Fetch the list of blobs and sequences used on a table.

We introspect the database to collect the information required by insert and update queries.

Parameters

$table_name: The non-prefixed name of the table.

Return value

An object with two member variables:

• 'blob_fields' that lists all the blob fields in the table.
• 'sequences' that lists the sequences used in that table.

File

includes/database/pgsql/schema.inc, line 104

Class

DatabaseSchema_pgsql

Code

public function queryTableInformation($table) {
  // Generate a key to reference this table's information on.
  $key = $this->connection
    ->prefixTables('{' . $table . '}');
  // Take into account that temporary tables are stored in a different schema.
  // \DatabaseConnection::generateTemporaryTableName() sets 'db_temporary_'
  // prefix to all temporary tables.
  if (strpos($key, '.') === FALSE && strpos($table, 'db_temporary_') === FALSE) {
    $key = 'public.' . $key;
  }
  else {
    $key = $this->getTempNamespaceName() . '.' . $key;
  }
  if (!isset($this->tableInformation[$key])) {
    $table_information = (object) array(
      'blob_fields' => array(),
      'sequences' => array(),
    );
    // The bytea columns and sequences for a table can be found in
    // pg_attribute, which is significantly faster than querying the
    // information_schema. The data type of a field can be found by lookup
    // of the attribute ID, and the default value must be extracted from the
    // node tree for the attribute definition instead of the historical
    // human-readable column, adsrc.
    $sql = <<<'EOD'
    SELECT pg_attribute.attname AS column_name, format_type(pg_attribute.atttypid, pg_attribute.atttypmod) AS data_type, pg_get_expr(pg_attrdef.adbin, pg_attribute.attrelid) AS column_default
    FROM pg_attribute
    LEFT JOIN pg_attrdef ON pg_attrdef.adrelid = pg_attribute.attrelid AND pg_attrdef.adnum = pg_attribute.attnum
    WHERE pg_attribute.attnum > 0
    AND NOT pg_attribute.attisdropped
    AND pg_attribute.attrelid = :key::regclass
    AND (format_type(pg_attribute.atttypid, pg_attribute.atttypmod) = 'bytea'
    OR pg_get_expr(pg_attrdef.adbin, pg_attribute.attrelid) LIKE 'nextval%')
    EOD;
    $result = $this->connection
      ->query($sql, array(
      ':key' => $key,
    ));
    if (empty($result)) {
      return $table_information;
    }
    foreach ($result as $column) {
      if ($column->data_type == 'bytea') {
        $table_information->blob_fields[$column->column_name] = TRUE;
      }
      elseif (preg_match("/nextval\\('([^']+)'/", $column->column_default, $matches)) {
        // We must know of any sequences in the table structure to help us
        // return the last insert id. If there is more than 1 sequences the
        // first one (index 0 of the sequences array) will be used.
        $table_information->sequences[] = $matches[1];
        $table_information->serial_fields[] = $column->column_name;
      }
    }
    $this->tableInformation[$key] = $table_information;
  }
  return $this->tableInformation[$key];
}

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