includes/libs/rdbms/database/IDatabase.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 use Wikimedia\ScopedCallback;
  27 use Wikimedia\Rdbms\LikeMatch;
  28 use Wikimedia\Rdbms\DBMasterPos;
  29
  30 /**
  31  * Basic database interface for live and lazy-loaded relation database handles
  32  *
  33  * @note: IDatabase and DBConnRef should be updated to reflect any changes
  34  * @ingroup Database
  35  */
  36 interface IDatabase {
  37         /** @var int Callback triggered immediately due to no active transaction */
  38         const TRIGGER_IDLE = 1;
  39         /** @var int Callback triggered by COMMIT */
  40         const TRIGGER_COMMIT = 2;
  41         /** @var int Callback triggered by ROLLBACK */
  42         const TRIGGER_ROLLBACK = 3;
  43
  44         /** @var string Transaction is requested by regular caller outside of the DB layer */
  45         const TRANSACTION_EXPLICIT = '';
  46         /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
  47         const TRANSACTION_INTERNAL = 'implicit';
  48
  49         /** @var string Transaction operation comes from service managing all DBs */
  50         const FLUSHING_ALL_PEERS = 'flush';
  51         /** @var string Transaction operation comes from the database class internally */
  52         const FLUSHING_INTERNAL = 'flush';
  53
  54         /** @var string Do not remember the prior flags */
  55         const REMEMBER_NOTHING = '';
  56         /** @var string Remember the prior flags */
  57         const REMEMBER_PRIOR = 'remember';
  58         /** @var string Restore to the prior flag state */
  59         const RESTORE_PRIOR = 'prior';
  60         /** @var string Restore to the initial flag state */
  61         const RESTORE_INITIAL = 'initial';
  62
  63         /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
  64         const ESTIMATE_TOTAL = 'total';
  65         /** @var string Estimate time to apply (scanning, applying) */
  66         const ESTIMATE_DB_APPLY = 'apply';
  67
  68         /** @var int Combine list with comma delimeters */
  69         const LIST_COMMA = 0;
  70         /** @var int Combine list with AND clauses */
  71         const LIST_AND = 1;
  72         /** @var int Convert map into a SET clause */
  73         const LIST_SET = 2;
  74         /** @var int Treat as field name and do not apply value escaping */
  75         const LIST_NAMES = 3;
  76         /** @var int Combine list with OR clauses */
  77         const LIST_OR = 4;
  78
  79         /** @var int Enable debug logging */
  80         const DBO_DEBUG = 1;
  81         /** @var int Disable query buffering (only one result set can be iterated at a time) */
  82         const DBO_NOBUFFER = 2;
  83         /** @var int Ignore query errors (internal use only!) */
  84         const DBO_IGNORE = 4;
  85         /** @var int Autoatically start transaction on first query (work with ILoadBalancer rounds) */
  86         const DBO_TRX = 8;
  87         /** @var int Use DBO_TRX in non-CLI mode */
  88         const DBO_DEFAULT = 16;
  89         /** @var int Use DB persistent connections if possible */
  90         const DBO_PERSISTENT = 32;
  91         /** @var int DBA session mode; mostly for Oracle */
  92         const DBO_SYSDBA = 64;
  93         /** @var int Schema file mode; mostly for Oracle */
  94         const DBO_DDLMODE = 128;
  95         /** @var int Enable SSL/TLS in connection protocol */
  96         const DBO_SSL = 256;
  97         /** @var int Enable compression in connection protocol */
  98         const DBO_COMPRESS = 512;
  99
 100         /**
 101          * A string describing the current software version, and possibly
 102          * other details in a user-friendly way. Will be listed on Special:Version, etc.
 103          * Use getServerVersion() to get machine-friendly information.
 104          *
 105          * @return string Version information from the database server
 106          */
 107         public function getServerInfo();
 108
 109         /**
 110          * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
 111          *
 112          * Unbuffered queries are very troublesome in MySQL:
 113          *
 114          *   - If another query is executed while the first query is being read
 115          *     out, the first query is killed. This means you can't call normal
 116          *     Database functions while you are reading an unbuffered query result
 117          *     from a normal Database connection.
 118          *
 119          *   - Unbuffered queries cause the MySQL server to use large amounts of
 120          *     memory and to hold broad locks which block other queries.
 121          *
 122          * If you want to limit client-side memory, it's almost always better to
 123          * split up queries into batches using a LIMIT clause than to switch off
 124          * buffering.
 125          *
 126          * @param null|bool $buffer
 127          * @return null|bool The previous value of the flag
 128          */
 129         public function bufferResults( $buffer = null );
 130
 131         /**
 132          * Gets the current transaction level.
 133          *
 134          * Historically, transactions were allowed to be "nested". This is no
 135          * longer supported, so this function really only returns a boolean.
 136          *
 137          * @return int The previous value
 138          */
 139         public function trxLevel();
 140
 141         /**
 142          * Get the UNIX timestamp of the time that the transaction was established
 143          *
 144          * This can be used to reason about the staleness of SELECT data
 145          * in REPEATABLE-READ transaction isolation level.
 146          *
 147          * @return float|null Returns null if there is not active transaction
 148          * @since 1.25
 149          */
 150         public function trxTimestamp();
 151
 152         /**
 153          * @return bool Whether an explicit transaction or atomic sections are still open
 154          * @since 1.28
 155          */
 156         public function explicitTrxActive();
 157
 158         /**
 159          * Get/set the table prefix.
 160          * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 161          * @return string The previous table prefix.
 162          */
 163         public function tablePrefix( $prefix = null );
 164
 165         /**
 166          * Get/set the db schema.
 167          * @param string $schema The database schema to set, or omitted to leave it unchanged.
 168          * @return string The previous db schema.
 169          */
 170         public function dbSchema( $schema = null );
 171
 172         /**
 173          * Get properties passed down from the server info array of the load
 174          * balancer.
 175          *
 176          * @param string $name The entry of the info array to get, or null to get the
 177          *   whole array
 178          *
 179          * @return array|mixed|null
 180          */
 181         public function getLBInfo( $name = null );
 182
 183         /**
 184          * Set the LB info array, or a member of it. If called with one parameter,
 185          * the LB info array is set to that parameter. If it is called with two
 186          * parameters, the member with the given name is set to the given value.
 187          *
 188          * @param string $name
 189          * @param array $value
 190          */
 191         public function setLBInfo( $name, $value = null );
 192
 193         /**
 194          * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
 195          *
 196          * @param IDatabase $conn
 197          * @since 1.27
 198          */
 199         public function setLazyMasterHandle( IDatabase $conn );
 200
 201         /**
 202          * Returns true if this database does an implicit sort when doing GROUP BY
 203          *
 204          * @return bool
 205          */
 206         public function implicitGroupby();
 207
 208         /**
 209          * Returns true if this database does an implicit order by when the column has an index
 210          * For example: SELECT page_title FROM page LIMIT 1
 211          *
 212          * @return bool
 213          */
 214         public function implicitOrderby();
 215
 216         /**
 217          * Return the last query that went through IDatabase::query()
 218          * @return string
 219          */
 220         public function lastQuery();
 221
 222         /**
 223          * Returns true if the connection may have been used for write queries.
 224          * Should return true if unsure.
 225          *
 226          * @return bool
 227          */
 228         public function doneWrites();
 229
 230         /**
 231          * Returns the last time the connection may have been used for write queries.
