pg_send_query

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

pg_send_query — Ejecuta una consulta PostgreSQL asíncrona

Descripción

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

pg_send_query() envía una consulta o varias consultas de manera asíncrona a la conexión connection. A diferencia de pg_query(), puede enviar varias consultas al mismo tiempo al servidor PostgreSQL y obtener los resultados uno por uno utilizando pg_get_result().

La ejecución del script no se bloquea durante la ejecución de las consultas. Se puede utilizar pg_connection_busy() para verificar si la conexión está ocupada (es decir, si la consulta se está ejecutando). Las consultas pueden ser canceladas con pg_cancel_query().

Aunque se puedan enviar varias consultas al mismo tiempo, no es posible enviar varias consultas en una conexión ocupada. Si se envía una consulta cuando la conexión está ocupada, esperará a que la consulta anterior termine y perderá todos sus resultados.

Parámetros

connection

El recurso de conexión de la base de datos PostgreSQL.

query

La consulta o las consultas SQL a ser ejecutadas.

Los datos contenidos en la consulta deben ser escaped correctamente.

Valores devueltos

Devuelve true en caso de éxito, false o 0 en caso de fallo. Utilice pg_get_result() para determinar el resultado de la consulta.

Historial de cambios

Versión	Descripción
8.1.0	El parámetro `connection` ahora espera una instancia de PgSql\Connection ; anteriormente, se esperaba un resource.

Ejemplos

Ejemplo #1 Ejemplo con pg_send_query()

<?php
  $dbconn = pg_connect("dbname=publisher") or die("Conexión imposible");

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

  $res1 = pg_get_result($dbconn);
  echo "Primera llamada a pg_get_result() : $res1\n";
  $rows1 = pg_num_rows($res1);
  echo "$res1 tiene $rows1 registros\n\n";

  $res2 = pg_get_result($dbconn);
  echo "Segunda llamada a pg_get_result() : $res2\n";
  $rows2 = pg_num_rows($res2);
  echo "$res2 tiene $rows2 registros\n";
?>

El ejemplo anterior mostrará :

Primera llamada a pg_get_result() : Resource id #3
Resource id #3 tiene 3 registros

Segunda llamada a pg_get_result() : Resource id #4
Resource id #4 tiene 1 registros

Ver también

pg_query() - Ejecuta una consulta PostgreSQL
pg_cancel_query() - Cancela una consulta asíncrona
pg_get_result() - Lee un resultado asíncrono de PostgreSQL
pg_connection_busy() - Verifica si la conexión PostgreSQL está ocupada

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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 ¶

14 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

-1

Ron Howard ¶

22 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

-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

-5

vincentdephily ¶

19 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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