CRM/Core/BAO/SchemaHandler.php

   1 <?php
   2 /*
   3  +--------------------------------------------------------------------+
   4  | CiviCRM version 5                                                  |
   5  +--------------------------------------------------------------------+
   6  | Copyright CiviCRM LLC (c) 2004-2019                                |
   7  +--------------------------------------------------------------------+
   8  | This file is a part of CiviCRM.                                    |
   9  |                                                                    |
  10  | CiviCRM is free software; you can copy, modify, and distribute it  |
  11  | under the terms of the GNU Affero General Public License           |
  12  | Version 3, 19 November 2007 and the CiviCRM Licensing Exception.   |
  13  |                                                                    |
  14  | CiviCRM is distributed in the hope that it will be useful, but     |
  15  | WITHOUT ANY WARRANTY; without even the implied warranty of         |
  16  | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.               |
  17  | See the GNU Affero General Public License for more details.        |
  18  |                                                                    |
  19  | You should have received a copy of the GNU Affero General Public   |
  20  | License and the CiviCRM Licensing Exception along                  |
  21  | with this program; if not, contact CiviCRM LLC                     |
  22  | at info[AT]civicrm[DOT]org. If you have questions about the        |
  23  | GNU Affero General Public License or the licensing of CiviCRM,     |
  24  | see the CiviCRM license FAQ at http://civicrm.org/licensing        |
  25  +--------------------------------------------------------------------+
  26  */
  27
  28 /**
  29  *
  30  * @package CRM
  31  * @copyright CiviCRM LLC (c) 2004-2019
  32  */
  33
  34 /**
  35  *  This file contains functions for creating and altering CiviCRM-tables structure.
  36  *
  37  * $table = array(
  38  *  'name'  => TABLE_NAME,
  39  *  'attributes' => ATTRIBUTES,
  40  *  'fields' => array(
  41  *    array(
  42  *      'name' => FIELD_NAME,
  43  *      // can be field, index, constraint
  44  *      'type' => FIELD_SQL_TYPE,
  45  *      'class'         => FIELD_CLASS_TYPE,
  46  *      'primary'       => BOOLEAN,
  47  *      'required'      => BOOLEAN,
  48  *      'searchable'    => TRUE,
  49  *      'fk_table_name' => FOREIGN_KEY_TABLE_NAME,
  50  *      'fk_field_name' => FOREIGN_KEY_FIELD_NAME,
  51  *      'comment'       => COMMENT,
  52  *      'default'       => DEFAULT, )
  53  *      ...
  54  *  ));
  55  */
  56 class CRM_Core_BAO_SchemaHandler {
  57
  58   /**
  59    * Create a CiviCRM-table
  60    *
  61    * @param array $params
  62    *
  63    * @return bool
  64    *   TRUE if successfully created, FALSE otherwise
  65    *
  66    */
  67   public static function createTable(&$params) {
  68     $sql = self::buildTableSQL($params);
  69     // do not i18n-rewrite
  70     CRM_Core_DAO::executeQuery($sql, [], TRUE, NULL, FALSE, FALSE);
  71
  72     $config = CRM_Core_Config::singleton();
  73     if ($config->logging) {
  74       // logging support
  75       $logging = new CRM_Logging_Schema();
  76       $logging->fixSchemaDifferencesFor($params['name'], NULL, FALSE);
  77     }
  78
  79     // always do a trigger rebuild for this table
  80     CRM_Core_DAO::triggerRebuild($params['name']);
  81
  82     return TRUE;
  83   }
  84
  85   /**
  86    * @param array $params
  87    *
  88    * @return string
  89    */
  90   public static function buildTableSQL(&$params) {
  91     $sql = "CREATE TABLE {$params['name']} (";
  92     if (isset($params['fields']) &&
  93       is_array($params['fields'])
  94     ) {
  95       $separator = "\n";
  96       $prefix = NULL;
  97       foreach ($params['fields'] as $field) {
  98         $sql .= self::buildFieldSQL($field, $separator, $prefix);
