(PHP 4 >= 4.2.0, PHP 5)
pg_cancel_query — Cancel an asynchronous query
$connection
   )pg_cancel_query() cancels an asynchronous query sent with pg_send_query(), pg_send_query_params() or pg_send_execute(). You cannot cancel a query executed using pg_query().
connection
     PostgreSQL database connection resource.
    Returns TRUE on success or FALSE on failure.
   
Example #1 pg_cancel_query() example
<?php
  $dbconn = pg_connect("dbname=publisher") or die("Could not connect");
  if (!pg_connection_busy($dbconn)) {
      pg_send_query($dbconn, "select * from authors; select count(*) from authors;");
  }
  
  $res1 = pg_get_result($dbconn);
  echo "First call to pg_get_result(): $res1\n";
  $rows1 = pg_num_rows($res1);
  echo "$res1 has $rows1 records\n\n";
  
  // Cancel the currently running query.  Will be the second query if it is
  // still running.
  pg_cancel_query($dbconn);
?>
The above example will output:
First call to pg_get_result(): Resource id #3 Resource id #3 has 3 records