Current File : /www/varak.net/wiki.varak.net/includes/libs/rdbms/database/IDatabase.php
<?php
/**
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
namespace Wikimedia\Rdbms;
use InvalidArgumentException;
use Wikimedia\ScopedCallback;
use RuntimeException;
use stdClass;
/**
* @defgroup Database Database
* This group deals with database interface functions
* and query specifics/optimisations.
*/
/**
* Basic database interface for live and lazy-loaded relation database handles
*
* @note IDatabase and DBConnRef should be updated to reflect any changes
* @ingroup Database
*/
interface IDatabase {
/** @var int Callback triggered immediately due to no active transaction */
const TRIGGER_IDLE = 1;
/** @var int Callback triggered by COMMIT */
const TRIGGER_COMMIT = 2;
/** @var int Callback triggered by ROLLBACK */
const TRIGGER_ROLLBACK = 3;
/** @var string Transaction is requested by regular caller outside of the DB layer */
const TRANSACTION_EXPLICIT = '';
/** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
const TRANSACTION_INTERNAL = 'implicit';
/** @var string Atomic section is not cancelable */
const ATOMIC_NOT_CANCELABLE = '';
/** @var string Atomic section is cancelable */
const ATOMIC_CANCELABLE = 'cancelable';
/** @var string Commit/rollback is from outside the IDatabase handle and connection manager */
const FLUSHING_ONE = '';
/** @var string Commit/rollback is from the connection manager for the IDatabase handle */
const FLUSHING_ALL_PEERS = 'flush';
/** @var string Commit/rollback is from the IDatabase handle internally */
const FLUSHING_INTERNAL = 'flush-internal';
/** @var string Do not remember the prior flags */
const REMEMBER_NOTHING = '';
/** @var string Remember the prior flags */
const REMEMBER_PRIOR = 'remember';
/** @var string Restore to the prior flag state */
const RESTORE_PRIOR = 'prior';
/** @var string Restore to the initial flag state */
const RESTORE_INITIAL = 'initial';
/** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
const ESTIMATE_TOTAL = 'total';
/** @var string Estimate time to apply (scanning, applying) */
const ESTIMATE_DB_APPLY = 'apply';
/** @var int Combine list with comma delimeters */
const LIST_COMMA = 0;
/** @var int Combine list with AND clauses */
const LIST_AND = 1;
/** @var int Convert map into a SET clause */
const LIST_SET = 2;
/** @var int Treat as field name and do not apply value escaping */
const LIST_NAMES = 3;
/** @var int Combine list with OR clauses */
const LIST_OR = 4;
/** @var int Enable debug logging */
const DBO_DEBUG = 1;
/** @var int Disable query buffering (only one result set can be iterated at a time) */
const DBO_NOBUFFER = 2;
/** @var int Ignore query errors (internal use only!) */
const DBO_IGNORE = 4;
/** @var int Automatically start a transaction before running a query if none is active */
const DBO_TRX = 8;
/** @var int Use DBO_TRX in non-CLI mode */
const DBO_DEFAULT = 16;
/** @var int Use DB persistent connections if possible */
const DBO_PERSISTENT = 32;
/** @var int DBA session mode; mostly for Oracle */
const DBO_SYSDBA = 64;
/** @var int Schema file mode; mostly for Oracle */
const DBO_DDLMODE = 128;
/** @var int Enable SSL/TLS in connection protocol */
const DBO_SSL = 256;
/** @var int Enable compression in connection protocol */
const DBO_COMPRESS = 512;
/**
* A string describing the current software version, and possibly
* other details in a user-friendly way. Will be listed on Special:Version, etc.
* Use getServerVersion() to get machine-friendly information.
*
* @return string Version information from the database server
*/
public function getServerInfo();
/**
* Turns buffering of SQL result sets on (true) or off (false). Default is "on".
*
* Unbuffered queries are very troublesome in MySQL:
*
* - If another query is executed while the first query is being read
* out, the first query is killed. This means you can't call normal
* Database functions while you are reading an unbuffered query result
* from a normal Database connection.
*
* - Unbuffered queries cause the MySQL server to use large amounts of
* memory and to hold broad locks which block other queries.
*
* If you want to limit client-side memory, it's almost always better to
* split up queries into batches using a LIMIT clause than to switch off
* buffering.
*
* @param null|bool $buffer
* @return null|bool The previous value of the flag
*/
public function bufferResults( $buffer = null );
/**
* Gets the current transaction level.
*
* Historically, transactions were allowed to be "nested". This is no
* longer supported, so this function really only returns a boolean.
*
* @return int The previous value
*/
public function trxLevel();
/**
* Get the UNIX timestamp of the time that the transaction was established
*
* This can be used to reason about the staleness of SELECT data
* in REPEATABLE-READ transaction isolation level.
*
* @return float|null Returns null if there is not active transaction
* @since 1.25
*/
public function trxTimestamp();
/**
* @return bool Whether an explicit transaction or atomic sections are still open
* @since 1.28
*/
public function explicitTrxActive();
/**
* Assert that all explicit transactions or atomic sections have been closed.
* @throws DBTransactionError
* @since 1.32
*/
public function assertNoOpenTransactions();
/**
* Get/set the table prefix.
* @param string|null $prefix The table prefix to set, or omitted to leave it unchanged.
* @return string The previous table prefix
* @throws DBUnexpectedError
*/
public function tablePrefix( $prefix = null );
/**
* Get/set the db schema.
* @param string|null $schema The database schema to set, or omitted to leave it unchanged.
* @return string The previous db schema
*/
public function dbSchema( $schema = null );
/**
* Get properties passed down from the server info array of the load
* balancer.
*
* @param string|null $name The entry of the info array to get, or null to get the
* whole array
*
* @return array|mixed|null
*/
public function getLBInfo( $name = null );
/**
* Set the LB info array, or a member of it. If called with one parameter,
* the LB info array is set to that parameter. If it is called with two
* parameters, the member with the given name is set to the given value.
*
* @param string $name
* @param array|null $value
*/
public function setLBInfo( $name, $value = null );
/**
* Set a lazy-connecting DB handle to the master DB (for replication status purposes)
*
* @param IDatabase $conn
* @since 1.27
*/
public function setLazyMasterHandle( IDatabase $conn );
/**
* Returns true if this database does an implicit sort when doing GROUP BY
*
* @return bool
* @deprecated Since 1.30; only use grouped or aggregated fields in the SELECT
*/
public function implicitGroupby();
/**
* Returns true if this database does an implicit order by when the column has an index
* For example: SELECT page_title FROM page LIMIT 1
*
* @return bool
*/
public function implicitOrderby();
/**
* Return the last query that went through IDatabase::query()
* @return string
*/
public function lastQuery();
/**
* Returns true if the connection may have been used for write queries.
* Should return true if unsure.
*
* @return bool
* @deprecated Since 1.31; use lastDoneWrites()
*/
public function doneWrites();
/**
* Returns the last time the connection may have been used for write queries.
* Should return a timestamp if unsure.
*
* @return int|float UNIX timestamp or false
* @since 1.24
*/
public function lastDoneWrites();
/**
* @return bool Whether there is a transaction open with possible write queries
* @since 1.27
*/
public function writesPending();
/**
* @return bool Whether there is a transaction open with pre-commit callbacks pending
* @since 1.32
*/
public function preCommitCallbacksPending();
/**
* Whether there is a transaction open with either possible write queries
* or unresolved pre-commit/commit/resolution callbacks pending
*
* This does *not* count recurring callbacks, e.g. from setTransactionListener().