  99         $separator = ",\n";
 100       }
 101       foreach ($params['fields'] as $field) {
 102         $sql .= self::buildPrimaryKeySQL($field, $separator, $prefix);
 103       }
 104       foreach ($params['fields'] as $field) {
 105         $sql .= self::buildSearchIndexSQL($field, $separator, $prefix);
 106       }
 107       if (isset($params['indexes'])) {
 108         foreach ($params['indexes'] as $index) {
 109           $sql .= self::buildIndexSQL($index, $separator, $prefix);
 110         }
 111       }
 112       foreach ($params['fields'] as $field) {
 113         $sql .= self::buildForeignKeySQL($field, $separator, $prefix, $params['name']);
 114       }
 115     }
 116     $sql .= "\n) {$params['attributes']};";
 117     return $sql;
 118   }
 119
 120   /**
 121    * @param array $params
 122    * @param $separator
 123    * @param $prefix
 124    *
 125    * @return string
 126    */
 127   public static function buildFieldSQL(&$params, $separator, $prefix) {
 128     $sql = '';
 129     $sql .= $separator;
 130     $sql .= str_repeat(' ', 8);
 131     $sql .= $prefix;
 132     $sql .= "`{$params['name']}` {$params['type']}";
 133
 134     if (!empty($params['required'])) {
 135       $sql .= " NOT NULL";
 136     }
 137
 138     if (!empty($params['attributes'])) {
 139       $sql .= " {$params['attributes']}";
 140     }
 141
 142     if (!empty($params['default']) &&
 143       $params['type'] != 'text'
 144     ) {
 145       $sql .= " DEFAULT {$params['default']}";
 146     }
 147
 148     if (!empty($params['comment'])) {
 149       $sql .= " COMMENT '{$params['comment']}'";
 150     }
 151
 152     return $sql;
 153   }
 154
 155   /**
 156    * @param array $params
 157    * @param $separator
 158    * @param $prefix
 159    *
 160    * @return NULL|string
 161    */
 162   public static function buildPrimaryKeySQL(&$params, $separator, $prefix) {
 163     $sql = NULL;
 164     if (!empty($params['primary'])) {
 165       $sql .= $separator;
 166       $sql .= str_repeat(' ', 8);
 167       $sql .= $prefix;
 168       $sql .= "PRIMARY KEY ( {$params['name']} )";
 169     }
 170     return $sql;
 171   }
 172
 173   /**
 174    * @param array $params
 175    * @param $separator
 176    * @param $prefix
 177    * @param bool $indexExist
 178    *
 179    * @return NULL|string
 180    */
 181   public static function buildSearchIndexSQL(&$params, $separator, $prefix, $indexExist = FALSE) {
 182     $sql = NULL;
 183
 184     // dont index blob
 185     if ($params['type'] == 'text') {
 186       return $sql;
 187     }
 188
 189     //create index only for searchable fields during ADD,
 190     //create index only if field is become searchable during MODIFY,
 191     //drop index only if field is no longer searchable and it does not reference
 192     //a forgein key (and indexExist is true)
 193     if (!empty($params['searchable']) && !$indexExist) {
 194       $sql .= $separator;
 195       $sql .= str_repeat(' ', 8);
 196       $sql .= $prefix;
 197       $sql .= "INDEX_{$params['name']} ( {$params['name']} )";
 198     }
 199     elseif (empty($params['searchable']) && empty($params['fk_table_name']) && $indexExist) {
 200       $sql .= $separator;
 201       $sql .= str_repeat(' ', 8);
 202       $sql .= "DROP INDEX INDEX_{$params['name']}";
 203     }
 204     return $sql;
 205   }
 206
 207   /**
 208    * @param array $params
 209    * @param $separator
 210    * @param $prefix
 211    *
 212    * @return string
 213    */
 214   public static function buildIndexSQL(&$params, $separator, $prefix) {
 215     $sql = '';
 216     $sql .= $separator;
 217     $sql .= str_repeat(' ', 8);
 218     if ($params['unique']) {
 219       $sql .= 'UNIQUE INDEX';
 220       $indexName = 'unique';
 221     }
 222     else {
 223       $sql .= 'INDEX';
 224       $indexName = 'index';
 225     }
 226     $indexFields = NULL;
 227
 228     foreach ($params as $name => $value) {
 229       if (substr($name, 0, 11) == 'field_name_') {