 232          * Should return a timestamp if unsure.
 233          *
 234          * @return int|float UNIX timestamp or false
 235          * @since 1.24
 236          */
 237         public function lastDoneWrites();
 238
 239         /**
 240          * @return bool Whether there is a transaction open with possible write queries
 241          * @since 1.27
 242          */
 243         public function writesPending();
 244
 245         /**
 246          * Returns true if there is a transaction open with possible write
 247          * queries or transaction pre-commit/idle callbacks waiting on it to finish.
 248          * This does *not* count recurring callbacks, e.g. from setTransactionListener().
 249          *
 250          * @return bool
 251          */
 252         public function writesOrCallbacksPending();
 253
 254         /**
 255          * Get the time spend running write queries for this transaction
 256          *
 257          * High times could be due to scanning, updates, locking, and such
 258          *
 259          * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
 260          * @return float|bool Returns false if not transaction is active
 261          * @since 1.26
 262          */
 263         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL );
 264
 265         /**
 266          * Get the list of method names that did write queries for this transaction
 267          *
 268          * @return array
 269          * @since 1.27
 270          */
 271         public function pendingWriteCallers();
 272
 273         /**
 274          * Is a connection to the database open?
 275          * @return bool
 276          */
 277         public function isOpen();
 278
 279         /**
 280          * Set a flag for this connection
 281          *
 282          * @param int $flag DBO_* constants from Defines.php:
 283          *   - DBO_DEBUG: output some debug info (same as debug())
 284          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 285          *   - DBO_TRX: automatically start transactions
 286          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 287          *       and removes it in command line mode
 288          *   - DBO_PERSISTENT: use persistant database connection
 289          * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
 290          */
 291         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING );
 292
 293         /**
 294          * Clear a flag for this connection
 295          *
 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_DEFAULT: automatically sets DBO_TRX if not in command line mode
 301          *       and removes it in command line mode
 302          *   - DBO_PERSISTENT: use persistant database connection
 303          * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
 304          */
 305         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING );
 306
 307         /**
 308          * Restore the flags to their prior state before the last setFlag/clearFlag call
 309          *
 310          * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
 311          * @since 1.28
 312          */
 313         public function restoreFlags( $state = self::RESTORE_PRIOR );
 314
 315         /**
 316          * Returns a boolean whether the flag $flag is set for this connection
 317          *
 318          * @param int $flag DBO_* constants from Defines.php:
 319          *   - DBO_DEBUG: output some debug info (same as debug())
 320          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 321          *   - DBO_TRX: automatically start transactions
 322          *   - DBO_PERSISTENT: use persistant database connection
 323          * @return bool
 324          */
 325         public function getFlag( $flag );
 326
 327         /**
 328          * @return string
 329          */
 330         public function getDomainID();
 331
 332         /**
 333          * Alias for getDomainID()
 334          *
 335          * @return string
 336          */
 337         public function getWikiID();
 338
 339         /**
 340          * Get the type of the DBMS, as it appears in $wgDBtype.
 341          *
 342          * @return string
 343          */
 344         public function getType();
 345
 346         /**
 347          * Open a connection to the database. Usually aborts on failure
 348          *
 349          * @param string $server Database server host
 350          * @param string $user Database user name
 351          * @param string $password Database user password
 352          * @param string $dbName Database name
 353          * @return bool
 354          * @throws DBConnectionError
 355          */
 356         public function open( $server, $user, $password, $dbName );
 357
 358         /**
 359          * Fetch the next row from the given result object, in object form.
 360          * Fields can be retrieved with $row->fieldname, with fields acting like
 361          * member variables.
 362          * If no more rows are available, false is returned.
 363          *
 364          * @param ResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
 365          * @return stdClass|bool
 366          * @throws DBUnexpectedError Thrown if the database returns an error
 367          */
 368         public function fetchObject( $res );
 369
 370         /**
 371          * Fetch the next row from the given result object, in associative array
 372          * form. Fields are retrieved with $row['fieldname'].
 373          * If no more rows are available, false is returned.
 374          *
 375          * @param ResultWrapper $res Result object as returned from IDatabase::query(), etc.
 376          * @return array|bool
 377          * @throws DBUnexpectedError Thrown if the database returns an error
 378          */
 379         public function fetchRow( $res );
 380
 381         /**
 382          * Get the number of rows in a result object
 383          *
 384          * @param mixed $res A SQL result
 385          * @return int
 386          */
 387         public function numRows( $res );
 388
 389         /**
 390          * Get the number of fields in a result object
 391          * @see https://secure.php.net/mysql_num_fields
 392          *
 393          * @param mixed $res A SQL result
 394          * @return int
 395          */
 396         public function numFields( $res );
 397
 398         /**
 399          * Get a field name in a result object
 400          * @see https://secure.php.net/mysql_field_name
 401          *
 402          * @param mixed $res A SQL result
 403          * @param int $n
 404          * @return string
 405          */
 406         public function fieldName( $res, $n );
 407
 408         /**
 409          * Get the inserted value of an auto-increment row
 410          *
 411          * The value inserted should be fetched from nextSequenceValue()
 412          *
 413          * Example:
 414          * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
 415          * $dbw->insert( 'page', [ 'page_id' => $id ] );
 416          * $id = $dbw->insertId();
 417          *
 418          * @return int
 419          */
 420         public function insertId();
 421
 422         /**
 423          * Change the position of the cursor in a result object
 424          * @see https://secure.php.net/mysql_data_seek
 425          *
 426          * @param mixed $res A SQL result
 427          * @param int $row
 428          */
 429         public function dataSeek( $res, $row );
 430
 431         /**
 432          * Get the last error number
 433          * @see https://secure.php.net/mysql_errno
 434          *
 435          * @return int
 436          */
 437         public function lastErrno();
 438
 439         /**
 440          * Get a description of the last error
 441          * @see https://secure.php.net/mysql_error
 442          *
 443          * @return string
 444          */
 445         public function lastError();
 446
 447         /**
 448          * mysql_fetch_field() wrapper
 449          * Returns false if the field doesn't exist
 450          *
 451          * @param string $table Table name
 452          * @param string $field Field name
 453          *
 454          * @return Field
 455          */
 456         public function fieldInfo( $table, $field );
 457
 458         /**
 459          * Get the number of rows affected by the last write query
 460          * @see https://secure.php.net/mysql_affected_rows
 461          *
 462          * @return int
 463          */
 464         public function affectedRows();
 465
 466         /**
 467          * Returns a wikitext link to the DB's website, e.g.,
 468          *   return "[https://www.mysql.com/ MySQL]";
 469          * Should at least contain plain text, if for some reason
 470          * your database has no website.
 471          *
 472          * @return string Wikitext of a link to the server software's web site
 473          */
 474         public function getSoftwareLink();
 475
 476         /**
 477          * A string describing the current software version, like from
 478          * mysql_get_server_info().
 479          *
 480          * @return string Version information from the database server.
 481          */
 482         public function getServerVersion();
 483
 484         /**
 485          * Closes a database connection.
 486          * if it is open : commits any open transactions
 487          *
 488          * @throws DBError
 489          * @return bool Operation success. true if already closed.
