pg_send_query

(PHP 4 >= 4.2.0, PHP 5)

pg_send_query Sendet eine asynchrone Abfrage

Beschreibung

bool pg_send_query ( resource $connection , string $query )

pg_send_query() sendet eine oder mehrere asynchrone Abfragen über die Verbindung connection. Im Unterschied zu pg_query() können hier mehrere Abfragen auf einmal an PostgreSQL gesendet und die Ergebnisse nacheinander mit pg_get_result() geholt werden.

Die Ausführung eines Skripts wird während der Abarbeitung der Anfragen nicht blockiert. Benutzen Sie die Funktion pg_connection_busy() um zu prüfen, ob die Verbindung gerade benutzt wird (z.B. ob gerade eine Abfrage ausgeführt wird). Mit der Funktion pg_cancel_query() können Abfragen gelöscht werden.

Obwohl man mehrere Abfragen auf einmal an den Server senden kann, können die Abfragen nicht über eine gerade benutzte Verbindung geschickt werden. Falls eine Abfrage gesendet wird, während die Verbindung benutzt wird, wird abgewartet, bis die letzte Abfrage fertig ist und alle Ergebnisse werden verworfen.

Parameter-Liste

connection

PostgreSQL Verbindungkennung.

query

Das oder die SQL-Anweisung(en), die ausgeführt werden sollen.

Rückgabewerte

Gibt bei Erfolg TRUE zurück. Im Fehlerfall wird FALSE zurückgegeben.

Benutzen Sie pg_get_result() um die Abfrageergebnisse zu ermitteln.

Beispiele

Beispiel #1 pg_send_query() Beispiel

<?php
  $dbconn 
pg_connect("dbname=publisher") or die("Verbindungsaufbau fehlgeschlagen");

  if (!
pg_connection_busy($dbconn)) {
      
pg_send_query($dbconn"select * from authors; select count(*) from authors;");
  }

  
$res1 pg_get_result($dbconn);
  echo 
"Der erste Aufruf von pg_get_result(): $res1\n";
  
$rows1 pg_num_rows($res1);
  echo 
"$res1 hat $rows1 Zeilen\n\n";
  
  
$res2 pg_get_result($dbconn);
  echo 
"Der zweite Aufruf von pg_get_result(): $res2\n";
  
$rows2 pg_num_rows($res2);
  echo 
"$res2 hat $rows2 Zeilen\n";  
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

Der erste Aufruf von pg_get_result(): Resource id #3
Resource id #3 hat 3 Zeilen

Der zweite Aufruf von pg_get_result(): Resource id #4
Resource id #4 hat 1 Zeilen

Siehe auch

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User Contributed Notes 6 notes

up
0
moodsey211 at gmail dot com
3 years ago
pg_send_query would not stop your script from executing but it would stop the script from exiting.

Example:

<?php
$con
= pg_connect('dbname=payroll');
pg_send_query('SELECT process_payroll()'); // Where process_payroll is a super long process
?>

You would still need to wait for the query to finish before the any display would be sent to the browser. And surprisingly, unlike pg_query this script would not generate the Maximum execution time error.
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0
rw burgholzer is name at deq dot virginia dot gov
5 years ago
Regarding the failure to process them all now, then retrieve the results later, I found that all queries would return successfully if I added a further condition to your while loop in the "stack_query()" method.

By adding:
&& (pg_transaction_status($conn) === PGSQL_TRANSACTION_IDLE ) )

Every query executed with no errors.

<?php
$conn
= pg_connect("dbname=dbname host=localhost user=psql ");
if (
$conn === FALSE)
  exit(
"Can't connect to db");

$q = array();
// send some queries
foreach (range(0, 50) as $i)
 
stack_query($q, $conn, "SELECT 'query $i' AS str;");
// receive them
while (true)
  {
   
$left = stack_query($q, $conn);
    echo
"$left left... ";
   
$result = pg_get_result($conn);
    if (
$left == 0 && $result === FALSE)
      break;
   
$row = pg_fetch_assoc($result);
   
// depending on race conditions, you wont get all your original queries here.
   
echo "got $row[str]\n";
  }

function
stack_query(&$queries, $conn, $sql = FALSE)
{
  if (
$sql !== FALSE)
   
$queries[] = $sql;
  while (
count($queries) && !pg_connection_busy($conn)  && (pg_transaction_status($conn) === PGSQL_TRANSACTION_IDLE ) )
   
pg_send_query($conn, array_shift($queries));
  return
count($queries) + (pg_connection_busy($conn) ? 1 : 0);
}
?>
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0
vincentdephily
8 years ago
Note that if you send a query without calling pg_get_result() for the previous one (supposing it has finished and the connection is not busy), the previous query will get discarded.