*
* @return bool
*/
public function writesOrCallbacksPending();
/**
* Get the time spend running write queries for this transaction
*
* High times could be due to scanning, updates, locking, and such
*
* @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
* @return float|bool Returns false if not transaction is active
* @since 1.26
*/
public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL );
/**
* Get the list of method names that did write queries for this transaction
*
* @return array
* @since 1.27
*/
public function pendingWriteCallers();
/**
* Get the number of affected rows from pending write queries
*
* @return int
* @since 1.30
*/
public function pendingWriteRowsAffected();
/**
* Is a connection to the database open?
* @return bool
*/
public function isOpen();
/**
* Set a flag for this connection
*
* @param int $flag DBO_* constants from Defines.php:
* - DBO_DEBUG: output some debug info (same as debug())
* - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
* - DBO_TRX: automatically start transactions
* - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
* and removes it in command line mode
* - DBO_PERSISTENT: use persistant database connection
* @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
*/
public function setFlag( $flag, $remember = self::REMEMBER_NOTHING );
/**
* Clear a flag for this connection
*
* @param int $flag DBO_* constants from Defines.php:
* - DBO_DEBUG: output some debug info (same as debug())
* - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
* - DBO_TRX: automatically start transactions
* - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
* and removes it in command line mode
* - DBO_PERSISTENT: use persistant database connection
* @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
*/
public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING );
/**
* Restore the flags to their prior state before the last setFlag/clearFlag call
*
* @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
* @since 1.28
*/
public function restoreFlags( $state = self::RESTORE_PRIOR );
/**
* Returns a boolean whether the flag $flag is set for this connection
*
* @param int $flag DBO_* constants from Defines.php:
* - DBO_DEBUG: output some debug info (same as debug())
* - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
* - DBO_TRX: automatically start transactions
* - DBO_PERSISTENT: use persistant database connection
* @return bool
*/
public function getFlag( $flag );
/**
* Return the currently selected domain ID
*
* Null components (database/schema) might change once a connection is established
*
* @return string
*/
public function getDomainID();
/**
* Alias for getDomainID()
*
* @return string
* @deprecated 1.30
*/
public function getWikiID();
/**
* Get the type of the DBMS, as it appears in $wgDBtype.
*
* @return string
*/
public function getType();
/**
* Fetch the next row from the given result object, in object form.
* Fields can be retrieved with $row->fieldname, with fields acting like
* member variables.
* If no more rows are available, false is returned.
*
* @param IResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
* @return stdClass|bool
* @throws DBUnexpectedError Thrown if the database returns an error
*/
public function fetchObject( $res );
/**
* Fetch the next row from the given result object, in associative array
* form. Fields are retrieved with $row['fieldname'].
* If no more rows are available, false is returned.
*
* @param IResultWrapper $res Result object as returned from IDatabase::query(), etc.
* @return array|bool
* @throws DBUnexpectedError Thrown if the database returns an error
*/
public function fetchRow( $res );
/**
* Get the number of rows in a query result. If the query did not return
* any rows (for example, if it was a write query), this returns zero.
*
* @param mixed $res A SQL result
* @return int
*/
public function numRows( $res );
/**
* Get the number of fields in a result object
* @see https://secure.php.net/mysql_num_fields
*
* @param mixed $res A SQL result
* @return int
*/
public function numFields( $res );
/**
* Get a field name in a result object
* @see https://secure.php.net/mysql_field_name
*
* @param mixed $res A SQL result
* @param int $n
* @return string
*/
public function fieldName( $res, $n );
/**
* Get the inserted value of an auto-increment row
*
* This should only be called after an insert that used an auto-incremented
* value. If no such insert was previously done in the current database
* session, the return value is undefined.
*
* @return int
*/
public function insertId();
/**
* Change the position of the cursor in a result object
* @see https://secure.php.net/mysql_data_seek
*
* @param mixed $res A SQL result
* @param int $row
*/
public function dataSeek( $res, $row );
/**
* Get the last error number
* @see https://secure.php.net/mysql_errno
*
* @return int
*/
public function lastErrno();
/**
* Get a description of the last error
* @see https://secure.php.net/mysql_error
*
* @return string
*/
public function lastError();
/**
* Get the number of rows affected by the last write query
* @see https://secure.php.net/mysql_affected_rows
*
* @return int
*/
public function affectedRows();
/**
* Returns a wikitext link to the DB's website, e.g.,
* return "[https://www.mysql.com/ MySQL]";
* Should at least contain plain text, if for some reason
* your database has no website.
*
* @return string Wikitext of a link to the server software's web site
*/
public function getSoftwareLink();
/**
* A string describing the current software version, like from
* mysql_get_server_info().
*
* @return string Version information from the database server.
*/
public function getServerVersion();
/**
* Close the database connection
*
* This should only be called after any transactions have been resolved,
* aside from read-only automatic transactions (assuming no callbacks are registered).
* If a transaction is still open anyway, it will be rolled back.
*
* @throws DBError
* @return bool Operation success. true if already closed.
*/
public function close();
/**
* Run an SQL query and return the result. Normally throws a DBQueryError
* on failure. If errors are ignored, returns false instead.
*
* If a connection loss is detected, then an attempt to reconnect will be made.
* For queries that involve no larger transactions or locks, they will be re-issued
* for convenience, provided the connection was re-established.
*
* In new code, the query wrappers select(), insert(), update(), delete(),
* etc. should be used where possible, since they give much better DBMS
* independence and automatically quote or validate user input in a variety
* of contexts. This function is generally only useful for queries which are
* explicitly DBMS-dependent and are unsupported by the query wrappers, such
* as CREATE TABLE.
*
* However, the query wrappers themselves should call this function.
*
* @param string $sql SQL query
* @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
* comment (you can use __METHOD__ or add some extra info)
* @param bool $tempIgnore Whether to avoid throwing an exception on errors...
* maybe best to catch the exception instead?
* @return bool|IResultWrapper True for a successful write query, IResultWrapper object
* for a successful read query, or false on failure if $tempIgnore set
* @throws DBError
*/
public function query( $sql, $fname = __METHOD__, $tempIgnore = false );
/**
* Free a result object returned by query() or select(). It's usually not
* necessary to call this, just use unset() or let the variable holding
* the result object go out of scope.
*
* @param mixed $res A SQL result
*/
public function freeResult( $res );
/**
* A SELECT wrapper which returns a single field from a single result row.
*
* Usually throws a DBQueryError on failure. If errors are explicitly
* ignored, returns false on failure.
*
* If no result rows are returned from the query, false is returned.
*
* @param string|array $table Table name. See IDatabase::select() for details.
* @param string $var The field name to select. This must be a valid SQL
* fragment: do not use unvalidated user input.
* @param string|array $cond The condition array. See IDatabase::select() for details.
* @param string $fname The function name of the caller.
* @param string|array $options The query options. See IDatabase::select() for details.
* @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
*
* @return mixed The value from the field
* @throws DBError
*/
public function selectField(
$table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
);
/**
* A SELECT wrapper which returns a list of single field values from result rows.
*
* Usually throws a DBQueryError on failure. If errors are explicitly
* ignored, returns false on failure.
*
* If no result rows are returned from the query, false is returned.
*
* @param string|array $table Table name. See IDatabase::select() for details.
* @param string $var The field name to select. This must be a valid SQL
* fragment: do not use unvalidated user input.
* @param string|array $cond The condition array. See IDatabase::select() for details.
* @param string $fname The function name of the caller.
* @param string|array $options The query options. See IDatabase::select() for details.
* @param string|array $join_conds The query join conditions. See IDatabase::select() for details.