 490          */
 491         public function close();
 492
 493         /**
 494          * @param string $error Fallback error message, used if none is given by DB
 495          * @throws DBConnectionError
 496          */
 497         public function reportConnectionError( $error = 'Unknown error' );
 498
 499         /**
 500          * Run an SQL query and return the result. Normally throws a DBQueryError
 501          * on failure. If errors are ignored, returns false instead.
 502          *
 503          * In new code, the query wrappers select(), insert(), update(), delete(),
 504          * etc. should be used where possible, since they give much better DBMS
 505          * independence and automatically quote or validate user input in a variety
 506          * of contexts. This function is generally only useful for queries which are
 507          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 508          * as CREATE TABLE.
 509          *
 510          * However, the query wrappers themselves should call this function.
 511          *
 512          * @param string $sql SQL query
 513          * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
 514          *     comment (you can use __METHOD__ or add some extra info)
 515          * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
 516          *     maybe best to catch the exception instead?
 517          * @throws DBError
 518          * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
 519          *     for a successful read query, or false on failure if $tempIgnore set
 520          */
 521         public function query( $sql, $fname = __METHOD__, $tempIgnore = false );
 522
 523         /**
 524          * Report a query error. Log the error, and if neither the object ignore
 525          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
 526          *
 527          * @param string $error
 528          * @param int $errno
 529          * @param string $sql
 530          * @param string $fname
 531          * @param bool $tempIgnore
 532          * @throws DBQueryError
 533          */
 534         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
 535
 536         /**
 537          * Free a result object returned by query() or select(). It's usually not
 538          * necessary to call this, just use unset() or let the variable holding
 539          * the result object go out of scope.
 540          *
 541          * @param mixed $res A SQL result
 542          */
 543         public function freeResult( $res );
 544
 545         /**
 546          * A SELECT wrapper which returns a single field from a single result row.
 547          *
 548          * Usually throws a DBQueryError on failure. If errors are explicitly
 549          * ignored, returns false on failure.
 550          *
 551          * If no result rows are returned from the query, false is returned.
 552          *
 553          * @param string|array $table Table name. See IDatabase::select() for details.
 554          * @param string $var The field name to select. This must be a valid SQL
 555          *   fragment: do not use unvalidated user input.
 556          * @param string|array $cond The condition array. See IDatabase::select() for details.
 557          * @param string $fname The function name of the caller.
 558          * @param string|array $options The query options. See IDatabase::select() for details.
 559          *
 560          * @return bool|mixed The value from the field, or false on failure.
 561          */
 562         public function selectField(
 563                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
 564         );
 565
 566         /**
 567          * A SELECT wrapper which returns a list of single field values from result rows.
 568          *
 569          * Usually throws a DBQueryError on failure. If errors are explicitly
 570          * ignored, returns false on failure.
 571          *
 572          * If no result rows are returned from the query, false is returned.
 573          *
 574          * @param string|array $table Table name. See IDatabase::select() for details.
 575          * @param string $var The field name to select. This must be a valid SQL
 576          *   fragment: do not use unvalidated user input.
 577          * @param string|array $cond The condition array. See IDatabase::select() for details.
 578          * @param string $fname The function name of the caller.
 579          * @param string|array $options The query options. See IDatabase::select() for details.
 580          *
 581          * @return bool|array The values from the field, or false on failure
 582          * @since 1.25
 583          */
 584         public function selectFieldValues(
 585                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
 586         );
 587
 588         /**
 589          * Execute a SELECT query constructed using the various parameters provided.
 590          * See below for full details of the parameters.
 591          *
 592          * @param string|array $table Table name
 593          * @param string|array $vars Field names
 594          * @param string|array $conds Conditions
 595          * @param string $fname Caller function name
 596          * @param array $options Query options
 597          * @param array $join_conds Join conditions
 598          *
 599          *
 600          * @param string|array $table
 601          *
 602          * May be either an array of table names, or a single string holding a table
 603          * name. If an array is given, table aliases can be specified, for example:
 604          *
 605          *    [ 'a' => 'user' ]
 606          *
 607          * This includes the user table in the query, with the alias "a" available
 608          * for use in field names (e.g. a.user_name).
 609          *
 610          * All of the table names given here are automatically run through
 611          * Database::tableName(), which causes the table prefix (if any) to be
 612          * added, and various other table name mappings to be performed.
 613          *
 614          * Do not use untrusted user input as a table name. Alias names should
 615          * not have characters outside of the Basic multilingual plane.
 616          *
 617          * @param string|array $vars
 618          *
 619          * May be either a field name or an array of field names. The field names
 620          * can be complete fragments of SQL, for direct inclusion into the SELECT
 621          * query. If an array is given, field aliases can be specified, for example:
 622          *
 623          *   [ 'maxrev' => 'MAX(rev_id)' ]
 624          *
 625          * This includes an expression with the alias "maxrev" in the query.
 626          *
 627          * If an expression is given, care must be taken to ensure that it is
 628          * DBMS-independent.
 629          *
 630          * Untrusted user input must not be passed to this parameter.
 631          *
 632          * @param string|array $conds
 633          *
 634          * May be either a string containing a single condition, or an array of
 635          * conditions. If an array is given, the conditions constructed from each
 636          * element are combined with AND.
 637          *
 638          * Array elements may take one of two forms:
 639          *
 640          *   - Elements with a numeric key are interpreted as raw SQL fragments.
 641          *   - Elements with a string key are interpreted as equality conditions,
 642          *     where the key is the field name.
 643          *     - If the value of such an array element is a scalar (such as a
 644          *       string), it will be treated as data and thus quoted appropriately.
 645          *       If it is null, an IS NULL clause will be added.
 646          *     - If the value is an array, an IN (...) clause will be constructed
 647          *       from its non-null elements, and an IS NULL clause will be added
 648          *       if null is present, such that the field may match any of the
 649          *       elements in the array. The non-null elements will be quoted.
 650          *
 651          * Note that expressions are often DBMS-dependent in their syntax.
 652          * DBMS-independent wrappers are provided for constructing several types of
 653          * expression commonly used in condition queries. See:
 654          *    - IDatabase::buildLike()
 655          *    - IDatabase::conditional()
 656          *
 657          * Untrusted user input is safe in the values of string keys, however untrusted
 658          * input must not be used in the array key names or in the values of numeric keys.
 659          * Escaping of untrusted input used in values of numeric keys should be done via
 660          * IDatabase::addQuotes()
 661          *
 662          * @param string|array $options
 663          *
 664          * Optional: Array of query options. Boolean options are specified by
 665          * including them in the array as a string value with a numeric key, for
 666          * example:
 667          *
 668          *    [ 'FOR UPDATE' ]
 669          *
 670          * The supported options are:
 671          *
 672          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
 673          *     with LIMIT can theoretically be used for paging through a result set,
 674          *     but this is discouraged for performance reasons.
 675          *
 676          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
 677          *     and then the first rows are taken until the limit is reached. LIMIT
 678          *     is applied to a result set after OFFSET.
 679          *
 680          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
 681          *     changed until the next COMMIT.
 682          *
 683          *   - DISTINCT: Boolean: return only unique result rows.
 684          *
 685          *   - GROUP BY: May be either an SQL fragment string naming a field or
 686          *     expression to group by, or an array of such SQL fragments.
 687          *
 688          *   - HAVING: May be either an string containing a HAVING clause or an array of
 689          *     conditions building the HAVING clause. If an array is given, the conditions
 690          *     constructed from each element are combined with AND.