 230         $indexName .= "_{$value}";
 231         $indexFields .= " $value,";
 232       }
 233     }
 234     $indexFields = substr($indexFields, 0, -1);
 235
 236     $sql .= " $indexName ( $indexFields )";
 237     return $sql;
 238   }
 239
 240   /**
 241    * @param string $tableName
 242    * @param string $fkTableName
 243    *
 244    * @return bool
 245    */
 246   public static function changeFKConstraint($tableName, $fkTableName) {
 247     $fkName = "{$tableName}_entity_id";
 248     if (strlen($fkName) >= 48) {
 249       $fkName = substr($fkName, 0, 32) . "_" . substr(md5($fkName), 0, 16);
 250     }
 251     $dropFKSql = "
 252 ALTER TABLE {$tableName}
 253       DROP FOREIGN KEY `FK_{$fkName}`;";
 254
 255     CRM_Core_DAO::executeQuery($dropFKSql);
 256
 257     $addFKSql = "
 258 ALTER TABLE {$tableName}
 259       ADD CONSTRAINT `FK_{$fkName}` FOREIGN KEY (`entity_id`) REFERENCES {$fkTableName} (`id`) ON DELETE CASCADE;";
 260     // CRM-7007: do not i18n-rewrite this query
 261     CRM_Core_DAO::executeQuery($addFKSql, [], TRUE, NULL, FALSE, FALSE);
 262
 263     return TRUE;
 264   }
 265
 266   /**
 267    * @param array $params
 268    * @param $separator
 269    * @param $prefix
 270    * @param string $tableName
 271    *
 272    * @return NULL|string
 273    */
 274   public static function buildForeignKeySQL(&$params, $separator, $prefix, $tableName) {
 275     $sql = NULL;
 276     if (!empty($params['fk_table_name']) && !empty($params['fk_field_name'])) {
 277       $sql .= $separator;
 278       $sql .= str_repeat(' ', 8);
 279       $sql .= $prefix;
 280       $fkName = "{$tableName}_{$params['name']}";
 281       if (strlen($fkName) >= 48) {
 282         $fkName = substr($fkName, 0, 32) . "_" . substr(md5($fkName), 0, 16);
 283       }
 284
 285       $sql .= "CONSTRAINT FK_$fkName FOREIGN KEY ( `{$params['name']}` ) REFERENCES {$params['fk_table_name']} ( {$params['fk_field_name']} ) ";
 286       $sql .= CRM_Utils_Array::value('fk_attributes', $params);
 287     }
 288     return $sql;
 289   }
 290
 291   /**
 292    * @param array $params
 293    * @param bool $indexExist
 294    * @param bool $triggerRebuild
 295    *
 296    * @return bool
 297    */
 298   public static function alterFieldSQL(&$params, $indexExist = FALSE, $triggerRebuild = TRUE) {
 299     $sql = str_repeat(' ', 8);
 300     $sql .= "ALTER TABLE {$params['table_name']}";
 301
 302     // lets suppress the required flag, since that can cause sql issue
 303     $params['required'] = FALSE;
 304
 305     switch ($params['operation']) {
 306       case 'add':
 307         $separator = "\n";
 308         $prefix = "ADD ";
 309         $sql .= self::buildFieldSQL($params, $separator, "ADD COLUMN ");
 310         $separator = ",\n";
 311         $sql .= self::buildPrimaryKeySQL($params, $separator, "ADD PRIMARY KEY ");
 312         $sql .= self::buildSearchIndexSQL($params, $separator, "ADD INDEX ");
 313         $sql .= self::buildForeignKeySQL($params, $separator, "ADD ", $params['table_name']);
 314         break;
 315
 316       case 'modify':
 317         $separator = "\n";
 318         $prefix = "MODIFY ";
 319         $sql .= self::buildFieldSQL($params, $separator, $prefix);
 320         $separator = ",\n";
 321         $sql .= self::buildSearchIndexSQL($params, $separator, "ADD INDEX ", $indexExist);
 322         break;
 323
 324       case 'delete':
 325         $sql .= " DROP COLUMN `{$params['name']}`";
 326         if (!empty($params['primary'])) {
 327           $sql .= ", DROP PRIMARY KEY";
 328         }
 329         if (!empty($params['fk_table_name'])) {
 330           $sql .= ", DROP FOREIGN KEY FK_{$params['fkName']}";
 331         }
 332         break;
 333     }
 334
 335     // CRM-7007: do not i18n-rewrite this query
 336     CRM_Core_DAO::executeQuery($sql, [], TRUE, NULL, FALSE, FALSE);
 337
 338     $config = CRM_Core_Config::singleton();
 339     if ($config->logging) {
 340       // CRM-16717 not sure why this was originally limited to add.
