pg_send_query

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

pg_send_query — Exécute une requête PostgreSQL asynchrone

Description

pg_send_query(PgSql\Connection $connection, string $query): int|bool

pg_send_query() envoie une requête ou des requêtes de manière asynchrone à la connexion connection. Contrairement à pg_query(), elle peut envoyer plusieurs requêtes à la fois au serveur PostgreSQL et obtenir les résultats un par un en utilisant pg_get_result().

L'exécution du script n'est pas bloquée durant l'exécution des requêtes. Utilisez pg_connection_busy() pour vérifier si la connexion est occupée (c'est-à-dire la requête est en train d'être exécutée). Les requêtes peuvent être annulées avec pg_cancel_query().

Bien que l'on puisse envoyer plusieurs requêtes en même temps, il n'est pas possible d'envoyer plusieurs requêtes sur une connexion occupée. Si une requête est envoyée alors que la connexion est occupée, elle attendra que la requête précédente soit terminée et perdra tous ses résultats.

Liste de paramètres

connection

La ressource de connexion de la base de données PostgreSQL.

query

La requête ou les requêtes SQL à être exécutées.

Les données contenues dans la requête doivent être échappées proprement.

Valeurs de retour

Retourne true en cas de succès, false ou 0 en cas d'échec. Utilisez pg_get_result() pour déterminer le résultat de la requête.

Historique

Version	Description
8.1.0	Le paramètre `connection` attend désormais une instance de PgSql\Connection ; auparavant, une ressource était attendu.

Exemples

Exemple #1 Exemple avec pg_send_query()

<?php
  $dbconn = pg_connect("dbname=publisher") or die("Connexion impossible");

  if (!pg_connection_busy($dbconn)) {
      pg_send_query($dbconn,"select * from auteurs; select count(*) from auteurs;");
  }
    
  $res1 = pg_get_result($dbconn);
  echo "Premier appel de pg_get_result() : $res1\n";
  $rows1 = pg_num_rows($res1);
  echo "$res1 a $rows1 enregistrements\n\n";
    
  $res2 = pg_get_result($dbconn);
  echo "Second appel de pg_get_result() : $res2\n";
  $rows2 = pg_num_rows($res2);
  echo "$res2 a $rows2 enregistrements\n";
?>

L'exemple ci-dessus va afficher :

Premier appel de pg_get_result() : Resource id #3
Resource id #3 a 3 enregistrements

Second appel de pg_get_result() : Resource id #4
Resource id #4 a 1 enregistrements

Voir aussi

pg_query() - Exécute une requête PostgreSQL
pg_cancel_query() - Annule une requête asynchrone
pg_get_result() - Lit un résultat PostgreSQL asynchrone
pg_connection_busy() - Vérifie si la connexion PostgreSQL est occupée

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User Contributed Notes 6 notes

down

rw burgholzer is name at deq dot virginia dot gov ¶

15 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);
}
?>

down

Mikewithme at yahoo dot com ¶

21 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

down

-1

moodsey211 at gmail dot com ¶

13 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.

down

-2

Likeyouover others at hotmail dot com ¶

21 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();
?>

down

-2

Ron Howard ¶

21 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.

down

-5

vincentdephily ¶

18 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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