 691          *
 692          *   - ORDER BY: May be either an SQL fragment giving a field name or
 693          *     expression to order by, or an array of such SQL fragments.
 694          *
 695          *   - USE INDEX: This may be either a string giving the index name to use
 696          *     for the query, or an array. If it is an associative array, each key
 697          *     gives the table name (or alias), each value gives the index name to
 698          *     use for that table. All strings are SQL fragments and so should be
 699          *     validated by the caller.
 700          *
 701          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
 702          *     instead of SELECT.
 703          *
 704          * And also the following boolean MySQL extensions, see the MySQL manual
 705          * for documentation:
 706          *
 707          *    - LOCK IN SHARE MODE
 708          *    - STRAIGHT_JOIN
 709          *    - HIGH_PRIORITY
 710          *    - SQL_BIG_RESULT
 711          *    - SQL_BUFFER_RESULT
 712          *    - SQL_SMALL_RESULT
 713          *    - SQL_CALC_FOUND_ROWS
 714          *    - SQL_CACHE
 715          *    - SQL_NO_CACHE
 716          *
 717          *
 718          * @param string|array $join_conds
 719          *
 720          * Optional associative array of table-specific join conditions. In the
 721          * most common case, this is unnecessary, since the join condition can be
 722          * in $conds. However, it is useful for doing a LEFT JOIN.
 723          *
 724          * The key of the array contains the table name or alias. The value is an
 725          * array with two elements, numbered 0 and 1. The first gives the type of
 726          * join, the second is the same as the $conds parameter. Thus it can be
 727          * an SQL fragment, or an array where the string keys are equality and the
 728          * numeric keys are SQL fragments all AND'd together. For example:
 729          *
 730          *    [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
 731          *
 732          * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
 733          *   with no rows in it will be returned. If there was a query error, a
 734          *   DBQueryError exception will be thrown, except if the "ignore errors"
 735          *   option was set, in which case false will be returned.
 736          */
 737         public function select(
 738                 $table, $vars, $conds = '', $fname = __METHOD__,
 739                 $options = [], $join_conds = []
 740         );
 741
 742         /**
 743          * The equivalent of IDatabase::select() except that the constructed SQL
 744          * is returned, instead of being immediately executed. This can be useful for
 745          * doing UNION queries, where the SQL text of each query is needed. In general,
 746          * however, callers outside of Database classes should just use select().
 747          *
 748          * @param string|array $table Table name
 749          * @param string|array $vars Field names
 750          * @param string|array $conds Conditions
 751          * @param string $fname Caller function name
 752          * @param string|array $options Query options
 753          * @param string|array $join_conds Join conditions
 754          *
 755          * @return string SQL query string.
 756          * @see IDatabase::select()
 757          */
 758         public function selectSQLText(
 759                 $table, $vars, $conds = '', $fname = __METHOD__,
 760                 $options = [], $join_conds = []
 761         );
 762
 763         /**
 764          * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
 765          * that a single row object is returned. If the query returns no rows,
 766          * false is returned.
 767          *
 768          * @param string|array $table Table name
 769          * @param string|array $vars Field names
 770          * @param array $conds Conditions
 771          * @param string $fname Caller function name
 772          * @param string|array $options Query options
 773          * @param array|string $join_conds Join conditions
 774          *
 775          * @return stdClass|bool
 776          */
 777         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
 778                 $options = [], $join_conds = []
 779         );
 780
 781         /**
 782          * Estimate the number of rows in dataset
 783          *
 784          * MySQL allows you to estimate the number of rows that would be returned
 785          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
 786          * index cardinality statistics, and is notoriously inaccurate, especially
 787          * when large numbers of rows have recently been added or deleted.
 788          *
 789          * For DBMSs that don't support fast result size estimation, this function
 790          * will actually perform the SELECT COUNT(*).
 791          *
 792          * Takes the same arguments as IDatabase::select().
 793          *
 794          * @param string $table Table name
 795          * @param string $vars Unused
 796          * @param array|string $conds Filters on the table
 797          * @param string $fname Function name for profiling
 798          * @param array $options Options for select
 799          * @return int Row count
 800          */
 801         public function estimateRowCount(
 802                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
 803         );
 804
 805         /**
 806          * Get the number of rows in dataset
 807          *
 808          * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
 809          *
 810          * Takes the same arguments as IDatabase::select().
 811          *
 812          * @since 1.27 Added $join_conds parameter
 813          *
 814          * @param array|string $tables Table names
 815          * @param string $vars Unused
 816          * @param array|string $conds Filters on the table
 817          * @param string $fname Function name for profiling
 818          * @param array $options Options for select
 819          * @param array $join_conds Join conditions (since 1.27)
 820          * @return int Row count
 821          */
 822         public function selectRowCount(
 823                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 824         );
 825
 826         /**
 827          * Determines whether a field exists in a table
 828          *
 829          * @param string $table Table name
 830          * @param string $field Filed to check on that table
 831          * @param string $fname Calling function name (optional)
 832          * @return bool Whether $table has filed $field
 833          */
 834         public function fieldExists( $table, $field, $fname = __METHOD__ );
 835
 836         /**
 837          * Determines whether an index exists
 838          * Usually throws a DBQueryError on failure
 839          * If errors are explicitly ignored, returns NULL on failure
 840          *
 841          * @param string $table
 842          * @param string $index
 843          * @param string $fname
 844          * @return bool|null
 845          */
 846         public function indexExists( $table, $index, $fname = __METHOD__ );
 847
 848         /**
 849          * Query whether a given table exists
 850          *
 851          * @param string $table
 852          * @param string $fname
 853          * @return bool
 854          */
 855         public function tableExists( $table, $fname = __METHOD__ );
 856
 857         /**
 858          * Determines if a given index is unique
 859          *
 860          * @param string $table
 861          * @param string $index
 862          *
 863          * @return bool
 864          */
 865         public function indexUnique( $table, $index );
 866
 867         /**
 868          * INSERT wrapper, inserts an array into a table.
 869          *
 870          * $a may be either:
 871          *
 872          *   - A single associative array. The array keys are the field names, and
 873          *     the values are the values to insert. The values are treated as data
 874          *     and will be quoted appropriately. If NULL is inserted, this will be
 875          *     converted to a database NULL.
 876          *   - An array with numeric keys, holding a list of associative arrays.
 877          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
 878          *     each subarray must be identical to each other, and in the same order.
 879          *
 880          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
 881          * returns success.
 882          *
 883          * $options is an array of options, with boolean options encoded as values
 884          * with numeric keys, in the same style as $options in
 885          * IDatabase::select(). Supported options are:
 886          *
 887          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
 888          *     any rows which cause duplicate key errors are not inserted. It's
 889          *     possible to determine how many rows were successfully inserted using
 890          *     IDatabase::affectedRows().
 891          *
 892          * @param string $table Table name. This will be passed through
 893          *   Database::tableName().
 894          * @param array $a Array of rows to insert
 895          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 896          * @param array $options Array of options
 897          *
 898          * @return bool
 899          */
 900         public function insert( $table, $a, $fname = __METHOD__, $options = [] );
 901
 902         /**
 903          * UPDATE wrapper. Takes a condition array and a SET array.
 904          *
 905          * @param string $table Name of the table to UPDATE. This will be passed through
 906          *   Database::tableName().