 341       // For example custom tables can have field length changes - which need to flow through to logging.
 342       // Are there any modifies we DON'T was to call this function for (& shouldn't it be clever enough to cope?)
 343       if ($params['operation'] == 'add' || $params['operation'] == 'modify') {
 344         $logging = new CRM_Logging_Schema();
 345         $logging->fixSchemaDifferencesFor($params['table_name'], [trim($prefix) => [$params['name']]], FALSE);
 346       }
 347     }
 348
 349     if ($triggerRebuild) {
 350       CRM_Core_DAO::triggerRebuild($params['table_name']);
 351     }
 352
 353     return TRUE;
 354   }
 355
 356   /**
 357    * Delete a CiviCRM-table.
 358    *
 359    * @param string $tableName
 360    *   Name of the table to be created.
 361    */
 362   public static function dropTable($tableName) {
 363     $sql = "DROP TABLE $tableName";
 364     CRM_Core_DAO::executeQuery($sql);
 365   }
 366
 367   /**
 368    * @param string $tableName
 369    * @param string $columnName
 370    * @param bool $l18n
 371    * @param bool $isUpgradeMode
 372    *
 373    */
 374   public static function dropColumn($tableName, $columnName, $l18n = FALSE, $isUpgradeMode = FALSE) {
 375     if (self::checkIfFieldExists($tableName, $columnName)) {
 376       $sql = "ALTER TABLE $tableName DROP COLUMN $columnName";
 377       if ($l18n) {
 378         CRM_Core_DAO::executeQuery($sql);
 379       }
 380       else {
 381         CRM_Core_DAO::executeQuery($sql, [], TRUE, NULL, FALSE, FALSE);
 382       }
 383       $domain = new CRM_Core_DAO_Domain();
 384       $domain->find(TRUE);
 385       if ($domain->locales) {
 386         $locales = explode(CRM_Core_DAO::VALUE_SEPARATOR, $domain->locales);
 387         CRM_Core_I18n_Schema::rebuildMultilingualSchema($locales, NULL, $isUpgradeMode);
 388       }
 389     }
 390   }
 391
 392   /**
 393    * @param string $tableName
 394    * @param bool $dropUnique
 395    */
 396   public static function changeUniqueToIndex($tableName, $dropUnique = TRUE) {
 397     if ($dropUnique) {
 398       $sql = "ALTER TABLE $tableName
 399 DROP INDEX `unique_entity_id` ,
 400 ADD INDEX `FK_{$tableName}_entity_id` ( `entity_id` )";
 401     }
 402     else {
 403       $sql = " ALTER TABLE $tableName
 404 DROP INDEX `FK_{$tableName}_entity_id` ,
 405 ADD UNIQUE INDEX `unique_entity_id` ( `entity_id` )";
 406     }
 407     CRM_Core_DAO::executeQuery($sql);
 408   }
 409
 410   /**
 411    * Create indexes.
 412    *
 413    * @param $tables
 414    *   Tables to create index for in the format:
 415    *     array('civicrm_entity_table' => 'entity_id')
 416    *     OR
 417    *     array('civicrm_entity_table' => array('entity_id', 'entity_table'))
 418    *   The latter will create a combined index on the 2 keys (in order).
 419    *
 420    *  Side note - when creating combined indexes the one with the most variation
 421    *  goes first  - so entity_table always goes after entity_id.
 422    *
 423    *  It probably makes sense to consider more sophisticated options at some point
 424    *  but at the moment this is only being as enhanced as fast as the test is.
 425    *
 426    * @todo add support for length & multilingual on combined keys.
 427    *
 428    * @param string $createIndexPrefix
 429    * @param array $substrLengths
 430    */
 431   public static function createIndexes($tables, $createIndexPrefix = 'index', $substrLengths = []) {
 432     $queries = [];
 433     $domain = new CRM_Core_DAO_Domain();
 434     $domain->find(TRUE);
 435     $locales = explode(CRM_Core_DAO::VALUE_SEPARATOR, $domain->locales);
 436
 437     // if we're multilingual, cache the information on internationalised fields
 438     static $columns = NULL;
 439     if (!CRM_Utils_System::isNull($locales) and $columns === NULL) {
 440       $columns = CRM_Core_I18n_SchemaStructure::columns();
 441     }
 442
 443     foreach ($tables as $table => $fields) {
 444       $query = "SHOW INDEX FROM $table";
 445       $dao = CRM_Core_DAO::executeQuery($query);
 446
 447       $currentIndexes = [];
 448       while ($dao->fetch()) {
 449         $currentIndexes[] = $dao->Key_name;
 450       }
 451
 452       // now check for all fields if the index exists
 453       foreach ($fields as $field) {
 454         $fieldName = implode('_', (array) $field);
 455
 456         if (is_array($field)) {
 457           // No support for these for combined indexes as yet - add a test when you
 458           // want to add that.
