDatabase::insert() for details.
1187 * @param array $selectOptions Options for the SELECT part of the query, see
1188 * IDatabase::select() for details.
1190 * @return ResultWrapper
1192 public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1193 $fname = __METHOD__
,
1194 $insertOptions = [], $selectOptions = []
1198 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1199 * within the UNION construct.
1202 public function unionSupportsOrderAndLimit();
1205 * Construct a UNION query
1206 * This is used for providing overload point for other DB abstractions
1207 * not compatible with the MySQL syntax.
1208 * @param array $sqls SQL statements to combine
1209 * @param bool $all Use UNION ALL
1210 * @return string SQL fragment
1212 public function unionQueries( $sqls, $all );
1215 * Returns an SQL expression for a simple conditional. This doesn't need
1216 * to be overridden unless CASE isn't supported in your DBMS.
1218 * @param string|array $cond SQL expression which will result in a boolean value
1219 * @param string $trueVal SQL expression to return if true
1220 * @param string $falseVal SQL expression to return if false
1221 * @return string SQL fragment
1223 public function conditional( $cond, $trueVal, $falseVal );
1226 * Returns a comand for str_replace function in SQL query.
1227 * Uses REPLACE() in MySQL
1229 * @param string $orig Column to modify
1230 * @param string $old Column to seek
1231 * @param string $new Column to replace with
1235 public function strreplace( $orig, $old, $new );
1238 * Determines how long the server has been up
1242 public function getServerUptime();
1245 * Determines if the last failure was due to a deadlock
1249 public function wasDeadlock();
1252 * Determines if the last failure was due to a lock timeout
1256 public function wasLockTimeout();
1259 * Determines if the last query error was due to a dropped connection and should
1260 * be dealt with by pinging the connection and reissuing the query.
1264 public function wasErrorReissuable();
1267 * Determines if the last failure was due to the database being read-only.
1271 public function wasReadOnlyError();
1274 * Wait for the replica DB to catch up to a given master position
1276 * @param DBMasterPos $pos
1277 * @param int $timeout The maximum number of seconds to wait for synchronisation
1278 * @return int|null Zero if the replica DB was past that position already,
1279 * greater than zero if we waited for some period of time, less than
1280 * zero if it timed out, and null on error
1282 public function masterPosWait( DBMasterPos
$pos, $timeout );
1285 * Get the replication position of this replica DB
1287 * @return DBMasterPos|bool False if this is not a replica DB.
1289 public function getSlavePos();
1292 * Get the position of this master
1294 * @return DBMasterPos|bool False if this is not a master
1296 public function getMasterPos();
1299 * @return bool Whether the DB is marked as read-only server-side
1302 public function serverIsReadOnly();
1305 * Run a callback as soon as the current transaction commits or rolls back.
1306 * An error is thrown if no transaction is pending. Queries in the function will run in
1307 * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1310 * This is useful for combining cooperative locks and DB transactions.
1312 * The callback takes one argument:
1313 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1315 * @param callable $callback
1316 * @param string $fname Caller name
1320 public function onTransactionResolution( callable
$callback, $fname = __METHOD__
);
1323 * Run a callback as soon as there is no transaction pending.
1324 * If there is a transaction and it is rolled back, then the callback is cancelled.
1325 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1326 * Callbacks must commit any transactions that they begin.
1328 * This is useful for updates to different systems or when separate transactions are needed.
1329 * For example, one might want to enqueue jobs into a system outside the database, but only
1330 * after the database is updated so that the jobs will see the data when they actually run.
1331 * It can also be used for updates that easily cause deadlocks if locks are held too long.
1333 * Updates will execute in the order they were enqueued.
1335 * The callback takes one argument:
1336 * - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1338 * @param callable $callback
1339 * @param string $fname Caller name
1342 public function onTransactionIdle( callable
$callback, $fname = __METHOD__
);
1345 * Run a callback before the current transaction commits or now if there is none.
1346 * If there is a transaction and it is rolled back, then the callback is cancelled.
1347 * Callbacks must not start nor commit any transactions. If no transaction is active,
1348 * then a transaction will wrap the callback.
1350 * This is useful for updates that easily cause deadlocks if locks are held too long
1351 * but where atomicity is strongly desired for these updates and some related updates.
1353 * Updates will execute in the order they were enqueued.
1355 * @param callable $callback
1356 * @param string $fname Caller name
1359 public function onTransactionPreCommitOrIdle( callable
$callback, $fname = __METHOD__
);
1362 * Run a callback each time any transaction commits or rolls back
1364 * The callback takes two arguments:
1365 * - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1366 * - This IDatabase object
1367 * Callbacks must commit any transactions that they begin.
1369 * Registering a callback here will not affect writesOrCallbacks() pending
1371 * @param string $name Callback name
1372 * @param callable|null $callback Use null to unset a listener
1376 public function setTransactionListener( $name, callable
$callback = null );
1379 * Begin an atomic section of statements
1381 * If a transaction has been started already, just keep track of the given
1382 * section name to make sure the transaction is not committed pre-maturely.