*
* @return array The values from the field
* @throws DBError
* @since 1.25
*/
public function selectFieldValues(
$table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
);
/**
* Execute a SELECT query constructed using the various parameters provided.
* See below for full details of the parameters.
*
* @param string|array $table Table name
* @param string|array $vars Field names
* @param string|array $conds Conditions
* @param string $fname Caller function name
* @param array $options Query options
* @param array $join_conds Join conditions
*
*
* @param string|array $table
*
* May be either an array of table names, or a single string holding a table
* name. If an array is given, table aliases can be specified, for example:
*
* [ 'a' => 'user' ]
*
* This includes the user table in the query, with the alias "a" available
* for use in field names (e.g. a.user_name).
*
* A derived table, defined by the result of selectSQLText(), requires an alias
* key and a Subquery instance value which wraps the SQL query, for example:
*
* [ 'c' => new Subquery( 'SELECT ...' ) ]
*
* Joins using parentheses for grouping (since MediaWiki 1.31) may be
* constructed using nested arrays. For example,
*
* [ 'tableA', 'nestedB' => [ 'tableB', 'b2' => 'tableB2' ] ]
*
* along with `$join_conds` like
*
* [ 'b2' => [ 'JOIN', 'b_id = b2_id' ], 'nestedB' => [ 'LEFT JOIN', 'b_a = a_id' ] ]
*
* will produce SQL something like
*
* FROM tableA LEFT JOIN (tableB JOIN tableB2 AS b2 ON (b_id = b2_id)) ON (b_a = a_id)
*
* All of the table names given here are automatically run through
* Database::tableName(), which causes the table prefix (if any) to be
* added, and various other table name mappings to be performed.
*
* Do not use untrusted user input as a table name. Alias names should
* not have characters outside of the Basic multilingual plane.
*
* @param string|array $vars
*
* May be either a field name or an array of field names. The field names
* can be complete fragments of SQL, for direct inclusion into the SELECT
* query. If an array is given, field aliases can be specified, for example:
*
* [ 'maxrev' => 'MAX(rev_id)' ]
*
* This includes an expression with the alias "maxrev" in the query.
*
* If an expression is given, care must be taken to ensure that it is
* DBMS-independent.
*
* Untrusted user input must not be passed to this parameter.
*
* @param string|array $conds
*
* May be either a string containing a single condition, or an array of
* conditions. If an array is given, the conditions constructed from each
* element are combined with AND.
*
* Array elements may take one of two forms:
*
* - Elements with a numeric key are interpreted as raw SQL fragments.
* - Elements with a string key are interpreted as equality conditions,
* where the key is the field name.
* - If the value of such an array element is a scalar (such as a
* string), it will be treated as data and thus quoted appropriately.
* If it is null, an IS NULL clause will be added.
* - If the value is an array, an IN (...) clause will be constructed
* from its non-null elements, and an IS NULL clause will be added
* if null is present, such that the field may match any of the
* elements in the array. The non-null elements will be quoted.
*
* Note that expressions are often DBMS-dependent in their syntax.
* DBMS-independent wrappers are provided for constructing several types of
* expression commonly used in condition queries. See:
* - IDatabase::buildLike()
* - IDatabase::conditional()
*
* Untrusted user input is safe in the values of string keys, however untrusted
* input must not be used in the array key names or in the values of numeric keys.
* Escaping of untrusted input used in values of numeric keys should be done via
* IDatabase::addQuotes()
*
* Use an empty array, string, or '*' to update all rows.
*
* @param string|array $options
*
* Optional: Array of query options. Boolean options are specified by
* including them in the array as a string value with a numeric key, for
* example:
*
* [ 'FOR UPDATE' ]
*
* The supported options are:
*
* - OFFSET: Skip this many rows at the start of the result set. OFFSET
* with LIMIT can theoretically be used for paging through a result set,
* but this is discouraged for performance reasons.
*
* - LIMIT: Integer: return at most this many rows. The rows are sorted
* and then the first rows are taken until the limit is reached. LIMIT
* is applied to a result set after OFFSET.
*
* - FOR UPDATE: Boolean: lock the returned rows so that they can't be
* changed until the next COMMIT.
*
* - DISTINCT: Boolean: return only unique result rows.
*
* - GROUP BY: May be either an SQL fragment string naming a field or
* expression to group by, or an array of such SQL fragments.
*
* - HAVING: May be either an string containing a HAVING clause or an array of
* conditions building the HAVING clause. If an array is given, the conditions
* constructed from each element are combined with AND.
*
* - ORDER BY: May be either an SQL fragment giving a field name or
* expression to order by, or an array of such SQL fragments.
*
* - USE INDEX: This may be either a string giving the index name to use
* for the query, or an array. If it is an associative array, each key
* gives the table name (or alias), each value gives the index name to
* use for that table. All strings are SQL fragments and so should be
* validated by the caller.
*
* - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
* instead of SELECT.
*
* And also the following boolean MySQL extensions, see the MySQL manual
* for documentation:
*
* - LOCK IN SHARE MODE
* - STRAIGHT_JOIN
* - HIGH_PRIORITY
* - SQL_BIG_RESULT
* - SQL_BUFFER_RESULT
* - SQL_SMALL_RESULT
* - SQL_CALC_FOUND_ROWS
* - SQL_CACHE
* - SQL_NO_CACHE
*
*
* @param string|array $join_conds
*
* Optional associative array of table-specific join conditions. In the
* most common case, this is unnecessary, since the join condition can be
* in $conds. However, it is useful for doing a LEFT JOIN.
*
* The key of the array contains the table name or alias. The value is an
* array with two elements, numbered 0 and 1. The first gives the type of
* join, the second is the same as the $conds parameter. Thus it can be
* an SQL fragment, or an array where the string keys are equality and the
* numeric keys are SQL fragments all AND'd together. For example:
*
* [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
*
* @return IResultWrapper Resulting rows
* @throws DBError
*/
public function select(
$table, $vars, $conds = '', $fname = __METHOD__,
$options = [], $join_conds = []
);
/**
* The equivalent of IDatabase::select() except that the constructed SQL
* is returned, instead of being immediately executed. This can be useful for
* doing UNION queries, where the SQL text of each query is needed. In general,
* however, callers outside of Database classes should just use select().
*
* @see IDatabase::select()
*
* @param string|array $table Table name
* @param string|array $vars Field names
* @param string|array $conds Conditions
* @param string $fname Caller function name
* @param string|array $options Query options
* @param string|array $join_conds Join conditions
* @return string SQL query string
*/
public function selectSQLText(
$table, $vars, $conds = '', $fname = __METHOD__,
$options = [], $join_conds = []
);
/**
* Single row SELECT wrapper. Equivalent to IDatabase::select(), except
* that a single row object is returned. If the query returns no rows,
* false is returned.
*
* @param string|array $table Table name
* @param string|array $vars Field names
* @param array $conds Conditions
* @param string $fname Caller function name
* @param string|array $options Query options
* @param array|string $join_conds Join conditions
*
* @return stdClass|bool
* @throws DBError
*/
public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
$options = [], $join_conds = []
);
/**
* Estimate the number of rows in dataset
*
* MySQL allows you to estimate the number of rows that would be returned
* by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
* index cardinality statistics, and is notoriously inaccurate, especially
* when large numbers of rows have recently been added or deleted.
*
* For DBMSs that don't support fast result size estimation, this function
* will actually perform the SELECT COUNT(*).
*
* Takes the same arguments as IDatabase::select().
