function DatabaseSchema_pgsql::queryTableInformation

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];
}