ช่วยด้วยค่ะ php connect กับ postgresql ไม่ได้ค่ะ มันขึ้น error บอกว่าเหมือนหาที่เก็บ ext ไม่เจอ

<?php 

$conn = pg_pconnect("dbname=publisher");
if (!$conn) {
  echo "An error occured.\n";
  exit;
}

$result = pg_query($conn, "SELECT author, email FROM authors");
if (!$result) {
  echo "An error occured.\n";
  exit;
}

$arr = pg_fetch_array($result, 0, PGSQL_NUM);
echo $arr[0] . " <- Row 1 Author\n";
echo $arr[1] . " <- Row 1 E-mail\n";

// As of PHP 4.1.0, the row parameter is optional; NULL can be passed instead,
// to pass a result_type.  Successive calls to pg_fetch_array will return the
// next row.
$arr = pg_fetch_array($result, NULL, PGSQL_ASSOC);
echo $arr["author"] . " <- Row 2 Author\n";
echo $arr["email"] . " <- Row 2 E-mail\n";

$arr = pg_fetch_array($result);
echo $arr["author"] . " <- Row 3 Author\n";
echo $arr[1] . " <- Row 3 E-mail\n";

?>