*
* @param string $table Table name
* @param string $var Column for which NULL values are not counted [default "*"]
* @param array|string $conds Filters on the table
* @param string $fname Function name for profiling
* @param array $options Options for select
* @param array|string $join_conds Join conditions
* @return int Row count
* @throws DBError
*/
public function estimateRowCount(
$table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
);
/**
* Get the number of rows in dataset
*
* This is useful when trying to do COUNT(*) but with a LIMIT for performance.
*
* Takes the same arguments as IDatabase::select().
*
* @since 1.27 Added $join_conds parameter
*
* @param array|string $tables Table names
* @param string $var Column for which NULL values are not counted [default "*"]
* @param array|string $conds Filters on the table
* @param string $fname Function name for profiling
* @param array $options Options for select
* @param array $join_conds Join conditions (since 1.27)
* @return int Row count
* @throws DBError
*/
public function selectRowCount(
$tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
);
/**
* Lock all rows meeting the given conditions/options FOR UPDATE
*
* @param array|string $table Table names
* @param array|string $conds Filters on the table
* @param string $fname Function name for profiling
* @param array $options Options for select ("FOR UPDATE" is added automatically)
* @param array $join_conds Join conditions
* @return int Number of matching rows found (and locked)
* @since 1.32
*/
public function lockForUpdate(
$table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
);
/**
* Determines whether a field exists in a table
*
* @param string $table Table name
* @param string $field Filed to check on that table
* @param string $fname Calling function name (optional)
* @return bool Whether $table has filed $field
* @throws DBError
*/
public function fieldExists( $table, $field, $fname = __METHOD__ );
/**
* Determines whether an index exists
* Usually throws a DBQueryError on failure
* If errors are explicitly ignored, returns NULL on failure
*
* @param string $table
* @param string $index
* @param string $fname
* @return bool|null
* @throws DBError
*/
public function indexExists( $table, $index, $fname = __METHOD__ );
/**
* Query whether a given table exists
*
* @param string $table
* @param string $fname
* @return bool
* @throws DBError
*/
public function tableExists( $table, $fname = __METHOD__ );
/**
* INSERT wrapper, inserts an array into a table.
*
* $a may be either:
*
* - A single associative array. The array keys are the field names, and
* the values are the values to insert. The values are treated as data
* and will be quoted appropriately. If NULL is inserted, this will be
* converted to a database NULL.
* - An array with numeric keys, holding a list of associative arrays.
* This causes a multi-row INSERT on DBMSs that support it. The keys in
* each subarray must be identical to each other, and in the same order.
*
* Usually throws a DBQueryError on failure. If errors are explicitly ignored,
* returns success.
*
* $options is an array of options, with boolean options encoded as values
* with numeric keys, in the same style as $options in
* IDatabase::select(). Supported options are:
*
* - IGNORE: Boolean: if present, duplicate key errors are ignored, and
* any rows which cause duplicate key errors are not inserted. It's
* possible to determine how many rows were successfully inserted using
* IDatabase::affectedRows().
*
* @param string $table Table name. This will be passed through
* Database::tableName().
* @param array $a Array of rows to insert
* @param string $fname Calling function name (use __METHOD__) for logs/profiling
* @param array $options Array of options
*
* @return bool
* @throws DBError
*/
public function insert( $table, $a, $fname = __METHOD__, $options = [] );
/**
* UPDATE wrapper. Takes a condition array and a SET array.
*
* @param string $table Name of the table to UPDATE. This will be passed through
* Database::tableName().
* @param array $values An array of values to SET. For each array element,
* the key gives the field name, and the value gives the data to set
* that field to. The data will be quoted by IDatabase::addQuotes().
* Values with integer keys form unquoted SET statements, which can be used for
* things like "field = field + 1" or similar computed values.
* @param array $conds An array of conditions (WHERE). See
* IDatabase::select() for the details of the format of condition
* arrays. Use '*' to update all rows.
* @param string $fname The function name of the caller (from __METHOD__),
* for logging and profiling.
* @param array $options An array of UPDATE options, can be:
* - IGNORE: Ignore unique key conflicts
* - LOW_PRIORITY: MySQL-specific, see MySQL manual.
* @return bool
* @throws DBError
*/
public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] );
/**
* Makes an encoded list of strings from an array
*
* These can be used to make conjunctions or disjunctions on SQL condition strings
* derived from an array (see IDatabase::select() $conds documentation).
*
* Example usage:
* @code
* $sql = $db->makeList( [
* 'rev_page' => $id,
* $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
* ], $db::LIST_AND );
* @endcode
* This would set $sql to "rev_page = '$id' AND (rev_minor = '1' OR rev_len < '500')"
*
* @param array $a Containing the data
* @param int $mode IDatabase class constant:
* - IDatabase::LIST_COMMA: Comma separated, no field names
* - IDatabase::LIST_AND: ANDed WHERE clause (without the WHERE).
* - IDatabase::LIST_OR: ORed WHERE clause (without the WHERE)
* - IDatabase::LIST_SET: Comma separated with field names, like a SET clause
* - IDatabase::LIST_NAMES: Comma separated field names
* @throws DBError
* @return string
*/
public function makeList( $a, $mode = self::LIST_COMMA );
/**
* Build a partial where clause from a 2-d array such as used for LinkBatch.
* The keys on each level may be either integers or strings.
*
* @param array $data Organized as 2-d
* [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
* @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
* @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
* @return string|bool SQL fragment, or false if no items in array
*/
public function makeWhereFrom2d( $data, $baseKey, $subKey );
/**
* Return aggregated value alias
*
* @param array $valuedata
* @param string $valuename
*
* @return string
*/
public function aggregateValue( $valuedata, $valuename = 'value' );
/**
* @param string $field
* @return string
*/
public function bitNot( $field );
/**
* @param string $fieldLeft
* @param string $fieldRight
* @return string
*/
public function bitAnd( $fieldLeft, $fieldRight );
/**
* @param string $fieldLeft
* @param string $fieldRight
* @return string
*/
public function bitOr( $fieldLeft, $fieldRight );
/**
* Build a concatenation list to feed into a SQL query
* @param array $stringList List of raw SQL expressions; caller is
* responsible for any quoting
* @return string
*/
public function buildConcat( $stringList );
/**
* Build a GROUP_CONCAT or equivalent statement for a query.
*
* This is useful for combining a field for several rows into a single string.
* NULL values will not appear in the output, duplicated values will appear,
* and the resulting delimiter-separated values have no defined sort order.
* Code using the results may need to use the PHP unique() or sort() methods.
*
* @param string $delim Glue to bind the results together
* @param string|array $table Table name
* @param string $field Field name
* @param string|array $conds Conditions
* @param string|array $join_conds Join conditions
* @return string SQL text
* @since 1.23
*/
public function buildGroupConcatField(
$delim, $table, $field, $conds = '', $join_conds = []
);
/**
* Build a SUBSTRING function.
*
* Behavior for non-ASCII values is undefined.
*
* @param string $input Field name
* @param int $startPosition Positive integer
* @param int|null $length Non-negative integer length or null for no limit
* @throws InvalidArgumentException
* @return string SQL text
* @since 1.31
*/
public function buildSubString( $input, $startPosition, $length = null );
/**
* @param string $field Field or column to cast
* @return string
* @since 1.28
*/
public function buildStringCast( $field );
/**
* @param string $field Field or column to cast
* @return string
* @since 1.31
*/
public function buildIntegerCast( $field );
/**
* Equivalent to IDatabase::selectSQLText() except wraps the result in Subqyery
*
* @see IDatabase::selectSQLText()
*
* @param string|array $table Table name
* @param string|array $vars Field names
* @param string|array $conds Conditions
* @param string $fname Caller function name
* @param string|array $options Query options
* @param string|array $join_conds Join conditions
* @return Subquery
* @since 1.31
*/
public function buildSelectSubquery(
$table, $vars, $conds = '', $fname = __METHOD__,
$options = [], $join_conds = []
);
/**
* Returns true if DBs are assumed to be on potentially different servers
*
* In systems like mysql/mariadb, different databases can easily be referenced on a single
* connection merely by name, even in a single query via JOIN. On the other hand, Postgres
* treats databases as fully separate, only allowing mechanisms like postgres_fdw to
* effectively "mount" foreign DBs. This is true even among DBs on the same server.