 907          * @param array $values An array of values to SET. For each array element,
 908          *   the key gives the field name, and the value gives the data to set
 909          *   that field to. The data will be quoted by IDatabase::addQuotes().
 910          * @param array $conds An array of conditions (WHERE). See
 911          *   IDatabase::select() for the details of the format of condition
 912          *   arrays. Use '*' to update all rows.
 913          * @param string $fname The function name of the caller (from __METHOD__),
 914          *   for logging and profiling.
 915          * @param array $options An array of UPDATE options, can be:
 916          *   - IGNORE: Ignore unique key conflicts
 917          *   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 918          * @return bool
 919          */
 920         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] );
 921
 922         /**
 923          * Makes an encoded list of strings from an array
 924          *
 925          * These can be used to make conjunctions or disjunctions on SQL condition strings
 926          * derived from an array (see IDatabase::select() $conds documentation).
 927          *
 928          * Example usage:
 929          * @code
 930          *     $sql = $db->makeList( [
 931          *         'rev_user' => $id,
 932          *         $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
 933          *     ], $db::LIST_AND );
 934          * @endcode
 935          * This would set $sql to "rev_user = '$id' AND (rev_minor = '1' OR rev_len < '500')"
 936          *
 937          * @param array $a Containing the data
 938          * @param int $mode IDatabase class constant:
 939          *    - IDatabase::LIST_COMMA: Comma separated, no field names
 940          *    - IDatabase::LIST_AND:   ANDed WHERE clause (without the WHERE).
 941          *    - IDatabase::LIST_OR:    ORed WHERE clause (without the WHERE)
 942          *    - IDatabase::LIST_SET:   Comma separated with field names, like a SET clause
 943          *    - IDatabase::LIST_NAMES: Comma separated field names
 944          * @throws DBError
 945          * @return string
 946          */
 947         public function makeList( $a, $mode = self::LIST_COMMA );
 948
 949         /**
 950          * Build a partial where clause from a 2-d array such as used for LinkBatch.
 951          * The keys on each level may be either integers or strings.
 952          *
 953          * @param array $data Organized as 2-d
 954          *    [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
 955          * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
 956          * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
 957          * @return string|bool SQL fragment, or false if no items in array
 958          */
 959         public function makeWhereFrom2d( $data, $baseKey, $subKey );
 960
 961         /**
 962          * Return aggregated value alias
 963          *
 964          * @param array $valuedata
 965          * @param string $valuename
 966          *
 967          * @return string
 968          */
 969         public function aggregateValue( $valuedata, $valuename = 'value' );
 970
 971         /**
 972          * @param string $field
 973          * @return string
 974          */
 975         public function bitNot( $field );
 976
 977         /**
 978          * @param string $fieldLeft
 979          * @param string $fieldRight
 980          * @return string
 981          */
 982         public function bitAnd( $fieldLeft, $fieldRight );
 983
 984         /**
 985          * @param string $fieldLeft
 986          * @param string $fieldRight
 987          * @return string
 988          */
 989         public function bitOr( $fieldLeft, $fieldRight );
 990
 991         /**
 992          * Build a concatenation list to feed into a SQL query
 993          * @param array $stringList List of raw SQL expressions; caller is
 994          *   responsible for any quoting
 995          * @return string
 996          */
 997         public function buildConcat( $stringList );
 998
 999         /**
1000          * Build a GROUP_CONCAT or equivalent statement for a query.
1001          *
1002          * This is useful for combining a field for several rows into a single string.
1003          * NULL values will not appear in the output, duplicated values will appear,
1004          * and the resulting delimiter-separated values have no defined sort order.
1005          * Code using the results may need to use the PHP unique() or sort() methods.
1006          *
1007          * @param string $delim Glue to bind the results together
1008          * @param string|array $table Table name
1009          * @param string $field Field name
1010          * @param string|array $conds Conditions
1011          * @param string|array $join_conds Join conditions
1012          * @return string SQL text
1013          * @since 1.23
1014          */
1015         public function buildGroupConcatField(
1016                 $delim, $table, $field, $conds = '', $join_conds = []
1017         );
1018
1019         /**
1020          * @param string $field Field or column to cast
1021          * @return string
1022          * @since 1.28
1023          */
1024         public function buildStringCast( $field );
1025
1026         /**
1027          * Change the current database
1028          *
1029          * @param string $db
1030          * @return bool Success or failure
1031          */
1032         public function selectDB( $db );
1033
1034         /**
1035          * Get the current DB name
1036          * @return string
1037          */
1038         public function getDBname();
1039
1040         /**
1041          * Get the server hostname or IP address
1042          * @return string
1043          */
1044         public function getServer();
1045
1046         /**
1047          * Adds quotes and backslashes.
1048          *
1049          * @param string|int|null|bool|Blob $s
1050          * @return string|int
1051          */
1052         public function addQuotes( $s );
1053
1054         /**
1055          * LIKE statement wrapper, receives a variable-length argument list with
1056          * parts of pattern to match containing either string literals that will be
1057          * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1058          * the function could be provided with an array of aforementioned
1059          * parameters.
1060          *
1061          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1062          * a LIKE clause that searches for subpages of 'My page title'.
1063          * Alternatively:
1064          *   $pattern = [ 'My_page_title/', $dbr->anyString() ];
1065          *   $query .= $dbr->buildLike( $pattern );
1066          *
1067          * @since 1.16
1068          * @return string Fully built LIKE statement
1069          */
1070         public function buildLike();
1071
1072         /**
1073          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1074          *
1075          * @return LikeMatch
1076          */
1077         public function anyChar();
1078
1079         /**
1080          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1081          *
1082          * @return LikeMatch
1083          */
1084         public function anyString();
1085
1086         /**
1087          * Returns an appropriately quoted sequence value for inserting a new row.
1088          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1089          * subclass will return an integer, and save the value for insertId()
1090          *
1091          * Any implementation of this function should *not* involve reusing
1092          * sequence numbers created for rolled-back transactions.
1093          * See https://bugs.mysql.com/bug.php?id=30767 for details.
1094          * @param string $seqName
1095          * @return null|int
1096          */
1097         public function nextSequenceValue( $seqName );
1098
1099         /**
1100          * REPLACE query wrapper.
1101          *
1102          * REPLACE is a very handy MySQL extension, which functions like an INSERT
1103          * except that when there is a duplicate key error, the old row is deleted
1104          * and the new row is inserted in its place.
1105          *
1106          * We simulate this with standard SQL with a DELETE followed by INSERT. To
1107          * perform the delete, we need to know what the unique indexes are so that
1108          * we know how to find the conflicting rows.
1109          *
1110          * It may be more efficient to leave off unique indexes which are unlikely
1111          * to collide. However if you do this, you run the risk of encountering
1112          * errors which wouldn't have occurred in MySQL.
1113          *
1114          * @param string $table The table to replace the row(s) in.
1115          * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1116          *    a field name or an array of field names
1117          * @param array $rows Can be either a single row to insert, or multiple rows,
1118          *    in the same format as for IDatabase::insert()
1119          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1120          */
1121         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ );
1122
1123         /**
1124          * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1125          *
1126          * This updates any conflicting rows (according to the unique indexes) using
1127          * the provided SET clause and inserts any remaining (non-conflicted) rows.