 459           $lengthName = '';
 460           $lengthSize = '';
 461         }
 462         else {
 463           // handle indices over substrings, CRM-6245
 464           // $lengthName is appended to index name, $lengthSize is the field size modifier
 465           $lengthName = isset($substrLengths[$table][$fieldName]) ? "_{$substrLengths[$table][$fieldName]}" : '';
 466           $lengthSize = isset($substrLengths[$table][$fieldName]) ? "({$substrLengths[$table][$fieldName]})" : '';
 467         }
 468
 469         $names = [
 470           "index_{$fieldName}{$lengthName}",
 471           "FK_{$table}_{$fieldName}{$lengthName}",
 472           "UI_{$fieldName}{$lengthName}",
 473           "{$createIndexPrefix}_{$fieldName}{$lengthName}",
 474         ];
 475
 476         // skip to the next $field if one of the above $names exists; handle multilingual for CRM-4126
 477         foreach ($names as $name) {
 478           $regex = '/^' . preg_quote($name) . '(_[a-z][a-z]_[A-Z][A-Z])?$/';
 479           if (preg_grep($regex, $currentIndexes)) {
 480             continue 2;
 481           }
 482         }
 483
 484         // the index doesn't exist, so create it
 485         // if we're multilingual and the field is internationalised, do it for every locale
 486         // @todo remove is_array check & add multilingual support for combined indexes and add a test.
 487         // Note combined indexes currently using this function are on fields like
 488         // entity_id + entity_table which are not multilingual.
 489         if (!is_array($field) && !CRM_Utils_System::isNull($locales) and isset($columns[$table][$fieldName])) {
 490           foreach ($locales as $locale) {
 491             $queries[] = "CREATE INDEX {$createIndexPrefix}_{$fieldName}{$lengthName}_{$locale} ON {$table} ({$fieldName}_{$locale}{$lengthSize})";
 492           }
 493         }
 494         else {
 495           $queries[] = "CREATE INDEX {$createIndexPrefix}_{$fieldName}{$lengthName} ON {$table} (" . implode(',', (array) $field) . "{$lengthSize})";
 496         }
 497       }
 498     }
 499
 500     // run the queries without i18n-rewriting
 501     $dao = new CRM_Core_DAO();
 502     foreach ($queries as $query) {
 503       $dao->query($query, FALSE);
 504     }
 505   }
 506
 507   /**
 508    * Get indexes for tables
 509    * @param array $tables
 510    *   array of table names to find indexes for
 511    *
 512    * @return array('tableName' => array('index1', 'index2'))
 513    */
 514   public static function getIndexes($tables) {
 515     $indexes = [];
 516     foreach ($tables as $table) {
 517       $query = "SHOW INDEX FROM $table";
 518       $dao = CRM_Core_DAO::executeQuery($query);
 519
 520       $tableIndexes = [];
 521       while ($dao->fetch()) {
 522         $tableIndexes[$dao->Key_name]['name'] = $dao->Key_name;
 523         $tableIndexes[$dao->Key_name]['field'][] = $dao->Column_name .
 524          ($dao->Sub_part ? '(' . $dao->Sub_part . ')' : '');
 525         $tableIndexes[$dao->Key_name]['unique'] = ($dao->Non_unique == 0 ? 1 : 0);
 526       }
 527       $indexes[$table] = $tableIndexes;
 528     }
 529     return $indexes;
 530   }
 531
 532   /**
 533    * Drop an index if one by that name exists.