*
* @return bool
* @since 1.29
*/
public function databasesAreIndependent();
/**
* Change the current database
*
* @param string $db
* @return bool True unless an exception was thrown
* @throws DBConnectionError If databasesAreIndependent() is true and an error occurs
* @throws DBError
* @deprecated Since 1.32
*/
public function selectDB( $db );
/**
* Set the current domain (database, schema, and table prefix)
*
* This will throw an error for some database types if the database unspecified
*
* @param string|DatabaseDomain $domain
* @since 1.32
* @throws DBConnectionError
*/
public function selectDomain( $domain );
/**
* Get the current DB name
* @return string|null
*/
public function getDBname();
/**
* Get the server hostname or IP address
* @return string
*/
public function getServer();
/**
* Adds quotes and backslashes.
*
* @param string|int|null|bool|Blob $s
* @return string|int
*/
public function addQuotes( $s );
/**
* LIKE statement wrapper, receives a variable-length argument list with
* parts of pattern to match containing either string literals that will be
* escaped or tokens returned by anyChar() or anyString(). Alternatively,
* the function could be provided with an array of aforementioned
* parameters.
*
* Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
* a LIKE clause that searches for subpages of 'My page title'.
* Alternatively:
* $pattern = [ 'My_page_title/', $dbr->anyString() ];
* $query .= $dbr->buildLike( $pattern );
*
* @since 1.16
* @return string Fully built LIKE statement
*/
public function buildLike();
/**
* Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
*
* @return LikeMatch
*/
public function anyChar();
/**
* Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
*
* @return LikeMatch
*/
public function anyString();
/**
* Deprecated method, calls should be removed.
*
* This was formerly used for PostgreSQL and Oracle to handle
* self::insertId() auto-incrementing fields. It is no longer necessary
* since DatabasePostgres::insertId() has been reimplemented using
* `lastval()` and Oracle has been reimplemented using triggers.
*
* Implementations should return null if inserting `NULL` into an
* auto-incrementing field works, otherwise it should return an instance of
* NextSequenceValue and filter it on calls to relevant methods.
*
* @deprecated since 1.30, no longer needed
* @param string $seqName
* @return null|NextSequenceValue
*/
public function nextSequenceValue( $seqName );
/**
* REPLACE query wrapper.
*
* REPLACE is a very handy MySQL extension, which functions like an INSERT
* except that when there is a duplicate key error, the old row is deleted
* and the new row is inserted in its place.
*
* We simulate this with standard SQL with a DELETE followed by INSERT. To
* perform the delete, we need to know what the unique indexes are so that
* we know how to find the conflicting rows.
*
* It may be more efficient to leave off unique indexes which are unlikely
* to collide. However if you do this, you run the risk of encountering
* errors which wouldn't have occurred in MySQL.
*
* @param string $table The table to replace the row(s) in.
* @param array $uniqueIndexes Either a list of fields that define a unique index or
* an array of such lists if there are multiple unique indexes defined in the schema
* @param array $rows Can be either a single row to insert, or multiple rows,
* in the same format as for IDatabase::insert()
* @param string $fname Calling function name (use __METHOD__) for logs/profiling
* @throws DBError
*/
public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ );
/**
* INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
*
* This updates any conflicting rows (according to the unique indexes) using
* the provided SET clause and inserts any remaining (non-conflicted) rows.
*
* $rows may be either:
* - A single associative array. The array keys are the field names, and
* the values are the values to insert. The values are treated as data
* and will be quoted appropriately. If NULL is inserted, this will be
* converted to a database NULL.
* - An array with numeric keys, holding a list of associative arrays.
* This causes a multi-row INSERT on DBMSs that support it. The keys in
* each subarray must be identical to each other, and in the same order.
*
* It may be more efficient to leave off unique indexes which are unlikely
* to collide. However if you do this, you run the risk of encountering
* errors which wouldn't have occurred in MySQL.
*
* Usually throws a DBQueryError on failure. If errors are explicitly ignored,
* returns success.
*
* @since 1.22
*
* @param string $table Table name. This will be passed through Database::tableName().
* @param array $rows A single row or list of rows to insert
* @param array $uniqueIndexes Either a list of fields that define a unique index or
* an array of such lists if there are multiple unique indexes defined in the schema
* @param array $set An array of values to SET. For each array element, the
* key gives the field name, and the value gives the data to set that
* field to. The data will be quoted by IDatabase::addQuotes().
* Values with integer keys form unquoted SET statements, which can be used for
* things like "field = field + 1" or similar computed values.
* @param string $fname Calling function name (use __METHOD__) for logs/profiling
* @throws DBError
* @return bool
*/
public function upsert(
$table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
);
/**
* DELETE where the condition is a join.
*
* MySQL overrides this to use a multi-table DELETE syntax, in other databases
* we use sub-selects
*
* For safety, an empty $conds will not delete everything. If you want to
* delete all rows where the join condition matches, set $conds='*'.
*
* DO NOT put the join condition in $conds.
*
* @param string $delTable The table to delete from.
* @param string $joinTable The other table.
* @param string $delVar The variable to join on, in the first table.
* @param string $joinVar The variable to join on, in the second table.
* @param array $conds Condition array of field names mapped to variables,
* ANDed together in the WHERE clause
* @param string $fname Calling function name (use __METHOD__) for logs/profiling
* @throws DBError
*/
public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
$fname = __METHOD__
);
/**
* DELETE query wrapper.
*
* @param string $table Table name
* @param string|array $conds Array of conditions. See $conds in IDatabase::select()
* for the format. Use $conds == "*" to delete all rows
* @param string $fname Name of the calling function
* @throws DBUnexpectedError
* @return bool|IResultWrapper
* @throws DBError
*/
public function delete( $table, $conds, $fname = __METHOD__ );
/**
* INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
* into another table.
*
* @warning If the insert will use an auto-increment or sequence to
* determine the value of a column, this may break replication on
* databases using statement-based replication if the SELECT is not
* deterministically ordered.
*
* @param string $destTable The table name to insert into
* @param string|array $srcTable May be either a table name, or an array of table names
* to include in a join.
*
* @param array $varMap Must be an associative array of the form
* [ 'dest1' => 'source1', ... ]. Source items may be literals
* rather than field names, but strings should be quoted with
* IDatabase::addQuotes()
*
* @param array $conds Condition array. See $conds in IDatabase::select() for
* the details of the format of condition arrays. May be "*" to copy the
* whole table.
*
* @param string $fname The function name of the caller, from __METHOD__
*
* @param array $insertOptions Options for the INSERT part of the query, see
* IDatabase::insert() for details. Also, one additional option is
* available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
* an auto-increment or sequence to determine any column values.
* @param array $selectOptions Options for the SELECT part of the query, see
* IDatabase::select() for details.
* @param array $selectJoinConds Join conditions for the SELECT part of the query, see
* IDatabase::select() for details.
*
* @return bool
* @throws DBError
*/
public function insertSelect( $destTable, $srcTable, $varMap, $conds,
$fname = __METHOD__,
$insertOptions = [], $selectOptions = [], $selectJoinConds = []
);
/**
* Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
* within the UNION construct.