1383 * This function can be used in layers (with sub-sections), so use a stack
1384 * to keep track of the different atomic sections. If there is no transaction,
1385 * start one implicitly.
1387 * The goal of this function is to create an atomic section of SQL queries
1388 * without having to start a new transaction if it already exists.
1390 * Atomic sections are more strict than transactions. With transactions,
1391 * attempting to begin a new transaction when one is already running results
1392 * in MediaWiki issuing a brief warning and doing an implicit commit. All
1393 * atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1394 * and any database transactions cannot be began or committed until all atomic
1395 * levels are closed. There is no such thing as implicitly opening or closing
1396 * an atomic section.
1399 * @param string $fname
1402 public function startAtomic( $fname = __METHOD__
);
1405 * Ends an atomic section of SQL statements
1407 * Ends the next section of atomic SQL statements and commits the transaction
1411 * @see IDatabase::startAtomic
1412 * @param string $fname
1415 public function endAtomic( $fname = __METHOD__
);
1418 * Run a callback to do an atomic set of updates for this database
1420 * The $callback takes the following arguments:
1421 * - This database object
1422 * - The value of $fname
1424 * If any exception occurs in the callback, then rollback() will be called and the error will
1425 * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1426 * In any case, such errors are expected to terminate the request, without any outside caller
1427 * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1428 * atomic section and uncommitted updates, which trashes the current request, requiring an
1429 * error to be displayed.
1431 * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1433 * @see DatabaseBase::startAtomic
1434 * @see DatabaseBase::endAtomic
1436 * @param string $fname Caller name (usually __METHOD__)
1437 * @param callable $callback Callback that issues DB updates
1438 * @return mixed $res Result of the callback (since 1.28)
1440 * @throws RuntimeException
1441 * @throws UnexpectedValueException
1444 public function doAtomicSection( $fname, callable
$callback );
1447 * Begin a transaction. If a transaction is already in progress,
1448 * that transaction will be committed before the new transaction is started.
1450 * Only call this from code with outer transcation scope.
1451 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1452 * Nesting of transactions is not supported.
1454 * Note that when the DBO_TRX flag is set (which is usually the case for web
1455 * requests, but not for maintenance scripts), any previous database query
1456 * will have started a transaction automatically.
1458 * Nesting of transactions is not supported. Attempts to nest transactions
1459 * will cause a warning, unless the current transaction was started
1460 * automatically because of the DBO_TRX flag.
1462 * @param string $fname Calling function name
1463 * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1466 public function begin( $fname = __METHOD__
, $mode = self
::TRANSACTION_EXPLICIT
);
1469 * Commits a transaction previously started using begin().
1470 * If no transaction is in progress, a warning is issued.
1472 * Only call this from code with outer transcation scope.
1473 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1474 * Nesting of transactions is not supported.
1476 * @param string $fname
1477 * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1478 * constant to disable warnings about explicitly committing implicit transactions,
1479 * or calling commit when no transaction is in progress.
1481 * This will trigger an exception if there is an ongoing explicit transaction.
1483 * Only set the flush flag if you are sure that these warnings are not applicable,
1484 * and no explicit transactions are open.
1486 * @throws DBUnexpectedError
1488 public function commit( $fname = __METHOD__
, $flush = '' );
1491 * Rollback a transaction previously started using begin().
1492 * If no transaction is in progress, a warning is issued.
1494 * Only call this from code with outer transcation scope.
1495 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1496 * Nesting of transactions is not supported. If a serious unexpected error occurs,
1497 * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1498 * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1500 * @param string $fname Calling function name
1501 * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1502 * constant to disable warnings about calling rollback when no transaction is in
1503 * progress. This will silently break any ongoing explicit transaction. Only set the
1504 * flush flag if you are sure that it is safe to ignore these warnings in your context.
1505 * @throws DBUnexpectedError
1506 * @since 1.23 Added $flush parameter
1508 public function rollback( $fname = __METHOD__
, $flush = '' );
1511 * Commit any transaction but error out if writes or callbacks are pending
1513 * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1514 * see a new point-in-time of the database. This is useful when one of many transaction
1515 * rounds finished and significant time will pass in the script's lifetime. It is also
1516 * useful to call on a replica DB after waiting on replication to catch up to the master.
1518 * @param string $fname Calling function name
1519 * @throws DBUnexpectedError
1522 public function flushSnapshot( $fname = __METHOD__
);
1525 * List all tables on the database
1527 * @param string $prefix Only show tables with this prefix, e.g. mw_
1528 * @param string $fname Calling function name
1532 public function listTables( $prefix = null, $fname = __METHOD__
);
1535 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1536 * to the format used for inserting into timestamp fields in this DBMS.
1538 * The result is unquoted, and needs to be passed through addQuotes()
1539 * before it can be included in raw SQL.
1541 * @param string|int $ts
1545 public function timestamp( $ts = 0 );
1548 * Convert a timestamp in one of the formats accepted by wfTimestamp()
1549 * to the format used for inserting into timestamp fields in this DBMS. If
1550 * NULL is input, it is passed through, allowing NULL values to be inserted
1551 * into timestamp fields.
