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