code: public function findUniqueIndexes($table)
      {
          $sql = $this->getCreateTableSql($table);
          $uniqueIndexes = [];
  
          $regexp = '/UNIQUE KEY\s+\`(.+)\`\s*\((\`.+\`)+\)/mi';
          if (preg_match_all($regexp, $sql, $matches, PREG_SET_ORDER)) {
              foreach ($matches as $match) {
                  $indexName = $match[1];
                  $indexColumns = array_map('trim', explode('`,`', trim($match[2], '`')));
                  $uniqueIndexes[$indexName] = $indexColumns;
              }
          }
  
          return $uniqueIndexes;
      }
docs: Returns all unique indexes for the given table.
  
  Each array element is of the following structure:
  
  ```php
  [
  'IndexName1' => ['col1' [, ...]],
  'IndexName2' => ['col2' [, ...]],
  ]
  ```
  
  @param TableSchema $table the table metadata
  @return array all unique indexes for the given table.