 534    *
 535    * @param string $tableName
 536    * @param string $indexName
 537    */
 538   public static function dropIndexIfExists($tableName, $indexName) {
 539     if (self::checkIfIndexExists($tableName, $indexName)) {
 540       CRM_Core_DAO::executeQuery("DROP INDEX $indexName ON $tableName");
 541     }
 542   }
 543
 544   /**
 545    * @param int $customFieldID
 546    * @param string $tableName
 547    * @param string $columnName
 548    * @param $length
 549    *
 550    * @throws Exception
 551    */
 552   public static function alterFieldLength($customFieldID, $tableName, $columnName, $length) {
 553     // first update the custom field tables
 554     $sql = "
 555 UPDATE civicrm_custom_field
 556 SET    text_length = %1
 557 WHERE  id = %2
 558 ";
 559     $params = [
 560       1 => [$length, 'Integer'],
 561       2 => [$customFieldID, 'Integer'],
 562     ];
 563     CRM_Core_DAO::executeQuery($sql, $params);
 564
 565     $sql = "
 566 SELECT is_required, default_value
 567 FROM   civicrm_custom_field
 568 WHERE  id = %2
 569 ";
 570     $dao = CRM_Core_DAO::executeQuery($sql, $params);
 571
 572     if ($dao->fetch()) {
 573       $clause = '';
 574
 575       if ($dao->is_required) {
 576         $clause = " NOT NULL";
 577       }
 578
 579       if (!empty($dao->default_value)) {
 580         $clause .= " DEFAULT '{$dao->default_value}'";
 581       }
 582       // now modify the column
 583       $sql = "
 584 ALTER TABLE {$tableName}
 585 MODIFY      {$columnName} varchar( $length )
 586             $clause
 587 ";
 588       CRM_Core_DAO::executeQuery($sql);
 589     }
 590     else {
 591       CRM_Core_Error::fatal(ts('Could Not Find Custom Field Details for %1, %2, %3',
 592         [
 593           1 => $tableName,
 594           2 => $columnName,
 595           3 => $customFieldID,
 596         ]
 597       ));
 598     }
 599   }
 600
 601   /**
 602    * Check if the table has an index matching the name.
 603    *
 604    * @param string $tableName
 605    * @param array $indexName
 606    *
 607    * @return bool
 608    */
 609   public static function checkIfIndexExists($tableName, $indexName) {
 610     $result = CRM_Core_DAO::executeQuery(
 611       "SHOW INDEX FROM $tableName WHERE key_name = %1 AND seq_in_index = 1",
 612       [1 => [$indexName, 'String']]
 613     );
 614     if ($result->fetch()) {
 615       return TRUE;
 616     }
 617     return FALSE;
 618   }
 619
 620   /**
 621    * Check if the table has a specified column.
 622    *
 623    * @param string $tableName
 624    * @param string $columnName
 625    * @param bool $i18nRewrite
 626    *   Whether to rewrite the query on multilingual setups.
 627    *
 628    * @return bool
 629    */
 630   public static function checkIfFieldExists($tableName, $columnName, $i18nRewrite = TRUE) {
 631     $query = "SHOW COLUMNS FROM $tableName LIKE '%1'";
 632     $dao = CRM_Core_DAO::executeQuery($query, [1 => [$columnName, 'Alphanumeric']], TRUE, NULL, FALSE, $i18nRewrite);
 633     $result = $dao->fetch() ? TRUE : FALSE;
 634     return $result;
 635   }
 636
 637   /**
 638    * Check if a foreign key Exists
 639    * @param string $table_name
 640    * @param string $constraint_name
 641    * @return bool TRUE if FK is found
 642    */
 643   public static function checkFKExists($table_name, $constraint_name) {
 644     $config = CRM_Core_Config::singleton();
 645     $dbUf = DB::parseDSN($config->dsn);
 646     $query = "
 647       SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
 648       WHERE TABLE_SCHEMA = %1
 649       AND TABLE_NAME = %2
 650       AND CONSTRAINT_NAME = %3
 651       AND CONSTRAINT_TYPE = 'FOREIGN KEY'
 652     ";
 653     $params = [
 654       1 => [$dbUf['database'], 'String'],
 655       2 => [$table_name, 'String'],
 656       3 => [$constraint_name, 'String'],
 657     ];
 658     $dao = CRM_Core_DAO::executeQuery($query, $params);
 659
 660     if ($dao->fetch()) {
 661       return TRUE;
 662     }
 663     return FALSE;
 664   }
 665
 666   /**
 667    * Remove a foreign key from a table if it exists.