1553 * The result is unquoted, and needs to be passed through addQuotes()
1554 * before it can be included in raw SQL.
1556 * @param string|int $ts
1560 public function timestampOrNull( $ts = null );
1563 * Ping the server and try to reconnect if it there is no connection
1565 * @param float|null &$rtt Value to store the estimated RTT [optional]
1566 * @return bool Success or failure
1568 public function ping( &$rtt = null );
1571 * Get replica DB lag. Currently supported only by MySQL.
1573 * Note that this function will generate a fatal error on many
1574 * installations. Most callers should use LoadBalancer::safeGetLag()
1577 * @return int|bool Database replication lag in seconds or false on error
1579 public function getLag();
1582 * Get the replica DB lag when the current transaction started
1583 * or a general lag estimate if not transaction is active
1585 * This is useful when transactions might use snapshot isolation
1586 * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1587 * is this lag plus transaction duration. If they don't, it is still
1588 * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1589 * indication of the staleness of subsequent reads.
1591 * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1594 public function getSessionLagStatus();
1597 * Return the maximum number of items allowed in a list, or 0 for unlimited.
1601 public function maxListLen();
1604 * Some DBMSs have a special format for inserting into blob fields, they
1605 * don't allow simple quoted strings to be inserted. To insert into such
1606 * a field, pass the data through this function before passing it to
1607 * IDatabase::insert().
1612 public function encodeBlob( $b );
1615 * Some DBMSs return a special placeholder object representing blob fields
1616 * in result objects. Pass the object through this function to return the
1619 * @param string|Blob $b
1622 public function decodeBlob( $b );
1625 * Override database's default behavior. $options include:
1626 * 'connTimeout' : Set the connection timeout value in seconds.
1627 * May be useful for very long batch queries such as
1628 * full-wiki dumps, where a single query reads out over
1631 * @param array $options
1634 public function setSessionOptions( array $options );
1637 * Set variables to be used in sourceFile/sourceStream, in preference to the
1638 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1639 * all. If it's set to false, $GLOBALS will be used.
1641 * @param bool|array $vars Mapping variable name to value.
1643 public function setSchemaVars( $vars );
1646 * Check to see if a named lock is available (non-blocking)
1648 * @param string $lockName Name of lock to poll
1649 * @param string $method Name of method calling us
1653 public function lockIsFree( $lockName, $method );
1656 * Acquire a named lock
1658 * Named locks are not related to transactions
1660 * @param string $lockName Name of lock to aquire
1661 * @param string $method Name of the calling method
1662 * @param int $timeout Acquisition timeout in seconds
1665 public function lock( $lockName, $method, $timeout = 5 );
1670 * Named locks are not related to transactions
1672 * @param string $lockName Name of lock to release
1673 * @param string $method Name of the calling method
1675 * @return int Returns 1 if the lock was released, 0 if the lock was not established
1676 * by this thread (in which case the lock is not released), and NULL if the named
1677 * lock did not exist
1679 public function unlock( $lockName, $method );
1682 * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1684 * Only call this from outer transcation scope and when only one DB will be affected.
1685 * See https://www.mediawiki.org/wiki/Database_transactions for details.
1687 * This is suitiable for transactions that need to be serialized using cooperative locks,
1688 * where each transaction can see each others' changes. Any transaction is flushed to clear
1689 * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1690 * the lock will be released unless a transaction is active. If one is active, then the lock
1691 * will be released when it either commits or rolls back.
1693 * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1695 * @param string $lockKey Name of lock to release
1696 * @param string $fname Name of the calling method
1697 * @param int $timeout Acquisition timeout in seconds
1698 * @return ScopedCallback|null
1699 * @throws DBUnexpectedError
1702 public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1705 * Check to see if a named lock used by lock() use blocking queues
1710 public function namedLocksEnqueue();
1713 * Find out when 'infinity' is. Most DBMSes support this. This is a special
1714 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1715 * because "i" sorts after all numbers.
1719 public function getInfinity();
1722 * Encode an expiry time into the DBMS dependent format
1724 * @param string $expiry Timestamp for expiry, or the 'infinity' string
1727 public function encodeExpiry( $expiry );
1730 * Decode an expiry time into a DBMS independent format
1732 * @param string $expiry DB timestamp field value for expiry
1733 * @param int $format TS_* constant, defaults to TS_MW
1736 public function decodeExpiry( $expiry, $format = TS_MW
);
1739 * Allow or deny "big selects" for this session only. This is done by setting
1740 * the sql_big_selects session variable.
1742 * This is a MySQL-specific feature.
1744 * @param bool|string $value True for allow, false for deny, or "default" to
1745 * restore the initial value
1747 public function setBigSelects( $value = true );
1750 * @return bool Whether this DB is read-only
1753 public function isReadOnly();
1756 * Make certain table names use their own database, schema, and table prefix
1757 * when passed into SQL queries pre-escaped and without a qualified database name
1759 * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1760 * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1762 * Calling this twice will completely clear any old table aliases. Also, note that
1763 * callers are responsible for making sure the schemas and databases actually exist.
1765 * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1768 public function setTableAliases( array $aliases );