Issue #3265842 by poker10: Backport DatabaseSchema_pgsql::findTables() improvements

    return (bool) $this->connection->query("SELECT 1 FROM pg_tables WHERE schemaname = :schema AND tablename = :table", array(':schema' => $prefixInfo['schema'], ':table' => $prefixInfo['table']))->fetchField();

  }

  /**

   * {@inheritdoc}

   */

  public function findTables($table_expression) {

    $individually_prefixed_tables = $this->connection->getUnprefixedTablesMap();

    $default_prefix = $this->connection->tablePrefix();

    $default_prefix_length = strlen($default_prefix);

    $tables = array();

    // Load all the tables up front in order to take into account per-table

    // prefixes. The actual matching is done at the bottom of the method.

    $results = $this->connection->query("SELECT tablename FROM pg_tables WHERE schemaname = :schema", array(':schema' => $this->defaultSchema));

    foreach ($results as $table) {

      // Take into account tables that have an individual prefix.

      if (isset($individually_prefixed_tables[$table->tablename])) {

        $prefix_length = strlen($this->connection->tablePrefix($individually_prefixed_tables[$table->tablename]));

      }

      elseif ($default_prefix && substr($table->tablename, 0, $default_prefix_length) !== $default_prefix) {

        // This table name does not start the default prefix, which means that

        // it is not managed by Drupal so it should be excluded from the result.

        continue;

      }

      else {

        $prefix_length = $default_prefix_length;

      }

      // Remove the prefix from the returned tables.

      $unprefixed_table_name = substr($table->tablename, $prefix_length);

      // The pattern can match a table which is the same as the prefix. That

      // will become an empty string when we remove the prefix, which will

      // probably surprise the caller, besides not being a prefixed table. So

      // remove it.

      if (!empty($unprefixed_table_name)) {

        $tables[$unprefixed_table_name] = $unprefixed_table_name;

      }

    }

    // Need to use strtolower on the table name as it was used previously by

    // DatabaseSchema_pgsql::buildTableNameCondition().

    // @see https://www.drupal.org/project/drupal/issues/3262341

    $table_expression = strtolower($table_expression);

    // Convert the table expression from its SQL LIKE syntax to a regular

    // expression and escape the delimiter that will be used for matching.

    $table_expression = str_replace(array('%', '_'), array('.*?', '.'), preg_quote($table_expression, '/'));

    $tables = preg_grep('/^' . $table_expression . '$/i', $tables);

    return $tables;

  }

  function renameTable($table, $new_name) {

    if (!$this->tableExists($table)) {

      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table doesn't exist.", array('@table' => $table, '@table_new' => $new_name)));