 668    *
 669    * @param $table_name
 670    * @param $constraint_name
 671    *
 672    * @return bool
 673    */
 674   public static function safeRemoveFK($table_name, $constraint_name) {
 675     if (self::checkFKExists($table_name, $constraint_name)) {
 676       CRM_Core_DAO::executeQuery("ALTER TABLE {$table_name} DROP FOREIGN KEY {$constraint_name}", []);
 677       return TRUE;
 678     }
 679     return FALSE;
 680   }
 681
 682   /**
 683    * Add index signature hash to DAO file calculation.
 684    *
 685    * @param string $table table name
 686    * @param array $indices index array spec
 687    */
 688   public static function addIndexSignature($table, &$indices) {
 689     foreach ($indices as $indexName => $index) {
 690       $indices[$indexName]['sig'] = $table . "::" .
 691         (array_key_exists('unique', $index) ? $index['unique'] : 0) . "::" .
 692         implode("::", $index['field']);
 693     }
 694   }
 695
 696   /**
 697    * Compare the indices specified in the XML files with those in the DB.
 698    *
 699    * @param bool $dropFalseIndices
 700    *  If set - this function deletes false indices present in the DB which mismatches the expected
 701    *  values of xml file so that civi re-creates them with correct values using createMissingIndices() function.
 702    *
 703    * @return array
 704    *   index specifications
 705    */
 706   public static function getMissingIndices($dropFalseIndices = FALSE) {
 707     $requiredSigs = $existingSigs = [];
 708     // Get the indices defined (originally) in the xml files
 709     $requiredIndices = CRM_Core_DAO_AllCoreTables::indices();
 710     $reqSigs = [];
 711     foreach ($requiredIndices as $table => $indices) {
 712       $reqSigs[] = CRM_Utils_Array::collect('sig', $indices);
 713     }
 714     CRM_Utils_Array::flatten($reqSigs, $requiredSigs);
 715
 716     // Get the indices in the database
 717     $existingIndices = CRM_Core_BAO_SchemaHandler::getIndexes(array_keys($requiredIndices));
 718     $extSigs = [];
 719     foreach ($existingIndices as $table => $indices) {
 720       CRM_Core_BAO_SchemaHandler::addIndexSignature($table, $indices);
 721       $extSigs[] = CRM_Utils_Array::collect('sig', $indices);
 722     }
 723     CRM_Utils_Array::flatten($extSigs, $existingSigs);
 724
 725     // Compare
 726     $missingSigs = array_diff($requiredSigs, $existingSigs);
 727
 728     //CRM-20774 - Drop index key which exist in db but the value varies.
 729     $existingKeySigs = array_intersect_key($missingSigs, $existingSigs);
 730     if ($dropFalseIndices && !empty($existingKeySigs)) {
 731       foreach ($existingKeySigs as $sig) {
 732         $sigParts = explode('::', $sig);
 733         foreach ($requiredIndices[$sigParts[0]] as $index) {
 734           if ($index['sig'] == $sig && !empty($index['name'])) {
 735             self::dropIndexIfExists($sigParts[0], $index['name']);
 736             continue;
 737           }
 738         }
 739       }
 740     }
 741
 742     // Get missing indices
 743     $missingIndices = [];
 744     foreach ($missingSigs as $sig) {
 745       $sigParts = explode('::', $sig);
 746       if (array_key_exists($sigParts[0], $requiredIndices)) {
 747         foreach ($requiredIndices[$sigParts[0]] as $index) {
 748           if ($index['sig'] == $sig) {
 749             $missingIndices[$sigParts[0]][] = $index;
 750             continue;
 751           }
 752         }
 753       }
 754     }
 755     return $missingIndices;
 756   }
 757
 758   /**
 759    * Create missing indices.
 760    *
 761    * @param array $missingIndices as returned by getMissingIndices()
 762    */
 763   public static function createMissingIndices($missingIndices) {
 764     $queries = [];
 765     foreach ($missingIndices as $table => $indexList) {
 766       foreach ($indexList as $index) {
 767         $queries[] = "CREATE " .
 768         (array_key_exists('unique', $index) && $index['unique'] ? 'UNIQUE ' : '') .
 769         "INDEX {$index['name']} ON {$table} (" .
 770           implode(", ", $index['field']) .
 771         ")";
 772       }
 773     }
 774
 775     /* FIXME potential problem if index name already exists, so check before creating */
 776     $dao = new CRM_Core_DAO();
 777     foreach ($queries as $query) {
 778       $dao->query($query, FALSE);
 779     }
 780   }
 781
 782 }