public function Connection::nextId in Drupal 10

Same name in this branch

1. 10 core/tests/fixtures/database_drivers/custom/fake/Connection.php \Drupal\Driver\Database\fake\Connection::nextId()
2. 10 core/modules/sqlite/src/Driver/Database/sqlite/Connection.php \Drupal\sqlite\Driver\Database\sqlite\Connection::nextId()
3. 10 core/modules/pgsql/src/Driver/Database/pgsql/Connection.php \Drupal\pgsql\Driver\Database\pgsql\Connection::nextId()
4. 10 core/modules/mysql/src/Driver/Database/mysql/Connection.php \Drupal\mysql\Driver\Database\mysql\Connection::nextId()

Retrieve a the next id in a sequence.

PostgreSQL has built in sequences. We'll use these instead of inserting and updating a sequences table.

File

core/modules/pgsql/src/Driver/Database/pgsql/Connection.php, line 260

Class

Connection

PostgreSQL implementation of \Drupal\Core\Database\Connection.

Namespace

Drupal\pgsql\Driver\Database\pgsql

Code

public function nextId($existing = 0) {

  // Retrieve the name of the sequence. This information cannot be cached
  // because the prefix may change, for example, like it does in tests.
  $sequence_name = $this
    ->makeSequenceName('sequences', 'value');

  // When PostgreSQL gets a value too small then it will lock the table,
  // retry the INSERT and if it's still too small then alter the sequence.
  $id = $this
    ->query("SELECT nextval('" . $sequence_name . "')")
    ->fetchField();
  if ($id > $existing) {
    return $id;
  }

  // PostgreSQL advisory locks are simply locks to be used by an
  // application such as Drupal. This will prevent other Drupal processes
  // from altering the sequence while we are.
  $this
    ->query("SELECT pg_advisory_lock(" . self::POSTGRESQL_NEXTID_LOCK . ")");

  // While waiting to obtain the lock, the sequence may have been altered
  // so lets try again to obtain an adequate value.
  $id = $this
    ->query("SELECT nextval('" . $sequence_name . "')")
    ->fetchField();
  if ($id > $existing) {
    $this
      ->query("SELECT pg_advisory_unlock(" . self::POSTGRESQL_NEXTID_LOCK . ")");
    return $id;
  }

  // Reset the sequence to a higher value than the existing id.
  $this
    ->query("ALTER SEQUENCE " . $sequence_name . " RESTART WITH " . ($existing + 1));

  // Retrieve the next id. We know this will be as high as we want it.
  $id = $this
    ->query("SELECT nextval('" . $sequence_name . "')")
    ->fetchField();
  $this
    ->query("SELECT pg_advisory_unlock(" . self::POSTGRESQL_NEXTID_LOCK . ")");
  return $id;
}