* @return bool
*/
public function unionSupportsOrderAndLimit();
/**
* Construct a UNION query
* This is used for providing overload point for other DB abstractions
* not compatible with the MySQL syntax.
* @param array $sqls SQL statements to combine
* @param bool $all Use UNION ALL
* @return string SQL fragment
*/
public function unionQueries( $sqls, $all );
/**
* Construct a UNION query for permutations of conditions
*
* Databases sometimes have trouble with queries that have multiple values
* for multiple condition parameters combined with limits and ordering.
* This method constructs queries for the Cartesian product of the
* conditions and unions them all together.
*
* @see IDatabase::select()
* @since 1.30
* @param string|array $table Table name
* @param string|array $vars Field names
* @param array $permute_conds Conditions for the Cartesian product. Keys
* are field names, values are arrays of the possible values for that
* field.
* @param string|array $extra_conds Additional conditions to include in the
* query.
* @param string $fname Caller function name
* @param string|array $options Query options. In addition to the options
* recognized by IDatabase::select(), the following may be used:
* - NOTALL: Set to use UNION instead of UNION ALL.
* - INNER ORDER BY: If specified and supported, subqueries will use this
* instead of ORDER BY.
* @param string|array $join_conds Join conditions
* @return string SQL query string.
*/
public function unionConditionPermutations(
$table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
$options = [], $join_conds = []
);
/**
* Returns an SQL expression for a simple conditional. This doesn't need
* to be overridden unless CASE isn't supported in your DBMS.
*
* @param string|array $cond SQL expression which will result in a boolean value
* @param string $trueVal SQL expression to return if true
* @param string $falseVal SQL expression to return if false
* @return string SQL fragment
*/
public function conditional( $cond, $trueVal, $falseVal );
/**
* Returns a command for str_replace function in SQL query.
* Uses REPLACE() in MySQL
*
* @param string $orig Column to modify
* @param string $old Column to seek
* @param string $new Column to replace with
*
* @return string
*/
public function strreplace( $orig, $old, $new );
/**
* Determines how long the server has been up
*
* @return int
* @throws DBError
*/
public function getServerUptime();
/**
* Determines if the last failure was due to a deadlock
*
* Note that during a deadlock, the prior transaction will have been lost
*
* @return bool
*/
public function wasDeadlock();
/**
* Determines if the last failure was due to a lock timeout
*
* Note that during a lock wait timeout, the prior transaction will have been lost
*
* @return bool
*/
public function wasLockTimeout();
/**
* Determines if the last query error was due to a dropped connection
*
* Note that during a connection loss, the prior transaction will have been lost
*
* @return bool
* @since 1.31
*/
public function wasConnectionLoss();
/**
* Determines if the last failure was due to the database being read-only.
*
* @return bool
*/
public function wasReadOnlyError();
/**
* Determines if the last query error was due to something outside of the query itself
*
* Note that the transaction may have been lost, discarding prior writes and results
*
* @return bool
*/
public function wasErrorReissuable();
/**
* Wait for the replica DB to catch up to a given master position
*
* @param DBMasterPos $pos
* @param int $timeout The maximum number of seconds to wait for synchronisation
* @return int|null Zero if the replica DB was past that position already,
* greater than zero if we waited for some period of time, less than
* zero if it timed out, and null on error
* @throws DBError
*/
public function masterPosWait( DBMasterPos $pos, $timeout );
/**
* Get the replication position of this replica DB
*
* @return DBMasterPos|bool False if this is not a replica DB
* @throws DBError
*/
public function getReplicaPos();
/**
* Get the position of this master
*
* @return DBMasterPos|bool False if this is not a master
* @throws DBError
*/
public function getMasterPos();
/**
* @return bool Whether the DB is marked as read-only server-side
* @since 1.28
*/
public function serverIsReadOnly();
/**
* Run a callback as soon as the current transaction commits or rolls back.
* An error is thrown if no transaction is pending. Queries in the function will run in
* AUTOCOMMIT mode unless there are begin() calls. Callbacks must commit any transactions
* that they begin.
*
* This is useful for combining cooperative locks and DB transactions.
*
* @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
*
* The callback takes the following arguments:
* - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
* - This IDatabase instance (since 1.32)
*
* @param callable $callback
* @param string $fname Caller name
* @return mixed
* @since 1.28
*/
public function onTransactionResolution( callable $callback, $fname = __METHOD__ );
/**
* Run a callback as soon as there is no transaction pending.
* If there is a transaction and it is rolled back, then the callback is cancelled.
*
* When transaction round mode (DBO_TRX) is set, the callback will run at the end
* of the round, just after all peer transactions COMMIT. If the transaction round
* is rolled back, then the callback is cancelled.
*
* Queries in the function will run in AUTOCOMMIT mode unless there are begin() calls.
* Callbacks must commit any transactions that they begin.
*
* This is useful for updates to different systems or when separate transactions are needed.
* For example, one might want to enqueue jobs into a system outside the database, but only
* after the database is updated so that the jobs will see the data when they actually run.
* It can also be used for updates that easily suffer from lock timeouts and deadlocks,
* but where atomicity is not essential.
*
* Avoid using IDatabase instances aside from this one in the callback, unless such instances
* never have IDatabase::DBO_TRX set. This keeps callbacks from interfering with one another.
*
* Updates will execute in the order they were enqueued.
*
* @note do not assume that *other* IDatabase instances will be AUTOCOMMIT mode
*
* The callback takes the following arguments:
* - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
* - This IDatabase instance (since 1.32)
*
* @param callable $callback
* @param string $fname Caller name
* @since 1.32
*/
public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ );
/**
* Alias for onTransactionCommitOrIdle() for backwards-compatibility
*
* @param callable $callback
* @param string $fname
* @return mixed
* @since 1.20
* @deprecated Since 1.32
*/
public function onTransactionIdle( callable $callback, $fname = __METHOD__ );
/**
* Run a callback before the current transaction commits or now if there is none.
* If there is a transaction and it is rolled back, then the callback is cancelled.
*
* When transaction round mode (DBO_TRX) is set, the callback will run at the end
* of the round, just before all peer transactions COMMIT. If the transaction round
* is rolled back, then the callback is cancelled.
*
* Callbacks must not start nor commit any transactions. If no transaction is active,
* then a transaction will wrap the callback.
*
* This is useful for updates that easily suffer from lock timeouts and deadlocks,
* but where atomicity is strongly desired for these updates and some related updates.
*
* Updates will execute in the order they were enqueued.
*
* The callback takes the one argument:
* - This IDatabase instance (since 1.32)
*
* @param callable $callback
* @param string $fname Caller name
* @since 1.22
*/
public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ );
/**
* Run a callback after each time any transaction commits or rolls back
*
* The callback takes two arguments:
* - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
* - This IDatabase object
* Callbacks must commit any transactions that they begin.
*
* Registering a callback here will not affect writesOrCallbacks() pending.
*
* Since callbacks from this or onTransactionCommitOrIdle() can start and end transactions,
* a single call to IDatabase::commit might trigger multiple runs of the listener callbacks.
*
* @param string $name Callback name
* @param callable|null $callback Use null to unset a listener
* @return mixed
* @since 1.28
*/
public function setTransactionListener( $name, callable $callback = null );
/**
* Begin an atomic section of SQL statements
*
* Start an implicit transaction if no transaction is already active, set a savepoint
* (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
* that the transaction is not committed prematurely. The end of the section must be
* signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
* have layers of inner sections (sub-sections), but all sections must be ended in order
* of innermost to outermost. Transactions cannot be started or committed until all
* atomic sections are closed.