1128          *
1129          * $rows may be either:
1130          *   - A single associative array. The array keys are the field names, and
1131          *     the values are the values to insert. The values are treated as data
1132          *     and will be quoted appropriately. If NULL is inserted, this will be
1133          *     converted to a database NULL.
1134          *   - An array with numeric keys, holding a list of associative arrays.
1135          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1136          *     each subarray must be identical to each other, and in the same order.
1137          *
1138          * It may be more efficient to leave off unique indexes which are unlikely
1139          * to collide. However if you do this, you run the risk of encountering
1140          * errors which wouldn't have occurred in MySQL.
1141          *
1142          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1143          * returns success.
1144          *
1145          * @since 1.22
1146          *
1147          * @param string $table Table name. This will be passed through Database::tableName().
1148          * @param array $rows A single row or list of rows to insert
1149          * @param array $uniqueIndexes List of single field names or field name tuples
1150          * @param array $set An array of values to SET. For each array element, the
1151          *   key gives the field name, and the value gives the data to set that
1152          *   field to. The data will be quoted by IDatabase::addQuotes().
1153          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1154          * @throws Exception
1155          * @return bool
1156          */
1157         public function upsert(
1158                 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1159         );
1160
1161         /**
1162          * DELETE where the condition is a join.
1163          *
1164          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1165          * we use sub-selects
1166          *
1167          * For safety, an empty $conds will not delete everything. If you want to
1168          * delete all rows where the join condition matches, set $conds='*'.
1169          *
1170          * DO NOT put the join condition in $conds.
1171          *
1172          * @param string $delTable The table to delete from.
1173          * @param string $joinTable The other table.
1174          * @param string $delVar The variable to join on, in the first table.
1175          * @param string $joinVar The variable to join on, in the second table.
1176          * @param array $conds Condition array of field names mapped to variables,
1177          *   ANDed together in the WHERE clause
1178          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1179          * @throws DBUnexpectedError
1180          */
1181         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1182                 $fname = __METHOD__
1183         );
1184
1185         /**
1186          * DELETE query wrapper.
1187          *
1188          * @param string $table Table name
1189          * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1190          *   for the format. Use $conds == "*" to delete all rows
1191          * @param string $fname Name of the calling function
1192          * @throws DBUnexpectedError
1193          * @return bool|ResultWrapper
1194          */
1195         public function delete( $table, $conds, $fname = __METHOD__ );
1196
1197         /**
1198          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1199          * into another table.
1200          *
1201          * @param string $destTable The table name to insert into
1202          * @param string|array $srcTable May be either a table name, or an array of table names
1203          *    to include in a join.
1204          *
1205          * @param array $varMap Must be an associative array of the form
1206          *    [ 'dest1' => 'source1', ... ]. Source items may be literals
1207          *    rather than field names, but strings should be quoted with
1208          *    IDatabase::addQuotes()
1209          *
1210          * @param array $conds Condition array. See $conds in IDatabase::select() for
1211          *    the details of the format of condition arrays. May be "*" to copy the
1212          *    whole table.
1213          *
1214          * @param string $fname The function name of the caller, from __METHOD__
1215          *
1216          * @param array $insertOptions Options for the INSERT part of the query, see
1217          *    IDatabase::insert() for details.
1218          * @param array $selectOptions Options for the SELECT part of the query, see
1219          *    IDatabase::select() for details.
1220          *
1221          * @return ResultWrapper
1222          */
1223         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1224                 $fname = __METHOD__,
1225                 $insertOptions = [], $selectOptions = []
1226         );
1227
1228         /**
1229          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1230          * within the UNION construct.
1231          * @return bool
1232          */
1233         public function unionSupportsOrderAndLimit();
1234
1235         /**
1236          * Construct a UNION query
1237          * This is used for providing overload point for other DB abstractions
1238          * not compatible with the MySQL syntax.
1239          * @param array $sqls SQL statements to combine
1240          * @param bool $all Use UNION ALL
1241          * @return string SQL fragment
1242          */
1243         public function unionQueries( $sqls, $all );
1244
1245         /**
1246          * Returns an SQL expression for a simple conditional. This doesn't need
1247          * to be overridden unless CASE isn't supported in your DBMS.
1248          *
1249          * @param string|array $cond SQL expression which will result in a boolean value
1250          * @param string $trueVal SQL expression to return if true
1251          * @param string $falseVal SQL expression to return if false
1252          * @return string SQL fragment
1253          */
1254         public function conditional( $cond, $trueVal, $falseVal );
1255
1256         /**
1257          * Returns a comand for str_replace function in SQL query.
1258          * Uses REPLACE() in MySQL
1259          *
1260          * @param string $orig Column to modify
1261          * @param string $old Column to seek
1262          * @param string $new Column to replace with
1263          *
1264          * @return string
1265          */
1266         public function strreplace( $orig, $old, $new );
1267
1268         /**
1269          * Determines how long the server has been up
1270          *
1271          * @return int
1272          */
1273         public function getServerUptime();
1274
1275         /**
1276          * Determines if the last failure was due to a deadlock
1277          *
1278          * @return bool
1279          */
1280         public function wasDeadlock();
1281
1282         /**
1283          * Determines if the last failure was due to a lock timeout
1284          *
1285          * @return bool
1286          */
1287         public function wasLockTimeout();
1288
1289         /**
1290          * Determines if the last query error was due to a dropped connection and should
1291          * be dealt with by pinging the connection and reissuing the query.
1292          *
1293          * @return bool
1294          */
1295         public function wasErrorReissuable();
1296
1297         /**
1298          * Determines if the last failure was due to the database being read-only.
1299          *
1300          * @return bool
1301          */
1302         public function wasReadOnlyError();
1303
1304         /**
1305          * Wait for the replica DB to catch up to a given master position
1306          *
1307          * @param DBMasterPos $pos
1308          * @param int $timeout The maximum number of seconds to wait for synchronisation
1309          * @return int|null Zero if the replica DB was past that position already,
1310          *   greater than zero if we waited for some period of time, less than
1311          *   zero if it timed out, and null on error
1312          */
1313         public function masterPosWait( DBMasterPos $pos, $timeout );
1314
1315         /**
1316          * Get the replication position of this replica DB
1317          *
1318          * @return DBMasterPos|bool False if this is not a replica DB.
1319          */
1320         public function getReplicaPos();
1321
1322         /**
1323          * Get the position of this master
1324          *
1325          * @return DBMasterPos|bool False if this is not a master
1326          */
1327         public function getMasterPos();
1328
1329         /**
1330          * @return bool Whether the DB is marked as read-only server-side
1331          * @since 1.28
1332          */
1333         public function serverIsReadOnly();
1334
1335         /**
1336          * Run a callback as soon as the current transaction commits or rolls back.
1337          * An error is thrown if no transaction is pending. Queries in the function will run in
1338          * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1339          * that they begin.
1340          *
1341          * This is useful for combining cooperative locks and DB transactions.
1342          *
1343          * The callback takes one argument:
1344          *   - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1345          *
1346          * @param callable $callback
1347          * @param string $fname Caller name
1348          * @return mixed
1349          * @since 1.28
1350          */
1351         public function onTransactionResolution( callable $callback, $fname = __METHOD__ );
1352
1353         /**
1354          * Run a callback as soon as there is no transaction pending.
1355          * If there is a transaction and it is rolled back, then the callback is cancelled.
1356          * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1357          * Callbacks must commit any transactions that they begin.