See for yourself (tested on php4.4.0, postgres8.0.4, Linux/FreeBSD) :
<?
$conn = pg_connect("dbname=template1 host=localhost user=pgsql");
if ($conn === FALSE)
  exit("Can't connect to db");

$q = array();
// send some queries
foreach (range(0, 500) as $i)
  stack_query($q, $conn, "SELECT 'query $i' AS str;");
// receive them
while (true)
  {
    $left = stack_query($q, $conn);
    echo "$left left... ";
    $result = pg_get_result($conn);
    if ($left == 0 && $result === FALSE)
      break;
    $row = pg_fetch_assoc($result);
    // depending on race conditions, you wont get all your original queries here.
    echo "got $row[str]\n";
  }

function stack_query(&$queries, $conn, $sql = FALSE)
{
  if ($sql !== FALSE)
    $queries[] = $sql;
  while (count($queries) && !pg_connection_busy($conn))
    pg_send_query($conn, array_shift($queries));
  return count($queries) + (pg_connection_busy($conn) ? 1 : 0);
}
?>

You will have to write a higher level of abstraction if you want a "send all queries now, receive them later" behaviour.
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0
Likeyouover others at hotmail dot com
11 years ago
<?php
// --------- OPEN CONN ---

  
$conn = pg_connect("host='127.0.0.1' dbname='test' user='usertest' password='passtest'");

// --------- OPEN FILE ---

  
$fp = fopen('logo.gif', "r");
  
$buffer = fread($fp, filesize('logo.gif'));
  
fclose($fp);

// --------- CREATE - INSERT OID ---

  
pg_exec($conn, "begin");

  
$oid = pg_locreate($conn);

  
$rs = pg_exec($conn,"INSERT INTO test(tipo, images) VALUES('A1', $oid);");
  
$handle = pg_loopen ($conn, $oid, "w");

  
pg_lowrite ($handle, $buffer);
  
pg_loclose ($handle);

  
pg_exec($conn, "commit");

// --------- OPEN - INSERT OID ---

  
$rs = pg_exec($conn, "SELECT images FROM test WHERE tipo = 'A1';");
  
$row = pg_fetch_row($rs, 0);

  
pg_exec($conn, "begin");
  
$loid = pg_loopen($conn, $row[0], "r");

  
header("Content-type: image/gif");

  
pg_loreadall($loid);
  
pg_loclose($loid);

  
pg_exec ($conn, "commit");

// --------- UNLINK OID ---

  
pg_exec($conn, "begin");

  
$loid = $row[0];
  
pg_lounlink($conn, $loid);

  
pg_exec ($conn, "commit");

// --------- DELETE OID ---

  
pg_exec($conn, "DELETE FROM test WHERE tipo = 'A1';");

// --------- CLOSE CONN ---

  
pg_close();
?>
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0
Mikewithme at yahoo dot com
11 years ago
Due to a bug, OLD API does not available with PHP 4.2.0 and 4.2.1.

PHP 4.2.2 will support OLD API again and will be kept long enough.

New API will be available PHP 4.2.0 to later versions.
yohgaki at php dot net
19-Jun-2002 04:00
Due to a bug, PHP 4.2.0 and 4.2.1 does not support pg_lo_import() old API. It's fixed in PHP 4.2.2.

BTW, new API will be always available from PHP 4.2.0 to later versions. Older API will be kept long enough, also.
ceco at noxis dot net
15-May-2002 09:08
it works for me (php-4.2.1)

not like this

int pg_lo_import ( string pathname [, resource connection])

but
int pg_lo_import ( resource connection, string pathname )

don't know the reason
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0
Ron Howard
11 years ago
If there is an error in one of your queries, the queries following it will not get executed, and there will *not* be an error message displayed. The only way I can think of to determine if an SQL error happened is to use pg_trace.

Example:

pg_send_query($connection,
    "SELECT id FROM users;
    SELECT * FROM customers;
     [INVALID-SQL-STATEMENT];
    SELECT name FROM countries;");

while ($result = pg_get_result($connection))
    $results[] = $result;

The $results array will only have two items in it.
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