*
* ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
* by discarding the section's writes. This should not be used for failures when:
* - upsert() could easily be used instead
* - insert() with IGNORE could easily be used instead
* - select() with FOR UPDATE could be checked before issuing writes instead
* - The failure is from code that runs after the first write but doesn't need to
* - The failures are from contention solvable via onTransactionPreCommitOrIdle()
* - The failures are deadlocks; the RDBMs usually discard the whole transaction
*
* @note callers must use additional measures for situations involving two or more
* (peer) transactions (e.g. updating two database servers at once). The transaction
* and savepoint logic of this method only applies to this specific IDatabase instance.
*
* Example usage:
* @code
* // Start a transaction if there isn't one already
* $dbw->startAtomic( __METHOD__ );
* // Serialize these thread table updates
* $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
* // Add a new comment for the thread
* $dbw->insert( 'comment', $row, __METHOD__ );
* $cid = $db->insertId();
* // Update thread reference to last comment
* $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
* // Demark the end of this conceptual unit of updates
* $dbw->endAtomic( __METHOD__ );
* @endcode
*
* Example usage (atomic changes that might have to be discarded):
* @code
* // Start a transaction if there isn't one already
* $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
* // Create new record metadata row
* $dbw->insert( 'records', $row, __METHOD__ );
* // Figure out where to store the data based on the new row's ID
* $path = $recordDirectory . '/' . $dbw->insertId();
* // Write the record data to the storage system
* $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
* if ( $status->isOK() ) {
* // Try to cleanup files orphaned by transaction rollback
* $dbw->onTransactionResolution(
* function ( $type ) use ( $fileBackend, $path ) {
* if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
* $fileBackend->delete( [ 'src' => $path ] );
* }
* },
* __METHOD__
* );
* // Demark the end of this conceptual unit of updates
* $dbw->endAtomic( __METHOD__ );
* } else {
* // Discard these writes from the transaction (preserving prior writes)
* $dbw->cancelAtomic( __METHOD__, $sectionId );
* }
* @endcode
*
* @since 1.23
* @param string $fname
* @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
* savepoint and enable self::cancelAtomic() for this section.
* @return AtomicSectionIdentifier section ID token
* @throws DBError
*/
public function startAtomic( $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE );
/**
* Ends an atomic section of SQL statements
*
* Ends the next section of atomic SQL statements and commits the transaction
* if necessary.
*
* @since 1.23
* @see IDatabase::startAtomic
* @param string $fname
* @throws DBError
*/
public function endAtomic( $fname = __METHOD__ );
/**
* Cancel an atomic section of SQL statements
*
* This will roll back only the statements executed since the start of the
* most recent atomic section, and close that section. If a transaction was
* open before the corresponding startAtomic() call, any statements before
* that call are *not* rolled back and the transaction remains open. If the
* corresponding startAtomic() implicitly started a transaction, that
* transaction is rolled back.
*
* @note callers must use additional measures for situations involving two or more
* (peer) transactions (e.g. updating two database servers at once). The transaction
* and savepoint logic of startAtomic() are bound to specific IDatabase instances.
*
* Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
*
* @note As a micro-optimization to save a few DB calls, this method may only
* be called when startAtomic() was called with the ATOMIC_CANCELABLE flag.
* @since 1.31
* @see IDatabase::startAtomic
* @param string $fname
* @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
* passing this enables cancellation of unclosed nested sections [optional]
* @throws DBError
*/
public function cancelAtomic( $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null );
/**
* Perform an atomic section of reversable SQL statements from a callback
*
* The $callback takes the following arguments:
* - This database object
* - The value of $fname
*
* This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
* If any exception occurs during execution of the callback, it will be handled as follows:
* - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
* (and only) statements executed during the atomic section. If that succeeds, then the
* exception will be re-thrown; if it fails, then a different exception will be thrown
* and any further query attempts will fail until rollback() is called.
* - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
* end of the section and the error will be re-thrown. Any further query attempts will
* fail until rollback() is called.
*
* This method is convenient for letting calls to the caller of this method be wrapped
* in a try/catch blocks for exception types that imply that the caller failed but was
* able to properly discard the changes it made in the transaction. This method can be
* an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
*
* Example usage, "RecordStore::save" method:
* @code
* $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
* // Create new record metadata row
* $dbw->insert( 'records', $record->toArray(), __METHOD__ );
* // Figure out where to store the data based on the new row's ID
* $path = $this->recordDirectory . '/' . $dbw->insertId();
* // Write the record data to the storage system;
* // blob store throughs StoreFailureException on failure
* $this->blobStore->create( $path, $record->getJSON() );
* // Try to cleanup files orphaned by transaction rollback
* $dbw->onTransactionResolution(
* function ( $type ) use ( $path ) {
* if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
* $this->blobStore->delete( $path );
* }
* },
* __METHOD__
* );
* }, $dbw::ATOMIC_CANCELABLE );
* @endcode
*
* Example usage, caller of the "RecordStore::save" method:
* @code
* $dbw->startAtomic( __METHOD__ );
* // ...various SQL writes happen...
* try {
* $recordStore->save( $record );
* } catch ( StoreFailureException $e ) {
* // ...various SQL writes happen...
* }
* // ...various SQL writes happen...
* $dbw->endAtomic( __METHOD__ );
* @endcode
*
* @see Database::startAtomic
* @see Database::endAtomic
* @see Database::cancelAtomic
*
* @param string $fname Caller name (usually __METHOD__)
* @param callable $callback Callback that issues DB updates
* @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
* savepoint and enable self::cancelAtomic() for this section.
* @return mixed $res Result of the callback (since 1.28)
* @throws DBError
* @throws RuntimeException
* @since 1.27; prior to 1.31 this did a rollback() instead of
* cancelAtomic(), and assumed no callers up the stack would ever try to
* catch the exception.
*/
public function doAtomicSection(
$fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
);
/**
* Begin a transaction. If a transaction is already in progress,
* that transaction will be committed before the new transaction is started.
*
* Only call this from code with outer transcation scope.
* See https://www.mediawiki.org/wiki/Database_transactions for details.
* Nesting of transactions is not supported.
*
* Note that when the DBO_TRX flag is set (which is usually the case for web
* requests, but not for maintenance scripts), any previous database query
* will have started a transaction automatically.
*
* Nesting of transactions is not supported. Attempts to nest transactions
* will cause a warning, unless the current transaction was started
* automatically because of the DBO_TRX flag.
*
* @param string $fname Calling function name
* @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
* @throws DBError
*/
public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT );
/**
* Commits a transaction previously started using begin().
* If no transaction is in progress, a warning is issued.
*
* Only call this from code with outer transcation scope.
* See https://www.mediawiki.org/wiki/Database_transactions for details.
* Nesting of transactions is not supported.
*
* @param string $fname
* @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
* constant to disable warnings about explicitly committing implicit transactions,
* or calling commit when no transaction is in progress.
*
* This will trigger an exception if there is an ongoing explicit transaction.
*
* Only set the flush flag if you are sure that these warnings are not applicable,
* and no explicit transactions are open.
*
* @throws DBError
*/
public function commit( $fname = __METHOD__, $flush = '' );
/**
* Rollback a transaction previously started using begin().
* If no transaction is in progress, a warning is issued.
*
* Only call this from code with outer transcation scope.
* See https://www.mediawiki.org/wiki/Database_transactions for details.
* Nesting of transactions is not supported. If a serious unexpected error occurs,
* throwing an Exception is preferrable, using a pre-installed error handler to trigger
* rollback (in any case, failure to issue COMMIT will cause rollback server-side).