1358          *
1359          * This is useful for updates to different systems or when separate transactions are needed.
1360          * For example, one might want to enqueue jobs into a system outside the database, but only
1361          * after the database is updated so that the jobs will see the data when they actually run.
1362          * It can also be used for updates that easily cause deadlocks if locks are held too long.
1363          *
1364          * Updates will execute in the order they were enqueued.
1365          *
1366          * The callback takes one argument:
1367          *   - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1368          *
1369          * @param callable $callback
1370          * @param string $fname Caller name
1371          * @since 1.20
1372          */
1373         public function onTransactionIdle( callable $callback, $fname = __METHOD__ );
1374
1375         /**
1376          * Run a callback before the current transaction commits or now if there is none.
1377          * If there is a transaction and it is rolled back, then the callback is cancelled.
1378          * Callbacks must not start nor commit any transactions. If no transaction is active,
1379          * then a transaction will wrap the callback.
1380          *
1381          * This is useful for updates that easily cause deadlocks if locks are held too long
1382          * but where atomicity is strongly desired for these updates and some related updates.
1383          *
1384          * Updates will execute in the order they were enqueued.
1385          *
1386          * @param callable $callback
1387          * @param string $fname Caller name
1388          * @since 1.22
1389          */
1390         public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ );
1391
1392         /**
1393          * Run a callback each time any transaction commits or rolls back
1394          *
1395          * The callback takes two arguments:
1396          *   - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1397          *   - This IDatabase object
1398          * Callbacks must commit any transactions that they begin.
1399          *
1400          * Registering a callback here will not affect writesOrCallbacks() pending
1401          *
1402          * @param string $name Callback name
1403          * @param callable|null $callback Use null to unset a listener
1404          * @return mixed
1405          * @since 1.28
1406          */
1407         public function setTransactionListener( $name, callable $callback = null );
1408
1409         /**
1410          * Begin an atomic section of statements
1411          *
1412          * If a transaction has been started already, just keep track of the given
1413          * section name to make sure the transaction is not committed pre-maturely.
1414          * This function can be used in layers (with sub-sections), so use a stack
1415          * to keep track of the different atomic sections. If there is no transaction,
1416          * start one implicitly.
1417          *
1418          * The goal of this function is to create an atomic section of SQL queries
1419          * without having to start a new transaction if it already exists.
1420          *
1421          * All atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1422          * and any database transactions cannot be began or committed until all atomic
1423          * levels are closed. There is no such thing as implicitly opening or closing
1424          * an atomic section.
1425          *
1426          * @since 1.23
1427          * @param string $fname
1428          * @throws DBError
1429          */
1430         public function startAtomic( $fname = __METHOD__ );
1431
1432         /**
1433          * Ends an atomic section of SQL statements
1434          *
1435          * Ends the next section of atomic SQL statements and commits the transaction
1436          * if necessary.
1437          *
1438          * @since 1.23
1439          * @see IDatabase::startAtomic
1440          * @param string $fname
1441          * @throws DBError
1442          */
1443         public function endAtomic( $fname = __METHOD__ );
1444
1445         /**
1446          * Run a callback to do an atomic set of updates for this database
1447          *
1448          * The $callback takes the following arguments:
1449          *   - This database object
1450          *   - The value of $fname
1451          *
1452          * If any exception occurs in the callback, then rollback() will be called and the error will
1453          * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1454          * In any case, such errors are expected to terminate the request, without any outside caller
1455          * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1456          * atomic section and uncommitted updates, which trashes the current request, requiring an
1457          * error to be displayed.
1458          *
1459          * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1460          *
1461          * @see Database::startAtomic
1462          * @see Database::endAtomic
1463          *
1464          * @param string $fname Caller name (usually __METHOD__)
1465          * @param callable $callback Callback that issues DB updates
1466          * @return mixed $res Result of the callback (since 1.28)
1467          * @throws DBError
1468          * @throws RuntimeException
1469          * @throws UnexpectedValueException
1470          * @since 1.27
1471          */
1472         public function doAtomicSection( $fname, callable $callback );
1473
1474         /**
1475          * Begin a transaction. If a transaction is already in progress,
1476          * that transaction will be committed before the new transaction is started.
1477          *
1478          * Only call this from code with outer transcation scope.
1479          * See https://www.mediawiki.org/wiki/Database_transactions for details.
1480          * Nesting of transactions is not supported.
1481          *
1482          * Note that when the DBO_TRX flag is set (which is usually the case for web
1483          * requests, but not for maintenance scripts), any previous database query
1484          * will have started a transaction automatically.
1485          *
1486          * Nesting of transactions is not supported. Attempts to nest transactions
1487          * will cause a warning, unless the current transaction was started
1488          * automatically because of the DBO_TRX flag.
1489          *
1490          * @param string $fname Calling function name
1491          * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1492          * @throws DBError
1493          */
1494         public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT );
1495
1496         /**
1497          * Commits a transaction previously started using begin().
1498          * If no transaction is in progress, a warning is issued.
1499          *
1500          * Only call this from code with outer transcation scope.
1501          * See https://www.mediawiki.org/wiki/Database_transactions for details.
1502          * Nesting of transactions is not supported.
1503          *
1504          * @param string $fname
1505          * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1506          *   constant to disable warnings about explicitly committing implicit transactions,
1507          *   or calling commit when no transaction is in progress.
1508          *
1509          *   This will trigger an exception if there is an ongoing explicit transaction.
1510          *
1511          *   Only set the flush flag if you are sure that these warnings are not applicable,
1512          *   and no explicit transactions are open.
1513          *
1514          * @throws DBUnexpectedError
1515          */
1516         public function commit( $fname = __METHOD__, $flush = '' );
1517
1518         /**
1519          * Rollback a transaction previously started using begin().
1520          * If no transaction is in progress, a warning is issued.
1521          *
1522          * Only call this from code with outer transcation scope.
1523          * See https://www.mediawiki.org/wiki/Database_transactions for details.
1524          * Nesting of transactions is not supported. If a serious unexpected error occurs,
1525          * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1526          * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1527          *
1528          * @param string $fname Calling function name
1529          * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1530          *   constant to disable warnings about calling rollback when no transaction is in
1531          *   progress. This will silently break any ongoing explicit transaction. Only set the
1532          *   flush flag if you are sure that it is safe to ignore these warnings in your context.
1533          * @throws DBUnexpectedError
1534          * @since 1.23 Added $flush parameter
1535          */
1536         public function rollback( $fname = __METHOD__, $flush = '' );
1537
1538         /**
1539          * Commit any transaction but error out if writes or callbacks are pending
1540          *
1541          * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1542          * see a new point-in-time of the database. This is useful when one of many transaction
1543          * rounds finished and significant time will pass in the script's lifetime. It is also
1544          * useful to call on a replica DB after waiting on replication to catch up to the master.
1545          *
1546          * @param string $fname Calling function name
1547          * @throws DBUnexpectedError
1548          * @since 1.28
1549          */
1550         public function flushSnapshot( $fname = __METHOD__ );
1551
1552         /**
1553          * List all tables on the database
1554          *
1555          * @param string $prefix Only show tables with this prefix, e.g. mw_
1556          * @param string $fname Calling function name
1557          * @throws DBError
1558          * @return array
1559          */
1560         public function listTables( $prefix = null, $fname = __METHOD__ );
1561
1562         /**
1563          * Convert a timestamp in one of the formats accepted by wfTimestamp()
1564          * to the format used for inserting into timestamp fields in this DBMS.