*
* Query, connection, and onTransaction* callback errors will be suppressed and logged.
*
* @param string $fname Calling function name
* @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
* constant to disable warnings about calling rollback when no transaction is in
* progress. This will silently break any ongoing explicit transaction. Only set the
* flush flag if you are sure that it is safe to ignore these warnings in your context.
* @throws DBError
* @since 1.23 Added $flush parameter
*/
public function rollback( $fname = __METHOD__, $flush = '' );
/**
* Commit any transaction but error out if writes or callbacks are pending
*
* This is intended for clearing out REPEATABLE-READ snapshots so that callers can
* see a new point-in-time of the database. This is useful when one of many transaction
* rounds finished and significant time will pass in the script's lifetime. It is also
* useful to call on a replica DB after waiting on replication to catch up to the master.
*
* @param string $fname Calling function name
* @throws DBError
* @since 1.28
*/
public function flushSnapshot( $fname = __METHOD__ );
/**
* Convert a timestamp in one of the formats accepted by wfTimestamp()
* to the format used for inserting into timestamp fields in this DBMS.
*
* The result is unquoted, and needs to be passed through addQuotes()
* before it can be included in raw SQL.
*
* @param string|int $ts
*
* @return string
*/
public function timestamp( $ts = 0 );
/**
* Convert a timestamp in one of the formats accepted by wfTimestamp()
* to the format used for inserting into timestamp fields in this DBMS. If
* NULL is input, it is passed through, allowing NULL values to be inserted
* into timestamp fields.
*
* The result is unquoted, and needs to be passed through addQuotes()
* before it can be included in raw SQL.
*
* @param string|int|null $ts
*
* @return string
*/
public function timestampOrNull( $ts = null );
/**
* Ping the server and try to reconnect if it there is no connection
*
* @param float|null &$rtt Value to store the estimated RTT [optional]
* @return bool Success or failure
*/
public function ping( &$rtt = null );
/**
* Get the amount of replication lag for this database server
*
* Callers should avoid using this method while a transaction is active
*
* @return int|bool Database replication lag in seconds or false on error
* @throws DBError
*/
public function getLag();
/**
* Get the replica DB lag when the current transaction started
* or a general lag estimate if not transaction is active
*
* This is useful when transactions might use snapshot isolation
* (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
* is this lag plus transaction duration. If they don't, it is still
* safe to be pessimistic. In AUTOCOMMIT mode, this still gives an
* indication of the staleness of subsequent reads.
*
* @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
* @throws DBError
* @since 1.27
*/
public function getSessionLagStatus();
/**
* Return the maximum number of items allowed in a list, or 0 for unlimited.
*
* @return int
*/
public function maxListLen();
/**
* Some DBMSs have a special format for inserting into blob fields, they
* don't allow simple quoted strings to be inserted. To insert into such
* a field, pass the data through this function before passing it to
* IDatabase::insert().
*
* @param string $b
* @return string|Blob
*/
public function encodeBlob( $b );
/**
* Some DBMSs return a special placeholder object representing blob fields
* in result objects. Pass the object through this function to return the
* original string.
*
* @param string|Blob $b
* @return string
*/
public function decodeBlob( $b );
/**
* Override database's default behavior. $options include:
* 'connTimeout' : Set the connection timeout value in seconds.
* May be useful for very long batch queries such as
* full-wiki dumps, where a single query reads out over
* hours or days.
*
* @param array $options
* @return void
* @throws DBError
*/
public function setSessionOptions( array $options );
/**
* Set variables to be used in sourceFile/sourceStream, in preference to the
* ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
* all. If it's set to false, $GLOBALS will be used.
*
* @param bool|array $vars Mapping variable name to value.
*/
public function setSchemaVars( $vars );
/**
* Check to see if a named lock is not locked by any thread (non-blocking)
*
* @param string $lockName Name of lock to poll
* @param string $method Name of method calling us
* @return bool
* @throws DBError
* @since 1.20
*/
public function lockIsFree( $lockName, $method );
/**
* Acquire a named lock
*
* Named locks are not related to transactions
*
* @param string $lockName Name of lock to aquire
* @param string $method Name of the calling method
* @param int $timeout Acquisition timeout in seconds
* @return bool
* @throws DBError
*/
public function lock( $lockName, $method, $timeout = 5 );
/**
* Release a lock
*
* Named locks are not related to transactions
*
* @param string $lockName Name of lock to release
* @param string $method Name of the calling method
*
* @return int Returns 1 if the lock was released, 0 if the lock was not established
* by this thread (in which case the lock is not released), and NULL if the named lock
* did not exist
*
* @throws DBError
*/
public function unlock( $lockName, $method );
/**
* Acquire a named lock, flush any transaction, and return an RAII style unlocker object
*
* Only call this from outer transcation scope and when only one DB will be affected.
* See https://www.mediawiki.org/wiki/Database_transactions for details.
*
* This is suitiable for transactions that need to be serialized using cooperative locks,
* where each transaction can see each others' changes. Any transaction is flushed to clear
* out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
* the lock will be released unless a transaction is active. If one is active, then the lock
* will be released when it either commits or rolls back.
*
* If the lock acquisition failed, then no transaction flush happens, and null is returned.
*
* @param string $lockKey Name of lock to release
* @param string $fname Name of the calling method
* @param int $timeout Acquisition timeout in seconds
* @return ScopedCallback|null
* @throws DBError
* @since 1.27
*/
public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
/**
* Check to see if a named lock used by lock() use blocking queues
*
* @return bool
* @since 1.26
*/
public function namedLocksEnqueue();
/**
* Find out when 'infinity' is. Most DBMSes support this. This is a special
* keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
* because "i" sorts after all numbers.
*
* @return string
*/
public function getInfinity();
/**
* Encode an expiry time into the DBMS dependent format
*
* @param string $expiry Timestamp for expiry, or the 'infinity' string
* @return string
*/
public function encodeExpiry( $expiry );
/**
* Decode an expiry time into a DBMS independent format
*
* @param string $expiry DB timestamp field value for expiry
* @param int $format TS_* constant, defaults to TS_MW
* @return string
*/
public function decodeExpiry( $expiry, $format = TS_MW );
/**
* Allow or deny "big selects" for this session only. This is done by setting
* the sql_big_selects session variable.
*
* This is a MySQL-specific feature.
*
* @param bool|string $value True for allow, false for deny, or "default" to
* restore the initial value
*/
public function setBigSelects( $value = true );
/**
* @return bool Whether this DB is read-only
* @since 1.27
*/
public function isReadOnly();
/**
* Make certain table names use their own database, schema, and table prefix
* when passed into SQL queries pre-escaped and without a qualified database name
*
* For example, "user" can be converted to "myschema.mydbname.user" for convenience.
* Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
*
* Calling this twice will completely clear any old table aliases. Also, note that
* callers are responsible for making sure the schemas and databases actually exist.
*
* @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
* @since 1.28
*/
public function setTableAliases( array $aliases );
/**
* Convert certain index names to alternative names before querying the DB
*
* Note that this applies to indexes regardless of the table they belong to.
*
* This can be employed when an index was renamed X => Y in code, but the new Y-named
* indexes were not yet built on all DBs. After all the Y-named ones are added by the DBA,
* the aliases can be removed, and then the old X-named indexes dropped.
*
* @param string[] $aliases
* @return mixed
* @since 1.31
*/
public function setIndexAliases( array $aliases );
}
/**
* @deprecated since 1.29
*/
class_alias( IDatabase::class, 'IDatabase' );
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