1565          *
1566          * The result is unquoted, and needs to be passed through addQuotes()
1567          * before it can be included in raw SQL.
1568          *
1569          * @param string|int $ts
1570          *
1571          * @return string
1572          */
1573         public function timestamp( $ts = 0 );
1574
1575         /**
1576          * Convert a timestamp in one of the formats accepted by wfTimestamp()
1577          * to the format used for inserting into timestamp fields in this DBMS. If
1578          * NULL is input, it is passed through, allowing NULL values to be inserted
1579          * into timestamp fields.
1580          *
1581          * The result is unquoted, and needs to be passed through addQuotes()
1582          * before it can be included in raw SQL.
1583          *
1584          * @param string|int $ts
1585          *
1586          * @return string
1587          */
1588         public function timestampOrNull( $ts = null );
1589
1590         /**
1591          * Ping the server and try to reconnect if it there is no connection
1592          *
1593          * @param float|null &$rtt Value to store the estimated RTT [optional]
1594          * @return bool Success or failure
1595          */
1596         public function ping( &$rtt = null );
1597
1598         /**
1599          * Get replica DB lag. Currently supported only by MySQL.
1600          *
1601          * Note that this function will generate a fatal error on many
1602          * installations. Most callers should use LoadBalancer::safeGetLag()
1603          * instead.
1604          *
1605          * @return int|bool Database replication lag in seconds or false on error
1606          */
1607         public function getLag();
1608
1609         /**
1610          * Get the replica DB lag when the current transaction started
1611          * or a general lag estimate if not transaction is active
1612          *
1613          * This is useful when transactions might use snapshot isolation
1614          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1615          * is this lag plus transaction duration. If they don't, it is still
1616          * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1617          * indication of the staleness of subsequent reads.
1618          *
1619          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1620          * @since 1.27
1621          */
1622         public function getSessionLagStatus();
1623
1624         /**
1625          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1626          *
1627          * @return int
1628          */
1629         public function maxListLen();
1630
1631         /**
1632          * Some DBMSs have a special format for inserting into blob fields, they
1633          * don't allow simple quoted strings to be inserted. To insert into such
1634          * a field, pass the data through this function before passing it to
1635          * IDatabase::insert().
1636          *
1637          * @param string $b
1638          * @return string|Blob
1639          */
1640         public function encodeBlob( $b );
1641
1642         /**
1643          * Some DBMSs return a special placeholder object representing blob fields
1644          * in result objects. Pass the object through this function to return the
1645          * original string.
1646          *
1647          * @param string|Blob $b
1648          * @return string
1649          */
1650         public function decodeBlob( $b );
1651
1652         /**
1653          * Override database's default behavior. $options include:
1654          *     'connTimeout' : Set the connection timeout value in seconds.
1655          *                     May be useful for very long batch queries such as
1656          *                     full-wiki dumps, where a single query reads out over
1657          *                     hours or days.
1658          *
1659          * @param array $options
1660          * @return void
1661          */
1662         public function setSessionOptions( array $options );
1663
1664         /**
1665          * Set variables to be used in sourceFile/sourceStream, in preference to the
1666          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1667          * all. If it's set to false, $GLOBALS will be used.
1668          *
1669          * @param bool|array $vars Mapping variable name to value.
1670          */
1671         public function setSchemaVars( $vars );
1672
1673         /**
1674          * Check to see if a named lock is available (non-blocking)
1675          *
1676          * @param string $lockName Name of lock to poll
1677          * @param string $method Name of method calling us
1678          * @return bool
1679          * @since 1.20
1680          */
1681         public function lockIsFree( $lockName, $method );
1682
1683         /**
1684          * Acquire a named lock
1685          *
1686          * Named locks are not related to transactions
1687          *
1688          * @param string $lockName Name of lock to aquire
1689          * @param string $method Name of the calling method
1690          * @param int $timeout Acquisition timeout in seconds
1691          * @return bool
1692          */
1693         public function lock( $lockName, $method, $timeout = 5 );
1694
1695         /**
1696          * Release a lock
1697          *
1698          * Named locks are not related to transactions
1699          *
1700          * @param string $lockName Name of lock to release
1701          * @param string $method Name of the calling method
1702          *
1703          * @return int Returns 1 if the lock was released, 0 if the lock was not established
1704          * by this thread (in which case the lock is not released), and NULL if the named
1705          * lock did not exist
1706          */
1707         public function unlock( $lockName, $method );
1708
1709         /**
1710          * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1711          *
1712          * Only call this from outer transcation scope and when only one DB will be affected.
1713          * See https://www.mediawiki.org/wiki/Database_transactions for details.
1714          *
1715          * This is suitiable for transactions that need to be serialized using cooperative locks,
1716          * where each transaction can see each others' changes. Any transaction is flushed to clear
1717          * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1718          * the lock will be released unless a transaction is active. If one is active, then the lock
1719          * will be released when it either commits or rolls back.
1720          *
1721          * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1722          *
1723          * @param string $lockKey Name of lock to release
1724          * @param string $fname Name of the calling method
1725          * @param int $timeout Acquisition timeout in seconds
1726          * @return ScopedCallback|null
1727          * @throws DBUnexpectedError
1728          * @since 1.27
1729          */
1730         public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1731
1732         /**
1733          * Check to see if a named lock used by lock() use blocking queues
1734          *
1735          * @return bool
1736          * @since 1.26
1737          */
1738         public function namedLocksEnqueue();
1739
1740         /**
1741          * Find out when 'infinity' is. Most DBMSes support this. This is a special
1742          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1743          * because "i" sorts after all numbers.
1744          *
1745          * @return string
1746          */
1747         public function getInfinity();
1748
1749         /**
1750          * Encode an expiry time into the DBMS dependent format
1751          *
1752          * @param string $expiry Timestamp for expiry, or the 'infinity' string
1753          * @return string
1754          */
1755         public function encodeExpiry( $expiry );
1756
1757         /**
1758          * Decode an expiry time into a DBMS independent format
1759          *
1760          * @param string $expiry DB timestamp field value for expiry
1761          * @param int $format TS_* constant, defaults to TS_MW
1762          * @return string
1763          */
1764         public function decodeExpiry( $expiry, $format = TS_MW );
1765
1766         /**
1767          * Allow or deny "big selects" for this session only. This is done by setting
1768          * the sql_big_selects session variable.
1769          *
1770          * This is a MySQL-specific feature.
1771          *
1772          * @param bool|string $value True for allow, false for deny, or "default" to
1773          *   restore the initial value
1774          */
1775         public function setBigSelects( $value = true );
1776
1777         /**
1778          * @return bool Whether this DB is read-only
1779          * @since 1.27
1780          */
1781         public function isReadOnly();
1782
1783         /**
1784          * Make certain table names use their own database, schema, and table prefix
1785          * when passed into SQL queries pre-escaped and without a qualified database name
1786          *
1787          * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1788          * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1789          *
1790          * Calling this twice will completely clear any old table aliases. Also, note that
1791          * callers are responsible for making sure the schemas and databases actually exist.
1792          *
1793          * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1794          * @since 1.28
1795          */
1796         public function setTableAliases( array $aliases );
1797 }